EPA-AA-TSS-91-1
The IM240 Transient I/M Dynamometer Driving Schedule
and The Composite I/M Test Procedure
William M. Pidgeon
Natalie Dobie
January 1991
Technical Support Staff
Emission Control Technology Division
Office of Mobile Sources
Environmental Protection Agency
-------
Table of Contents
1.0 Introduction 1
2 . 0 Background 1
3.0 The Problem 2
4.0 Old Technology versus New Technology 3
5.0 IM240 versus CDH-226 3
6.0 IM240 Description 6
7.0 Composite I/M Test Procedure 7
7 .1 Dynamometer Settings 7
7 .2 Sampling Methods 9
7 .3 CITP Steady-State Modes 10
8 .0 Summary 10
Appendix 1
IM240 Speed Versus Time Table A-l
Appendix 2
Comparative Statistics A-6
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1. 0 Introduction
The United States Environmental Protection Agency (EPA) is
evaluating new test procedures for use as Inspection/Maintenance C/M)
tests. Two tests under consideration are the IM240, a new driving
schedule developed by the U.S. EPA, and the CDH-226, a driving schedule
developed earlier by the Colorado Department of Health. EPA's focus on
these procedures as possible alternatives to current I/M tests has
aroused interest. The purpose of this document is to provide
descriptive information about these tests to the I/M community.
Statistical results from the first year of testing on the IM240 and the
CDH-226 will be published later.
This document also provides information on EPA's Composite I/M
Test Procedure (CITP), a lengthy testing sequence designed to evaluate
the effectiveness of a large number of potential alternative I/M tests,
including the IM240 and the CDH-226.
The IM240 and CDH-226 driving schedules are both based on EPA's
Federal Test Procedure (FTP), which certifies compliance with federal
vehicle emission standards for carbon monoxide (CO), unburned
hydrocarbons (HC), and nitrogen oxides (NOx). Since a significant
portion of the I/M community is relatively unfamiliar with certification
procedures, the following section provides the basic background needed
to understand the foundations of the IM240 and the CDH-226.
2.0 Background
In order for vehicle emissions to be controlled effectively, they
must be evaluated under real world conditions. With this in mind, the
United States has designed it's vehicle emission control strategy around
tests that measure emissions while replicating actual driving
conditions. These tests stem from the development in 1965 of the LA-4
road route, which was designed to approximate a typical morning trip to
work in rush-hour traffic in Los Angeles.1 In 1972, the EPA shortened
the LA-4 from 12 to 7.5 miles and adapted it for use in the laboratory
on a chassis dynamometer, a device that simulates vehicle load and
inertia weight.2 Since known as the Urban Dynamometer Driving Schedule
(UDDS), it is the driving schedule used to conduct the FTP.
1 Mass, G. C., Sweeney, M. P., and Pattison, J. N., "Laboratory
Simulation of Driving Conditions in the Los Angeles Area," SAE Paper No.
660546, August 1966.
2 Kruse, R. E. and Huls, X. A., "Development of the Federal Urban
Driving Schedule," SAE Paper No. 730553, May 1973.
-------
The FTP is the "golden standard" for determining vehicle emission
levels, but it is expensive and time consuming. The EPA has approved
six shorter tests for use by I/M programs in their evaluation of ir.-use
vehicle emissions. All six currently approved I/M tests are steady-
state (one-speed) tests. Five are unloaded, and one is loaded. These
tests are described in the Code of Federal Regulations, Title 40, Part
81, Sections 2209 - 2214. Considerably less resource intensive than the
FTP, short tests were designed to provide a more easily used but still
reliable method of identifying vehicles that exceed FTP standards.
3.0 The Problem
The short I/M tests do not always correlate well to the FTP,
however. Limitations in the tests themselves and, perhaps more
importantly, changes in vehicle design have undermined the ability of
current short tests to identify a vehicle's excess emissions (i.e.,
emissions above the federal standards). I/M tests originally were
designed for a vehicle fleet that is rapidly being displaced by new
technology, computer-controlled vehicles. New technology vehicles are
equipped with improved emission control components, such as three-way
catalysts, closed-loop fuel control, and fuel injection, which have
changed the way vehicles respond to emission tests.3
These changes have implications for the future effectiveness of
I/M programs. The effectiveness of short emission tests can be
expressed in terms of overall failure rate, excess emissions identified
(identification rate), errors of commission, and errors of omission.
Errors of commission (Ec), or false failures, occur when vehicles fail
an I/M test but pass the FTP. Errors of omission (Eo), or false passes,
occur when vehicles pass the I/M test but fail the FTP. Based on these
measures, EPA studies indicate that current short tests have become .less
effective in identifying excess emissions since the introduction of new
technology vehicles in 1981. The challenge now is to ensure that I/M
tests keep pace with changing technology so that they remain an
effective tool for vehicle emission control.
3 Armstrong, J., Brzezinski, D. J., Landman, L., and Glover, E. L.,
"Inspection/Maintenance in the 1990's," SAE Paper No. 870621, February
1987.
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4 .0 Old Technology versus New Technology
Old technology, pre-computer-controlled vehicles have emission-
related components that operate on a continuum. For example, if the
air-fuel mixture at idle is too rich, then the air-fuel mixture is
likely to be too rich across much of the operating range of the vehicle
(i.e., cruise, acceleration, deceleration). For this reason a test
performed only at idle or only at 30 mph is likely to identify pre-
computer-controlled vehicles that malfunction to a sufficient degree to
fail the FTP test also. This continuum characteristic is an inherent
feature of many mechanically controlled systems, including other
emission-control components like the ignition system's distributor,
which controls the ignition timing.
The newer, computer-controlled vehicles that are becoming an ever
larger fraction of the fleet are not constrained by the continuum
characteristic of mechanical devices. A computer can include discrete
instructions for the air-fuel mixture at idle that have little bearing
on the mixture at 30 mph or during an acceleration from 10 mph to 20
mph. For this reason, a vehicle with low emissions at idle or 2500 rpm
or 30 mph can in principal have unacceptably high emissions during other
modes. Furthermore, EPA studies show that some vehicles with very high
FTP emissions do indeed pass a steady-state test, such as an idle test.
By the same logic, a vehicle with high idle emissions may pass the FTP
because the emissions are low through most of the vehicle's other
operating modes. An idle test falsely fails such vehicles. Transient
tests, on the other hand, are responsive to changing emission levels
during different modes of vehicle operation and thus overcome the
limitations of steady-state testing on computer-controlled vehicles.
5.0 ZM240 versus CDH-226
In the face of changing technology, EPA's objective was to find a
short transient test that would identify high emitting vehicles as
defined by their FTP emissions, while minimizing errors of commission.
Initially, the CDH-2264 seemed to offer the best possibility for a
viable I/M test. Since then, EPA has developed the IM240 as a possible
improvement on the CDH-226.
4 Ragazzi, R. A., Stokes, J. T., and Gallagher, G. L., "An Evaluation of
a Colorado Short Vehicle Emission Test (CDH-226) in Predicting Federal
Test Procedure (FTP) Failures," SAE Paper No. 852111, October 1985.
-------
A characteristic of the CDH-226 that stands out when compared to
Che UDDS is that the CDH-226 is smoother (i.e., less transient), so it
requires less throttle action (see Figure 1 en page 5). Throttle action
is an important variable affecting vehicle emissions and could be
important in identifying malfunctioning vehicles.
Take oxygen sensor operation as an example. As oxygen sensors
deteriorate, their response time lags. This deteriorating response time
can allow the air-fuel mixture to increasingly deviate from
stoichiometric (14.7:1), the ratio at which 3-way catalysts most
efficiently oxidize HC and CO and simultaneously reduce NOx (see Figure
2 below). This is important because three-way catalyst conversion
efficiency rapidly deteriorates with air-fuel mixture deviations from
stoichiometric. During steady-state operation, the fuel metering system
adjusts to deliver a stoichiometric mixture, which should stay
relatively constant. Throttle movement cften causes the mixture to
change, and as throttle action increases, che ability of the metering
system to maintain stoichiometry becomes increasingly dependent on the
response time of the oxygen sensor. A highly transient driving schedule
requires more throttle action than a smooth schedule, so a deteriorated
oxygen sensor is more likely to be identified on a highly transient
schedule than on a smooth schedule. The same logic can also be extended
to other components of emission control systems. A driving schedule can
be made too transient, however. An I/M test requiring more throttle
action than the UDDS might unacceptably increase test variability and
thereby increase the error of commission rate.
Figuza 2: Air-Fuel Ratios and Conversion Efficiency
100-
* 9S-
"O 90-
-«
ys
*2 s
«c
« .
1870H
*
14.4 14.7 15.0
AIR/FUEL RATIO*
BICH • | • «.6AN
•Converted from equivalence ratios used in the original.
Source: Rivard, J. G., "Closed-Loop Electronic Fuel Injection
Control of the Internal Combustion Engine," SAE Paper No. 730005,
January 1973, p. 4.
-------
Figure 1: Comparison of Dynamometer Driving Schedules
CDH-226 Driving Schedule
(mph)
50-
40-
30-
20
10-
0
0
50 100 150 200 250 300
Time
Hills 1 & 2 of the Urban Dynamometer Driving Schedule
(mph)
50-
40-
30
20-
10-
0
50 100 150 200 250 300
Time
IM240 Driving Schedule
50
40-
Speed 30.
(mph)
20-
10-
0
50 100 150 200 250 300
Time
-------
For these reasons, EPA decided to develop a more transient
alternative to the CDH-226, to make the new test similar to the HDDS,
and to evaluate both procedures to determine which is better for I/.M
testing. EPA's alternative was dubbed the IM240 since it was designed
for I/M testing with a duration of 240 seconds.
6.0 IM240 Description
The IM240 driving schedule is depicted graphically in Figure i.
Appendix 1 provides a speed-versus-ti.-ne table in one-second increments.
The table also lists the UDDS segments that were used to create the
IM240.
The IM240 was patterned closely on the first two "hills" of the
UDDS. It uses actual segments of the UDDS and incorporates the UDDS's
peak speed of 56.7 miles per hour. Testing over the entire range of
speeds was considered important to detect malfunctioning vehicles given
the discontinuous operating characteristics of computer-controlled
vehicles. Using actual segments of the UDDS was considered important to
help improve correlation and minimize errors of commission and errors of
omission.
The two large decelerations from hills 1 and 2 are the only
segments that were not taken directly from the UDDS. The deceleration
rate for both hills was set at 3.5 mph/sec, whereas the maximum
deceleration rate from the UDDS is 3.3 mph/sec. The higher deceleration
rate prevents the IM240 from exceeding four minutes, which was taken
somewhat arbitrarily to be a measurable upper limit for a test time that
would allow an adequate rate of vehicle processing, or throughput. The
3.5 mph/sec rate, which has been used successfully in the CDH-226, also
allows time for an idle and an additional transient portion on hill 2
(between 140 seconds and 158 seconds).
As seen in Appendix 2, the IM240 differs statistically from the
CDH-226. Because of differences in design, it was speculated that one
of the tests might correlate better than the other to the FTP.
The IM240 test is run in two segments. The shorter segment is 94
seconds in duration, which was an informed guess as to the minimum
amount of time needed to realize significant improvements in FTP
correlation. For comparison, EPA has divided the CDH-226 into two
segments as well, the shorter segment being 86 seconds. By dividing
each test into two parts, EPA can evaluate the effectiveness of the
entire test as well as the effectiveness of each of the shorter
segments.
-------
The test procedure stipulates tr.at the engine is running with the
transmission in gear before the driving schedule begins. Ixhaust
sampling begins simultaneously with the start cf the driving scneduie.
IM240 testing is being performed separately and in conjunction
with other short tests, including the C2H-226, in the Composite ;,M Test
Procedure, which is described below.
7.0 Composite I/M Test Procedure
The EPA has devised the multi-purpose Composite I/M Test Procedure
(CITP) -.0 evaluate the effectiveness of the IM240, the CDH-226, and
potential steady-state alternatives to current I/M tests. The goal of
the program is to identify emission tests wnich balance the need for
high FTP correlation and high identification rates against cost,
equipment, and time requirements. Acceptable alternative tests would be
sopnisticated enougn to measure the emissions of r.ew cecnnoiogy
venicies adequately while conforming to the constraints of an I/M
program.
CITP testing is being performed at EPA's Motor Vehicle Emission
Laboratory (MVEL) in Ann Arbor, Michigan and under contract at the
Automotive Testing Laboratories (ATL) facility in New Carlisle, Indiana,
just outside of South Bend. All Emission Factor Program- test vehicles
receive the CITP after the as-received FTP test on Indolene test fuel.
7.1 Dynamometer Settings
The CITP sequence consists of 11 test modes run over 77 minutes.
At EPA's lab, the CITP is divided into two parts, A and B, which differ
by the dynamometer settings used (see Table 1). (Because of different
equipment configurations, testing at the ATL facility is done in four
pares.) Pare A is performed using the certification dynamometer
settings, which require an expensive multiple curve dynamometer and a
complicated process for determining the proper road load and inertia
weight settings for each vehicle. In Part B, the dynamometer settings
are limited in order to evaluate the tradeoff between cost and FTP
correlation that is associated with less sophisticated dynamometers.
5 The Emission Factor Program tests vehicles owned by the general
public. Data from these in-use vehicles are used with a computer model
known as MOBILE4 to calculate the emission rates of in-use vehicles.
These emission rates are then used with air quality models to estimate
the contribution of mobile source emissions to ambient air pollution.
-------
Modes of the Composite I/M Test Procedure
for use with Emission factors Vehicles
SEGMENT
NO NAME
1
2
3
4
5
•
6
7
8
9
10
11
IM240 (2x)
IM240
S3 Series
IM240
CDH226
TECH BREAK
SS50
COH226
2-Mode Idle
Restart
TECH BREAK
SS50
IM240
SS Series
MODE
IH240
IM240
IM240
20 mph
Idle-N
30 mph
Idle-N
40 mph
Idle-N
50 mph
Idle-N
IM240
CDH226
50 mph '
COH226
Idle-N
2500 rpm
Idle M
Eng. off
2500 rpm
Idle-N
50 mph
IH240
20 mph
Idle-N
30 mph
Idle-N
40 mph
Idle-N
50 mph
Idlc-N
TYPE
Trans
Trans
Stdy St
••
t*
M
M
•«
M
Trana
Trans
N/A
Stdy St
Trans
Stdy St
(•
M
«l
N/A
Stdy St
Trans
Stdy St
it
••
M
M
M
••
TOTAL
Loaded
M
Loaded
Loaded
Unloaded
Loaded
Unloaded
Loaded
Unloaded
Loaded
Unloaded
Loaded
Loaded
Loaded
Loaded
Unloaded
1*
ti
M
•I
Loaded
Loaded
Loaded
Unloaded
Loaded
Unloaded
Loaded
Unloaded
Loaded
Unloaded
DYNO
Cert
Cert
Cert
M
M
Cert
Cert
2-IH
2-IH
N/A
M
2-IH
2-IH
Trim
M
• •
••
MODE CUM
PAU SAMP DOR DOR
Cert Raw
Cert CVS+Raw
Cert Raw
M II
I* M
M M
*f M
M M
Cert Raw
Cert CVS » Raw
Cert Raw
Cert CVS+Raw
N/A Raw
M ••
t* ••
• t «•
•• M
Cert Raw
Cert CVS t Raw
Clay Raw
•I M
*• M
It M *
»• »•
*• M
1* M
4
4
4
2
1
2
1
2
1
2
1
4
4
10
3
4
0.5
0.5
1
0.2
0.5
1
5
3
4
2
1
2
1
2
1
2
1
77
4
a
12
14
15
17
18
20
21
23
24
28
32
3
7
8
8
9
9
10
11
3
7
9
10
12
13
15
16
18
19
NOTES
1. Clayton loading is 30IIP Q 50mph (cubic curve)
2. 50 mph cruise at Clayton loadings may be dropped for small vehicles
3. 2-IW requires IH settings of 2500 or 3500. depending on vehicle
4. Oyno settings will need to be changed prior to steps 6 and 11
NOTES
Harmup; compare raw vs CVS sampling
Hiqh throttle action transient
Compare var-PAU/f ixed-apd ( var-PAU/var-spd
Modes: 20/ I /30/1 /40/I/50/ I 62 min/cruiae.l min/I
Harmup
Moderate throttle action transient
Harmup
Compare cert IH to simple IH approach
Conventional I/M
Harmup
Compare cert IH to simple IH approach
Compare Clayton aingle-curve to cert curves
van 2.21-
11/16/89
-------
The dynamometer settings in Part 3 are li.-rj.teci to two possible inertia
weight settings of 2500 or 3500 pounds, ciepenaing en the weight of the
vehicle. Steady-state loaded modes ;..-. Part 3 are performed with cnly a
single setting (30 hp @ 50 mph) for ail venicies to simulate the Clayton
single-curve dynamometers. A yet-to-De-ccmpieted comparison of test
results between carts A and 3 will help co determine whether the expense
of certification-type dynamometers is justified.
7.2 Sampling Methods
The CITP also allows EPA to compare methods of measuring exhaust
emissions. The entire CIT? series undergoes second-by-second raw
exhaust measurements. MVEL uses an Allen 3AR-80 specification analyzer
-o gather and analyze the sample and a Macintosh running EPA's GAS-4
program for data collection. ATL uses a Gordon-Darby analyzer to
i.naiyze the sample ana an IBM-compatible computer for data collection.
In addition to raw exnaust measurements, which reveal the
concentration of pollutants (percentage or parts per million), loaded
transient modes also are analyzed using Constant Volume Sampling (CVS),
which reveals mass emissions (grams per mile). Raw exhaust
measurements, while less complicated and less expensive than CVS, do not
account for differences in the size of the exhaust stream and so do not
accurately measure the total mass of pollutants emitted.6 Constant
Volume Sampling, on the other hand, does measure the mass of pollutants
but requires complicated and expensive equipment. If certain
assumptions are made, mathematical formulas can be applied to raw
exhaust measurements so that they can be expressed as approximate mass
measurements. 3y comparing the results of these calculations to the
actual CVS readings, the accuracy of the calculated mass results can be
5 CVS measurements provide a much better indication of vehicle emission
levels than raw exhaust measurements. A raw exhaust reading of 200 ppm
HC from a small motorcycle and the same 200 ppm reading from a large
truck (which is entirely possible) suggest that the two vehicles pollute
equally. However, such a conclusion is wrong. The truck will have a
much higher volume of exhaust. Over a given one-mile drive, the
motorcycle may only emit 50 cubic feet of exhaust gases, whereas the
truck may emit 500 cubic feet, with both vehicles emitting 200 ppm HC
over the mile, the total amount of HC emitted by the truck will be 10
times greater than the amount emitted by the motorcycle. A Constant
Volume Sampler allows the total emissions per mile to be measured; a raw
exhaust analyzer does not.
-------
determined. If the identification rates, errors of commission, and
errors of omission from the raw exhaust calculations compare favorably
zo the CVS readings, use of the less expensive, less complicated raw
exhaust method may be justified.
7.3 CITP Steady-State Modes
In addition to the IM240 and the CDH-226, the CITP includes a
loaded steady-state test at 50 mpn (SSSO) , a two-mode idle restart test,
and a steady-state series. The steady-state test at 50 mph is run for
three minutes as a warm-up for the IM240 and the CDH-226. The two-mode
idle segment is approximately four minutes in duration. This test
consists of an engine restart inserted between sequences of idle and
2500 rpm operation. The two-mode idle was included in the CITP because
it is representative of tests currently being used in many I/M programs.
The steady state series contains .oaaed modes at 20, 20, -iO, and
30 mph separated by an idle. This series represents an intermediate
step between the idle test and the loaded transient schedule. Its
advantages over loaded transient cycles include the cost savings of raw
gas versus CVS analyzers and of single versus multiple curve
dynamometers. In addition, unlike loaded transient cycles, the steady-
state series does not require the use of driving schedules or related
equipment or technician skills.7
8. 0 Summary
Changes in vehicle technology have created the need for more
sophisticated I/M tests. In response to this need, the EPA has
developed the IM240, a short transient test, as a possible alternative
to current I/M tests. The EPA is evaluating the IM240 as well as the
CDH-226 and several steady-state tests in the Composite I/M Test
Procedure. CITP testing is ongoing, and the results will be published
at a later date.
7 McCargar, J., Memorandum to Richard D. Lawrence, October 19, 1989,
U.S. EPA, Emission Control Technology Division, Technical Support Staff.
10
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Appendix 1
IM240 Soeeci versus Tine Table
UDDS
Equiv Tir.e
sees .
16
17
18
19
20
21
22
23
24
25
26
27
23
2 3
20
31
22
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
IM240
Speed
mph
0
0
0
0
0
3
5.9
3.6
11.5
14.3
16.9
17.3
13 1
2D.7
2 1 7
22.4
22.5
22.1
21.5
20.9
20.4
19.8
17
14.9
14.9
15.2
15.5
16
17.1
19.1
21.1
22.7
22.9
22.7
22.6
21.3
19
17.1
15.8
15.8
17.7
19.8
21.6
23.2
24.2
24.6
24.9
25
IM240
Accel Rate
r.ph/sec
0
0
0
0
3
2.9
2.7
2.9
2.8
2.6
0.4
0.3
2 . 6
^
0.7
0.1
-0.4
-0.6
-0.6
-0.5
-0.6
-2.8
-2.1
0
0.3
0.3
0.5
1.1
2
2
1.6
0.2
-0.2
-0.1
-1.3
-2.3
-1.9
-1.3
0
1.9
2.1
1.8
1.6
1
0.4
0.3
0.1
Actual Time
sees.
3
4
5
5
7
3
9
10
11
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
•Engine is running and transmission is in gear before
driving schedule and exhaust sampling begin.
A-l
-------
Actual Time
sacs .
48
49
50
51
52
53
54
55
56
57
53
59
60
61
62
63
64
55
66
67
63
69
70
71
72
73
74
75
76
77
78
79
30
81
32
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
UDDS
£quiv Time
sees .
30
81
32
83
84
95
36
37
38
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
163
164
165
IM240
Speed
mph
25.7
26.1
26.7
27.5
28.6
29.3
29.8
30.1
30.4
30.7
30.7
30.5
30.4
30.3
30.4
30.'8
jO.4
29.9
29.5
29.8
30.3
30.7
30.9
31
30.9
30.4
29.8
29.9
30.2
30.7
31.2
31.8
32.2
32.4
32.2
31.7
28.6
25.1
21.6
18.1
14.6
11.1
7.6
4.1
0.6
0
0
0
0
0
3.3
6.6
IM240
Accel Rate
.Tvph/sec
0.7
0.4
0.6
0.8
1.1
0.7
0.5
0.3
0.3
0.3
0
-0.2
-0.1
-0.1
0.1
0.4
-0.4
-0.5
-0.4
0.3
0.5
0.4
0.2
0.1
-0.1
-0.5
-0.6
0.1
0.3
0.5
0.5
0.6
0.4
0.2
-0.2
-0.5
-3.1
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-0.6
0 Bag 2
0
0
0
3.3
3.3
A-2
-------
Actual Time
sees .
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
UDDS
Equiv Time
sees .
166
167
168
169
170
171
172
173
174
175
176
178
179
181
182
183
184
135
186
187
188
189
190
29
30
31
32
33
34
35
36
37
38
53
54
55
56
57
58
191
192
66
67
68
69
70
71
72
73
74
75
76
IM240
Speed
mph
9.9
13.2
16.5
19.8
22.2
24.3
25.8
26.4
25.7
25.1
24.7
25.2
25.4
27.2
26.5
24
22.7
19.4
17.7
17.2
18.1
18.6
20
20.7
21.7
22.4
22.5
22.1
21.5
20.9
20.4
19.8
17
17.1
15.8
15.8
17.7
19.8
21.6
22.2
24.5
24.7
24.8
24.7
24.6
24.6
25.1
25.6
25.7
25.4
24.9
25
IM240
Accel Race
mph/sec
3.3
3.3
3.3
3.3
2.4
2.1
1.5
0.6
-0.7
-0.6
-0.4
0.5
0.2
1.8
-0.7
-2.5
-1.3
-3.3
-1.7
-0.5
0.9
0.5
1.4
0.7
1
0.7
0.1
-0.4
-0.6
-0.6
-0.5
-0.6
-2.8
0.1
-1.3
0
1.9
2.1
1.8
0.6
2.3
0.2
0.1
-0.1
-0.1
0
0.5
0.5
0.1
-0.3
-0.5
0.1
A-3
-------
Actual Time
sees .
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
UDDS
Equiv Ti.T.e
sees .
77
78
79
30
81
3->
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
209
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
IM240
Speed
mph
25.4
26
26
25.7
26.1
^5.7
27.3
30.5
33.5
36.2
37.3
39.3
40.5
42.1
43.5
45.1
•46
46.3
47.5
47.5
47.3
47.2
47.2
47.4
47.9
48.5
49.1
49.5
50
50.6
51
51.5
52.2
53.2
54.1
54.6
54.9
55
54.9
54.6
54.6
54.8
55.1
55.5
55.7
56.1
56.3
56.6
56.7
56.7
56.3
56
IM240
Accel Rate
mph /sec
0.4
0.6
0
-0.3
0.4
0.6
0.6
3.2
3
2.7
1.1
2
1.2
1.6
1.4
1.6
0.9
0.8
0.7
0
-0.2
-0.1
0
0.2
0.5
0.6
0.6
0.4
0.5
0.6
0.4
0.5
0.7
1
0.9
0.5
0.3
0.1
-0.1
-0.3
0
0.2
0.3
0.4
0.2
0.4
0.2
0.3
0.1
0
-0.4
-0.3
A-4
-------
Actual Time
sees .
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
UDDS
Equiv Time
sees .
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
IM240
Speed
mph
55
53.4
51.6
51.8
52.1
52.5
53
53.5
54
54.9
55.4
55.6
56
56
55.8
55.2
54.5
53.6
52.5
51.5
50.5
48
44.5
41
37.5
34
30.5
27
23.5
20
16.5
13
9.5
6
2.5
0
IM240
Accel Rate
mph /sec
-1
-1.6
-1.8
0.2
0.3
0.4
0.5
0.5
0.5
0.9
0.5
0.2
0.4
0
-0.2
-0.6
-0.7
-0.9
-1.1
-1
-1
-2.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-3.5
-2.5
A-5
-------
Actual :
sees
204
205
i-.e
iquiv Ti.-e
sees.
IM240
. 4
IM240
eel ?.a-e
r.p.-./sec
33
212
213
214
215
216
217
213
219
223
224
225
226
127
223
229
230
231
232
233
234
235
236
237
233
239
<.
-)
<.
: •
50.
48
44.
41
37.
34
30.
27
23.
20
16 .
13
5
9
4
5
3
2
5
5
^
^
5
5
5
5
5
5
9.5
6
2.5
0
-\
•j .
0.
,-\
V .
A
U .
0.
0.
0
-0.
-0.
-0.
-0.
- ;_ _
_ 1
-1
-2.
-3.
-3.
-3.
-3.
-3.
-3.
-3.
-3.
-3.
-3.
-3.
-3.
-3.
-2.
5
5
9
5
2
4
-i
4.
6
7
9
7_
5
5
5
5
3
5
5
5
5
5
5
5
5
5
5
A-5
-------
Acoendix 2
Corr.paraci
"
Idle Hades
IM240
i u me s • c r
idle Periods
(sec)
.3.0
3.0
Percent of Length :f
Total First Idle
Schedule (sec)
3.3
.9.0
.9.9
4.0
20.0
Average
Idle Time
(sec)
4.5
14.4
15.0
Standard
Deviation
Idle Time
C.7
10.7
12.3
I.M240
C2H-225
race Speed
t.T.ph)
30.0
19.5
22.3
Speeds
Average Speed
' Without
Idle Modes
(.T.ph)
30.8
24.1
27.9
Maximum Speed
(mph)
56.7
56.7
51.3
IM240
•JDOS
CDH-226
0-10 mph
5.2
13.8
9.4
10 mph Segments
'.r ;f Drivir.y Schedule in gaeh 10 rr.ph
(without idle modes)
.0-20 moh 20-30 moh 30-40 mch
18.3
19.2
12.7
34.3
45.9
46.4
13.9
11.0
8.3
40-50 mph
8.7
3.4
19.9
SQ-SQ moh
19.1
6.6
3.3
Average Rate of Acgeleration fm
IM240
uDDS
CDH-226
0 - 1 0 mph
3.1
2.3
2.3
10-20 mph
1.6
1.8
2.0
20-30 mph
0.83
0.72
0.74
30-40 mph
0.86
0.67
1.4
40-50 mph
0.85
0.80
0.53
SO-SO m=h
0.43
0.38
0.57
Average Rate of Deceleration fm
IM240
UDDS
CDH-226
0 - i 0 mph
3.5
2.4
2.0
10-20 mph
2.3
2.1
1.7
20-30 mph
1.1
0.81
0.70
30-40 mph
1.2
0.54
1.4
40-50 mph
2.0
0.61
0.61
SO-SO mph
0.79
0.42
0.40
A-6
-------
EPA-AA-TSS-91-1
The IM240 Transient I/M Dynamometer Driving Schedule
and The Composite I/M Test Procedure
William M. Pidgeon
Natalie Dobie
January 1991
Technical Support Staff
Emission Control Technology Division
Office of Mobile Sources
Environmental Protection Agency
-------
"EPA-AA-TSS-91-1
The IM240 Transient I/M Dynamometer Driving Schedule
and The Composite I/M Test'Procedure
William M. Pidgeon
Natalie Dobie
January 1991
Technical Support Staff
Emission Control Technology Division
Office of Mobile Sources
Environmental Protection Agency
-------
Table of Contents
1. 0 Introduction 1
2 .0 Background 1
3.0 The Problem 2
4 . 0 Old Technology versus New Technology 3
5.0 IM240 versus CDH-226 3
6.0 IM240 Description 6
7.0 Composite I/M Test Procedure. 7
7 .1 Dynamometer Settings 7
7.2 Sampling Methods 9
7.3 CITP Steady-State Modes 10
8.0 Summary 10
Appendix 1
IM240 Speed Versus Time Table A-l
Appendix 2
Comparative Statistics A-6
-------
1.0 Introduction
The United States Environmental Protection Agency (EPA) is
evaluating new test procedures for use as Inspection/Maintenance (I/M)
tests. Two tests under consideration are the IM240, a new driving
schedule developed by the U.S. EPA, and the CDH-226, a driving schedule
developed earlier by the Colorado Department of Health. EPA's focus on
these procedures as possible alternatives to current I/M tests has
aroused interest. The purpose of this document is to provide
descriptive information about these tests to the I/M community.
Statistical results from the first year of testing on the IM240 and the
CDH-226 will be published later.
This document also provides information on EPA's Composite I/M
Test Procedure (CITP), a lengthy testing sequence designed to evaluate
the effectiveness of a large number of potential alternative I/M tests,
including the IM240 and the CDH-226.
The IM240 and CDH-226 driving schedules are both based on EPA's
Federal Test Procedure (FTP), which certifies compliance with federal
vehicle emission standards for carbon monoxide (CO), unburned
hydrocarbons (HC), and nitrogen oxides (NOx). Since a significant
portion of the I/M community is relatively unfamiliar with certification
procedures, the following section provides the basic background needed
to understand the foundations of the IM240 and the CDH-226.
2.0 Background
In order for vehicle emissions to be controlled effectively, they
must be evaluated under real world conditions. With this in mind, the
United States has designed its vehicle emission control strategy around
tests that measure emissions while replicating actual driving
conditions. These tests stem from the development in 1965 of the LA-4
road route, which was designed to approximate a typical morning trip to
work in rush-hour traffic in Los Angeles.1 In 1972, the EPA shortened
the LA-4 from 12 to 7.5 miles and adapted it for use in the laboratory
on a chassis dynamometer, a device that simulates vehicle load and
inertia weight.2 Since known as the Urban Dynamometer Driving Schedule
(UDDS), it is the driving schedule used to conduct the FTP.
1 Hass, G. C., Sweeney, M. P., and Pattison, J. N., "Laboratory
Simulation of Driving Conditions in the Los Angeles Area," SAE Paper No
660546, August 1966.
2 Kruse, R. E. and Huls, T. A., "Development of the Federal Urban
Driving Schedule," SAE Paper No. 730553, May 1973.
-------
The FTP is the "golden standard" for determining vehicle emission
levels, but it is expensive and time consuming. The EPA has approved
six shorter tests for use by I/M programs in their evaluation of in-use
vehicle emissions. All six currently approved I/M tests are steady-
state (one-speed) tests. Five are unloaded, and one is loaded. These
tests are described in the Code of Federal Regulations, Title 40, Part
81, Sections 2209 - 2214. Considerably less resource intensive than the
FTP, short tests were designed to provide a more easily used but still
reliable method of identifying vehicles that exceed FTP standards.
3 . 0 The Problem
The short I/M tests do not always correlate well to the FTP,
however. Limitations in the tests themselves and, perhaps more
importantly, changes in vehicle design have undermined the ability of
current short tests to identify a vehicle's excess emissions (i.e.,
emissions above the federal standards). I/M tests originally were
designed for a vehicle fleet that is rapidly being displaced by new
technology, computer-controlled vehicles. New technology vehicles are
equipped with improved emission control components, such as three-way
catalysts, closed-loop fuel control, and fuel injection, which have
changed the way vehicles respond to emission tests.3
These changes have implications for the future effectiveness of
I/M programs. The effectiveness of short emission tests can be
expressed in terms of overall failure rate, excess emissions identified
(identification rate), errors of commission, and errors of omission.
Errors of commission (Ec), or false failures, occur when vehicles fail
an I/M test but pass the FTP. Errors of omission (Eo), or false passes,
occur when vehicles pass the I/M test but fail the FTP. Based on these
measures, EPA studies indicate that current short tests have become less
effective in identifying excess emissions since the introduction of new
technology vehicles in 1981. The challenge now is to ensure that I/M
tests keep pace with changing technology so that they remain an
effective tool for vehicle emission control.
3 Armstrong, J., Brzezinski, D. J., Landman, L., and Glover, E. L.,
"Inspection/Maintenance in the 1990's," SAE Paper No. 870621, February
1987.
-------
4.0 Old Technology versus New Technology
Old technology, pre-computer-controlled vehicles have emission-
related components that operate on a continuum. For example, if the
air-fuel mixture at idle is too rich, then the air-fuel mixture is
likely to be too rich across much of the operating range of the vehicle
(i.e., cruise, acceleration, deceleration). For this reason a test
performed only at idle or only at 30 mph is likely to identify pre-
computer-controlled vehicles that malfunction to a sufficient degree to
fail the FTP test also. This continuum characteristic is an inherent
feature of many mechanically controlled systems, including other
emission-control components like the ignition system's distributor,
which controls the ignition timing.
The newer, computer-controlled vehicles that are becoming an ever
larger fraction of the fleet are not constrained by the continuum
characteristic of mechanical devices. A computer can include discrete
instructions for the air-fuel mixture at idle that have little bearing
on the mixture at 30 mph or during an acceleration from 10 mph to 20
mph. For this reason, a vehicle with low emissions at idle or 2500 rpm
or 30 mph can in principal have unacceptably high emissions during other
modes. Furthermore, EPA studies show that some vehicles with very high
FTP emissions do indeed pass a steady-state test, such as an idle test.
By the same logic, a vehicle with high idle emissions may pass the FTP
because the emissions are low through most of the vehicle's other
operating modes. An idle test falsely fails such vehicles. Transient
tests, on the other hand, are responsive to changing emission levels
during different modes of vehicle operation and thus overcome the
limitations of steady-state testing on computer-controlled vehicles.
5.0 IM240 versus CDH-226
In the face of changing technology, EPA's objective was to find a
short transient test that would identify high emitting vehicles as
defined by their FTP emissions, while minimizing errors of commission.
Initially, the CDH-2264 seemed to offer the best possibility for a
viable I/M test. Since then, EPA has developed the IM240 as a possible
improvement on the CDH-226.
4 Ragazzi, R. A., Stokes, J. T., and Gallagher, G. L., "An Evaluation of
a Colorado Short Vehicle Emission Test (CDH-226) in Predicting Federal
Test Procedure (FTP) Failures," SAE Paper No. 852111, October 1985.
-------
A characteristic of the CDH-226 that stands out when compared to
the UDDS is that the CDH-226 is smoother (i.e., less transient), so it
requires less throttle action (see Figure 1 on page 5). Throttle action
is an important variable affecting vehicle emissions and could be
important in identifying malfunctioning vehicles.
Take oxygen sensor operation as an example. As oxygen sensors
deteriorate, their response time lags. This deteriorating response time
can allow the air-fuel mixture to increasingly deviate from
stoichiometric (14.7:1), the ratio at which 3-way catalysts most
efficiently oxidize HC and CO and simultaneously reduce NOx (see Figure
2 below). This is important because three-way catalyst conversion
efficiency rapidly deteriorates with air-fuel mixture deviations from
stoichiometric. During steady-state operation, the fuel metering system
adjusts to deliver a stoichiometric mixture, which should stay
relatively constant. Throttle movement often causes the mixture to
change, and as throttle action increases, the ability of the metering
system to maintain stoichiometry becomes increasingly dependent on the
response time of the oxygen sensor. A highly transient driving schedule
requires more throttle action than a smooth schedule, so a deteriorated
oxygen sensor is more likely to be identified on a highly transient
schedule than on a smooth schedule. The same logic can also be extended
to other components of emission control systems. A driving schedule can
be made too transient, however. An I/M test requiring more throttle
action than the UDDS might unacceptably increase test variability and
thereby increase the error of commission rate.
Figure 2: Air-Fuel Ratios and Conversion Efficiency
100-
93-
60-
14.4 14.7 15.0
AIR/FUEL RATIO*
RICH « [ • LEAN
*Converted from equivalence ratios used in the original.
Source: Rivard, J. G., "Closed-Loop Electronic Fuel Injection
Control of the Internal Combustion Engine," SAE Paper No. 730005,
January 1973, p. 4.
-------
Figure 1: Comparison of Dynamometer Driving Schedules
CDH-226 Driving Schedule
50-
40-
Speed 30.
(mph)
20-
10-
0-
0
50 100 150 200 250 300
Time
Hills 1 & 2 of the Urban Dynamometer Driving Schedule
50-
40-
Speed 30.
(mph)
20-j
10
0
50-
40-
Speed 30.
(mph)
20 1
10
0
50 100 150 200 250 300
Time
IM240 Driving Schedule
50 100 150 200 250 300
Time
-------
For these reasons, EPA decided to develop a more transient
alternative to the CDH-226, to make the new test similar to the UDDS,
and to evaluate both procedures to determine which is better for I/M
testing. EPA's alternative was dubbed the IM240 since it was designed
for I/M testing with a duration of 240 seconds.
6.0 IM240 Description
The IM240 driving schedule is depicted graphically in Figure I.
Appendix 1 provides a speed-versus-time table in one-second increments.
The table also lists the UDDS segments that were used to create the
IM240.
The IM240 was patterned closely on the first two "hills" of the
UDDS. It uses actual segments of the UDDS and incorporates the UDDS's
peak speed of 56.7 miles per hour. Testing over the entire range of
speeds was considered important to detect malfunctioning vehicles given
the discontinuous operating characteristics of computer-controlled
vehicles. Using actual segments of the UDDS was considered important to
help improve correlation and minimize errors of commission and errors of
omission.
The two large decelerations from hills 1 and 2 are the only
segments that were not taken directly from the UDDS. The deceleration
rate for both hills was set at 3.5 mph/sec, whereas the maximum
deceleration rate from the UDDS is 3.3 mph/sec. The higher deceleration
rate prevents the IM240 from exceeding four minutes, which was taken
somewhat arbitrarily to be a measurable upper limit for a test time that
would allow an adequate rate of vehicle processing, or throughput. The
3.5 mph/sec rate, which has been used successfully in the CDH-226, also
allows time for an idle and an additional transient portion on hill 2
(between 140 seconds and 158 seconds).
As seen in Appendix 2, the IM240 differs statistically from the
CDH-226. Because of differences in design, it was speculated that one
of the tests might correlate better than the other to the FTP.
The IM240 test is run in two segments. The shorter segment is 94
seconds in duration, which was an informed guess as to the minimum
amount of time needed to realize significant improvements in FTP
correlation. For comparison, EPA has divided the CDH-226 into two
segments as well, the shorter segment being 86 seconds. By dividing
each test into two parts, EPA can evaluate the effectiveness of the
entire test as well as the effectiveness of each of the shorter
segments.
-------
The case procedure stipulates that the engine is running with the
transmission in gear before the driving schedule begins. Zxhaust
sampling begins simultaneously with the start of the driving schedule.
IM240 testing is being performed separately and in conjunction
with other short tests, including the CDH-226, in the Composite I/M Test
Procedure, which is described below.
7.0 Composite I/M Test Procedure
The EPA has devised the multi-purpose Composite I/M Test Procedure
(CITP) to evaluate the effectiveness of the IM240, the CDH-226, and
potential steady-state alternatives to current I/M tests. The goal of
the program is to identify emission tests which balance the need for
high FTP correlation and high identification rates against cost,
equipment, and time requirements. Acceptable alternative tests would be
sophisticated enough to measure the emissions of new technology
vehicles adequately while conforming to the constraints of an I/M
program.
CITP testing is being performed at EPA's Motor Vehicle Emission
Laboratory (MVEL) in Ann Arbor, Michigan and under contract at the
Automotive Testing Laboratories (ATL) facility in New Carlisle, Indiana,
just outside of South Bend. All Emission Factor Program5 test vehicles
receive the CITP after the as-received FTP test on Indolene test fuel.
7 .1 Dynamometer Settings
The CITP sequence consists of 11 test modes run over 77 minutes.
At EPA's lab, che CITP is divided into two parts, A and B, which differ
by the dynamometer settings used (see Table 1). (Because of different
equipment configurations, testing at the ATL facility is done in four
parts.) Part A is performed using the certification dynamometer
settings, which require an expensive multiple curve dynamometer and a
complicated process for determining the proper road load and inertia
weight settings for each vehicle. In Part B, the dynamometer settings
are limited in order to evaluate the tradeoff between cost and FTP
correlation that is associated with less sophisticated dynamometers.
5 The Emission Factor Program tests vehicles owned by the general
public. Data from these in-use vehicles are used with a computer model
known as MOBILE4 to calculate the emission rates of in-use vehicles.
These emission rates are then used with air quality models to estimate
the contribution of mobile source emissions to ambient air pollution.
-------
-------
ATTACHMENT A
Specifications
for
Electric Chassis Dynamometers
U.S. Environmental Protection Agency
Motor Vehicle Emission Laboratory
2565 Plymouth Road
Ann Arbor, MI 48105
ATTACHMENT A
RFP C10008 IT 1
37 Pages
-------
Specifications for Electric Chassis Dynamometers
Table of Contents
1.0 General Features , 1
1.1 Equipment 1
1.2 Component Preparation 2
1.3 Documentation 2
1.4 Ambient Operating Conditions 3
1,5 Electrical Specifications 3
1.6 Electronic Control 4
1.7 Roll(s) 4
1.8 Inertia Simulation 5
1.9 Vehicle Restraint System 6
1.10 Lift Platform and Roll Brakes ..6
1.11 Safety Devices 6
1.12 Instrumentation 7
1.13 Bearings and Lubrication Intervals 8
1.14 Covering of the Dynamometer Pit 9
2.0 4 Wheel-Drive Chassis Dynamometer Requirements 9
2.1 Set-up 9
2.2 Requirements for Roll Synchronization 10
2.3 Operation Mode 2WD/4WD 10
2.4 Wheelbase Adjustment 10
2.5 Vehicle Restraint System 10
3.0 System Processor Requirements 11
3.1 General Computer Requirements 11
3.2 Processor Modes/Functions 11
3.2.1 Road Load Inertia Simulation Mode 12
3.2.2 Self-motoring Mode 13
3.2.3 Dynamometer and Vehicle Coastdown Test 14
3.3 Interface with Master/Host Computer System 15
3.4 Real-Time Data Monitoring 15
3.5 Electric Dynamometer Data Acquisition Package 16
4.0 Acceptance Tests, Procedures, and Criteria 17
4.1 General Acceptance Provisions 17
4.2 Testing Requirements and Overview 17
4.2.1 Reporting 17
4.2.2 Vehicle Torque Wheel System 18
4.2.3 Data Acquisition (Hardware/Software) 19
4.2.4 Data Analysis and Presentation 19
-------
Specifications for Electric Chassis Dynamometers
4.3 Component Review and Calibration Tests 19
4.3.1 Installation and Mechanical Review 19
4.3.2 Structural and Dimensional Review 19
4.3.2.1 Frame , 19
4.3.2.2 Bearings and Lubrication 20
4.3.2.3 Roller Geometry 20
4.3.3 System Operation and Calibration Review 20
4.3.3.1 Mechanical Inertia Determination 20
4.3.3.2 Torque Cell Calibration 21
4.3.3.3 Torque Transducer Virtual Span & Zero 21
4.3.3.4 Speed Measurement 22
4.3.3.5 Acceleration Meas'irement 22
4.3.3.6 Tune Measurement 22
4.3.3.7 Computer 22
4.4 Dynamometer Characterization Tests 22
4.4.1 Endurance Testing 22
4.4.2 Electrical Inertia Simulation Response 23
4.4.3 Operational Response Characterization 23
4.4.3.1 Dynamometer Self-motoring 23
4.4.3.2 Steady State Speed Loading 26
4.4.3.3 Fixed Acceleration Rate 26
4.4.3.4 Neutral Coastdown Rolling Load 27
4.4.3.5 Urban Dynamometer Driving Schedule (UDDS-505 seconds) 27
Appendices:
A Electric Dynamometer Acceptance Cross Reference
B Figure 1 Dynamometer Rise and Settling Time Illustration
Figure 2 Steady State Dynamometer Load Curves
C Figure 3 Force versus Acceleration (dV/dt)
Figure 4 Example of Mean Force Value Graphs
D Symbols and Specification Terminology
E Glossary of Acceptance Criteria Terminology
F Response Characteristics of a Second Order System to a Unit S tep Function
-------
Specifications for Electric Chassis Dynamometers
1.0 General Features
Federal regulations for exhaust emissions and fuel economy of motor vehicles specify tests
using chassis dynamometers. The purpose of the chassis dynamometer is to duplicate the
forces encountered by a vehicle moving on a road by modeling those characteristics with a
stationary vehicle on a rotating surface. EPA envisions a variety of testing needs to address
future regulations. A key feature of the recent Qean Air Act Amendments is that the test
conditions appropriately simulate "real-world" conditions.
The optimal dynamometer utilizes the latest technology through a digitally-controlled,
electrically-activated, motor-absorber that supplements mechanical inertia, optional
flywheels, and frictional forces with electrical load forces based on specific equations and
coefficients. The test cell, dynamometer, and vehicle operate as a system under various
ambient conditions to provide maximum flexibility and ease of operation. In all cases, the
loading capabilities, control algorithms and other operating characteristics of these
dynamometers must be able to accurately and precisely simulate the forces encountered by a
vehicle on the road.
While twin roll dynamometers have traditionally been used at MVEL for most testing, this
acquisition allows vehicle loading by means of either a twin roll or single roll configuration
if the performance specifications contained herein are met The twin roll configuration shall
have synchronous roll speeds and shall apply the total load force through a symmetrically
balanced design so that the forces at the roll/tire contact points contribute uniformly to the
total simulation of the road forces. The single roll dynamometer shall have a 48" diameter
roll and shall be the system configuration installed in the Cold Test Facility (CTF) at a
minimum.
The chassis dynamometer shall conform to the requirements specified herein.
1.1 Equipment
The dynamometer shall be designed and constructed to be capable of operating on a
continuous basis (24 hours per day, 7 days per week). It shall withstand all static and
dynamic loads which are encountered during vehicle testing, and shall not produce any
vibrations which may impair the operation of the vehicle or dynamometer.
The dynamometer components shall be capable of withstanding shock loading from
maximum acceleration/deceleration forces, such as locked vehicle brake at 60 mph, wide
open throttle (WOT), emergency shutdown, or any system malfunction(s) that induces
abrupt forces, without damage to any component(s).
The dynamometer system shall consist of the following components, at a minimum,
arranged in a configuration that optimizes the physical dimensions, system response
characteristics, and flexibility to simulate various loading schemes:
- the roll(s) in a structure or frame suitable for this application
- a vehicle inertia simulation system
- an electric motor-absorber system
- all pneumatic and/or hydraulic components
- all operator and driver interface panels, displays, controls, and interface wiring for
the computer system
- all calibration devices
- a means to ensure safe and efficient installation and removal of the vehicle
- a vehicle restraint system to limit the dynamic lateral and fore/art travel of the -
vehicle
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Specifications for Electric Chassis Dynamometers
• safety equipment, including noise and EFI suppression
• all electrical cabling, piping, tubing, and cabinets
- installation, checkout, and warranty
- complete documentation including construction, installation, operation, service,
parts, etc.
Additional details of these requirements are contained in other paragraphs throughout this
document.
The dynamometers shall be installed in the test cells as specified by Delivery Order, which
shall include a test cell configuration plan.
Repair service and spare parts shall be available within one working day of request during
the one year warranty period.
1.2 Component Preparation
All surfaces of the dynamometer system shall be treated with protective coatings (such as
plating, primers, epoxy, etc.) or made from materials that will prevent rust, scaling,
flaking, or chalking under all the operating conditions of the test cell environment.
Rotating parts such as roll(s), flywheels or shafts, and other non-paintable parts, shall be
protected from corrosion by applying suitable treatments.
1.3 Documentation
Five (5) copies of the documentation of the dynamometer system shall be provided to the
Project Officer upon delivery of each dynamometer. The documentation shall be in English
and shall include, at a minimum, the following:
• the dynamometer mechanical layout
- schematics of all pneumatic and hydraulic components
• color coded and/or numbered schematics and wiring lists of all electric components
- technical and operational manual(s), including a complete description of the system
control algorithms, performance measures, calibration procedures, system hardware
and software operation, response characteristics and system source code.
- pans list(s)
- recommended, on-hand, spare parts list
• maintenance and calibration instructions
The operation manual(s) shall include complete information on the dynamometer's
functions, capabilities and user interface procedures.
The parts list shall include, at a minimum, the following:
• All subcontractors' parts, ID enable the government to obtain precise information,
including addresses and phone numbers
- The model and/or part number designations of ail component parts
One set of recommended on-hand spare parts shall be supplied, at time of installation, for
each dynamometer provided. As an option, the contractor may guarantee delivery of these
parts per the one working day time period specified in Section 1.1.
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Specifications for Electric Chassis Dynamometers
1.4 Ambient Operating Conditions
The dynamometer shall be used to test vehicles exposed to the following ambient
conditions: (See Note)
test cell temperature: 0 to +110 °F
relative humidity: 0 to 90%
altitude: up to 3,300 feet for all units except the Denver location
Note: The dynamometer performance shall not be affected by the conditions applied to the
vehicle test environment The vehicle test environment and dynamometer operating
environment may be separately controlled spaces. The objective is to maintain frictional
stability and to minimise component exposure to adverse conditions. Air for the
temperature control of the dynamometer shall be taken from a dry air source so that
condensation in the dynamometer system is prevented.
1.5 Electrical Specifications
The system shall operate with the following electrical voltages:
•
120 V (± 10%) 60 Hz instrumentation only
480 V (± 10%) 60 Hz (three phase, four wire)
The motor-absorber electrical interface shall be regenerative (i.e., generated power shall be
fed back to the grid.)
The equipment shall be grouped into the following sections:
1. electronic and display
2. power
The electronic and display section shall be installed in a standard 19" rack, which may be in
a separate cabinet from the power section. The operator interface cabinet shall be located in
the dynamometer control room for operator access.
The controls at the electronic and display section shall include, at a minimum:
• emergency stop switch
- operator interface and displays
Two switches shall also be accessible from the vehicle driver's seat door. If these switches
are operable from the control room, a safety interlock or alert to the driver shall be installed.
• vehicle alignment switch
. lift platform switch
• roll brake switch
The minimum requirements for instrumentation at the power section are as follows:
- emergency stop switch
- main power switch
- armature-current display (may be installed inside the cabinet)
- armature-voltage display (may be installed inside the cabinet)
- running-time (hour) meter
- fault protection circuits)
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Specifications for Electric Chassis Dynamometers
Installation shall conform to the latest editions of the National Electric Code (NEC) and
Building Officials Code Administrators International (BOCA).
1.6 Electronic Control
The speed and load control circuitry shall be based on digital microcomputers or
microprocessors. Low current or power conversion circuitry may be excluded from this
requirement.
The electrical power driving all electrically actuated relays, solenoids, valves, and motors
shall be electrically isolated from the power source for the dynamometer control circuitry,
computer, and interfaces.
All electrically actuated relays, solenoids, and valves shall be protected by zero switching
or diode clamping so that no back EMF electrical noise is generated,
The electrical power driving the dynamometer control circuits shall be immune to all
electrical noise. The system shall not feed damaging or detrimental electrical noise into the
power grid. Electromagnetic fields caused by the dynamometer shall be controlled or
suppressed to prevent any interference in the test vehicle or dynamometer
electrical/electronic control systems. The contractor shall provide and install any isolation
devices required for operation.
The dynamometer shall be protected from uncontrolled acceleration of the motor-absorber.
The motor-absorber shall also have current limit protection to prevent system damage from
power grid faults of short duration (<20 ms).
1.7 Rollfs)
A roll shall be defined as a cylindrical contact surface that applies the load forces to the tires
on the test vehicle's drive axle(s). A roll may be a single cylinder or mechanically linked
multiple cylinders. A twin roll dynamometer cradle consists of two rolls per vehicle drive
axle which operate at synchronous speeds and impose forces at each tire contact point that
are similar in magnitude. A single roll dynamometer consists of one roll per vehicle drive
axle. The rolls, bearings, and power transfer loading devices shall be sized and configured
to withstand the road load forces and axle loads of the specific test vehicles. These forces
and loads shall include those values typically encountered from on-road vehicle
performance tests conducted at wide open throttle from zero up to a maximum of 100 mph.
The requirements shall be the following:
nominal roll diameter (twin roll) 20 inches
tire contact angle (twin roll center spacing) 66° on a 24" contact circle
twin roll center spacing => 2 (roll diam/2 + 24/2)(sin 33°)
nominal roll diameter (single roll) 48 inches
roll diameter determination tolerance ± 0.02% of nominal diameter
difference in cylinder diameters per roll set ± 0.02% of nominal diameter
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Specifications for Electric Chassis Dynamometers
roll width spacing shall accommodate:
vehicle inside track width (LDV) * 36 inches
vehicle outside track width (LDV) 86 inches
vehicle inside track width (MDV) * 36 inches
vehicle outside track width (MDV) 108 inches
roll surface roughness (See Note)
roll surface minimum hardness Rockwell B90
roll dynamic balance quality (twin roll) ANSI STD G2.5
roll dynamic balance quality (single roll) ANSI STD G6.3
roll axis parallelism (twin roll) 0.020 inches TIR *
roll concentricity (twin roll) 0.004 inches TIR
roll concentricity (single roll) 0.010 inches TIR
* LDV = Light Duty Vehicle
MDV = Medium Duty Vehicle
TIR = Total Indicated Runout
• Note: Roll surface finish shall provide minimum tire slippage and a tractive effort that is
comparable to a vehicle operating on a typical dry, road surface. Roll surface roughness
shall also not produce abnormal tire tread wear.
The speed of twin rolls shall be synchronized to within ±0.1 mph at all operating
conditions. Synchronization shall be accomplished by mechanical or electrical coupling.
The total force applied by the roll(s) to the vehicle shall be the sum of the forces (including
inertia) from each tire/roll contact point The parasitic loss of the coupling device shall be
stable and compensated for during all modes of vehicle or dynamometer operation.
For the 4WD system, the dynamometer rolls shall be nominally installed flush with the
level, finished floor. When testing on a 2WD system, the contractor shall provide a
method for maintaining the vehicle in a horizontal (± 1% grade) attitude when the drive tires
are supported by the roll(s). The overall width of the LDV dynamometer shall be
minimized to fit within the test cell, which will have an interior width of 16 feet The
overall width of the MDV dynamometer shall be less than 20 feet The dynamometer
frames shall be supported above the subfloor space in a manner that allows air recirculation
in the subfloor area. The test vehicle is to be approximately located at the geometric center
of the air flow stream of the test chamber, and in a consistent relation to the exhaust
sampling system connectors which shall be in fixed locations in the subfloor space. The
dynamometers) and the vehicle restraint system(s) shall be capable of testing both rear
wheel drive vehicles and front wheel drive vehicles.
1.8 Inertia Simulation
The total inertia (mechanical plus electrical) to be simulated shall be selectable to within at
least ± 10 pounds. This value shall be used to calculate the total road force required. The
accuracy of the total road force imposed, including the inertia force, shall be within ± 1%
of this calculated formula value under all operating conditions within acceleration rates of ±
8 mph/sec. The electrical inertia simulation shall provide response characteristics that
result in total torque wheel loading that is comparable to a mechanical inertia system. For
LDV dynamometers, the range of total inertia simulation shall be from 1,000 Ibs. to 6,000
Ibs. For MDV vehicles, the range of total inertia simulation shall be from 1,000 Ibs. to
12,000 Ibs.
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Specifications for Electric Chassis Dynamometers
The contractor shall measure and verify the value of the base inertia and all incremental
mechanical inertia values of the dynamometers. Results of these tests shall be included in
the documentation.
Any mechanical flywheels used as part of the inertia shall be dynamically balanced to the
same quality standard, or better, as used for the roll(s). The control panel shall provide an
indication and verification of the positive engagement and disengagement for each
flywheel. The contractor shall provide, during any continuous closed throttle deceleration
to zero, a means of reducing the braking force required from the drive axle. This force
reduction shall be sufficient to prevent drive axle brake damage or failure.
1.9 Vehicle Restraint System
A vehicle restraint system shall be provided and installed with each dynamometer in a
manner that enables unobstructed vehicle ingress and egress from any perimeter wall of the
test celL
The vehicle restraint system shall safely restrain all vehicles at all operating conditions. The
vehicle restraint system shall center the drive wheel(s) of the vehicle on the roll(s).
•
The vehicle restraint system shall limit lateral and fore/aft motion of the vehicle to ± 0.5"
without imparting any adverse vertical or horizontal forces on the vehicle or vehicle tires,
and shall be easily installed, or engaged by the operator in less than ten minutes. Vehicle
removal from the restraint system and the test cell shall be possible in less than two
minutes.
1.10 Lift Platform and Roll Brakes
A lift platform situated between the rolls (on a twin roll configuration) shall be installed.
A roll brake which securely locks the roll(s) shall be installed
When the lift platform is raised and the roll brake is actuated, the vehicle shall enter and
leave the dynamometer without causing roll spin.
Operation of the roll brake shall be independent of the lift platform.
The lift platform shall be capable of being activated by a driver seated in the vehicle.
The lift platform shall be operable only when the roll(s) are not rotating. A roll speed
interlock system shall prevent raising of the lift platform and non-emergency engagement of
the roll brakes while the roll(s) are rotating.
The lift platform shall be capable of holding a vehicle in the raised position for a minimum
of 24 hours.
The roll brake and lift platform shall be replaceable within four hours and without removing
any system components which may change the dynamometer calibration.
1.11 Safety Devices
All safety devices for protection of the equipment shall be as independent of the processor
as practical.
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Specifications for Electric Chassis Dynamometers
Warning lights on the dynamometer, indicating the status of the lift platform and roll
brakes, shall be visible from the driver of the vehicle.
The dynamometer shall have the following personnel safety devices:
A safety barrier shall be installed to prevent personnel contact with the roll(s) during
vehicle testing and during dynamometer roll operation without a vehicle. If a single
roll dynamometer consists of two roller cylinders, or a twin roll cradle consists of
four roller cylinders, the area between the rolls/cylinders shall be covered to provide
a surface that facilitates personnel safety and allows vehicle movement.
An emergency stop switch shall be installed in the dynamometer test cell, at the
vehicle, and at the electronic and display cabinet, and also at the power cabinet if it
is separate. The emergency stop function shall cause shutdown (braking) of the
dynamometer using the electric motor-absorber working at the maximum current
limits. In the event the electric motor-absorber is unable to decelerate the roll(s) to
zero, the roll brake may be used. In all cases, the roll(s) shall be decelerated to zero
mph in less than 5 seconds and shall not damage the dynamometer system.
An emergency shutdown function shall be triggered automatically by the processor
when any of the following limits are exceeded:
- dynamometer's maximum speed (fixed value)
- vehicle's maximum speed (value input during calibration)
- vehicular movement (>0.5 inches)
An emergency warning function shall be triggered automatically by the processor
when any of the following limits are exceeded:
- excessive armature or field current of the motor-absorber
- overheating of the motor-absorber
- malfunction of the dynamometer cooling system
- malfunction of the power transfer system
- power failure
- other conditions needed to protect the dynamometer or personnel
These conditions do not warrant an immediate shutdown of the dynamometer
system but rather a warning of a condition that requires immediate attention.
An indicator of activation of the emergency stop function, shutdown, or warning
shall be installed in the dynamometer test cell (visible from the vehicle driver's seat)
and in the dynamometer control room. The indicator shall be operational at all
including during power failures.
1.12 Instrumentation,
Display meters shall be installed to provide for speed, force, and horsepower readings for
both the vehicle driver and the operator console.
The roll revolution and associated speed measurements shall be monitored by digital or
optical sensors. A speed measurement method on each roll, and one for the vehicle wheel
shall be installed to monitor roll(s) speed, to determine the angular velocity of the drive tire,
and to verify roll speed synchronization under all test conditions. Measured speed shall
have an accuracy and a resolution of a minimum of ± 0.05 mph at any speed. The speed
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Specifications for Electric Chassis Dynamometers
measurement system shall be drift-free and shall require no analog calibration. Test
distance driven shall be determined to a resolution of one pan in 2000.
The acceleration and deceleration rates (mph/sec) of the roU(s) shall be determined by
electrical or numerical methods. All acceleration rates shall be accurate to within ± 0.01
mph/sec or ± 1% of the acceleration rate, whichever is greater, and shall be determined
within 100 ms of true occurrence.
The dynamometer shall have a torque measurement system to indicate the forces being
applied to the dynamometer roll(s). This system shall be capable of indicating torque
readings to a resolution of 0.05% of rated output or ± 0.2 ft-lbs, and shall be capable of
sampling data at a rate of 1 KHz or higher.
The performance specifications of the torque transducer shall be the following:
hysteresis: less than ± 0.1 % of rated output
zero/shunt drift less than ± 0.1 % of rated output in a 24 hour period
repeatability: less than ± 0.05% of rated output
nonlinearity: less than ±0.1% of rated output (See Note)
accuracy: less than ± 0.1% of rated output at all values between.
± 10-100% of rated output based on the best fit
calibration regression
Note: Nonlinearity is defined as the deviation at mid-
scale from a straight line connecting the zero and ± full-
scale values, expressed as a percent of the rated output.
Calibration of the torque transducer for both positive and negative torque by the dead
weight lever arm technique shall be provided. An electronic shunt calibration value shall be
correlated to this dead weight technique. Torque transducer verification procedures under
dynamic operation shall also be provided,
Elapsed time measurements shall have an accuracy and resolution of at least ± 0.01
seconds.
The design of the road load control system shall measure the force and determine the
horsepower delivered at the roll surface(s) based on the applied torques, accelerations, and
speeds of the roll(s). This system shall compensate for the mass and parasitic friction both
inside and outside the control loop of the dynamometer.
Separate digital displays, easily seen by the driver, shall be provided for the following
parameters, at a minimum-
Roll speed (mph)
Tractive force (Ibs)
Tractive horsepower (hp)
1.13 Bearings and Lubrication Intervals
All bearings, gears, or coupling devices shall be designed to have minimum and stabilized
frictional losses.
All bearings shall have a service life of at least 30,000 hours. All parts requiring
lubrication shall be lubricated before delivery. All lubrication points shall be easily
accessible and well documented. The lubricants, lubrication system, or the dynamometer
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Specifications for Electric Chassis Dynamometers
system configuration shall not generate, into the test cell enclosure, hydrocarbon emissions
that would adversely affect a vehicle running loss test at 100 °F.
The fractional losses of the dynamometer at all environmental conditions shall be
thoroughly characterized for all modes of operation. Steady speed (50 mph) factional
losses shall remain within ± 0.1 hp of the final stabilized value following a ten minute
warm-up period.
1.14 Covering of the Dynamometer Pit
The area around the roll(s) shall be covered by slip-resistant plates capable of supporting
test vehicles.
All floor plates shall be secure, and if moveable during dynamometer wheeibase
adjustments, shall not cause any opening in the floor surface following the adjustment.
The weight of a single plate shall not exceed 115 Ibs.
2.0 4 Wheel-Drive Chassis Dynamometer Requirements
«
The basic requirements for a 2WD chassis dynamometer shall also apply to the 4WD
version. Additional 4WD requirements are described in this section, and are to be applied
as appropriate to single or twin roll configurations.
2.1 Set-up
The dynamometer chassis frames shall be installed on a support base and shall provide
torsional stiffness and alignment performance.
The front and rear roll, or sets of rolls, shall be parallel to within 0.08 inches as measured
by the cemerline differential across the maximum roll width.
The front and rear roll, or sets of rolls, shall be electrically or electrohydraulically
adjustable to the vehicle wheelbase. This adjustment process shall indicate the final
wheelbase distance and shall utilize adjustment methods to assure the vehicle tire contact
points are uniformly loaded. After adjustment, the roll chassis positions shall remain
positively fixed on the base frame, even during power or hydraulic failures.
Operation of either 4WD or 2WD shall be selectable. Operation in the 2WD mode shall be
possible with either roll or set of roils. The non-driven rolls, in a twin roll configuration,
shall be locked with the lift platform down to act as a vehicle wheel chock.
On a twin roll configuration, a mechanism or method controlled by the processor shall
provide speed synchronization between the front and rear roll of each drive axle cradle.
On a twin roll configuration, to ensure ease of vehicle handling when entering or leaving
the dynamometer, each set of twin rolls shall have a lift platform and a roll brake. The
raising and lowering of both lifts shall be synchronized in the 4WD mode.
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Specifications for Electric Chassis Dynamometers
2.2 Requirements for Roll Synchronization
The speed of all rolls shall be synchronized to within ± 0.1 mph at all operating conditions.
The parasitic losses of any mechanical synchronization shall be independent of the selected
wheelbase and shall be stable and compensated for, by the system, under all operating
modes.
2.3 Operation Mode 2WD/4WD
The 4WD dynamometer shall be usable as a 2WD dynamometer as well Either roll or set
of rolls (front or back) shall be usable for 2WD operation.
The synchronization of the rolls or roll sets shall be controllable by the processor. The
display shall indicate the configuration of the dynamometer at all times.
The configuration of the dynamometer (4WD or 2WD) shall be stored in the road load
model or test data set
The roll or set of rolls which is not used in the 2WD configuration shall be locked using the
roll brake.
The calibration, compensation, and storage of the dynamometer losses shall be maintained
in both 2WD and 4WD configurations.
2.4 Wheelbase Adjustment
The distance between the front and back roll, or sets of rolls, shall be continuously
adjustable between 80 and 130 inches. The time required for adjusting the dynamometer to
any wheelbase in the 80 to 130 inch range shall not exceed five minutes. A provision to
extend the wheelbase to 180 inches shall be installed with setup requiring no more than one
hour.
The wheelbase spacing shall be automatically adjustable to the vehicle .wheelbase, this
condition shall be indicated by a zero speed, null restraint force and centered axles.
The wheelbase shall be adjustable while the dynamometer is in either 2WD or 4WD
configuration.
The value of the final wheelbase setting shall be read and stored to within ±0.2% of the
nominal wheelbase.
2.5 Vehicle Restraint System
A vehicle restraint system shall be installed with each dynamometer that enables
unobstructed vehicle ingress and egress from any perimeter wall of the test cell
The vehicle restraint system shall be capable of safely restraining all vehicles at all operating
conditions.
The vehicle restraint system shall limit lateral and fore/aft motion of the vehicle to ± 0.5"
without imparting any adverse vertical or horizontal force on the vehicle, and shall be easily
installed, or engaged by the operator in less than ten minutes. Vehicle removal from the
restraints and test cell shall be possible in less than two minutes.
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Specifications for Electric Chassis Dynamometers
3 . 0 System Processor Requirements
3. 1 General Computer Requirements
The. signal cabling shall not cause malfunctions due to capacitive or inductive interference.
Dynamometer operating system software, control software and parameters, and data
acquisition interfaces shall be stored and accessed using commercially available standard
microcomputer hardware. The contractor shall provide a complete description of the
hardware and operating software. Access to all software (including source code) and
operation parameters shall be provided
All analog input and output signal converters shall have a nominal ± ten volt range with a
minimum of 0.005 volts per bit resolution.
All digital input/output channels shall be 0 to 5 volt TTL (transistor-transistor-logic) and
shall be optically isolated from their source.
Error messages and the operating hours counter shall function at all times.
*
It shall be possible for personnel without special computer experience to operate the
dynamometer processor and the peripheral units, including the input of parameter changes.
The dynamometer shall operate in both a local mode without interaction with a remote
computer system, and in a client/server mode, while connected to a remote system that
contains vehicle test parameters and data sets^uid may be used to receive or send data sets
of test information or calibration.
3.2 Processor Modes/Functions
The dynamometer processor shall support, at a minimum, the following operation modes
and tests:
- road load simulation mode
- self-motoring mode
- dynamometer coastdown test
- quick check coastdown test
- speed control mode
- torque control mode
- acceleration mode
. calibration nvxte
The dynamometer processor shall check all processor functions (e.g., CPU, memory, and
input/output channels) using an on-line diagnostics program.
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Specifications for Electric Chassis Dynamometers
3.2.1 Road Load ^n^rria Simulation Mode
The load applied by the dynamometer shall simulate the rolling resistance, aerodynamic
drag, and inertia forces that occur on the road according to the following formula:
FR =* A + B*V + C*V2+ D*W -i- M*dV/dt (See Note)
where:
FR= total vehicle road load force to be applied at the surfaces of the rolls
A a constant load coefficient (friction)
B a load coefficient dependent on velocity (speed boost)
C = load coefficient dependent on velocity squared (windage)
D » grade coefficient (-,+) [sin 6 ]
W = weight of vehicle
M = effective vehicle mass, taking into account the rotational masses
V = velocity of the roller surfaces
dV / dt = acceleration rate of the roller surfaces
Note: The total force is the sum of the individual forces applied by each roller surface.
*
The simulation of the total road force, including the inertia force shall be ± 1 % of its
formula value under all operating conditions and at all velocities. All dynamometer
configurations, mechanical and electrical, shall produce comparable results that are not
significantly different from the standpoint of accuracy, precision, or reproducibility.
The system response time shall be less than 100 milliseconds. System response time shall
be defined as the time lag between a step change in demanded force at the roll surface, and
the occurrence of 90% of the final demand value. Total response shall include mechanical
delay, measurement lag. computational time, and power control electrical response
parameters that will be combined to provide a critically damped response function.
Appendices E and F provide response definitions.
In road load simulation mode, sets of coefficients containing road load curves and inertias
shall be directly accessible from the system storage device within ten seconds.
All data sets shall have a sufficient number of characters in their nomenclature to provide
uniquely identifiable names for retrieval.
In simulation mode, all functions shall be performed, and the error value monitored by the
dynamometer processor.
Calibration for frictional losses shall be automated.
For any inertia configuration, the processor shall determine a friction curve using a steady
speed, constant acceleration or deceleration, or a coastdown procedure. The user shall
have the capability to manually set the frictional loss coefficients.
The frictional losses shall be compensated for over the entire speed range.
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Specifications for Electric Chassis Dynamometers
The frictional losses shall be modeled by the following equation:
F =a +b*v+c*v +d*v + e * (m * dv/dt) (See Note)
o o o o o o
where:
F = total dynamometer frictional losses outside the force control loop
a = constant frictional loss coefficient
o
b = frictionai loss coefficient dependent on velocity
c = fricrionai loss coefficient dependent on velocity squared
d = frictional loss coefficient dependent on velocity cubed (optional)
e = frictional loss coefficient dependent on acceleration
m = effective vehicle mass, taking the rotational masses into account
v = velocity of the roll surfaces
Note: Frictional losses shall be determined on each roll, incremental mechanical inertia,
and coupler and shall be compensated for in the road load function. These losses shall also
be determined as a function of the acceleration power transfer.
The system shall support polynomial fits up to 3rd order.
The dynamometer processor shall retrieve historical data sets from on-line disk storage or
from a remote server.
The prevailing dynamometer rotational direction shall be part of the stored calibration data,
as well as a specific date/time stamp associated with each run.
All dynamometer loss coefficients shall be part of the long-term data storage, and shall be
readily available for trend analysis and quality control functions.
3.2.2 Self-motoring Mode
The motor-absorber system shall motor both the roll(s) and the inertia system. This shall
allow the following procedures to be executed, at a minimum-
- vehicle alignment
- dynamometer warm-up
- coastdown and acceleration tests
- speed signal checks
- dynamometer calibration
- dynamic torque verification
- system response characterization
The desired acceleration/deceleration rate and final speed shall be specified by the operator
and automatically controlled through the dynamometer processor.
The roll(s) shall be motored, or "jogged", during vehicle alignment by use of a momentary
contact device.
The motor-absorber shall be capable of accelerations and decelerations of the base
mechanical inertia at any rate between 0 and 10 mph/sec.
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Specifications for Electric Chassis Dynamometers
3.2.3 Dynamometer and Vehicle Coastdown Test
The dynamometer shall perform continuous or incremental coastdown tests. These tests
shall be performed with or without a vehicle on the roll(s). If a vehicle is used, the
transmission shall be in neutral during the coastdown.
During the coastdown test, the dynamometer shall achieve a stabilized speed above the
selected upper speed limit (v^p^.) and then coast down to the selected lower speed limit
(vlower) ^der *"* influence ofthe selected road load model Speed, torque, acceleration,
time, and other pertinent data shall be digitally recorded or logged at the specific sampling
rate (0.1 or 1.0s) for subsequent regression analysis.
The maximum vupper shall be 80.0 mph.
The minimum Vjowef shall be 5.0 mph.
The minimum vmtervaj shall be 5.0 mph.
The coastdown range is vupper to vlower
The number of coastdowns to be performed shall be selectable by the operator.
At the conclusion of each coastdown the following values shall be displayed, at a
minimum;
For the selected coastdown range:
- the upper and lower speeds of the range
• the elapsed range time: t - t
upper lower
- calculated coefficients a , b , andc using the coastdown data of the entire
00 O
curve
For each selected speed interval within the coastdown range:
- the upper and lower speeds of the interval
- the elapsed interval time: t - t
vl V2
- actual absorbed horsepower
- difference between motor-absorber power and actual absorbed power.
The operator shall have the ability to automatically conduct the standard coastdown test as
defined in 40CFR §86.118-78. Tide 40: Chapter I - Environmental Protection Agency,
Pan 86, Subpart B, Section-86.118-78 - Dynamometer Calibration.
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Specifications for Electric Chassis Dynamometers
3.3 Interface with Master/Host Computer System
The dynamometer processor shall have the ability to communicate using, at a minimum, an
RS-232 interface to a master/host computer system. IEEE-488, RS-422, Ethernet, and
Appletalk are acceptable supplemental protocols. The specifications for the RS-232
communication to the master/host computer shall be as follows:
selectable baud rate(s): 1200, 2400,4800, 9600, or 19200 bits per second
selectable character size: 7 bits, or 8 bits
selectable parity: even, odd, or none
selectable parity bit* 0 bit, or 1 bit
The dynamometer processor shall exchange all necessary information, including
commands, data, error messages, and reports with the master/host computer system. The
dynamometer processor shall provide the remote computer system with the following
values, at a minimum:
- all site and vehicle data relevant to the test setup
- operation mode
- data set name of road load model
• mechanical, electrical, and total inertia simulated on each roll
- coefficients of road load model
• coefficients of dynamometer loss curve on each roll
- the effective rolling radius of the tires, as determined under minimum load (neutral
coast down or steady speed motoring) at 50 mph.
The dynamometer shall be operational in a remote mode with minimal interaction by the
operator. In this mode, any test data or commands that must be entered to configure or
control the dynamometer for a test may be accessed from a remote computer system instead
of from the dynamometer processor's input devices, such as keyboard, keypad, or mouse.
3.4 Real-Time Data Monitoring
During dynamometer operation, the following real-time data (either as analog, digital, or
computed data) shall be available for a remote computer, either directly from the
dynamometer hardware or from the dynamometer processor for each roll(s):
- wheel speed and accel/decel rate
- front/rear roll speed and accel/decel rate (actual and demand)
(twin roil dynamometer)
- roll speed and accel/decel rate (actual and demand)
(single roll dynamometer)
- torques (actual, demand, and error)
- horsepowers (actual, demand, and error)
- inertia simulations (actual, demflfHit and error)
-distances (roU revolutions pulses)
- status of roll brake (on, off)
-status of vehicle lift (up, down)
- status of local/remote control (local, remote)
The dynamometer system shall log or store data for later batch transfer as a tab delimited
text file or in a compatible format to a remote computer.
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Specifications for Electric Chassis Dynamometers
3.5 Electric Dynamometer Data Acquisition Package
Each dynamometer shall be supplied with a separate microcomputer capable of running the
EPA Video Driver's Aid (VDA) application module and accessing the VDA file server via
the EOD Laboratory Network System. This microcomputer system shall collect the
dynamometer speed signals and monitor all other test parameters. The system (or
equivalent) shall include, at a minimum-
-One Macintosh ELfx chassis with 6 NuBus slots, 8 MBytes RAM, 210MB internal disk,
and extended keyboard.
-One Color monitor 19" or larger diagonal screen at 70-75 pixels per inch, including video
card(s).
-One Lab View 2.0 (runtime) or later software to access data from the NuBus hardware.
-Three NuBus cards from National Instruments
NB-MIO-16XL18, NB-MIO-16XH18, and NB-DMA2800
-One NB Series RTSI Bus cable from National Instruments
-Two SSR (8 module mounting racks) with SC-2050 Adapters and 2 CB-50 Terminal
Strips
-One NuBus card to enable Ethernet communications
-One NuBus card to generate the video signal for a color projector to display the VDA trace
as a rear screen image from outside the vehicle test celL
One system shall be used in the instrumented vehicle for the acceptance testing. Therefore,
it shall be shipped to EPA a minimum of 60 days prior to commencement of contractor
performance testing.
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Specifications for Electric Chassis Dynamometers
4.0 Acceptance Tests. Procedures, and CHtfHa.
4.1 General Acceptance Provisions
The contractor shall complete all performance tests before shipment of the dynamometers)
to EPA.
The contractor shall supply complete procedures for performing parasitic loss corrections
for EPA review before beginning any testing.
The contractor shall supply all collected data for EPA review before shipment of the
dynamometers). EPA shall complete all reviews within 15 days of receipt
EPA shall reserve the right to observe the performance testing at the contractor's facility.
The contractor shall give the EPA Project Officer a minimum of 15 days written notice prior
to the start of any performance testing.
No authorization to ship the dynamometers) shall be made until acceptance of the
dynamometer's performance is approved by the EPA Project Officer. The contractor shall
accept full responsibility for any equipment, supplies, or materials shipped prior to
Government approval
4.2 Testing Requirements and Overview
EPA shall reserve the right to waive specific testing if other means or data are available to
verify the criteria and/or performance.
Appendix A is a cross reference guide to specific dynamometer requirements and the
subsequent tests which will be used to verify the requirements.
4.2.1 Reporting
The contractor shall submit a report to the EPA Project Officer for each dynamometer
within 30 days of completion of the contractor's performance testing. The report shall
contain, at a minimum, all information required under Sections 4.2.4 and 4.3, as well as:
A. A complete description of all parameters related to and including the raw test data
collected including:
1. Test dates
2. Personnel
3. Location (test site and dynamometer serial number)
4. Ambient conditions (including time of day, barometer, temperature, and
humidity)
5. Exact tire specification and configuration [tire pressure, tire radii (free-
hanging, flat surface, and dynamometer roUer-to-axle center)]
6 Axle loads (both drive and non-drive)
7. Total empty vehicle weight
8. Driver weight
9. Percent fuel fill and tank capacity (in gallons)
10. Vehicle drive axle brake and bearing drag
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Specifications for Electric Chassis Dynamometers
B . A summary table for the testing results (Section 4.4.3.5) indicating all speeds and
torque measurements and statistics on the repetitive tests.
C . All setup parameters used in the configuration of the subject dynamometer to
perform the requirements of Section 4.0.
D . A complete list of all test and signal conditioning equipment, including make, model
number, resolution, and measurement rates for each parameter.
4.2.2 Vehicle Torque Wheel System
A vehicle shall be instrumented with torque wheels for the tests in sections 4.4.3.2 thru
4.4.3.5. The wheel torque measurement system shall have a torque reading resolution of ±
0.05% of each dead weight data point when calibrated using certified weights (±0.1%
accurate), traceable to an international standards organization. The dead weight calibration
shall have uniformly spaced calibration points from marimnm to minimum and all response
readings shall deviate less than 0.2% of point for each calibration point (from -100 to +100
percent of the torque transducer's full scale) for both positive and negative torque
calibrations. Weights shall be applied both sequentially and in random order as shown in
the table below, in percent of full scale:
Positive
Load Unload
zero/shunt
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
zero/shunt
zero/shunt
-10%
-20%
-30%
•40%
-50%
-60%
-70%
-80%
-90%
-100%
Negative
Unload
-100%
-90%
-80%
-70%
-60%
-50%
-40%
-30%
-20%
-10%
zero/shunt
Random
20%
80%
30%
zero/shunt
-80%
-30%
-100%
zero/shunt
10%
90%
60%
-40%
-10%
-20%
zero/shunt
50%
40%
1 00%
zero/shunt
-30%
-80%
-90%
The torque wheel system shall totalize wheel revolutions and vehicle positive and negative
torque separately, as well as sampling wheel angular speed and torque at least 20 rimes per
second.
The speed used for a driver's trace and the speed used for the dynamometer load setting
control loop shall be synchronized within ±0.1 mph for all required tests.
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Specifications for Electric Chassis Dynamometers
4.2.3 Data Acquisition
The contractor shall provide a vehicle with a General Motors five lug bolt pattern on the
wheels (4.5" center-to-center spacing between every other lug nut) to measure and record
test data using R14 wheels and steel belted radial tires. Test data shall be collected using
torque wheels and data acquisition equipment supplied by EPA. EPA will use a Macintosh
Hx computer with National Instruments 16-bit resolution hardware and Lab VIEW 2.0
software to acquire all data.
4.2.4 Data Analysis and Presentation
All testing results shall be supplied with summary tables containing the following, at a
minimum!
1 . Elapsed Time (seconds; xxx.xx)
2 . Driver's Trace and Vehicle Speed (mph; xjutx)
3 . Wheel Encoder Frequency (Sample Period Hz and Total Counts)
4 . Wheel Angular Velocity and Accelerations (mph, mph/sec ; xxxx)
5 . * Front Roll Encoder Readings (Sample Period Hz and Total Counts)
6. * Front Roll Velocities and Accelerations (mph, mph/sec ; xx.xx)
7 . * Rear Roll Encoder Reading (Sample Period Hz and Total Counts)
8 . * Rear Roll Velocities and Accelerations (mph, mph/sec; xx.xx)
9 . Power Absorption Unit Torque (Ft-Lb; xxxjc)
1 0. Power Absorption Unit Horsepower (hp; xx.xx)
1 1 . Power Absorption Unit Amperage (Amps; xx.xx)
1 2. Vehicle Wheel Torque (Ft-Lb; xxx.x)
1 3 . Vehicle Wheel Horsepower (hp; xx.xx)
1 4. Drive Trace Roll to Vehicle Drive Wheel Angular Velocity Ratio
15. All Dynamometer Settings
* Note: On a single roll dynamometer, a single roll reading shall be supplied.
The specified data for all tests shall be supplied in tab delimited ASCII text files as a
function of sample collection time, sampled at least 20 times per second. The data may be
recorded in SI or English units and convened to the units specified above providing the
resolution and format of the raw data complies with the required specifications.
4.3 Component Review and Qalihrarinn Tests
4.3.1 Installation and Mechanical Review
Typiral installation diagrams and pit cp*^ifirarinns shall hg pmvuierf fnr evaluation Final
installation diagrams and pit specifications shall be provided with the requirements of the
performance data.
4.3.2 Structural and Dimensional Review
4.3.2.1 Frame
Frame deflection shall not adversely affect dynamometer performance or operation. Front
and rear roll parallelism and alignment shall not change over the range of test vehicles the
dynamometer is capable of testing. Engineering data and/or analysis shall be provided to
document this requirement.
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Specifications for Electric Chassis Dynamometers
4.3.2.2 Bearings and Lubrication
Motoring torque versus elapsed time data shall be provided to document this characteristic.
Parasitic losses shall be stable to within ± 0. 1 hp in ten minutes or less at an average speed
of 50 mph, after the dynamometer is started from a two-hour idle period, with a
dynamometer enclosure temperature of 70-80 °F. Stabilized bearing friction shall remain
constant within ± 2% between the dynamometer contractor's recommended calibration
periods for vehicle test environment temperatures between 0 and 100 °F. The contractor
shall include the parasitic calibration frequency per 1000 miles of use needed to eliminate
changes > 0. 1 hp at 50 mph.
4.3.2.3 Roller Geometry
The contractor shall document physical measurements that confirm dimensional
requirements such as diameter, roller set parallelism, roll spacing, and surface finish.
4.3.3 System Operation ?nd ("alifrrarinn Review
The contractor shall submit, for EPA review, the torque, speed, and acceleration calibration
procedures as well as the proposed electrical and base mechanical inertia simulation
verification procedure 15 days before the performance and submission of results from
calibrations.
4.3.3.1 Mechanical Inertia Determination
The contractor shall supply a complete summary of all physical components of the
dynamometer and their individual contribution to total calculated mechanical inertia. The
description shall include diagrams of physical layout and specific definition of which
components are inside or outside the dynamometer's control loop.
The contractor shall provide verification of physical measurements to document that
components have been built to specification. The total system inertia for each flywheel
combination shall be verified to ± 0. 15% of stated value. The total system inertia shall be
verified through dynamic tests using the dynamometer system.
The contractor shall submit documentation that the mechanical inertia weights are balanced
to within the tolerances specified by the balance quality level specified in Section 1.7. The
documentation shall contain the actual procedure and data or information generated as proof
of compliance with this requirement.
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Specifications for Electric Chassis Dynamometers
4.3.3.2
Torque Cell Calibration
The contractor shall provide all measurement data including documentation of the effective
fixture arm length. The dead weight calibration shall have uniformly spaced calibration
points from maximum to minimum. All calibration points must be accurate to < ± 0.1 % of
full scale (FS) for each calibration point (from -100 to +100 percent of the torque
transducer's FS) for both positive and negative torque calibration weights. Calibration
weights (± 0.1 % accurate) shall be directly traceable to an international standards
organization. On both positive and negative torque calibrations, weights shall be applied
both sequentially and in random order shown in the table below, in percent of full scale.
The contractor shall supply data to substantiate that the dynamometer torque measuring
system satisfies the following requirements:
Positive
Load
zero/shunt
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Unload
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
zero/shunt
zero/shunt
-10%
•20%
-30%
-40%
-50%
-60%
-70%
-80%
-90%
-100%
Negative
Unload
-100%
-90%
-80%
-70%
-60%
-50%
-40%
-30%
-20%
-10%
zero/shunt
Random
20%
80%
30%
zero/shunt
-80%
-30%
-100%
zero/shunt
10%
90%
60%
-40%
-1 0%
-20% •
zero/shunt
50%
40%
1 00%
zero/shunt
-30%
-80%
-90%
4.3.3.3
Hysteresis
Repeatability
Non-Linearity
Zero and Shunt Drift
Rise Time to 90% of Load
Time Constant
Toraue Transducer Virtual Snan & Zero
±0.1% of full scale
±0.05% of full scale
±0.1% of full scale
±0.1% over 24 hours
< 10
< 50 milliseconds
Dynamometer controller software calculations may be used to minimize torque transducer/signal
conditioning drift The following equations describe this software technique. Other methods may
be described or proposed if shown to produce comparable results. If the contractor utilizes any of
these techniques, test data shall be provided to verify the accurate performance.
Vm(G)
B
where:
V. = Corrected Output
V = Measured Output
m T
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Specifications for Electric Chassis Dynamometers
G =
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Specifications for Electric Chassis Dynamometers
A maximum shock loading test shall be performed, to establish the structural integrity of all
system components. This test sequence shall consist of:
1. The dynamometer, set at its base inertia weight, shall motor itself from 0 to 60 mph
at the maximum motor hp and the emergency stop shall be activated to decelerate the
dynamometer to zero mph five consecutive times within one half hour.
Immediately followed by:
2. A vehicle shall be properly positioned and normally restrained on the dynamometer.
The vehicle shall be operated at wide open throttle for approximately five seconds,
then the vehicle brakes locked for approximately one second (until the driver's trace
speed decreases discernibly). This sequence shall be repeated until the vehicle's
speed reaches 60 mph.
4.4.2 Electrical Inertia Simulation Response
Simulation response shall be reported as the dynamometer torque response to a simulated
step change in speed signal The response definitions are contained and illustrated in
Appendices E and F. The inertia settings shall be base mechanical inertia, 2,000 and 5,500
Ibs. Six mph/sec and 0.5 mph/sec acceleration and deceleration sawtooth profiles and
square wave steady speeds shall be simulated using a signal generator.
Response time in all cases shall be less than 100 milliseconds.
4.4.3 Operational Response Characterization
4.4.3.1 Dynamometer Self-motoring
The following tests shall be performed before shipment.
A. Parasitic Losses Determinations and Stability:
The dynamometer shall assess and compensate for the vehicle loads that are attributable to
tire/roller and dynamometer mechanical parasitic losses. The following tests are designed
to simulate daily use and subsequent stability of the dynamometer parasitic losses.
The subject dynamometer shall perform coastdowns (with and without a vehicle), with all
dynamometer load coefficients set at zero, and calculate the equation of parasitic losses
(Ibs. force) from 60 to 10 mph. The dynamometer shall accept a target total vehicle road
load curve and r^Vp"toff the required coefficients necessary to match the vehicle load curve
and compensate for the previously calculated parasitic losses.
Once the dynamometer has been warmed according to the contractor's published
procedure, the dynamometer shall perform a no load coastdown (at dynamometer base
inertia weight) and rai^niqw the coefficients to describe die parasitic losses.
An assessment of the parasitic friction transient behavior shall be performed The
dynamometer shall be allowed to sit for a minimum of two hours. The dynamometer shall
then motor itself through a series of steady speeds each 30-seconds in duration, at 10, 20,
30, 40, 50, and 60 mph, followed by a no load neutral coastdown from 65 to 10 mph. The
steady state/coastdown sequence shall be repeated for a total of five sequences performed
within one hour.
NOTE: If the coastdown exceeds five minutes with no electrical load, a constant electrical
force may be applied to limit the coastdown to five minutes.
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Specifications for Electric Chassis Dynamometers
On the final sequence following the 60 tnph steady state, the dynamometer shall motor
itself to 80 mph within ten seconds and maintain this speed for 30 seconds prior to the no
load neutral coastdown.
The data supplied shall verify all coastdown calculation capabilities.
B. Steady State Verification of Parasitic Friction Stability:
The measured steady state horsepower values after ten minutes shall be within ± 0. Ihp of
the stabilized values, calculated using the dynamometer-produced parasitic loss equation.
C. Mechanical Base Inertia Verification:
The dynamometer shall be programmed to operate at its base inertia weight (Base inertia
shall be defined as the inertia weight with no electrical or incremental mechanical inertia
engaged.) Using a constant acceleration rate the dynamometer shall accelerate to 65 mph
and then decelerate at the same rate to 0 mph. The collected force data shall be corrected for
the parasitic forces and then used to verify the mechanical base inertia by the following
equation:
Force = (— ) a
vg'
where:
W = Base Inertia Weight (Ibs)
g = Gravitational Constant (32. 17 ft/sec2)
a = Accel/Deed Rate
combining with g produces the following calculated inertia equation:
= F / 0.045585(dV/dt)m
where:
= CalCTitosqd Mechanical Inertia Weight (Ibs.)
= Sample Interval Net Roller Surface Force
Measured by Dynamometer (Ibs.)
3 Measured Interval Acceleration (mph/sec)
The accel/decel procedure shall be repeated five times at rates of 1, 3, and 6 mpn/second or
whichever of these rates the dynamometer can achieve, as well as the maximum
dynamometer motoring horsepower.
The avenge value of Wcafced at each accel and deccl rate shall be within ± 0.2% of the
contractor's specified Base Inertia Weight. These tests shall be applied to verify the
incremental trtf^^m"!^! Jivcr"3 values available.
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Specifications for Electric Chassis Dynamometers
D. Verification of Friction Compensation:
Friction compensation accuracy shall be checked with a warmed dynamometer and all road-load
simulation coefficients (F = A + BV + CW) set to zero for each of three separate inertia weight
settings (Base Inertia Weight, 2000 Ibs., and 5500 Ibs.). After motoring to 50 mph, the
dynamometer shall be switched to road simulation mode and shall compensate for all parasitic
losses. Speed drift versus time shall be used to determine the compensation error.
ferror = compensation error Obs) = m (AV) (0.045585VAt
where: m = actual inertia
A V = speed drift (mph)
At = time over speed change (sec)
In addition, the friction compensation accuracy shall be recorded at steady speeds of 10.
20, 30,40, and 60 mph for each of the above inertia settings.
The compensation error at each speed shall not exceed the equivalent of ± 0.1 hp at any
steady state speed.
E. Road-Load Curve Simulation and Repeatability:
Accuracy and repeatability of the road load curve shall be determined from five separate 65
to 10 mph continuous neutral coastdown tests (without a vehicle) at each load setting from
below. Coastdown force shall be determined at speeds of 60, SO, 40, 30, 20, and 10 mph.
The error (e0 at each coastdown point is the difference between the calculated force and the
measured coastdown force:
_ — B P
°i ~ r calced" rm
Fcatei
Fm =(0.045585) (I) (dV/dt)
where:
dV/dt = Measured (or calculated) Sample Interval
Acceleration (20 samples/sec sampling rate)
I » Inertia weight setting Obs)
The following road-load horsepower and inertia conditions shall be measured:
DYNAMOMETER BASE INERTIA
A » B = C =4) and I = Dynamometer Base Inertia
LDV MINIMUM
A = 26.25 lb., B = C = 0, and I = 2,000 Ib.
LDV MAXIMUM
A = 187.5 lb., B = C = 0, and I» 5,500 lb.
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Specifications for Electric Chassis Dynamometers
. Accuracy shall be defined as the average force error. Repeatability shall be defined as two
times the standard deviation, for each speed point
Coastdown accuracy and repeatability versus speed shall be documented for the minimum
and maximum force curves and shall not be significantly different, at a 90% statistical
confidence level, from the subject dynamometer's own accuracy and repeatability at its base
mechanical inertia weight setting.
4.4.3.2 Steady State Speed Loading
This shall be performed before shipment, with a vehicle.
The stabilized dynamometer shall be programmed with two loading curves (see Appendix
B Figure 2). The contractor shall perform steady state tests ranging from 10 to 60 mph in
five mph increments. Each shall be of 30 seconds duration, (ascending or descending
order) for each dynamometer load set curve. Five replicates of each run shall be recorded.
All load setting and driver's trace speed signals shall remain within ±0.1 mph during the
data recording periods.
The dynamometer and vehicle wheel force data from each steady state/speed shall be
graphed versus speed (mph). The dynamometer force data from five runs shall be within
± 1 % of a curve of the mean values (from 10 to 60 mph) for the five replicate runs. The
mean values for each speed increment shall be calculated by the formula in the example at
the end of this section. The data shall be graphed in the same manner as shown in
Appendix C, Figure 4.
4.4.3.3 Fixed Acceleration Rate
This shall be performed before shipment, with a vehicle.
The dynamometer shall compensate for all dynamometer and vehicle tire/roll interface
parasitic losses (i. e., the measured wheel uxque, at steady state speeds, shall equal 0).
The vehicle shall accelerate the dynamometer for 2000 and 5500 pound inertia weight
settings. The contractor shall perform acceleration test sequence.* for 1, 3, and 6 mph/sec
accelerations from 0 to 60 mph. The sequences shall consist of one run per acceleration
rate and inertia setting (six runs).
The dynamometer roller force and vehicle wheel force data from each acceleration shall be
graphed versus the dynamometer acceleration rate (dV/dt). Ail dynamometer roller force
data shall be within ± 1 % of a curve of the calculated force values versus acceleration rate.
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Specifications for Electric Chassis Dynamometers
The vehicle wheel force data shall not exhibit a variability greater than that exhibited for the
same acceleration rates performed under test track conditions. Each ideal inertial
acceleration force value shall be calculated by the following formula:
= M^t (0.045585)(dV/dt)
where:
= Calculated Instantaneous Force (Ibs.)
M«a = Set Inertia Weight flbs.)
dV/dt = Measured (or calculated) Sample Interval Acceleration
(at 20 samples/sec sampling rate)
See Appendix C Figure 3 for an example of how the data shall be graphed.
4.4.3.4 Neutral Coastdown Rolling 1
This shall be performed before shipment, with a vehicle.
The contractor shall perform neutral coastdown tests from 65 to 10 mph consisting of five
replicate runs per inertia weight using the load curves and inertia weights (2000 and 5500)
used in Sections 4.4.3.2 and 4.4.3.3.
The dynamometer and vehicle wheel force data shall be graphed versus dynamometer
speed. The dynamometer roller force data shall be within ± 1 %of a curve of the mean
values (from 60 to 10 mph) for the five runs. The data shall be graphed in the same
manner as in Appendix C, Figure 4.
4.4.3.5 Urban Dynamometer Driving Schedule fUDDS-505 seconds)
This shall be performed before and after shipment, with a vehicle.
Testing at the contractor's facility shall consist of the collection of the same data on each
dynamometer which the contractor shall deliver under this contract. Each set of 4WD
dynamometer roll(s) shall be tested in the 2WD dynamometer configuration.
The testing shall be conducted on a dynamometer with a vehicle using load curves and a
test inertia weight specified by EPA. A minimum of five sequential UDDS - 505 tests shall
be run for each test specified.
The data required under Sections 4.2.1 and 4.2.4 shall be logged at a sample rate of 20Hz
and stored in a disk file by the system computer for the first 505 seconds of the UDDS.
The collected data shall be supplied to EPA for review and evaluation. Statistical analysis
of the replicate tests shall be performed by EPA to quantify the performance characteristics
of the dynamometer/vehicle system operating under transient driving schedules. The
contractor shall correct all performance deficiencies that are found to be statistically
significant relative to the other dynamometers produced and tested.
Real Time Performance Monitor
The dynamometer controller software shall perform the following analysis of the force
error profile. Statistics on the values of the force error versus reference force and velocity
shall be generated. The dynamometer software shall report the minimum, maximum,
average, standard deviation, and number of values collected for the force error for each ten
mph speed interval during the test phase. The contractor shall state the calculation
frequency and cutoff speed used for data acquisition. This technique shall be used to
monitor all tests.
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Specifications for Electric Chassis Dynamometers
System performance shall be verified through the analysis of the force error signal The
equation for the force error signal is as follows:
Em =100*(Fm-Fr)/Fr
where:
Em = Force Error Signal
Fm = Measured Force
Fr = Reference Force
Measurements shall be made during each vehicle UDDS • 505 seconds sequence performed
in this section.
The average force error signal over the UDDS - 505 seconds shall be within ± 1% o"cr the
entire speed range.
Page 28 6/5/91 4:50 PM
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3.
4.
Appendix A
Electric Dyno Acceptance Cross Reference
Ambient Conditions Operation
a. Narrative
Wheel Base Adjustment
a. Within ±0.08'
Roll Balance
IW Determination
3.
4.
5.
Speed Measurement Accuracy
a. ± 0.0.5 MPH
Acceleration Measurement
a. 0-10 MPH/see Range
b. t 0.01 MPH/sec Accuracy
Elapsed Tune
a. ±0.01 seconds
Torque
a. ± 0.2 ft-Mrain 1000 samples/sec)
b. ±0.1% hysteresis
c. ±0.1% zero shunt drift
d. ±0.1% Repeatability
±0.1% Linearity
e.
ResponM
a. < 100 msec to 90%
1. Align Vehicle Procedure
2. Warm-Up
3. Coastdown/Acceleration
a. Any from 010 10 MPH/sec
OR Max Avail power
(1.3.6 MPH/sec Accels)
b. Base Inertia Verification
4. From Panel by Operator
5. Steady Stales Parasitic Losses Stability
a. Shall remain < 10.1 HP (ALL Speeds)
Tests Performed With a Vehicle
1. Inertia Simulation
a. Parasitic Losses Compensated
b. 2000 & 5500 Ibs IW
( 1. 3.6 MPH/sec)
c. M»F/(dV/dt)
2. Acceleration Me
a. Include Zero
b. Within 1001
3. Response
a. < 100 millisec lag to 90%
1. Road Load Simulation Accuracy
a. Repeauole ± 1%
2, Access coefficients within
10
1. Rofl Synchronization
±0.1 MPH ALL Tests
2. Restraint System
1. Road Load plus Inertia Simulation
a. ±1% of Value Set
1 Max Velocity 80 MPH
3. Min Velocity 5 MPH
4. Min Interval 3 MPH
5. Data Display
a. Upper A Lower Speeds of Range
and Interval
b. Elapsed Tune
c. Caked Coeffieats
d. Actual Power Absorbed
1. Test Distance
a. ±1 Point in 2000
2. Positive Load Repeatability
3. Negative Load Repeatability
4. Error Signal Verification
-------
Appendix B • Figure 1 Dynamometer
Response Rise and Settling Time Illustration
Rise Time
•Settling Ti
Elapsed Time
Appendix B • Figure 2
Steady State Dynamometer Load Curves
J3
t in.
100-
90.
80.
70.
60
50
40
30
• '
^
9^
X
V
s
/,
V
f
>
/
J
/
/
//
Y
• Dynamometer Load Curve #1
F = 39.504 + 0.11258V * 1.5581e-2V*2
• Dynamometer Load Curve #2
F = 26.752 - 6.1254*-5V * 22903e-2V*2
Speed(MPH)
-------
Appendix C - Figure 3
Force verses Acceleration (dV/dt)
e
a
o
Ideal Calculated Force (Set Inertia Weight)
• "^™" -1% Minimum Limit
+1% Maximum Limit
Actual Measured Force
dV/dt
Appendix C - Figure 4
Example of Mean Force Value Graphs
V)
I.
4)
-------
Appendix D
Symbols and Specification Terminology
SYMBOLS
A
a
B
b
C
c
D
F
FE
FEF
g
M
n
P
r2
S
sin 9
t
dt
At
V
VE
dV
DV
W
0)
dV/di
du/dt
UNITS
Constant rolling resistance parameter
Constant friction characteristic
Speed proportional rolling resistance parameter
Speed proportional friction characteristic
Speed squared (wind) resistance parameter
Speed squared friction characteristic
Parameter for braking and miscellaneous forces
Thrust parallel to road or tangential to roll
Force Error
Force error fraction
Gravitational acceleration
Effective mass
Number of data points
Power transmitted through roll surface
Regression coefficient
Distance roll surface moved since distance counter reset
Sine of hill angle above (+) or below (-) horizontal
Time
Derivative of time
Finite time interval
Speed over road or roll surface
Speed error
Derivative of speed
Finite change of speed
Gross weight of vehicle including passengers
Angular velocity
Linear acceleration
Angular acceleration
N, Ib
N, Ib
N/kph, Ib/mph
N/kph, Ib/mph
N/(kph)2, lb/(mph)2
N/(kph)2, lb/(mph)2
dimensionless
N, Ib
N, Ib
dimensionless
9.807 m/sec2 or 35.32 kph/sec
32.17 ft/sec2 or 21.93 mph/see
N, Ib
kW.hp
dimensionless
m, ft
dimensionless
sec
sec
kph, mph
kph, mph
kph, mph
kph, mph
N, Ib
rads/sec
m/sec2, ft/sec2
rads/sec2
Subscripts
a
c
d
g
i
m
o
R
1, 1-2, 2-3
Average
Device which provides load in a complex chassis roll system
Correction for gravitational and engineering units:
Multiplied by 35.31 kph/sec in SI
OR
Multiplied by 21.93 mph/sec in Imperial system
Inside control loop
Measured
Outside control loop
Road equivalent
From point 1, 1 to 2, 2 to 3, etc.
-------
Appendix E
Glossary of Acceptance Criteria Terminology
Overshoot
Percent Overshoot
Delay Time
Rise Time (Tr)
Settling Time (Ts)
Time Constant (t)
Transport Lag (Tj)
Reaction Tune
Response Tune
The overshoot is the maximum difference between the transient
and steady-state output of a system in response to a unit step
input. Overshoot is a measure of relative stability and is often
represented as a percentage of the final value of the steady-state
output
where:
ss
peak value
steady state or final value of c(t)
The time delay is defined as the time required for the response to a
unit step function input to reach 50 percent of the final value.
The rise time is customarily defined as the time required for the
response to a unit-step function input to rise from 10 to 90 percent
of the final value.
The settling time is defined as the time required for the response to
a unit-step function input to reach and remain within a specified
percentage (frequently 2 to 5 percent) of its final value.
The predominant time constant is an alternative measure of settling
rime. The envelope of the transient response decays to 37 percent
of its initial value in t seconds.
The transport lag is the delay in the onset of a change in feedback
as a response to a change in system output
The system reaction nmg j$ defined as the minimum rime lag
between an input change and the resultant change in system output
and is the direct summation of the unrelated, forward transport
lags in the system. Reaction time is sometimes incorrectly
referred to as Response Time.
The response time is defined as the lag between an input change
and the time the response rises to 90 percent of the final value.
-------
RESPONSE CHARACTERISTICS OF A SECOND ORDER SYSTEM TO A UNIT STEP FUNCTION
Overshoot
Unit step input
Response tune
System reaction lime
Cftponentu!
envelope of
the transient
response
Rise unit I uiie constant
TJ
•o
A
a
a.
DcUy in i ic
Stilling nine u> wnliin
t K% of dual value
»•-- 2'Jt 01 *»%
-------
Engineering Operations Division Test Procedures
Gas Laboratory
Col A Col B
TP 101 Preparation of Gravimetric Binary Gas Mixtures
TP 105A Gas Naming
TP 403 Gas Correlation
TP 502 Gas Cylinder Change
Chemistry Laboratory
TP 106B Analysis of Alcohols Extracted from Gasoline
TP 108A Vapor Pressure of Gasoline and Gasoline-Oxygenate Blends
TP 109 Test for Lead-in-Gasoline by Atomic Absorption Spectrometry
Calibration and Verification
TP 202 Dynamometer Calibration - Frictional Horsepower
TP 204 Gas Analyzer Calibration Curve Generation
TP 205 Span Point Change Notice
TP 207A Dynamometer Calibration - Road Load Power Control Electronics
TP 210 Critical Flow Orifice Calibration
TP 211 Calibration, Operational Verification, and Preventive Maintenance of the
Leeds and Northrup Ambient Temperature Monitoring System
TP 213A Calibration and Verification of Digital Barometers
TP 214 Calibration, Operational Verification, and Preventive Maintenance of General
Eastern Dew-point Meters
TP 215 Dry Gas Meter Calibration
TP 302A Dynamometer Calibration Verification
TP 303 Analyzer Monthly Curve Verification
Vehicle Emission Laboratory
TP 701B Vehicle Inspection and Acceptance
TP 702D Vehicle Fuel Exchange
TP 703C Vehicle Preconditioning (Video Drivers Aid)
TP 704C Diurnal Heat Build (No Evap) Test
TP 705B Diurnal Evaporative Emission (Heat Build) Test
TP 707C Sample Collection of the Urban Dynamometer Exhaust Emission Test (Video
Drivers Aid)
TP 708C Sample Analysis of the Urban Dynamometer Exhaust Emission Test
TP 709C Hot Soak Evaporative Emission Test
TP 710B Sample Collection of the Highway Fuel Economy Test (Video Drivers Aid)
TP 711A Sample Analysis of the Highway Fuel Economy Test
TP 712A Quick Check Coastdown
TP 713B Sample Collection, Continuous Hydrocarbon Analysis, and Particulate
Collection of the Light Duty Diesel Test
TP 714A Diesel Particulate Filter Handling and Weighing
Please complete the back section before returning this form
-------
Engineering Operations Division Procedure Documentation Request
Please type or clearly print your name, mailing address, and business phone number in
the area provided below.
Please register my name on the Quality Control External Mailing. I wish to
receive future documentation for the procedures checked on the front of
this form.
Name:
Address:
Phone: Area Code (
-------
>*
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
ANN ARBOR. MICHIGAN 48105
May 23, 1986
OFFICE OF
AIR AND RADIATION
SUBJECT: Calibration and Maintenance Services
FROK:
TO:
David W. Perkins, Supervisor
Calibration and Kaintenance Group
James D. Carpenter, Chief
Facility Support Branch
Attached is a summary of the services currently provided by the Gas
Analysis Lab. It covers the service, tolerances, frequency and it identifys
the group to whom these services are provided.
Also attached, are updated versions of diagnostic and other test equipment
checks performed by the Calibration and Kaintenance Group.
If you have any questions or comments please contact me.
Attachments
-------
GAS LAB SERVICES
AREA
Provide NBS and Gravimebric standards
Provide Secondary standards
Provide working gasea
Provide specialty gases
Provide pure propane for CFO Kits
Provide FID fuels
Provide N2
Provide zero grade air
FREQUENCY
2 years or
as required
Renamed every
year or as
required
As required
As required
As required
As required
As required
As required
TOLERANCE
±0.52
±0.3*
+1.0%
less than 0.5$ contamination
+2% of 40-60# blend
less than 1 ppmC hydrocarbon,
1 ppm CO, 400 ppm C02 and
0.1 ppm NO contamination
18 - 2\% 02,less than 1 ppmC
hydrocarbons, 10 ppm CO, 400 ppm
C02 and 0.1 ppm NO contamination
GROUP COVERED
TPB, TEB(EOD),
SDSB(HD)
-------
-2-
AREA
Test Equipment Checks
FREQUENCY
I. Analysis System Checks
A. Blended Cas
Cross-check Bag (SAC)
Daily
B. CH^ Sample Correlation
C. NOx Analyzer Converter
Efficiency Check
D. NO/NOx Flow Balance
1. Check the NO and NOx response
with a known .concentration of
NO/NOx
E. CH4 Peaking and Characterization
1. CH4 SAE procedure J-1151A
2 Weeks
Weekly
4 months
3 months
Analysis Systems
TOLERANCE
GROUP COVERED
Response based on standard
deviation (sigma) levels
listed in QC comments.
Includes all laboratory
analysis sites.
Any reading outside of 3
sigma - immediate shut down.
Rerun of analyzers affected
after repair.
Two of three readings outside
of 2 sigma - Investigate within
1-2 days. Rerun of analyzers
affected after repair.
Four of five reading outside of
1 sigma - Investigate within
3-4 days. Rerun of analyzers
affected after repair.
Trends or biases - investigated
as time permits and at scheduled
monthly curve verifications.
Response based on the criterion
listed above.
TPB
minimum conversion of-
N02 to NO. Investigation
required below 95$ level.
NO should read
less than NOx,
+1 ppm from tag
Outlined in procedure
TPB, TEB (E&D),
SDSB (HD)
TPB, TEB (E«D)
SDSP (HD)
-------
-4-
AREA
TEST EQUIPMENT CHECKS - Analyzers
FREQUENCY TOLERANCE
II. Analyzers
A. HC
1. Calibration Gases
a. Zero - HC free air
b. Major - Air
c. Minor -
2. Types of PIDs
a. Cold PIDs
l) Bag Measurement
2) SHED Measurement
b. Heated FIDs
l) Diesel Measurement
3. Types of Fuels
a. H2/N2 Bag
b. H2/He Diesel & SHED
4. Flow
a. 4 scfh bypass
5. Verifications
6. New Curves
Monthly
As needed
Per Proc. 303
Per Proc. 204 A1
GROUP COVERED
TPB, TEB (E&D),
SDSB (HD)
TPB, TEB (BSD),
SDSB (HD)
TPB, TEB (E«D),
SDSB (HD)
TPB, TEB (E«D),
SDSB (HD)
TPB, TEB (BAD),
SDSB (HD)
TPB, TEB (E*D),
SDSB (HD)
1. Per final draft issued 6/1/82.
-------
TEST EQUIPMENT CHECKS - Analyzers
-5-
ARFA
FREQUENCY
TOLERANCE
GROUP COVERED
a. Curve Fit Deviations^
b. Degree of Fit
c. Number of data points
Special checks
a. Methane Response
B. C02
1. Calibration Gases
a. Zero - N2
b. Major - N2
c. Minor - C02
2. Optical Filter
3.
4.
a.
Cell Length
a. 0.3 inch
Flow
Monthly
Secondaries +1% of point.
On-line working gas + \%
of Nominal concentration
Ave. Dev +0.5% of point
3rd
7 or more including zero.
1.10 to 1.20?
TPB, TEB (E&D),
SDSB (HD)
TPB, TEB (BSD),
SDSB (HD)
TPB, TEB (BSD),
SDSB (HD)
TPB, TEB (E&D),
SDSB (HD)
TPB, TEB (ESD),
SDSB (HD)
2. In special cases or ranges tolerances can exceed these limits, but still meet Federal Register tolerances on
non-certification sites.
3. Ratio of the response to a 50 ppm CH^ cylinder. Response in C^Hfl x .3
C}?4 Concentration of the cylinder
-------
-6-
AREA
5. Verifications
6. New Curves
a. Curve Fit Deviations^
b. Degree of Pit
c. Number of data points
d. Nonlinearity
7. Special C(>2 Curves
Monthly Updates*
CO (LCD & HCO)
1. Calibration Gases
a. Zero - N2
b. Major - N2
c. Minor - CC-2
2. Optical Filters
a. HCO (MSA)
1) CaF2
b. LCO (Bendix)
l) Optical and Band
Pass Filter
TEST EQUIPMENT CHECKS - Analyzers
FREQUENCY TOLERANCE
Monthly
As needed
As needed
Per Proc. 303
Per Proc. 204A1
Secondaries +1% of point.
On-line working gas +_ 1$
of Nominal concentration
Ave. Dev K).5^ of point
3rd
9 or more including zero.
Less than 15.0$
•••0.1 defections
GROUP COVERED
TPB, TEB (ESD),
SDSB (HD)
TPB, TEB (E«D),
SDSB (HD)
TPB
TPB, TEB (BSD),
SDSB (HD)
TPB, TEB (ESD),
SDSB (HD)
1. Per final draft issued 6/1/82.
2. In special cases or ranges tolerances can exceed these limits, but still meet Federal Register tolerances on
non-certification sites.
4. Per EPCN No. 046 4/2/82
-------
AREA
TEST EQUIPMENT CHECKS - Analyzers
FREQUENCY TOLERANCE
-7-
GROUP COVERED
3. Cell Length
a. HCO (MSA)
1) 3.5 inch
b. LCD (Bendix)
l) 11 1/8 inch
4. Flow
a. 6 ecfh (HCO & LCO)
5. Verifications
6. New Curves
a. Curve Fit Deviations^
b. Degree of Fit
c. Number of data points
d. Nonlinearity
HCO * LCO
D. NOx
1. Gases
a. Zero - HC free air
b. Major - N2
c. Minor - NO
Monthly Per Proc. 303
As needed Per Proc. 204A1
Secondaries +1% of point.
On-line working gas +_ 1%
of Nominal concentration
Ave. Dev +0.5$ of point
9 or more including zero.
Less than 15.0$
TPB, TEB (BSD),
SDSB (HD)
TPB, TEB (BSD),
SDSB (HD)
TPB, TEB (E&D),
SDSB (HD)
TPB, TEB (E
-------
AREA
2. Plow
a. 2.0 1pm
3. Verifications
4. New Curves
a. Curve Fit Deviations^
b. Degree of Pit
c. Number of data points
E. CH4
1. Gases
a. Zero - HC free air
b. Major - Air
c. Minor - CJfy
2. Fuel
a. H2/He
3. Flow
a. 3.5 scfh
4. Verifications
TEST EQUIPMENT CHECKS - Analyzers
FREQUENCY TOLERANCE
Monthly
As needed
Per Proc. 303
Per Proc. 204A1
Secondaries +1% of point.
On-line working gas +_ \%
of Nominal concentration
Ave. Dev +0.5# of point
2nd
7 or more including zero.
-8-
GROUP COVERED
TPB, TEB (E*D),
SDSB (HD)
TPB, TEB (E&D),
SDSB (HD)
TPB, TEB (E&D),
SDSB (HD)
TPB, TEB (E«D),
SDSB (HD)
Monthly
Per Proc. 303
TPB, TEB (E
-------
-9-
Test Equipment Checks - Analyzers
AREA FREQUENCY TOLERANCE , GROUP COVERED
5. New Curves As needed Per Proc. 204A1 TPB, TEB (E&D),
SDSB (HD)
a. Curve Fit Deviations2 Secondaries +1# of point.
On-line working gas +_ 1%
of Nominal concentration
Ave. Dev +0.5% of point
b. Degree of Fit 2nd
c. Number of data points 7 or more including zero.
1. Per final draft issued 6/1/82.
2. In special cases or ranges tolerances can exceed these limits, but still meet Federal Register tolerances
on non-certification sites.
-------
Test Equipment Checks - VAST Diesel Site
-10-
AREA
FREQUENCY
TOLERANCE
GROUP COVERED
III. VAST Diesel Site
A. Blower (over Room 532)
1. Check oil level
B. Pump Operation
1. Check sample and fluid
pump operation
Weekly
Weekly
C. Bulk Stream Filter
1. Check the differential pressure Weekly
across the filter on the 700 cfm
range
D. A004 Operation
1. Check A004 zero, span, sample Weekly
E. A016 Operation
1. Check A016 zero, span, sample Weekly
F. Temperatures and Oven
1. Check the system temperatures Weekly
G. Tunnel Inspection
1. Visually inspect the tunnel 6 Months
D. Motors on Pumps and Circulators
1. Oil each motor and pump bearing 3 Months
E. Meter Calibration
1. Check fuel dispensed with 6 Months
5-gallon standard
F. Temperature Calibration
1. Check fuel temperature with 6 Months
temperature standard
Add or change
as needed
Less than 6" 1^0 drop
+0.2 deflection
+0.2 deflection
As posted
Clean as needed
+ 0.1 gal
+ 2°F
TPB
TPB
TPB
TPB
TPB
TPB
TPB
TPB
TPB
TPB
-------
Test Equipment Checks - VAST Diesel Site
-11-
AREA
FREQUENCY
TOLERANCE
G. Fuel Filters
1. Replace filters in dispenser 6 Months
H. Process Fluid
1. Check level 6 Months
2. Check inhibitor level in fluid Yearly
I. Process Tank Bottoms
1. Draw off sediment from four Yearly
process tank bottoms
J. Liquid Hydrocarbon Detectors
1. Calibrate and test for proper Yearly
operation
K. Diesel Particulate Dry Gas
Meter Calibration
1. Verification Monthly
1/2 to 7/8 full
+0.5# Dev. from best fit
line. Slope +0.5^ from
active slope.
GROUP COVERED
TPB
TPB
TPB
TPB
TPB, TEB (E&D)
2. Tylan Adjustment
As needed
TPB
-------
-3-
Test Equipment Checks - Analysis Systems
AREA FREQUENCY TOLERANCE GROUP COVERED
F. CO Analyzer H20/C02 Interference
1. Injec.t'3$ C02 bubbled through Yearly Federal Register TPB, TEB (E&D)
room temperature water using tolerance = + \% SDSB (HD)
the LCO and HCO analyzers of full scale" or +3 ppm
on ranges below 300 ppm
G. Replace FID batteries Yearly TPB, TEB (E«D),
SDSB (HD)
-------
-12-
Test Equipment Checks - Alarms
AREA FREQUENCY TOLERANCE GROUP COVERED
IV. Alarms
A. Toxic Gas Warning System
1. Force cal and sample 50 ppm Weekly +_ 5 ppm TPB, TEB (E#D)
CO check one site SDSB (HD)
2. Sample a bag of 25 ppm NOx and 6 Months +_ 5 ppm TPB, TEB (E#D)
50 ppm CO from each pick-up ~~ SDSB (HD)
3. Random check two sites 2 Weeks _+_ 5 ppm TPB, TEB (E&D)
SDSB (HD)
B. Combustible Gas Alarms
1. Check calibration of meters with Yearly Meter set 25$ of LEL, TPB - SHEDS &
a bag of 5250 ppm propane (Change (Alarm set 20# fueling area
transducers of LEL)
every 2 yrs)
-------
-13-
Test Equipment Checks - Soak Area
AREA FREQUENCY TOLERANCE GROUP COVERED
Soak Area
A. Check soak area temperature recorder 2 Months +_ 1°F TPB
B. Check Laboratory Barometers
1. Calibrate barometers monthly j^.03 "HG TPB, TEB(E
-------
-14-
Test Equipment Checks - Fuel System
AREA FREQUENCY TOLERANCE GROUP COVERED
VI. Fuel System
A. Temperature Controls
1. Check fuel temperature Daily at 45-52eF Test TPB
startup 45-708F Prep
B. Visual Check, Indoor, and Outdoor
1. Check reteniton dike and pits Weekly TPB
for debris and water
2. Check for leaks at fittings Weekly TPB
3. Manually cycle pneumatic valves Weekly TPB
C. Heat Pump Air Filters
1. Visually inspect and change 2 Weeks TPB
if needed
-------
Test Equipment Checks - CVS's
-15-
AREA
VII. CVS
A. Tracer Gas Injection
B. Venturi Cleaning and Operational
Checks
1. Visually inspect venturi
2. Check pressure and temperature
transducers and Vmix computer
3. Check CVS dilution filters
CVS Maintenance
1. Change sample filter elements
2. Clean probes, check fittings
and lines
3. Check cyclonic separators
4. Visually check exhaust pipe
gaskets and boots
5. Pressure check exhaust pipe
6. CPO Kits. Verify active
coefficients
FREQUENCY
Weekly
TOLERANCE
Yearly
Yearly
Yearly
Weekly
Monthly
Monthly
Weekly
Yearly
Yearly
+2.Q% recovery. Failure
require two additional
propanes within +1.8^.
Includes diesel heated
FID bag and continuous
integrated samples.
Clean if necessary
+2% of calculated
Less than 1" H20 drop
Probe vacuum less
than 12" Hg
Replace as necessary
0.5*
GROUP COVERED
TPB
TPB, TEB (E«D)
TPB, TEB (E*D)
TPB, TEB (E«D)
SDSB (HD)
TPB
TPB
TPB
TPB
TPB
TPB, TEB (E«D)
SDSB (HD)
-------
Test Equipment Checks - SHED's
-16-
AREA
FREQUENCY
TOLERANCE
GROUP COVERED
VIII. SHEDS
A. Air Plow and Visual Inspection
1. Check mixing air flow rate
2. Visually inspect for leaks
5. Safety check the door and cable
B. Background Check
1. Check the background at the
beginning and end of a 4-hour
period, with the door closed.
C. 4-hour Retention
SHED Volumetric Check
SHED SAC
Yearly
Yearly
Yearly
Yearly
Monthly
Monthly
Weekly
600-1000 CFM
0.4 grams/4hrs
•^4% Retention of
injected propane for
a 4-hour period. Rerun
retention after repairs
are completed.
+2% Measured versus
calculated volume
(based on FID response).
Any reading outside
of the analysis sites,
three sigma.
TPB
TPB
TPB
TPB
TPB
TPB
TPB
-------
-17-
AREA
IX. Dynamometers
A. Dynamometers Calibration
Verification Procedure
TP-302A
Test Equipment Checks
FREQUENCY
B. Dyno Maintenance
1. Check mag plugs
2. Clean screens in water lines,
fittings and lines
3. Lube bearings and couplings
4. Check bonding on rolls
C. H20 Softeners
1. Check with soap test
D. QC Timers
1. Check set points 4.50 and 5.50
volts and the 5.00 volt drivers aid
cal signal
E. Dew Point Meters
1. As outlined in Procedures
TP 211 and TP 214 Procedures
2. Clean mirrors
Weekly
Monthly
Monthly
6 Months
Monthly
6 Months
(Replace
yearly)
4 Months
Weekly and
Monthly
30 days
Dynamometer
TOLERANCE
+1 second - actual
versus theoretical
coastdown times. +0.2
HP thumbwheel versus
indicated. +0.1 second
QC timer versus master
timer. Rerun procedure
for area affected after
repair.
Replace if needed
Replace if needed
If less than a 50$
reduction in hard
water content, replace
softner
+0.01 volts
GROUP COVERED
TPB
TPB
TPB
TPB
TPB
TPB, TEB (E«D)
TPB
Per test procedure
TPB
TPB
-------
-18-
Test Equipment Checks - Dynamometer
AREA FREQUENCY TOLERANCE GROUP COVERED
P. Tire Gauges
1. Check on site tire gauge with 6 Months +_ 2 psi TPB
master gauge
G. Raw Exhaust Analyzers
1. HC, CO, and C02 Span Check 2 Weeks _+ 5% Full Scale TPB
with bottles
-------
EOD TEST PROCEDURE
TITLE
Critical Flow Orifice Calibration
ORIGINATOR
David Munday, Mechanical Engineer, Calibration and Maintenance
RESPONSIBLE ORGANIZATION
Calibration and Maintenance
TYPE OF TEST REPORT
Computer Generated
REPORT DISTRIBUTION
Calibration and Maintenance
Page 1 of 20
NUMBER
TP 210A
IMPLEMENTATION DATE
02-03-92
DATA FORM NO.
Form 2 10-01
COMPUTER PROGRAM
CFO Calibration Program
SUPERSEDES
TP210
REMARKS/COMMENTS
REVISIONS
REVISION
NUMBER
REVISION
DATE
EPCN
NUMBER
DESCRIPTION
IMPLEMENTATION APPROVAL
Test Procedure authorized on 02-03-92 by EPCN #102
-------
Revision: 0
Date: 02-03-92
Critical Flow Orifice Calibration
TP210A
Page 2 of 20
TABLE OF CONTENTS
1. Purpose 3
2. Test Article Description 3
3. References 3
4. Required Equipment 3
5. Precautions 5
6. Visual Inspection 5
7. Test Article Preparation 5
8. Test Procedure 7
9. Data Input 8
10. Data Analysis 11
11. Data Output 12
12. Acceptance Criteria 12
13. Quality Control Provisions 13
Attachment A, CFO Calibration Schematic 15
Attachment B, Brooks Vol-U-Meter System 16
Attachment C, CFO Kit/Cart Information 17
Attachment D, CFO Calibration Data, Form 210-01.... 18
Attachment E, CFO Calibration Report 19
Attachment F, MTS CFO Implementation Report 20
-------
Revision: 0
Date: 02-03-92
Critical Flow Orifice Calibration
TP210A
Page 3 of 20
I. Purpose
The purpose of this procedure is to calibrate the Critical Flow Orifice (CFO) Kit for verifying
Constant Volume Sampler (CVS) performance.
2 . Test Article Description
Critical flow orifices are used for propane tracer gas injections.
3. References
3.1 "Instruction Manual for the Critical Flow Orifice Kit Model 210;" Horiba Instruments
Inc.; November 1978
3.2 Letter from Horiba Instruments, Inc., to MSAPC QA Staff, August 1979
3.3 "Brooks Vol-U-Meter Operating Instructions," Models 1052 through 1058; Brooks
Instrument Division, Emerson Electric Company, 407 West Vine Street, Hatfield, PA
19440; December 1977; Revision A
3.4 Code of Federal Regulations. Vol. 40; Revised as of July 1, 1990; Parts 86 to 99,
Section 86.119
3.5 Memo; David L. Munday; November 5, 1991; Subject: "Equations for CFO Calibration'
4. Required Equipment
The following is a list of the equipment used to perform a CFO calibration:
4.1 Instrument grade propane
4.2 Conoflow single stage regulator; 0-125 Ib spring, non-relief type
4.3 Shutoff valve
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Critical Flow Orifice Calibration
TP210A
Page 4 of 20
4.4 The following components are contained in the CFO kit (see Attachment A, page 15):
4.4.1 Precision pressure gauge; 0-100 psig, 8-inch diameter scale or larger, graduated
in 0.2-psig increments
4.4.2 Thermometer, 0-120 °F, graduated in 0.5 °F increments
4.5 The following components are contained in the Brooks Vol-U-Meter System (see
Attachment B, page 16):
4.5.1 Brooks Vol-U-Meter Control Box
4.5.2 Valves; 3-way solenoid activated; two required
4.5.3 Connection tubing and large, non-restricting vent and dump lines
4.5.4 Back-pressure manometer; 0-4 inches of water, graduated in 0.5-inch
increments
4.5.5 Brooks Vol-U-Meter, Model 1057; 3500-cc capacity (this is known as the
Brooks Prover)
4.6 Seeka F5 optical sensors; two required
Note: One sensor is mounted at the 500-cc mark and the other is mounted at the 2000-cc mark
(see Attachment B, Figure 2, page 16).
4.7 DCI Timer with toggle switch
4.8 Mensor Digital Pressure Gauge (central barometer), Model 11900; 0-32 inches of Hg,
graduated in 0.001-inch increments.
4.9 Vertex Floor Scale, Model 2158; equipped with Toledo Indicators, Model 8146
Note: The scale is located in the large soak area.
4.10 CFO Kit/Can Information (see Attachment C, page 17)
4.11 Form 210-01, "CFO Calibration Data" (see Attachment D, page 18)
4.12 "CFO Calibration Report" (see Attachment E, page 19)
4.13 "MTS CFO Implementation Report" (see Attachment F, page 20)
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Critical Flow Orifice Calibration
TP210A
Page 5 of 20
5. Precautions
5.1 Cylinders containing compressed gases are used for this procedure. The technician must
be familiar with the "EPA Laboratory Safety Manual" sections dealing with the safe
handling, storage, and use of compressed gas cylinders.
5.2 The gas cylinders and equipment must be checked for leakage, damage, and cleanliness.
5.3 Use the Brooks Vol-U-Meter only with approved gases (see the operating manual for
details).
5.4 Although CFO kits have orifices for use with CO, pure CO should not be used because
of its extremely toxic properties. For safety reasons, EPA does not permit CO injections
as a routine practice.
5.5 The CFO kit must be in the gas lab prior to the start of the calibration for a minimum of
20 minutes to ensure the kit is at room temperature.
5.6 After each adjustment is made to the targeted pressure, the flow rate is allowed to stabilize
for a minimum of two minutes.
5.7 The precision pressure gauge is graduated in 0.2-psig increments but must be read to the
nearest 0.1 psig.
6. Visual Inspection
6.1 Inspect all fittings with a leak detection fluid when the system is pressurized to 85 psig
(see Section 7 for details).
6.2 Verify that the CFO kit precision pressure gauge reading is zero when the shutoff valve is
closed.
6.3 Verify that the Brooks Vol-U-Meter back-pressure manometer reading is zero on the left
side of the u-tube when the Control Box is in the "off" position. If it is not zero, release
the set screws on the sliding metal scale and adjust it so the zero mark lines up with the
bottom of the meniscus (on the left side).
7. Test Article Preparation
1.1 Disconnect the rosette from the cylinder pressure line.
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Revision: 0
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Critical Flow Orifice Calibration
TP210A
Page 6 of 20
7.2 Using the Vertex floor scale, weigh the CFO kit/can (CFO kit, propane cylinder, and
cart). Record the CFO total weight on Form 210-01. The CFO Calibration Program
calculates the net weight of the propane in the tank by subtracting the tare weight
(displayed on each kit/can combination) from the total CFO kit/can weight. (See
Attachment C, page 17 for details.)
For a valid calibration, the net weight of the propane in the tank must be greater than 25
Ibs. If it is not, replace the propane cylinder.
7.3 Ensure that the DCI timer and the Brooks Vol-U-Meter Control Box are plugged into an
electrical outlet. If not, plug them in and allow the equipment to warm up for a minimum
of two hours.
7.4 Push the Brooks Vol-U-Meter Control Box button to the "off position.
7.5 Connecl-the cylinder pressure line to the Brooks Vol-U-Meter Control Box inlet pressure
fitting.
7.6 Adjust the regulator to 85 psig and allow the pressure to stabilize for a minimum of two
minutes*
7.7 Push the Brooks Vol-U-Meter Control Box button to the "flow" position.
7.8 Verify that there are no fluctuations in the piston movement and back-pressure manometer
reading. If fluctuations exist, notify the Calibration and Maintenance (C&M) Manager.
7.9 When the piston reaches the top optical sensor, turn the cylinder valve counterclockwise
to the "closed" position. The system will now be pressurized.
7.10 Inspect all fittings with a leak detection fluid.
7.11 Push the Brooks Vol-U-Meter Control Box button to the "off position.
7.12 On Foira210-01, Section A, record all the required data. The previous calibration date
and active coefficients are stored in the CFO folder. The CFO folder is stored in the Gas
Lab. The cylinder number, purity, and vendor are located on the tank.
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Critical Flow Orifice Calibration
TP210A
Page 7 of 20
8. Test Procedure
A total of 24 data points are collected for a CFO calibration. Each data point consists of a
measured supply pressure, within the 60 to 95 psig range, and an elapsed time reading. The
target pressure starts at 60 psig and increases to 95 psig, in 5-psig increments, then decreases
from 95 to 60 psig in 5-psig increments.
To provide random confirmation data, the operator then sets 60, 75, 85, 70, 90, 95, 80, and 65
psig.
For each of the target pressures, perform the following steps:
Sequence Description
100 Turn the cylinder valve clockwise to the "open" position.
101 Push the Brooks Vol-U-Meter Control Box button to the "off position.
102 Adjust the regulator to set the supply pressure to within ±0.4 psi of the target pressure,
e.g., 60 psig must be 59.6 - 60.4 psig, 75 psig must be 74.6 - 75.4 psig, etc., for all
target data points.
103 Allow the set pressure to stabilize for a minimum of two minutes. The stabilized
pressure must be within ±0.4 psig of the target pressure.
104 Read the precision pressure gauge to the nearest 0.1 psig.
105 On Form 210-01, Section B, record the observed pressure under the column Actual
psig.
106 When the Brooks Vol-U-Meter piston has descended to the bottom of the chamber,
push the DCI toggle switch to the right to stop the timer. Reset the rimer to zero by
pushing the toggle switch to the left.
Note: If this is the start of the calibration process, the piston will already be at the bottom of
the chamber.
107 Push the Brooks Vol-U-Meter Control Box button marked "flow." This directs the
flow into the Brooks Vol-U-Meter, causing the piston to rise.
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Critical Flow Orifice Calibration
TP210A
Page 8 of 20
Sequence Description
108 Verify that the Brooks Vol-U-Meter back-pressure manometer reading is 1.5 inches of
water. If it is not, notify the C&M Manager.
109 The DCI timer will start when the optical sensor is activated by the top edge of the
piston reaching the 500 cc mark on the steel scale.
110 Continue to flow the gas until the piston reaches the upper optical sensor (2000-cc
mark). The DCI timer will automatically stop when the top edge of the piston reaches
this point, thus indicating the elapsed time to flow 1500 cc.
111 Push the Brooks Vol-U-Meter Control Box button marked "off."
On Form 210-01, under the column marked At seconds (XX.XXX), record the
elapsed time obtained from the timer readout.
Note: The At must be recorded before the Brooks Vol-U-Meter piston reaches the lower
optical sensor (timer automatically resets). If the time has not been recorded prior to the
piston reaching this point, repeat Steps 102 through 111.
112 Repeat Steps 102 through 111 for each of the 24 calibration target pressures listed on
Form 210-01 and record the required data. Each target pressure must be set in the
order shown on Form 210-01.
113 When all of the required data points have been collected, complete Form 210-01,
Section C.
Note: See the Data Processing Flow Chart on page 9.
9. Data Input
9.1 The technician opens the CFO Calibration Program (on the C&M Macintosh computer)
and enters the data recorded on Form 210-01.
9.2 When all data has been entered, use the scroll bar and move the screen view to the right
and preview the "CFO Calibration Report."
9.3 The technician verifies that the "CFO Calibration Report" does not contain any acceptance
criteria flags. If flags appear, see Section 12 for corrective action.
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Critical Flow Orifice Calibration
TP210A
Page 9 of 20
Data Processing Flow Chart
Collect raw data using
CFO Cal Data Form
/Input the raw data
/ T, P and AT
Data processing using
CFO Calibration Program
(Excel)
Examine output of
CFO Cal report
Meets
acceptance
criteria and
QC
No
Yes
Computer operations
updates coefficients & generates
MTS CFO Implementation Report
Examine MTS CFO Implementation
& CFO Calibration Reports
Laboratory Automation
diagnoses errors in
coefficient data base
Yes
No
CFO Cal. Data Form, Report
MTS CFO Implementation
documented
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Critical Flow Orifice Calibration
TP210A
Page 10 of 20
9.4 The technician saves the file by pressing the "Save Report" button. This will
automatically save the data to the CFO Calibration folder on the hard drive and assign the
file name as "CFO Cal Kit # NNNNN MM/DD/YY." The NNNNN will contain the kit
number, and the MM/DD/YY will have the date that the data were entered into the
computer.
9.5 The technician then prints the "CFO Calibration Report" by clicking on the "Print
Report" button.
9.6 A technician, other than the one performing the CFO calibration, verifies that the data in
the "CFO Calibration Report" and Form 210-01 are the same.
If no corrections are needed, the technician signs and dates the "CFO Verification
Report." The report is taken to the C&M Manager.
If corrections are needed, they are identified on the report and it is returned for corrective
action to the technician who performed the CFO calibration. The technician makes the
corrections and repeats Steps 9.1 through 9.5.
9.7 The C&M Manager then signs and dates the "CFO Calibration Report," indicating that the
coefficients can be updated on MTS.
9.8 The technician inserts a blank 4-inch floppy diskette into the Macintosh drive. He/She
opens the CFO Calibration folder and copies the file named 1011D-CFOCAL onto the
floppy.
9.9 At the computer input/output window, the technician completes a job request form.
He/She then places the job request form, the 4-inch floppy diskette (with the electronic
copy of the 1011D-CFOCAL file), and the signed paper copy of the "CFO Calibration
Report" into an envelope.
The envelope is then placed in the input basket. Computer operations will check that the
C&M Manager has signed the report before implementing the MTS coefficients.
Implementation of the new coefficients on MTS makes them available to the Tracer Gas
Injection Program (1011S-TGI).
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Revision: 0
Date: 02-03-92
Critical Flow Orifice Calibration
TP210A
Page 11 of 20
9.10 Computer operations will generate an MTS CFO Implementation Report (see attached
sample) containing the following information:
Kit#
Coefficients A, B, and C
Entered By
Implementation Date
9.11 The envelope containing the 4-inch floppy diskette and paper copies of the "CFO
Calibration Report" and the "MTS CFO Implementation Report" are placed in the output
basket where they can be picked up by the technician.
9.12 The technician verifies that the data in the "CFO Calibration Report" and "MTS CFO
Implementation Report" are the same. If no corrections are needed, the technician signs
and dates the "CFO Calibration Report."
If corrections are needed, they are identified on the "MTS CFO Implementation Report"
and it is taken to the Laboratory Automation Group for corrective action.
9.13 When Steps 9.1 through 9.12 have been completed, the technician opens the CFO
Calibration Program and pushes the "Update Data Base" button. This will update the
CFO calibration data file named "1011D-CFOCAL" with the new coefficients.
10. Data Analysis
10.1 The "CFO Calibration Report" is examined for acceptance criteria flags, (f flags appear,
see Section 12 for corrective action.
10.2 The data in the "CFO Calibration Report" and Form 210-01 are compared independently
by two technicians.
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Date: 02-03-92
Critical Flow Orifice Calibration
TP210A
Page 12 of 20
10.3 The "CFO Calibration Report" is reviewed and signed by the C&M Manager authorizing
that the coefficients can be updated on MTS.
10.4 The technician compares data in the "CFO Calibration Report" and "MTS CFO
Implementation Report" to ensure that they are the same.
If no corrections are needed, the technician signs and dates the CFO Calibration Report.
//. Data Output
11.1 The "CFO Calibration Report," "MTS CFO Implementation Report," and Form 210-01
are filed in the C&M CFO folder.
11.2 The technician notifies the C&M midnight shift that the CFO kit has been calibrated and is
ready for use.
12. Acceptance Criteria
The data must meet the following six criteria to be valid; a flag will be displayed on the "CFO
Calibration Report" if the data do not meet the criteria.
12.1 The net weight of propane in the tank must be greater than 25 Ibs. prior to the start of the
calibration. If not, Flag #1 appears on the spreadsheet and the calibration is void.
Replace the propane cylinder, return to Section 7, complete a new Form 210-01, and
repeat the calibration procedure.
12.2 The difference between the start and end back-pressure readings must be 0.0 inches H.,0
(a reading other than zero indicates friction in the Vol-U-Meter tube). If it is not zero,
Flag #2 appears on the spreadsheet and the calibration is void. Notify the C&M
Manager, return to Section 7, complete a new Form 210-01, and repeat the calibration
procedure.
12.3 The difference between the start and end barometric pressure readings must be less than
or equal to 0.12 inches Hg. If not, Flag #3 appears on the spreadsheet and the
calibration is void. Return to Section 7, complete a new Form 210-01, and repeat the
calibration procedure. If after a second calibration attempt the data are not within this
limit, notify the C&M Manager.
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Date: 02-03-92
Critical Flow Orifice Calibration
TP210A
Page 13 of 20
12.4 The difference between the start and end CFO kit thermometer temperature readings must
be less than or equal to 2.0 °F. If not, Flag #4 appears on the spreadsheet and the
calibration is void. Allow the kit temperature to stabilize for a minimum of two hours,
return to Section 7, complete a new Form 210-01, and repeat the calibration procedure.
If after a second calibration attempt the data are not within this limit, notify the C&M
Manager.
12.5 The percent of point deviation from the best fit curve must be within ±0.3% . If not,
Flag #5 appears on the spreadsheet and the out-of-tolerance data points (actual psig and
At seconds) may be rerun one more time. Cross out the bad data with a single line and
initial the area. Open the CFO Calibration Program and make the necessary changes. If
the flag persists, the calibration is void.
12.5.1 Clean the CFO kit ruby orifice fitting in a sonic bath.
12.5.2 Return to Section 7, complete a new Form 210-01, and complete the calibration
procedure.
12.5.3 If after a second complete calibration attempt the data are not within the
specified tolerance, replace the ruby. Return to Section 7, complete a new
Form 210-01, and complete the calibration procedure.
12.6 The previous calibration date entered into the computer must match the previous
calibration date stored in the data base. If not. Flag #6 appears on the spreadsheet
indicating that the coefficients are inactive. Look up the previous calibration date in the
CFO folder and verify that the correct date has been recorded on Form 210-01. If the
calibration date is recorded correctly, a computer problem may exist or a report may be
missing in the CFO folder; notify the C&M Manager.
13. Quality Control Provisions
13.1 The fittings are inspected with a leak detection fluid.
13.2 The CFO kit precision pressure gauge is verified to read zero when the shutoff valve is
closed.
13.3 The Brooks Vol-U-Meter back-pressure manometer is verified to be reading zero (for the
left side of the u-tube) when the Control Box is in the "off position and the piston is at
rest on the bottom.
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Revision: 0
Date: 02-03-92
Critical Flow Orifice Calibration
TP210A
Page 14 of 20
13.4 If the DCI timer and the Brooks Vol-U-Meter Control Box are not plugged in, they are
allowed to warm up for a minimum of two hours.
13.5 The piston movement and back-pressure manometer reading are verified to ensure that
there are no fluctuations.
13.6 The flow rate is allowed to stabilize for a minimum of two minutes after each adjustment.
13.7 The net weight of the propane in the tank must be greater than 25 Ibs.
13.8 The CFO kit temperature is allowed to stabilize for 20 minutes prior to performing the
calibration.
13.9 When the piston is moving, the back-pressure manometer must read 1.5 inches of water.
13.10 Actual pressure must be within ± 0.4 psig of the target pressure.
-------
o-
c
T: j
R
CFO
Kit
LEGEND
C Cylinder, propone
R Regulator, non-relief type
V Valve, shutoff
CFO Critical Flow Orifice kit
P Pressure gouge, precision
T Thermometer, kit
QD Quick Disconnect
CB Control Box, Brooks Vol-U-Meter
5V 1,2 Solenoid Valve, three-troy
VM Vol-U-Meter, Brooks
BPM Bock-Pressure Manometer
TFM Totalizing Flow Meter
(Tube/Piston)
CB VM
(See Figure 2)
Figure 1 CFG Calibration Schematic
-------
OFF(VENT)
FROM CFO
t
Brooks Vol-U-Meter
Control Box
V
2OOO cc
Brooks Vol-U-Meter
Back Pressure
Manometer
Seeka F5
Optical Sensor
Optical Sensor
Bracket
Volume Scale (cc)
DCI Timer
I xxx.xxx"!
RESET C3C> STOP
500 cc
Toggle
Switch
Seeka F5
Optical sensor
OFF(VENT) FLOW
Figure 2 Brooks Vol-U-Meter. Control Box and DCI Timer
-------
Date: 02-03-92 TP210A Attachment C Page 17 of 20
CFO Kit/Can Information
The propane weight is determined by subtracting the CFO kit/cart tare weight, displayed on each
kit/can combination, from the CFO kit/cart total weight. The propane weight must be greater
than 25 Ibs. for a valid calibration.
The following items contribute to the CFO kit/cart total weight:
1. CFO kit
2. Propane cylinder with valve, regulator, and propane gas
3. Portable can
The following items contribute to the CFO kit/can tare weight:
1. CFO kit
2. Empty propane cylinder with valve and regulator
3. Portable can
Listed below are the tare weights of the CFO kits currently in use. Note that the CFO tare
weights differ from kit to kit.
Kit Number Empty Propane CFO Kit/Can Tare Weight
Cylinder (Ib) (Ib) (Ib) ~
038625 95 183 278
086942 95 180 275
181102 95 150 245
181103 95 150 245
106380 95 182 277
-------
Date: 02-03-92
TP210A Attachment D
Page 18 of 20
Section A:
Technician's Name:
CFO Kit Number:
Current Date:
Date of Previous Calibration:
Calibration Stan Time:
Start CFO Kit Thermometer Temp
Section B: Collect 24 calibration
Target psig
(D 60
(2) 65
(3) 70
(4) 75
(5) 80
(6) 85
(7) 90
(8) 95
(9) 95
(10) 90
(11) 85
(12) 80 A
(13) 15(f~^
(14) 70\^— -.
(15) 65 v
(16) 60 ^.
(17) 60 \>
(18) 75
(19) 85
(20) 70
(21) 90
(22) 95
(23) 80
(24) 65
Section C:
Calibration End Time:
End CFO Kit Thermometer Temp:
Rubv Cleaned YES
Comments:
CFO Calibration Data
Cylinder #:
points in
Actual
(D
(2)
(3)
(4)
(5)
(6)
(7)
<*><
(9) X
r^
WOK
W3)
\V
\ ) 05)
^(16)
(17)
(18)
(19)
(20)
(21)
(22)
(23)
(24)
NO
Cylinder Vendor:
Cylinder Puritv:
CFO Total Weight:
Start Back Pressure:
°F Start Barometer:
the order listed below. /
*\
psig, (XX.X) At second
/? (1)
/ v
A\(2)
„ \\H
/r\\ V\ ,
^ ;/ $y
A \T ,1
\\\ \\ m
\\\\ \7
X \\\\ )/ (8)
v\\\\\ \V (9)
\\ \ N \ )/
\\ X \ ^ (10)
\\ -^ (11)
"V (13)
(14)
(15)
(16)
(17)
(18)
(19)
(20)
(21)
(22)
(23)
(24)
End Back Pressure:
°F End Barometer:
Ruby Replaced
Ib
inches H-,O
//-\ inches Hz
u
dsUM-XXX)
\T />
\\^/
\v
;/
inches H-,0
inches Hz
YES NO
Form 21 0-01:02-03-92
-------
1
CH) Kit No: I0636O
CFOKit
Number
106360
IS'
,
1
2
3
4
5
6
7
0
10
11
12
13
14
15
16
17
IS
10
20
21
22
23
24
Actual
PSIG
60.0
650
700
750
aoo
aso
000
QSO
QSO
000
aso
800
7SO
700
650
600
600
7SO
aso
700
ODD
QSO
800
650
START
END
AV&. '
FLAGS
Technician
Name
Parker
Bock
Pressure
CH201
1.5
1.6
16
-
^^7
^FLA^//
•v
••
«5
<5
UUmJJIK: oc Limt Rags ire present
This CFQ Kit has problems. This is nsmple report.
^
/ 1
1
16
'2
3
14
20
4
13
IS
5
12
23
6
11
19
7
10
21
*
0
22
Delta
Vol
(DC)
1500
FLAS
Acliial
rtu;
CFQ Total
3QO
era
Fare Veiojrt
277
Propane
Weigh*
(Iba)
23
* 1
Delta t
(SEES)
/^0> 134061
^/76C/ 133.864
/ ,60 1 33626
^r^SS
Pro oe-
Date af
Previous Calibration
8/1/41
Coefficients
A= 256I13E-06
B= 7.442A7E-D3
C= -1336I8E-02
RUBY
CLEANED
REPLACED
VE&^JO
Nb
P,*-^1^
0530202
0531112
0532011
0571227
0560822
057 2644
Iff ^ 11 7.01 4\ 0607547
^-^ICr 1I&5SB\ 0600715
\r70 ^mM4^VO 606171
^TS/
ao
ao
ao
as
as
as
00
00
00
05
05
OS
DATA VERIFIED ftY:
COf FFICIEHTfi OK
TO IrPlEMEHT:
4O(i33l J 6650241
^1 01021 -/ SJ65 2000
103.084 0680646 \
102711 ^06Q21ST^
102003^-^ Ofid0256
QtA32^'
07.755^
07.7fl6\\
02.053 '^
02.775
8B.4HI
8B507
8B3fl7
^ 0.726660
0.727242
0.726037
^QCT^TO
0*33176
0*33230^
0*34321 \
^•J^'+B'P^+C
0530606
0530606
0530606
0571006
057 1006
0571006
0610871
0610071
0610871
0650200
0650200
0650200
0680364
0680364
0689364
0727703
JJ1727703
^^.7«5a77\
0*33515
OOCnFKIEMTfi VERIFIED ftV:
HSe±Oan-30-1«fl2 I3:J4 A
Date
ii/e/rQi
Near
Coefficients
B= 0.43046E-D3
C- -1.21324E-OI
Sfriff
-0088
0088
0258
0)048
-0218
0208
-0548
-0.108
-0448
-0018
0288
028
0)068
0.428
0.148
-0.158
-0088
-0.128
-0.148
OJQ58
-0038
-0028
-0048
0.108
FLAG£
«5
«S
fs
<*
DATEJ
DATE:
DATE:
Date: 02-03-92 TP 21 OA Attachment E Page 19 of 20
-------
Date: 02-03-92
TP210A Attachment F
Page 20 of 20
MTS CFO Implementation Report
Implementation Date:
-------
EOD TEST PROCEDURE
TITLE
Gas Analyzer Calibration Curve Generation
ORIGINATOR
Linda Hormes
RESPONSIBLE ORGANIZATION
Laboratory Engineering Branch, Calibration and Maintenance Group
TYPE OF TEST REPORT
Analyzer Calibration Curve Analysis
REPORT DISTRIBUTION
C&M, Analyzer Sites, QC, and Data Validation
Page 1 of
12
NUMBER
TP204
IMPLEMENTATION
11-14-79
DATE
DATA FORM NO.
LB-205
DB-AA-601
COMPUTER PROGRAM
1251C-CALB
SUPERSEDES
N/A
REMARKS/COMMENTS
REVISIONS
REVISION
NUMBER
(1)
REVISION
DATE
12/15/88
EPCN
NUMBER
EPCN 70
DESCRIPTION
This EPCN authorized use of the Horiba NDIR CO/CO2 analyzers.
IMPLEMENTATION APPROVAL
Test Procedure authorized on 11/14/19
-------
Revision: 0
Date: 11-14-79
Gas Analyzer Calibration Curve Generation
TP204
Page 2 of 12
TABLE OF CONTENTS
1. Purpose 3
2. Test Article Description 3
3. References 3
4. Required Equipment 3
5. Precautions 4
6. Visual Inspection 4
7. Test Article Preparation 4
8. Test Procedure 7
9. Data Input 9
10. DataHandling , 11
11. Data Review and Validation 11
12. Acceptance Criteria.. ;... 11
13. Quality Control Provisions 12
14. Documentation 12
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Gas Analyzer Calibration Curve Generation
TP204
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1. Purpose
The purpose of this procedure is to generate analyzer calibration curves for all ranges of all
analyzers used by Light Duty, Heavy Duty, and Evaluation and Development These curves are
then used in the monthly analyzer calibration verifications (TP-303) which are done to assess
analyzer curve stability. A new curve must be generated whenever an existing curve is found to
be out of tolerance, when a new analyzer is placed into service, when two or more secondary
standard cylinders have been replaced, or when the top secondary standard cylinder is named or
replaced. NOTE: Whenever a new curve is generated, a Span Point Change Notice must be
completed. Refer to Test Procedure 205, Span Point Change Notice.
2. Test Article Description
All gas analyzers used for measuring vehicle exhaust and evaporative emissions
3. References
3.1 Federal Register. Vol. 42, No. 124; June 28,1977; Sections 86.121-78 to 86.124-78
3.2 EPA memo, Subject: Light Duty Testing Operations Tolerances; T. Hudyma; April 14,
1977
3.3 EPA Laboratory Safety Manual
4. Required Equipment
4.1 Calibrated digital voltmeter (DVM) with .01 volt resolution or better
4.2 Secondary standard calibration cylinders for the appropriate gas and range being
analyzed. See Step 7.13 for the method of selecting the correct cylinders. All secondary
cylinders must have undergone Test Procedure 403, Gas Correlation, before they may be
used as calibration gases.
4.3 Portable calibration line of Teflon covered with braided stainless steel for introducing the
calibration gases into the analysis system
4.4 Form AA-601, Exhaust Gas Analyzer Data Form
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Gas Analyzer Calibration Curve Generation
TP204
Page 4 of 12
4.5 Form LB-205, Span Point Change Notice
5. Precautions
5.1 The technician performing the calibration must be familiar with the Laboratory Safety
Manual, especially Chapters 2 through 6, which deal with the safe handling of
compressed gases.
5.2 Cylinder carts must not obstruct doorways at the analysis sites. Doorways must remain
closed to insure effectiveness of the fire extinguishing system.
5.3 The technician must insure that there is no leakage of toxic gases and that the analyzer is
properly vented to the exhaust ventilation system.
5.4 Any time a new curve is generated or updated, a span point change notice must be filed
and the new span point posted at that analysis site as soon as the point is known. No
official testing may be done until the new span point is posted.
6. Visual Inspection
Inspect the portable calibration line for cracks, bends, worn spots, etc.
7. Test Article Preparation
1.1 Verify that the analyzer is operating according to the specifications given in the instruction
manual and/or in-house analyzer specification sheet.
(1) 7.2 Verify that the analyzer is set in the proper operating configuration:
NOx analyzer (TECO 10A): OZONE - "ON"
POWER - "ON"
NO-NOx - "NOx"
Methane analyzer "CONTINUOUS CYCLE"
(Bendix 8295) timer switch - "AUTO"
valve switch - "AUTO"
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Gas Analyzer Calibration Curve Generation
TP204
Page 5 of 12
Values for pressure, temperature, and flow rates which must be observed are posted at
the individual sites and on the curve printout Refer to the instruction manual and/or the
in-house analyzer specification sheet for more detailed instructions, or consult with the
Team Leader.
7.3 Check that the strip chart recorder has sufficient paper and is inking properly.
7.4 Check the calibration label on the calibrated DVM to insure that the due date has not been
exceeded. If it has, the DVM must be recalibrated before the curve generation can
proceed.
7.5 Allow the strip chart recorder sufficient warm-up time (minimum of 20 minutes).
7.6 Check the electrical zero of the strip chart by shorting the input terminals and adjusting to
zero ±. 1 % of full scale.
7.7 Attach the calibrated DVM to the analyzer output jack.
7.8 Using the on-line working gases, zero and span the instrument on the appropriate
multiplier range to verify that the strip chart recorder reading and analysis bench DVM
reading equal the calibrated DVM reading ± .2% of full scale. If this tolerance is
exceeded, make the necessary adjustments to the recorder or bench DVM and repeat the
zero and span check.
7.9 While performing Step 7.8, verify that the analyzer output noise level is less than ± .5%
of full scale. Noise is defined as short-term cyclical variation of a signal from some
average value.
7.10 While performing Step 7.7, verify that the analyzer output drift does not exceed ± .2% of
full scale per two minutes. Drift is defined as long-term directional change of value.
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Gas Analyzer Calibration Curve Generation
TP204
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7.11 Record the following data on the strip chart:
Analyzer vendor
Date
Test site number
Operator's name and ID number
Gas analyzed and dilutent gas (e.g., CO/N2)
Full scale (100%) voltage
Sample flow rate
Monitor set point on magnehelic
Zero gain setting
Span gain setting
Air pressure (hip and GC analyzers)
Fuel pressure (FID and GC analyzers)
Sample pressure (FID and GC analyzers)
Fuel type (FID and GC analyzers)
Standard laboratory range
Full scale concentration value of range being analyzed
Analyzer property ID number
7.12 At analysis sites where a calibration port IS provided, turn off the span gas flow to the
untested analyzers by closing the valves of the appropriate gases located in the master gas
control box at the site. This prevents waste of span gases. Switch the analyzer being
used to the OFF mode and select SPAN for the on-site analyzers not being tested. This
prevents waste of calibration gases.
At analysis sites where a calibration port is NOT provided, switch the analyzer to the
SPAN mode.
7.13 Select the proper secondary standards to be used as data points in the curve. The curve
should include these cylinders whose concentrations will produce the following
approximate deflection reading at the range being calibrated:
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Gas Analyzer Calibration Curve Generation
TP204
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Nonlinear Analyzers Approximate Chart Deflections
(NDIR - minimum of 8 data points) 95
80
70
60
50
40
25
15
Linear Analyzers Approximate Chart Deflections
(FID, HFID, Chemil, 90
GC minimum of 6 data points) 75
60
45
30
15
If enough cylinders are not available to meet these requirements, consult the Team Leader
for further action. More cylinders may be used in the curve to provide Quality Control
data on gas concentration uniformity.
All secondary standards must have black sticker labels giving the EPA-named
concentration.
. Test Procedure
Test Sequence Test Description
101 Using the portable calibration line, connect the top secondary cyUnder to be used in the
curve to the appropriate instrument gas input port.
102 Adjust the instrument gas flow rate and pressure as closely as possible to the rates
posted at the analysis site. Continue to monitor them throughout the procedure.
103 Zero the instrument using the on-line zero gas adjust the zero potentiometer until a
stable and accurate zero is obtained.
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Gas Analyzer Calibration Curve Generation
TP204
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Test Sequence Test Description
A stable reading is defined as one minute of measurement in which the drift variation is
not more than ± .2% of full scale from the set point and the noise variation is not more
than + .5% from that same set point The numerical value of the reading is the
operator's estimate of the average reading occurring during the measurement period.
The calibrated DVM is used for all measurements.
104 Span the instrument by connecting the highest concentration secondary cylinder to the
analyzer and adjusting the span potentiometer until the DVM reading reflects the percent
of the actual concentration compared with the full scale of the range being analyzed.
For example, if the range is 0-250 ppm and the top bottle is 230 ppm, adjust the DVM
reading to 92% of full scale (230 ppm = 92% of 250 ppm). Or the span reading from
the previous curve may be used again if the top bottle has not been renamed or
replaced.
105 Zero the instrument and allow the reading to stabilize. If the original zero does not
return within + .3% of full scale, adjust the potentiometer until it does and repeat Step
104. Indicate the measurement area on the strip chart.
106 Span the instrument using the highest concentration secondary cylinder and allow the
reading to stabilize without adjusting the potentiometer. If the DVM reading does not
match the original span reading obtained in Step 104, repeat Steps 105-106. For each
reading taken, write the cylinder number, the FJA-named concentration, and the
observed DVM reading on the strip chart near the measurement area. Circle the DVM
reading.
107 Run the curve.
Introduce the sequence of secondary calibration cylinders to be used as data points in
the curve, in descending order of concentration. Obtain a stable DVM reading for each
without adjusting the potentiometer.
108 Zero the instrument
After the lowest concentration standard has been recorded, reintroduce the zero gas and
obtain a stable reading. If the reading has drifted more than ± .3% of full scale from
the reading obtained in Step 105, repeat Steps 101-108. If the tolerance limit is still
exceeded, the drift problem must be corrected before the curve can be completed.
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Gas Analyzer Calibration Curve Generation
TP204
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Test Sequence Test Description
109 Respan the instrument
Reintroduce the highest concentration standard for a reference span point. If the
reading has drifted more than ± .3% of full scale from the reading obtained in Step 106,
repeat Steps 101-108. If the tolerance limit is still exceeded, the drift problem must be
corrected before the curve can be completed.
110 Introduce the working span gas and obtain a stable reading without adjusting the
potentiometer. Record the reading on the strip chart where it occurs along with the
actual concentration and cylinder number. (This step provides information for TP-
205.)
111 Zero the instrument
If the zero point has drifted more than ± .3% of full scale, repeat Steps 103-110. If the
zero point is still out of tolerance, the drift problem must be corrected before the curve
can be completed.
112 After testing is completed, turn the site span gases back on if they have been shut off.
9. Data Input
9.1 The operator writes the cylinder number, the EPA-named concentration (found on the
sticker tape attached to the cylinder), and the observed DVM reading on the strip chart
near the measurement area. Zero and span points are indicated as such. The on-line
working gas is identified as "WG." All DVM readings are circled.
9.2 The operator completes Form AA-601 for each range analyzed.
9.2.1 Lines 1-3, Instrument Identification, are completed using the codes on the back
of the form.
9.2.2 Line 4, Limits, is completed. The deflection limits define the upper and lower
limits of valid deflection readings on the DVM. The range change limits define
the upper and lower deflection readings on the DVM that signal the need for a
range change to computers on real-time systems.
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Gas Analyzer Calibration Curve Generation
TP204
Page 10 of 12
9.3
On Line 5, Operator's Comments, the range being analyzed is given in % or
ppm. The reason for the curve generation is given (e.g., analyzer maintenance,
new top cylinder, old curve out of tolerance, etc.). Any special operating
instructions or comments about the test must appear here.
Columns 1-11 of Line 7 are completed using the codes on the back of the form
as follows:
Cols. 1-2 "zero-span type" - always "01" (no software zero and span)
Cols. 4-5 "curve form" - "01," which forces the curve through zero
Col. 8 "degree of fit" - depends on the linearity of the analyzer,
usually "2" for NOx, methane and "3" for CO, CO2, and HC
Col. 11 "weight factor" - always "2," which minimizes percent of
point deviations
Col. 23 "X" in "to be filed"
9.2.5 Lines 10-29 are concerned with the cylinders involved in the analysis.
Cols. 1-12 the cylinder numbers are listed
Col. 14 applicable only if a gas blender was used
Col. 16 "X" if the cylinder is "to be named" (working gases)
Cols. 20-32 not applicable
Cols. 34-44 the known or nominal concentration is listed for each cylinder
Col. 46 "X" if the cylinder is to be used as a calibration data point
(secondary standard cylinders)
All such cylinders must have a known concentration value.
Cols. 48-55 the DVM readings written on the strip chart are entered
The operator completes Form LB-205 for each range analyzed. Refer to TP-205.
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Gas Analyzer Calibration Curve Generation
TP204
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10. Data Handling
10.1 The completed Form AA-601 is submitted for processing.
10.2 The printout, Analyzer Calibration Curve Analysis, is obtained after processing.
11. Data Review and Validation
11.1 The technician examines the Analyzer Calibration Curve Analysis for each analyzer range
and determines the validity of the curves.
11.1.1 All figures in the column under "curve fit deviation" marked"% point" must be
within ± 1% for the curve to be valid. The "average deviation" found at the
bottom of this section may not be more than + .5%.
11.1.2 Percent deviations should be random with respect to +/- signs. If like signs are
clustered in the center and/or at the ends of the curve, the degree of fit may have
to be increased by one order. Consult with the Team Leader in such cases.
11.1.3 If inflection points are flagged in the printout, these must be investigated by
Quality Control before the curve is accepted.
11.1.4 The percent of nonlinearity should not be more than 10% for all analyzers
except NDIRs. If the nonlinearity of an NDIR exceeds 15%, it is investigated
by the Team Leader before the curve is accepted.
If the curve is valid, the procedure is complete and a Span Point Change Notice
must be generated. Refer to TP-205.
If the curve is not valid, refer to the attachment, Troubleshooting Flowchart for
Invalid Analyzer Curves, for corrective measures.
12. Acceptance Criteria
12.1 All zero and span rechecks must fall within ± .3% of full scale of the original readings.
The curve must be valid according to the criteria set in Section 11.1.
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Gas Analyzer Calibration Curve Generation
TP204
Page 12 of 12
13. Quality Control Provisions
13.1 All analytical instruments must be properly warmed up and in a test-ready mode prior to
use.
13.2 All DVMs used in the procedure must have undergone a routine calibration within the
past 90 days.
13.3 At least eight data points should be used in curves for nonlinear analyzers. At least six
data points should be used in curves for linear analyzers. If these numbers cannot be
met, the Team Leader is consulted before the curve is run.
14. Documentation
14.1 Copies of the Analyzer Calibration Curve Analysis are signed and dated by the
Calibration and Maintenance Supervisor and distributed as follows:
One copy is retained by Computer Operations for update purposes.
One copy is stored in the Calibration and Maintenance active curve file, replacing the old
curve if applicable. The old curve is stored in the inactive file.
One copy is kept in a file at the analyzer site. The old curve is destroyed.
One copy is sent to Quality Control through Computer Operations.
14.2 The Span Point Change Notice is submitted to Data Validation for verification and
distribution.
14.3 The strip chart is filed in Calibration and Maintenance under the analyzer site number and
date of completion.
A copy of Form AA-601 is filed under the analyzer site number and date of completion
in Calibration and Maintenance.
-------
TP204 - Gas" Analyzer Calibration Curve Generation
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-------
EXHAUST GAS ANALYZER CALIBRATION DATA FORM
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-------
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-------
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-------
TROUBLESHOOTING FLOWCHART FOR INVALID ANALYZER CURVES
! SEE TEAM
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j LOCATE PRO-
, BLEM
-------
SPAN POINT CHANGE NOTICE
NEW SPffl BOTTLE''
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CURRENT SPAN CYLINDER NUMBER
EPA TAG/CONCENTRATION
/
POSTED SPAN SET POINT
NEW SPAN CYLINDER NUMBER
'
EPA TAG CONCENTRATION ; Y3
CHECK RESPONSE / XO
UPPER CHART D^FL. BRACKET 12
LOWER CHART DEFL\ BRACKET U
v^
UPPER CONCENTRATION BRACKET Y2
LOWER CONCENTRATION BRACKET n
Y2 - Yl / \ AY
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% DIFFERENCE = YO - Y3 v inna,
(MUST BE <±1«)
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NOTE: If nd data i,s available for the old span bottle, \he new bottle-most be
checked-tfsfng secondaries. See-form LB205B. \
X2 = the next higher chart deflection to XO on the curve cal-ibration table
XI = the next lower chart deflection to XO on the curve calibration table
Y2 = the next higher cone, corresponding to X2 on the curve calibration table
Yl = the next lower cone, corresponding to XI on the curve calibration table
LB205A
-------
EOD TEST PROCEDURE
TITLE
Dynamometer Calibration Verification
ORIGINATOR
Don Paulsell
RESPONSIBLE ORGANIZATION
Calibration and Maintenance, Light Duty Diagnostics
TYPE OF TEST REPORT
Computer Report, Data Base Analysis
REPORT DISTRIBUTION
File hard copy in diagnostics; data and results are in computer file.
Page 1 of 12
NUMBER
TP 302A
IMPLEMENTATION DATE
8/16/82
DATA FORM NO.
Form EOD 302-01
COMPUTER PROGRAM
LCS E.DCHECK, DYPLOT
SUPERSEDES
TP302
REMARKS/COMMENTS
The three test procedures which deal with calibration and verification of Clayton chassis dynaometers are:
TP 202, Dynamometer Calibration - Fricu'onal Horsepower
TP 207 A, Dynamometer Calibration - RLPC Electronics
TP 302A, Dynamometer Calibration Verification
REVISIONS
REVISION
NUMBER
REVISION
DATE
EPCN
NUMBER
DESCRIPTION
IMPLEMENTATION APPROVAL
Test Procedure authorized on 08/16/82
-------
Revision: 0
Date: 8-1642
Dynamometer Calibration Verification
TP302A
Page 2 of 12
TABLE OF CONTENTS
1. Purpose 3
2. Test Article Description 3
3. References 3
4. Required Equipment 3
5. Precautions 4
6. Visual Inspection 4
7. Test Article Preparation 5
8. Test Procedure 5
9. Data Input 9
10. Data Handling 9
11. Data Review and Validation 10
12. Acceptance Criteria 10
13. Quality Control Provisions 11
14. Documentation 12
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Revision: 0
Date: 8-1642
Dynamometer Calibration Verification
TP302A
Page 3 of 12
1. Purpose
This procedure is used to verify several aspects about the calibration of a Clayton ECE-50
dynamometer in fulfillment of the requirements of 40 CFR 86. The verification involves making
simple checks on the control and display functions and performing several coastdowns at
different inertia weight and horsepower settings. It is assumed that the electronics have been
calibrated as specified in the Clayton manual and TP 207A and that the dynamometer has been
calibrated using TP 202.
2 . Test Article Description
2.1 A direct drive, variable inertia (1000-6875 in 125-pound increments) chassis
dynamometer (Clayton ECE-50) with automatic road load power control capability and
digital display of horsepower and speed
2.2 The original Clayton circuit has been rewired so that the indicated horsepower is based
solely on front roll speed and torque, but the front/rear roll speed indication is still
selectable.
2.3 Some dynamometers have been modified to display a 5-volt reference signal for driver
trace recorders and speed displays.
3. References
3.1 Federal Register. Vol. 42, No. 124; Tuesday, June 28, 1977; 86.116-82 (d)(3), 86.118-
78 (b)
3.2 Clayton Instruction Manual R-8713
3.3 "Proceedings of the Quality Control Symposium on Dynamometers" - June 27,1977,
held at EPA
3.4 Engineering Operations Division files on dynamometers
4. Required Equipment
4.1 Dyno calibrator vehicle - 4000 point, V-8, fitted with lifting jacks and recording
equipment
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Revision: 0
Date: 8-16-82
Dynamometer Calibration Verification
TP302A
Page 4 of 12
4.2 Master coastdown timer and cabling, plus the 60-tooth gear speed sensor assembly
4.3 Extension cords, as required
4.4 Data Sheet (Form EOD 302-01)
5. Precautions
5.1 Inflate the drive tires to 45 psig to protect against damage from heat and distortion.
5.2 Align the vehicle on the dynamometer rolls and attach the cable winch loosely enough to
allow the vehicle to rise to its full lift height
5.3 Operate the cooling fan within 12 inches of the vehicle radiator.
5.4 Vent the vehicle exhaust to the building exhaust system.
5.5 The coastdowns should be run right after warm-up of the dynamometer to insure that the
bearing friction remains stable.
5.6 The cable between the master coastdown timer and the dynamometer electronics box must
be securely connected to insure good electrical contact.
5.7 Verify the action of the vehicle lift while the car is stopped. It should raise quickly but
lower slowly.
5.8 Always verify that the cable, chocks, and electrical lines to the vehicle are disconnected
before the vehicle is removed from the dyno.
6. Visual Inspection
6.1 Verify that the speed and torque meters read 00.0 when the car is off the dynamometer
and the roll brake is not applied. Have C&M check and adjust the voltages or meters if
the readings exceed ±. 1.
6.2 Other visual inspections are performed as part of the test procedure.
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Revision: 0
Dale: 8-16-82
Dynamometer Calibration Verification
TP302A
Page 5 of 12
7. Test Article Preparation
7.1 Place the coastdown vehicle on the dyno and set the MECO brake switch on to enable the
lift; connect the 60-tooth gear, torque and speed signals, and the 115 VAC power plug.
7.2 Chock the front wheels and attach the winch cable loosely.
7.3 Verify the proper operation of the vehicle lift jacks, coastdown timer, and totalizing
counters.
7.4 Verify that the vehicle factor pot is set to a value of zero.
7.5 Verify that the master timer is triggered by the Clayton tach signal and that the speed
counter totalizes the "digital" tach signal from the 60-tooth gear.
8. Test Procedure
Eight inertia weights are verified twice a month. Four weights and horsepowers are done each
week as shown in Table A and on the data sheet The rear roll friction is verified weekly as part
of the warm-up process.
Sequence Description
101 Obtain a blank data sheet (Form EOD 302A-01) for the dyno being tested.
102 Enter all data and obtain the calibration thumbwheel values needed for the coastdowns.
These are on the dyno calibration tables and/or on a lookup table in the calibrator
vehicle.
103 Review the recent data for the dynamometer to highlight aspects which may require
close observation or need to be noted in the comments.
201 Engage the 6875-pound inertia and set the thumbwheel to the value shown in the
current version of Table A.
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Revision: 0
Date: 8-16-82
Dynamometer Calibration Verification
TP302A
Page 6 of 12
Sequence Description
202 Place the speed selector to FRONT.
203 Lower the dyno lift brake and slowly turn the rollers to verify all flywheels are
engaged.
204 Accelerate to a steady 50 mph and maintain this speed to warm up the PAU and
flywheel bearings. Perform Steps 205-210 during this warm-up period.
205 Dial the four thumbwheel values shown on line 2 of the data sheet and record the
indicated horsepower at FR=50 mph.
206 Set TW= 10 and set the timer module to MANUAL/STOP. Reset all counters to zero.
Resume and maintain the speed a FR=50±. 1 mph.
207 Switch the Count/Stop switch to COUNT for about 10 seconds. On the data sheet,
record the torque, speed, and time counts, as well as the IHp meter reading. Reset the
timer module to AUTO/STOP. Verify that the set points are dialed to 45 and 55.
208 Verify the operation of the coastdown timer module four times during the last 5 minutes
of warm-up by performing a dyno coastdown (vehicle lift activated). The 6875-pound
inertia is used; the thumbwheel setting is selected to give AHp equal to 13.5. The
thumbwheel can be selected from the dyno calibration or the current version of Table A.
209 Record the coastdown time for each run on line 3 of the data sheet. This time should be
approximately 31 seconds.
210 If the difference in times (MAX-MEN) is less than .3 seconds, the dynamometer is
stable and the inertia coastdowns may begin. If not, perform additional coastdowns to
see if four consistent values can be obtained. If the tolerance cannot be achieved,
continue testing but report the condition to C&M and VA&T.
211 Change the coastdown timer trigger input from the Front Roll to the Rear Roll tach
banana jack on the dyno.
212 Accelerate to 60+ 2 mph, hold that speed for about five seconds, and activate the
vehicle lift, allowing the dyno to coast down by itself to 30 mph.
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Revision: 0
Date: 8-16-82
Dynamometer Calibration Verification
TP302A
Page 7 of 12
Sequence Description
213 Record the RR coastdown time on line 3 of the data sheet and the value of RRFHp Cal
from the current version of Table A.
214 Listen for abnormal noise during this coastdown and verify that the coastdown timer
trigger points are functioning within + . 1 mph of 55 and 45.
215 Lower the vehicle and stop the dyno.
216 Raise the dyno lift and engage the 4000-pound inertia. Set the thumbwheel to a value
of 10.0. Change the coastdown input to the Front Roll tach banana jack and set the
master timer selector to AUTO/STOP.
217 Trace the template ramp-up and ramp-down profiles (0-60 @ 2.5 mph/sec separated by
a 1-minute cruise at 60 mph) on a driving trace. Thread the driver's aid to prepare for
the transient PAU performance test
218 Set the low trigger point at 5 mph. Leave the high trigger at 55 mph.
219 Lower the dyno lift. Accelerate to 50 mph FR to verify the horsepower and inertia
operation. Stop the vehicle. Reset the counters.
220 Turn on the driver's aid chart feed. When the ramp trace is reached, accelerate the
vehicle at the constant rate to 60 mph, staying within + 2 mph at any point in time.
221 Switch the Auto/Manual switch to MANUAL to hold the counts until they can be
recorded on line 4 of the data sheet
222 Maintain about 60 mph, switch to AUTO, and reset the counters.
223 When the ramp-down trace is reached, decelerate at the constant rate to a complete stop.
Record the counter readings.
224 Shut off the driver's aid. Reset the low trigger point to 45 mph.
225 Remove the driver's trace so it can be stapled to the data sheet later.
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Revision: 0
Date: 8-16-82
Dynamometer Calibration Verification
TP302A
Page 8 of 12
Sequence Description
300 INERTIA CQASTDOWN TESTS
301 For each inertia coastdown shown in Table A, perform the following steps:
302 Stop the vehicle and raise the roll brake.
303 Select the inertia weight and set the thumbwheel horsepower determined from the
current version of Table A. Inertia weights are to be run in the sequence specified in
Table A for the respective weeks.
304 Lower the roll brake and verify the inertia flywheel engagement.
305 Accelerate to 50 mph as indicated on the speed meter and note the indicated horsepower
at a steady 50 mph.
306 Record the indicated horsepower on the data sheet
307 Accelerate to 60 mph and maintain speed until the readings stabilize. Set to
AUTO/STOP and reset all the counters to zero.
308 Activate the vehicle lifting device, maintaining dyno speed until the tires clear the
rollers; then release the accelerator pedal.
309 Allow the inertia assembly to decelerate through the 55-45 speed interval. Note the
indicated horsepower as the inertia speed passes 50 mph.
310 Record this indicated horsepower on the data sheet.
311 Record the times from the master and quick check timers on the data sheet If the
master timer does not work, record the quick check timer data in the master time
column and indicate the switch in the comments on Line 1.
312 Repeat Steps 302 - 312 for each inertia included on the schedule specified in Table A.
313 Lower the vehicle, stop the dyno, and raise the lift brake.
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Revision: 0
Date: 8-16-82
Dynamometer Calibration Verification
TP302A
Page 9 of 12
Sequence Description
314 Perform the visual check of the 1-second tolerance (master-theoretical) and submit the
data for computer processing as specified in Section 10. Validate the results as
specified in Section 12. Repeat any points that exceed the tolerances.
315 If all results are acceptable, disconnect all electrical wires and restraints from the
vehicle.
316 Verify that the lift pads are fully retracted, turn off the MECO brake switch, and remove
the vehicle from the dyno site.
9. Data Input
9.1 Verify that all entries on the data sheet are complete and within the ranges of
reasonableness. Data not collected can be blank or zeros.
9.2 Submit the data sheet to Operations for processing by the LCS program E.DCHECK.
10. Data Handling
10.1 The attached flow chart illustrates how the data are processed and stored.
10.2 Data sheet entries should be keypunched and batch processed on LCS.
10.3 The report will be printed and the data stored. The report consists of three pages - the
data echo, the verification report, and a quality control summary. These are shown in the
attachments. Read/Write errors on the data file are also indicated by a record dump in the
QC summary.
10.4 The results also are written to an LCS file for statistical and graphical analyses, obtainable
by typing BREAK, then "$RUN DYPLOT" on a production "Prod" DecWriter.
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Revision: 0
Date: 8-16-82
Dynamometer Calibration Verification
TP302A
Page 10 of 12
11. Data Review and Validation
11.1 All entries and calculations are checked by Data Control for reasonable results. If entry
errors are detected, the data is corrected and reprocessed.
11.2 Data Control verifies that the acceptance criteria of Section 12 are met
11.3 Any data or results on the printout that do not meet the criteria are either flagged on page
2 under Quality Control Comments or circled in black ink by Data Control. This printout
is used for the copy distribution.
12. Acceptance Criteria
The following criteria are checked by the technician responsible at the time the procedure is
performed. These criteria represent Federal Register compliance. If either of them cannot be
met, the dynamometer is immediately removed from service, and may not be used until C&M has
resolved the problem and verified the acceptability of the dynamometer
12.1 Verification Data Coastdown Time Difference (Master/Theoretical): (Step 311) This
value must not exceed + 1.0 second. Any value outside these limits should be
reconfirmed by the technician performing the verification.
12.2 Verification Data IHp (3) Steady 50 mph: (Step 306) All values must be less than or
equal to ± 0.2 Hp of the thumbwheel setting.
The following criteria are checked by Data Control after the data are processed and are
either flagged under Quality Control Comments or circled if they are exceeded. Copies of
the data report are distributed to the C&M and VA&T Supervisors for evaluation. The
C&M Supervisor is responsible for resolution of the indicated problem(s) as soon as time
permits. The dynamometer remains in use until the investigation is complete. At that
time, the C&M Supervisor will document the justification for deviation or remove the
dynamometer from service.
12.3 Warm-up Thumbwheel Check: (Step 205) The differences between IHp @ 50 readings
and the thumbwheel settings should not exceed + 0.3. The average difference should not
exceed ± 0.2.
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Revision: 0
Date: 8-16-82
Dynamometer Calibration Verification
TP302A
Page 11 of 12
12.4 PAU Hysteresis Check: (Steps 220-223) The hysteresis between ramp-up and ramp-
down data should not exceed 1 mph, 1 ft-lb, or 0.4 Hp.
12.5 Warm-up Coastdown: (Step 209) The difference (MAX-MIN) in coastdown times
should not exceed 0.3 seconds.
12.6 50 mph Speed Check. 6Q-Tooth Gear (Step 207) The front roll speed calibration should
agree within + 0.2 mph of the 60-tooth absolute measurement. If die speed calibration is
acceptable, the torque and Hp differences from theoretical should be ± 1 ft-lb and + 0.4
Hp, or approximately ± 4%.
12.7 Rear Roll FHp Check: (Step 213) This value should not be less than 0.150 FHp and not
greater than 0.350 FHp.
12.8 Verification Data IHp & 50 mph During Coastdown: (Step 310) These values should
not exceed ± 0.2 Hp of the indicated horsepower at a steady 50 mph and should not
exceed + 0.3 Hp of the thumbwheel setting.
12.9 Master/Quick Check At Difference: The quick check timer on the site should agree with
the master timer within ± 0.1 second.
13. Quality Control Provisions
13.1 The acceptance criteria in Section 12 are monitored by the Quality Control Group for
trends and offsets. If a significant offset is noticed, QC immediately brings it to the
attention of C&M, who must take corrective action to restore the central tendency of the
data to near the zero line. If the four-month average of the verification coastdowns
exceeds ± 0.5 seconds, C&M will investigate the trend.
13.2 The general behavior of each dynamometer is presented at the monthly diagnostic meeting
and priorities for corrective action are set at that time. Any outstanding deviations (Steps
12.3-12.9) are also discussed.
13.3 Corrective actions must be reviewed and approved by the C&M Supervisor before the
dyno site is released for testing. Verbal notification of approval should be made to the
VA&T Supervisor. A written description of the corrective action should be sent to
VA&T and QC for documentation purposes.
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Revision: 0
Date: 8-16-82
Dynamometer Calibration Verification
TP302A
Page 12 of 12
13.4 After any repair that does not require a full calibration (TP 202 or TP 207A), this
procedure or the applicable pans should be repeated before the dyno is accepted for
testing.
14. Documentation
14.1 The monthly summaries are copied and distributed to VA&T, C&M, and Quality Control.
The data sheet, printout, and ramp trace are filed in a dyno file folder as specified.
14.2 Corrective actions must be documented in sufficient detail to provide a "before" and
"after" comparison of dynamometer performance. Quality Control must receive a copy
for audit purposes.
-------
DYNAMOMETER CALIBRATION VERIFICATION DATA SHEET
GENERAL
INFORMATION
SOmph FR
-------
TABLE A - DYNAMOMETER VERIFICATION TEST DATA (AS OF 07/01/82) AND FLYWHEEL ENGAGEMENT CHART
TP-302A
DYNO
SITE
CAL DATE
MM-DD-YY
AVG.
RRFHP
THUMBWHEEL HP SETTINGS FOR PREP AND VERIFICATION COASTDOWNS
FLYWHEEL
ENGAGEMENT
CHART
IW =
AHP =
t.At
D001
D002
D003
D004
D005
D006
D007
D207
D208
D209
08-14-81
02-23-81
05-19-82
10-30-80
03-27-8O
09-26-81
01-30-80
03-23-81
06-25-80
08-09-79
.308
.262
.169
.239
.235
.257
.301
.195
.272
.341
2K2
2*1
IK
TRIM
500
250
125
16875
13.5
30.927
10.6
10.2
10. 8
10.4
10.2
9.9
9.5
10.5
9.7
9.8
PREP
X
X
X
X
X
X
X
5000
15.2
19.977
12.9
12.7
13.1
12.8
12.9
12.4
12.2
12.7
12.2
12.2
4000
12.2
19.911
10.2
9.9
10.1
10.0.
10.1
9.5
9.4
9.9
9.4
9.4
3500
10.6
20.052
8.8
8.4
8.6
8.8
8.5
8.1
7.9
8.7
8.0
8.1
3000
9.2
19.803
7.5
7.1
7.5
7.5
7.4
7.1
6.8
7.5
7.1
6.8
FIRST & THIRD WEEKS
X
X
X
X
X
X
X
X
X
X
X
2500
7.6
19.977
5.9
5.5
5.6
5.8
5.6
5.2
5.2
5.7
5.3
5.2
2250
6.9
19.803
5.2
5.0
4.8
5.2
5.0
4.5
4.5
5.1
4.7
4.5
2125
6.5
19.850
4.8
4.6
4.6
4.9
4.7
4.2
4.1
4.7
4.5
4.0
2000
6.0
20.243
4.4
4.2
4.2
4.5
4.3
3.8
3.8
4.4
4.1
3.8
SECOND & FOURTH WEEKS
X
X
X
X
X
X
X
X
X
X
X
-------
Dynamometer Verification Data Processing
Perform
TP-302A
Fill in the
data sheet.
Submit to
Operations.
I
Operations
inputs via
batch on LCS
Report
Run E.DCHECK
on LCS
I
Dynamometer Verification Summary
Store
Results
on
D.DCHECK
"Break" then
$RUN DYPLOT
on LCS PROD
Decwriter
Enter the
dates for the
plot period
requested.
Reports/plots
Process
data
-------
07/02/83
09:3;:3C
R.UCHECK
SYS1KMS KEAl.-l]
PHI •• •• •• IM •• ••
IMt: MONfflTTPb.l^*^ Y *^ff!)D ^^m PjJf^ 5^^
******************************************
** DYNAMOMETER C AL IliK»T ION VERIFICATION «*
** INPUT DATA ECHO **
** SITE: 0007 DATE: b-3o-82 •»
t*****************************************
GENERAL
INFORMATION
SUE
***«
D007 •
DATE
MO DY YR
*»-**-**
6-30-62*
TIME
Hh MN
* * : **
5:30"
bAHO-
MtTER
***,**
2B.9H *
ID
**** *
17211
COMMENTS
*************************************************
UbEO UC TIMER •
50KiPH FH
TW=10.0
.**.*
10.0 .
WAKM-UP ANU CHECK
TW VS 1HP
Tw=5.0
**.*
5.0 •
Tw=15.0
»*.»
15.0.
**.*
10.0
**.*
0.0
SPEEU CHECK TKslO.O
60 TOIUH GEAR
GEAR TOKljUfc
COONTS COUNTS OtL T
******. ******. **.***
1«90J.« 9517.C 9.613.
IHP
• *.«
10.0'
MHM-OP
COASTOOWNS
TW
*V.«
****.
6tt75..
f)EL Tl
**.***
31/713,
DEL T2
**.***
31.706 .
UEI. 13
•*.«**
31.712.
OEL T<*
**.***
31.616.
DEL T(KR)
***.***
31.153*
FHP CAL
* . * **
0.301«
SPEED TORUOE
PAU
HYSTERESIS
**.*
10.0'
RAMP-OP hi a. 5 MPH/SEC
GEAR
IW COONTS
****. ******.
"4000..
( 5-55 I-.PH )
TllHUIIE
COUNTS lit I. T
**»***. **.***
10003; 20.415.
HAMp-OOWN 3 2.5 MPH/SEC
( 55-5
GEAR TUHuUt
COUNTS COUNTS
******. ******
DEL T
**.**•
20.025
VERIFICATION
DATA
[.«
« *** .
5000.'
flOOO.'>
3500.'
3000..
AHP
**.*
15. 2«
I. .2"
10. 6»
S.2.
TW
* * . *
12. 2«
9.<4«
B.O.
6.6«
HP a>
50 SS
** . *
12.3 •
9.1 '
tt.O •
6.9 -
HP a
50 UC
** .» .
12.3.
9.5.
8.1-
7.0 .
MAS (EH
DEL T
**,***
19,«'40*
19.930*
19.fl<40«
19.790.
OCHECK
DEL T
**.***
19.«<4U*
19.930*
19.B«0 *
19.790 t
-------
07/02/B2
09:31:30
R.DCHECK
SYS
******************************************
«* DYNAMUMETEW CALIBRATION VERIFICATION «»
** VERIFICATION REPORT **
** SITE: ooo/ DATE: 6-3o-»2 *•
******************************************
GENERAL INPUT DATA
******************
DATE: 6-30-62 BAROMETER: 26.96 INHG
OPERATOR in: 17261 DYNO SITE: D007
COMMENIS: USED UC llMER
PROCESSED: 07/02/H2 09:29:20
ALL DATA AND RESOLTS HAVE BEEN VERIFIED
FOR CORRECTNESS AND ACCEPTABILITY
VERIFIED B» ti^JilijU.1
FILE ONE COPY IN THE DIAGNOSTICS
DOCUMENTATION FILE AND DISTRIBUTE THE OTHERS
WARM-DP AND CHECK
*****************
IHPii DIFF HUFF
Tw "SOSb l»iP-rw IHP-TW
10.0
5.0
15.0
10.0
1 (I . 0
5.0
ib.o
10.0
0.00
0.00
0.00
0.00
0.000
0.000
0.000
0.000
AVE
0.00
0.00
2.5 MPH/SEC iwa 4000 TW= 10.0
PAII HYbTEKESIS CHECK
*****************************
SPEED TOKUUh IHP
RAMP-UH
RAMP-DOWN
DIFF
AVE
TMtOK
OIFF (A-T)
X01FF
31.b24
32.060
0.556
31.602
30.000
1.802
6.007
13. 244
13.362
0.130
13.313
12.000
1.313
10.S43
3.069
3.177
0.067
3.133
2.6t><4
0.469
17.609
WARM-UP
TW= 9.5
*********
DEL Tl =
DEL T2 =
DEL 13 =
DEL T4 =
MAX-MlN =
MEAN =
ST DEV =
XCV =
Iw= 6B75
********
31.713
31.7B6
31.742
31.816
0.1030
31.764
0.0442
O.U91
REAR ROLL IW=155
*****************
DEL T = 31.152
FHP CHK = 0.302
PHP CAL =
OEL FHP =
XUEL FHP =
50-MPH SPEED CHECK
TW=10.0, faO-TUOTH GEAR
***************************
SPt EO
TORUDE IHP
0.301
0.001
0.366
AVE
THEUH
UIFK
XOIFF
50.602
bO.UOO
CoTTo^
iTToTr
26.7hO
27.6^5
(-0.270
-0.999
10.0
10.2
-0.2
-2.2
UUALITY-COIMTROL COMMENTS
(»S KEFEK TO TP-302A CwITEHIA)
****************************************
5)50MPH CHK, i'DIFF CSHU>.2;TO«0>1; IhH>.4)
DYNAMOMETER VEHIF1CAIION DATA
*****************************
1W
AHP
HP i) HP «' MASTER UCHECK DUF
50SS 50UC OEL T OEL 1 OtL T
OIFK X01FF
THEOR MASTER- MASTER-
UEL T IhfcuR THtOH
5000 IS.2 12.2 12.3 12.3 19.B40 I
4000 12.2 9.4 9.4 9.5 19.930 14.930
3500 10.6 0.0 B.U tt.l 19.H40 19.B40
3000 9.2 b.6 6.9 7.0 19.790 19.790
o.ooo
0.000
0.000
o.ooo
If. 977 .
19.911
20.052
19.803
-0.137
0.019
-0.212
-0.013
-0.666
0.093
-1.059
-0.1)67
AVERAGES 0.000
-0.066 -0.430
-------
0*7/02/82
09:31:30
H.UCHECK
SYSTKt-.!)
PNOD
PAGE
A*****************************************
** UYNAI«<)ntTEK CAl.I'IKAT ION VERIFICATION **
** flJIJK MONTH lUJALlfY CUN1KOL SUMMARY **
** siu:: 0007 DATE: b-30-82 **
******************************************
AVERAGE OIFF
DATE
MM-OO-YK
3- 3-62
3-10-82
3-17-82
3-24-82
3-30-82
a- 8-62
4-22-82
4-26-82
5- 4-62
5-12-82
5-19-82
5-26-62
6- 3-82
6-11-82
6-16-62
6-23-82
6-30-82
RH
FHP
0.296
0.267
0.315
0.309
0.305
0.320
0.307
0.298
0.2h«.
0.316
0.000
0.304
0.420
0.305
0.290
0.321
0.302
OIFF
IHP-TW
-0.020
-0.050
-0.050
0.000
0.000
0.000
o.oou
-0.050
-0.070
0.050
o.uoo
-0.050
-0.020
o.ooo
-0.050
0.050
0.000
XDIFF
IhP-1*
-0.30
-0.50
-0.50
0.00
0.00
0.00
0.00
-0.50
-0.60
0.50
0.00
-0.50
-0.30
0.00
-0.50
0.50
0.00
PAU
SPEED
-0.60
-0.40
0.47
0.21
-0.7»
-0.04
0.00
0.11
-0.11
0.54
0.00
-0.07
0.00
0.00
0.00
0.38
0.56
OIFFtOOwN-UH)
lOKUUfc
-0.163
-0.286
0.565
0.345
-O.i50
0.144
0.000
0.038
O.OH3
0.382
0.000
0.235
0.000
0.000
0.000
0.446
0.136
IMP
-0.11
-0.10
0.17
0.10
-0. 15
0.03
O.UO
0.02
0.01
0.14
0.00
0.05
0.00
0.00
o.oo
0.13
0.09
6H/5
KEAN
31.0H3
29.968
31.302
31 .026
30.95b
30.703
30.876
30.HU5
30.416
30.779
0.000
31.047
30.h38
30.773
31.214
30.985
31.7b4
b" FH
SPEfcU
-0.006
-0.019
0.036
0.042
0.116
0.1»b
0.104
0.060
0.049
0.060
0.000
0.034
0.020
0.000
0.000
0.060
0.602
UIFF CHECK
TUKUUE
-0.261
0.000
-0.314
-0.317
-0.214
-0.1/2
0.175
-0.277
-0.279
-0.267
0.000
-0.364
-0.365
0.000
-0.351
-0.181
-0.270
IMP
-0.100
0.000
-0.100
-0.100
-0.100
0.000
0.000
-0. 100
-0.100
-0.100
0.000
-0.100
-0.100
0.000
-0.100
-0.100
-0.200
TIMtK
M-OC
-0.059
-0.066
-0.066
-0.064
-0.056
-0.073
0.000
-0.075
-0.074
-0.067
-0.081
-0.100
-0.092
-0.103
0.088
0.076
0.000
OIFF
M-1HEUR
0.254
-0.105
0.619
0.023
0.177
-0.221
-0.207
-0.069
-0.206
0.072
-0.263
0.436
-0.263
0.048
0.021
0.260
-0.086
X01FF
M-ThEOR
1.273
-0.530
3.100
0.112
0.665
-1 .106
-1.038
-0.445
-1.041
0.362
-1.317
2.192
-1.320
0.241
0.105
1.301
-0.430
AVERAGES
********
N =
MIN
MAX
AVERAGE
STO OEV
16 10 10
0.267 -0.070 -0.80
0.420 0.050 0.50
0.310 -0.026 -0.29
0.031 0.032 0.33
12 12 \
-------
25.105
in water, the water in the exhaust gas must not be allowed to condense.
The NO2 sample train must be heated to about 175°F.
Exhaust gas samples (such as those collected in bags), which have been
allowed to stand for a few minutes or longer, will contain larger concentra-
tions of NOi than tail pipe exhaust samples which were analyzed immedi-
ately, because upon standing the NO oxidizes to NO>.
C2.1 Theory—The principle of operation of the ultraviolet analyzers
is based on the differential absorption of light energy at 4000 A where
NO] has a strong absorption band. Light is supplied by a tungsten filament
lamp with calibration accomplished with known low concentrations of
NO2 in stainless steel cylinders. Extreme caution must be used in achieving
a clean sample system for calibration and exhaust analysis.
C2.2 Interference—No response is obtained from an NO2 ultraviolet
analyzer with a 13.5 in cell for the following gases:
12% CO2 + 5% CO
567 ppm hexane
1000 ppm propane
Water saturated Nj
There is a slight interference from NO. Approximately 1 ppm NOj is
indicated for each 130 ppm of NO.
CONSTANT VOLUME SAMPLER SYSTEM FOR EXHAUST
EMISSIONS MEASUREMENT—SAE J1094a
SAE Recommended Practice
Kr|Mirl til Anhuntilivr KlIllsMont (:*>inillllltT;i|)|IliAr(l Jtillr 1H7 I ,imlii>MI|ilrlrlv Irv isi-d l>\ Auloinnlivr Km
Scope—This SAE Recommended Practice describes uniform laboratory
techniques for employing (he constant volume sampler (CVS) system in
measuring various constituents in the exhaust gas of gasoline engines installed
on passenger cars and light trucks. The techniques described relate particu-
larly to CVS systems employing positive displacement pumps. In some areas
of CVS practice, alternate procedures are given as a guide toward develop-
ment of uniform laboratory techniques.
The report includes (he following sections:
I. Introduction
-'. Definitions
3. Test Equipment
3.1 Sampler
3.'2 Bag Analysis
3.3 Modal Analysis
3.4 Instrument Operating Procedures
3.5 Supplementary Discussions
3.6 Tailpipe Connections
3.7 Chassis Dynamometer
4. Operating and Calibrating Procedure
4.1 Calibration
4.2 Operating Procedures
5. Data Analysis
5.1 Bag Analysis
5.2 Modal Analysis
5.3 Background
5.4 Fuel Economy
6. Safety
/. Introduction: Development of CVS System—Constant volume sampler
(CVS) systems have been used since the late 1950s. The engine exhaust to be
sampled is diluted with ambient air so that the total combined flow rate of
exhaust and dilution air mix is nearly constant lor all engine operating
conditions. The CVS system is sometimes called a variable dilution sampler.
Recently constant volume sampler systems have been abbreviated PDP-CVS
or CFV-CVS. The PDP-CVS system is the older system that uses a positive
displacement pump to maintain a constant total flow. The CFV-CVS system
uses a critical flow venturi to maintain a nearly constant total flow. Some of
the newer CFV systems no longer use a heat exchanger to bring the mix of
engine exhaust and dilution air to a constant temperature, but instead moni-
tor the mix temperature continuously in order to calculate the total flow
accurately. These CFV systems are not constant volume samplers, but since
they are used to measure emissions, the units are discussed here.
Hydrocarbons in the dilution air were recognized from the first as a prob-
lem in the CVS procedure. Studies were initiated on the feasibility of remov-
ing the unwanted hydrocarbons. As a result, the installation of charcoal filters
in the dilution air system was chosen as the most practical solution. Charcoal
does not remove any of the hydrocarbon materials, but it does stabilize their
concentration level during a given test and thereby permit the collection of an
accurate background sample.
2. Definition!—The following definitions apply to the term indicated as the
term is used in this recommended practice.
2.1 Analytical Train—A general term to define the entire system re-
quired to sample and analyze a particular constituent in exhaust gas. Typi-
cally, this train will include items such as tubing, condenser, paniculate filter,
sample pump, analytical instrument, and flow meter.
2.2 Calibration Curve—Normally, the dependent vai iable^, the concen-
tration of the calibration gas, is plotted as a function of the independent
variable x, the instrumental voltage. For nonlinear analyzers, a polynomial of
degree no greater than the fourth power is used. Sufficient data points should
:\|ilil I'l
H. Kill ....... 1 1 h.ilivi-
be used to adequately define the analyzer response. The calibration curve
should agree to within 1% of the measured data point.
2.3 Calibration Frequency — Analyzers should be checked at least
monthly to determine if significant change has occurred in the calibration. In
addition, the calibration should be verified when a problem is suspected and
when large gain shifts are observed.
2.4 Calibrating Gas — A gas mixture of accurately known concentration
which is used periodically to calibrate the analytical instruments. Usually,
calibration requires a number of mixtures of different concentrations. Cali-
brating gases are usually divided into groups such as NBS standard reference
gases, golden standards, primary standards, and working gases. The naming of
the working gases should be traceable to the NBS standard reference gases.
2.5 Chassis Dynamometer — A laboratory power absorption unit capable
of simulating to a limited degree the road operation of a vehicle. The dyna-
mometer should possess the capability to simulate the inertia and road load
power developed by a vehicle.
2.6 Chemiluminescent (CL) Analyzer — An instrument which measures
nitric oxide by measuring the intensity of chemiluminescent radiation from
the reaction of nitric oxide with ozone. The addition of a converter will permit
the measurement of the oxides of nitrogen.
2.7 Chock — A block or wedge that prevents movement of the wheels of a
vehicle.
2.8 Coastdown — The procedure used to determine the total horsepower
absorbed by a dynamometer at 50 mph (80 km/h). The time required for the
rolls to coast down from 55-45 mph (88-72 km/h) is observed.
2.9 Constant Volume Sampler (CVS)— A device for collecting samples
of diluted exhaust gas. The exhaust gas is diluted with air in a manner that
keeps the total flow rate of exhaust gas and dilution air constant throughout
the test. The device permits measuring mass emissions on a continuous basis
and also, through use of a second pump, allows a proportional mass sample to
be collected.
2.10 Converter— A thermal or catalytic: reaction device which usually
precedes the chemiluminescent analyzer and converts oxides of nitrogen to
nitric oxide. The converter may also convert ammonia and other nitrogen
containing compounds to nitric oxide.
2.11 Counter — A mechanical and/or electrical device that totalizes the
number of revolutions of the CVS for each test phase.
2.12 Curve Fitting — See calibration curve, Lagrangian fit, polynomial fit.
2.13 Detector — That component in an analytical instrument which is
sensitive to a particular gas.
2.14 Dilution Air — Ambient air which is passed through filters to stabi-
lize the background hydrocarbon concentration and which is used to dilute
the vehicle exhaust.
2.15 Dilution Factor — Based on stoichiometric equation for fuel with
composition CH1SS, the dilution factor is defined as:
_ 13.4 _
CO2 + (HC + CO) x 10-4
where CO2 is equal to the concentration in dilute exhaust sample in mole
percent, HC in ppm carbon equivalent, and CO in ppm corrected for water
vapor and CO2 extraction.
2.16 Dilution Ratio — The ratio of CVS volume to exhaust volume,
usually found by dividing the undiluted exhaust CO.2 concentration by the
dilute CO2 concentration.
2.17 Driver Aid— An instrument used to guide the vehicle driver in
operating the vehicle in accordance with the specified acceleration, decelera-
tion, and cruise operating modes of a specific driving procedure.
2.18 Exhaust Emissions — Substances emitted to the atmosphere from
-------
25.106
any opening downstream from the exhaust port of a motor vehicle engine.
2.19 Fifth Wheel—A calibrated wheel, axle and tachometer generator
assembly that can be used to determine the true speed of the vehicle (by
towing the wheel assembly), or true speed of the dynamometer rolls (by
permitting the rolls to drive the fifth wheel assembly).
2.20 Filter Cell—That portion of the NDIR instrument which is tilled
with a particular gas in order to reduce interference signals.
2.21 Flame loni/alion Detector (FID)—A hydrogen-air tlame detector
that produces a signal proportional to the mass How rate of hydrocarbons
entering the Maine per unit time.
2.22 Hang-Up—The absorption-desorption of sample (mainly higher
molecular weight hydrocarbons) from the surfaces of the sample system that
can cause instrument response delay and lower concentration at the analyzer.
followed by higher readings in subsequent tests.
2.23 Heat Exchanger—An air-to-air or air-to-water heat exchanger.
which is used to control the temperature of the dilution air-exhaust gas
mixture.
2.24 Horsepower
'-'.24.1 ABSORBED HORSEPOWER—Total horsepower absorbed by the absorp-
tion unit of the dynamometer and by the frictional components of the dyna-
mometer.
2.24.2 ABSORBED HORSEPOWER AT 50 MPII (80.5 KM/H) ROAD LOAD—The
dynamometer setting values for various inertia weight vehicles published in
the* Federal Register.
2.24.3 FRICTIONAL HORSEPOWER—Horsepower absorbed by the frictional
components of the dynamometer.
2.24.4 INDICATED HORSEPOWER—Horsepower values indicated by the
horsepower meter of the dynamometer.
J.24.5 INDICATED HORSEPOWER AT 50 MPII (80.5 KM/H) ROAD LOAD—The
dynamometer setting values, determined by calibration, that correspond to
the dynamometer setting values published in the Federal Register.
2.25 Inertia Weights—A series of rotating disks used on a chassis dyna-
mometer to simulate to the nearest 125, 250, or 500 Ib (57, 113, or 227kg)
increments of the test weight of a vehicle during accelerations and decelera-
tions. The inertia weights have no effect during steady states.
2.26 Lagrangian Fit—A computer technique used to interpolate polyno-
mial curves generated from a set of data points (calibration points). ;V data
points are required to generate a curve to N — I deg. A feature of this
technique is that the interpolated curve goes through each data point exactly.
2.27 Laminar Flow Element (LFE)—A flow rate measuring device that
has a linear relationship between How rate and pressure drop.
2.28 Light-Duty Vehicle—A motor vehicle designed for transportation of
persons or property on a street or highway and weighing 6000 Ib (2722 kg)
gvw or less.
2.29 Loaded Vehicle Weight—The curb weight of a light-duty vehicle
plus 300 Ib (136kg).
2.30 Mixing Device—A device that is used in the main flow stream of a
CVS to promote mixing of the exhaust gas with the dilution air.
2.31 Mode—A particular operating condition (for example, acceleration.
cruise, deceleration, or idle) of a test cycle.
2.32 Nondispersive Infrared (NDIR) Analyzer—An instrument to de-
termine carbon monoxide, carbon dioxide, nitric oxide, and hydrocarbons in
exhaust gas. Now primarily being used lor carbon monoxide and carbon
dioxide determinations.
2.33 Normalizing Gas (Span Gas)—A single calibrating gas blend rou-
tinely used in calibration of each analytical instrument.
2.34 Optical Filter—That portion of the NDIR instrument which elimi-
nates wavelength regions where interference signals are obtained.
2.35 Oxides of Nitrogen—The sum total of the nitric oxide and nitrogen
dioxide in a sample expressed as nitrogen dioxide.
2.36 Ozonator—An electrical device that generates ozone from oxygen-
or air.
2.37 Parts per Million Carbon—The mole fraction of hydrocarbon
measured on a methane equivalence basis.
2.38 Polynomial Fit—A technique of generating a calibration curve from
a set of points.
2.39 Positive Displacement Pump—A CVS blower, gas pump, or con-
stant displacement pump that delivers a metered amount of air per revolution
measured at inlet conditions.
2.40 Probe—A sample line inserted into the exhaust stream of a vehicle
or engine in such a manner as to obtain a homogeneous or well-mixed exhaust
sample.
2.41 Reference Cell—That portion of the NDIR instrument that is
usually filled with air (sometimes nitrogen) and provides the reference signal
to the detector.
2.42 Remote Filter Box—Particular CVS design that has the dilution air
filters and mixing chamber housed in a separate cabinet which can be located
close to the tailpipe of the test vehicle.
2.43 Sample Cell—That portion of the NDIR instrument which contains
the flowing sample gas.
2.44 Stratification—Variation in concentration of a sample stream when
samples are taken at different points on a cross section of the mixed CVS
stream just ahead of the CVS positive displacement pump.
2.45 Tailpipe Pressure—The static pressure measured at the tailpipe
when a CVS is connected to a test vehicle.
3. Tett Facilities and Equipment
3.1 Sampler—CVS systems can exist in a variety of physical configura-
tions, but all of them permit measuring emissions of vehicles.
3.1.1 BASIC EQUIPMENT—The principal component of a CVS is either the
positive displacement pump (PDF) of the older models or the critical flow
venturi (CFV) of more recent designs. The positive displacement pump
consists of a pair of symmetrical rotating, two-lobe impellers driven in oppo-
site directions and encased by a housing. A critical flow venturi CVS has a
CVS compressor unit that is used in conjunction with the critical flow venturi.
Fig. 1 shows a sketch of a CFV-CVS.
3. I.I.I A dilution air filter system consisting of a paniculate (dust) filter,
a charcoal filter, and a second paniculate filter which removes airborne
particles, stabilizes hydrocarbons, and traps charcoal particles.
3.1.1.2 A flexible coupling to the tailpipe of the test car brings in undi-
luted exhaust gas to the mixing chamber.
3.1.1.3 A mixing chamber combines the automotive exhaust from the
test car and the dilution air into a homogeneous (nonstralilicd) mixture.
3.1.1.4 A heat exchanger is used to control the temperature of the ex-
haust gas dilution air mixture. The heat exchanger should be capable of
controlling the temperature of the dilute exhaust gas ±; 10°F (5.6°C) during
testing. In some models of CVS, a temperature controller regulates both the
flow of cooling water or hot water (from a hot water heater) through the heat
exchanger to control mixture temperature. In other models of CVS, the
dilution air is preheated so that the temperature controller regulates the flow
of cooling water through the heat exchanger in order to control the mixture
temperature.
3.1.1.5 A secondary heater system maintains the heat exchanger at a
temperature to prevent water condensation.
3.1.1.6 A sampling system transfers the exhaust-air mixture from the
positive displacement pump inlet to the bag at a constant flow rate. The
minimum sample flow rate should be 10 ft:1/h (0.28 m3/h). Each sampling
system consists of fiberglass filter, a diaphragm type pump, a How control
valve, and a flow meter or other gas measuring device. All of the surfaces in
contact with the sample air or air-gas mixture are stainless steel or other
nonreactive material.
3.1.1.7 A similar sampling system collects dilution air from a point just
downstream of the air filter and transfers it to a separate bag.
3.1.1.8 An evacuation and purge pump to remove the excess sample from
the bags and purge the bags with clean air.
3.1.1.9 A set of bags (sample and background) and appropriate controls
is needed for each of the test phases.
3.1.2 SUPPLEMENTARY EQUIPMENT—In addition to the above basic equip-
ment, the following items can be added for operating convenience:
3.1.2.1 A muffler located after the CVS pump to reduce the noise.
3.1.2.2 A four-speed motor, transmission, or other suitable means for
driving the positive displacement pump will permit a choice of different
dilution ratios.
3.1.2.3 An optional remote control operating station containing the
counter, the operations logic module, and the various control function
switches and indicator lights that permit convenient operator control at a
distance from the CVS console.
3.1.2.4 Optional modal analysis at the analytical bench during the filling
of the bag is made possible through the use of a separate sampling probe(s).
One probe is used if continuous modal analysis is conducted using undiluted
exhaust.1 The second probe in this case is used to monitor diluted CO.j which
is used as a tracer gas to determine engine flow. Tail pipe sample should either
be returned to the CVS bulk stream if the amount withdrawn is a significant
fraction of total exhaust flow (greater than l'7<), or the loss in tail pipe sample
should be corrected mathematically.
3.2 Analysis Instrumentation—Bag Analysis
3.2.1 SCHEMATIC—Fig. 1 is a sketch of the sampling and analysis train that
is a typical flow schematic for the bag analysis of engine exhaust using the
CVS.
3.2.2 COMPONENT DESCRIPTION—The following components are* suggested
for the CVS bag sampling and analytical systems for the analysis of carbon
monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOX), carbon dioxide
(CO2), and oxygen (O2):
'Two probes are required if continuous modal analysis is conducted using undiluted
exhaust.
-------
25.107
FIG. t-GFV-CVS SAMPLER UNIT
3.2.2.1 NDIR analyzers for measurement ol CO and CO., with cells of
appropriate length for concentration ranges being measured. Typical ranges
are shown in Table I.
3.2.2.2 Chemiluminescent (CL) NO analyzer or equivalent NDIR NO
analyzer are both equipped with a. bypass and NO2 to NO converter for the
measurement of NOS with concentration range selection as shown in Table 1.
3.2.2.3 FID for measurement of HC. The instrument employed should be
capable of measuring HC for ranges shown in Table 1.
3.2.2.4 Oxygen analyzer for measurement of O2 with range of measure-
ment as shown in Table 1.
3.2.2.5 Values V,2 used to direct the sample or purge air to the analyzers.
3.2.2.6 Valves V,, V4, Vg (optional). V9, and V,0 used to direct the
sample, zero gas, or span gas streams to the analyzers.
3.2.2.7 Filters F, and F.2 for removing paniculate materials from the
sample prior to analysis. A glass fiber filter of at least 7 cm diameter is
suitable.
3.2.2.8 Pumps P, and P2 to move the sample through the system. Pumps
should have stainless steel or aluminum chambers with diaphragms and valves
made from or covered with an inert material, such as Teflon. Free air capacity
should be approximately 40 ft3/h (1.1 nv'/h). Pumps P., for bypass How of
Chemiluminescent analyzer and vacuum pump P4 (optional depending upon
the design of the Chemiluminescent analyzer) for evacuation of the Chemi-
luminescent reactor chamber.
3.2.2.9 Needle valves N,, NH, N7, and N,, to regulate sample gas flow to
the analyzers.
3.2.2.10 Needle valves N2, N5, N8, and N12 to regulate span gas flow to
the analyzers.
3.2.2.1! Optional valve V9 used to direct CO2 span gas through the
water bubbler for checking the performance of drier and absorber system or to
check the H2O and CO2 interference rejection characteristics of the CO
analyzer. Needle valve N20 is used to regulate CO2 flow.
3.2.2.12 Needle valves N3, N6, N9, N13, and N)5 to regulate zero gas flow
to the analyzers.
TABU 1—TYPICAL LOW RANGES FOR ANALYSIS OF HC, CO, CO,,
NO,, AND O, IN SPARK IGNITION ENGINE EXHAUST
HC
CO
1975
1976
CO,
Dilute CO,
02
Ranges
CVS Bag Sample
0-30 ppmC
0- 1 00 ppm
0-250 ppm
0-10 ppm
0-2.0%
—
0-21%
Undiluted Exhaust Gal
0-500 ppmC
0-0.3%
0-2500 ppm
0-250 ppm
0-15%
0-5%
0-10%
3.2.2.13 Flow meters FL,, FL2, FL3, and FL4 to indicate span gas, zero
gas, and sample flow to the analyzers.
3.2.2.14 Water trap T,, if necessary, to partially remove water and a
valve N14 to allow the trap to be drained.
3.2.2.15 Optional2 sample conditioning columns CR, and CR2 contain-
ing ascarite to remove CO2 from the CO analysis stream, and WR, and VVR2
containing indicating CaSO4 or indicating silica gel to remove the remainder
of the water. Equivalent drying techniques such as diffusion driers may be
used.
3.2.2.16 Optional valves V6 and V7 to permit switching from exhausted
absorbing columns to fresh columns.
3.2.2.17 Optional water bubbler W, to allow saturation of CO, span gas
to check the efficiency of the absorbing columns in the CO system.
3.3 Analysis Instrumentation—Modal Analysis (Undiluted Exhaust Gas)
3.3.1 GENERAL—Fig. 3 is a schematic drawing of the sampling and analysis
train that is recommended for the modal analysis of spark ignition engine
exhaust using the CVS. The system is very similar to that required for bag
analysis, with the exception that water traps are required on all instrument
sampling streams and an additional CO2 analyzer is required. In addition,
instruments of only approximately '/,„ the sensitivity of those used for bag
analysis are needed. This system is based upon measuring continuously undi-
luted exhaust gas concentrations of HC, CO, NO,, and CO2 and the diluted
exhaust CO2 concentration.
The undiluted and diluted exhaust CO., concentrations are used to calcu-
late a dilution factor which, in conjunction with the total diluted volume, can
be used to calculate the vehicle exhaust volume. With the calculated exhaust
volume and the undiluted exhaust concentrations, the modal mass emissions
of each pollutant can be calculated as described in paragraph 5.2.2.
3.3.2 COMPONENT DESCRIPTION—The following components are recom-
mended for the analytical systems for the modal analysis of CO, HC, NO.,
CO2, and O2.
3.3.2.1 NDIR analyzers for measurement of CO and CO2 with cells of
appropriate length for the concentration ranges being measured. Typical
ranges are shown in Table 1.
3.3.2.2 The CO2 analyzer for the measurement of CO2 in the diluted
exhaust stream can be modified to the extent that the reference cell is replaced
with a second sampling cell through which dilution air is passed during
sampling. This feature will automatically correct the measured CO2 in the
diluted exhaust for the amount of CO2 in the dilution air.
3.3.2.3 Chemiluminescent (CL) NO analyzer equipped with a bypass
2The criteria for CO interference by CO2 and water is given in the Federal Register,
Vol. 39, No. 101, May 23, 1974: "A CO instrument will be considered to be essentially
free of CO2 and water vapor interference if its response to a mixture of 3% CO2 in Nz,
which has been bubbled through water at room temperature (68-86° F), produces an
equivalent CO response, as measured on the most sensitive CO range, which is less than
1% of full scale CO concentration on instrument ranges above 300 pptn CO or less than
3 ppm on instrument ranges below 300 ppm CO."
-------
25.108
FIG. 2-BAG SAMPLING AND ANALYSIS TRAIN
and a NO; 10 NO convener for the measurement of NO, with the concentra-
tion range selection as shown in Table I.
3.3.2.4 FID for measurement of HC. The instrument should be capable
of measuring HC for the ranges shown in Table I.
3.3.2.5 Oxygen analyzer for measurement of O., with range of measure-
ment'shown in Table I.
3.3.2.6 Valves V, and V,., used to direct (he sample of purge air to the
analyzers or to purge air to the blowout traps.
3.3.2.7 Valves V,, \\, V,,, V10. V14, and V,,, used to direct the sample.
zero gas. or span gas streams to the analyzers. Valve V4 is used to direct the
span gas to the O.j sensor.
FIG. 3—MODAL SAMPLING AND ANALYSIS TRAIN
3.3.2.8 Filters F,, F.,. K.,. and F, for removing the paniculate from the
sample prior to analysis. A class tiber typo of at least 7 cm in diameter is
suitable.
3.3.2.9 Pumps P,, P.j, P.,, and P., to move the sample through the system.
Pump P5 for bypass How of the chemiluminescent analyzer and vacuum pump
PU (optional dependent on design of chemiluminescent analyzer) for evacua-
tion of the chemiluminescent reactor chamber. Pumps should have stainless
steel or aluminum chambers with diaphragms and valves made from or
covered with an inert material, such as Teflon. Free air capacity should be
approximately 40 fr'.'h (1.1 nr'/h).
3.3.2.10 Needle valves N.J, N;l. N,,,. N,._,, N,-, and N1!t to regulate sample
gas flow to the analyzers.
3.3.2.11 Needle valves N,. Nrt, N,,. N,a. arid N.,., to regulate span gas flow
to the analyzers.
3.3.2.12 Optional valve V'.,, used to direct CO., span gas through the
water bubbler for checking the performance of the absorbers in the CO
analyzer stream. Needle valve N,, (optional) is used to regulate CO._, flow.
3.3.2.13 Needle valves N5, N7. N,,. N,v N;,,, and N.j, to regulate zero gas
flow to the analvzers.
3.3.2.14 Flow meters KM,. KM... KM.,. KM.,, KM,,, and KM(i to indicate
span gas, zero gas. and sample flow to the analyzers.
3.2.2.15 Water traps T,, F... and T-, to partially remove water and valves
N.,,. N1.,,,. and N.JI; to allow the traps to be drained.
3.2.2.16 Optional sample conditioning columns OR, and CR.j containing
ascaritc in remove CO., from the CO analysis stream, and WR, and WR,
containing indicating CaSO, or indicating silica gel to remove the remainder
of the water. Ascaritc produces water when it removes CO.. from the stream.
Equivalent drying techniques such as diffusion driers may be used. The
volume of the conditioning columns must be sufficient to be effective for the
duration of the lest. Some operational ranges for continuous analysis may not
require water and CO., removal. Some new CO instruments do not have
water or CO., response.
3.3.2.17 Optional valves V,,, and V'.,0 to permit switching from the
exhausted absorbing columns to fresh columns.
3.3.2.18 Optional water bubbler W, to allow saturation of CO.. span gas
to check the efficiency of the absorbing columns in the CO system.
3.3.2.19 Needle valves N,, NB, N,,, and N|(i to regulate ihc bypass
sample Mow.
3.4 Instrument Operating Procedures—Follow the instrument manufac-
turer's start-up and operating procedure for the particular type instrument
being used. In addition, the following minimum calibration and instrument
checks should be included.
3.4.1 INITIAL—The following instrument checks should be accomplished
prior to making emission measurements with the instruments:
3.4.1.1 Optimise h'lD Resptmse
(a) Set burner fuel and air settings as prescribed by the manufacturer.
Present burner fuel composition now recommended is tiO'v- He, 40r'i H...
However, best composition for burner fuel is now being investigated. Ignite
the burner and set sample flow. Wait until the analyzer stabilizes before
proceeding. Optimize the KID as suggested in SAK Procedure J25-I (June,
1971).
(b) Determine the optimum burner fuel flow for maximum response. A
blend of 60'/< He and 40" H., is recommended for use as the burner fuel. The
use of other fuels could produce a correlation problem. Introduce propane in
N.j at a concentration level of approximately 300 ppmC for undiluted gas
analysis and propane in air for bag analysis. Vary the burner fuel flow to
obtain ihc peak response. Normally, there is a plateau in the region of peak
response. Select a flow in this region which results in the least variation in
response with minor fuel flow variations.
(c) Determine optimum airflow. Set the burner fuel flow as determined in
paragraph 3.4.l.l(b) and vary airflow to obtain maximum response. If the
airflow is too high, excessive noise may result.
(d) If the airflow is significantly different from that used in paragraph
3.4.1.1(b), repeat step (b) with the new airflow.
3.4.1.2 Determine Oxygen Response of FID Analyzer—Variations in the oxy-
gen content of the sample can affect the FID response. This effect must be
determined and minimized.
(a) CVS bag analysis
(I) Set flows as determined in paragraph 3.4.1.1 and ignite the burner.
Wait for stabilization. Normally, the burner is operated continuously to avoid
the stabilization problem.
(2) Zero the analyzer on HC free air.
(3) Determine the oxygen response by introducing propane gas at a
concentration of approximately 30 ppmC in the following diluents: 100% N2,
95% N2/5% O2, 90% N,/IO% O,, 85% N,/15% O,, and 100% air.
(4) Using the propane in the air gas as the baseline for no O2 correction,
plot a curve of the oxygen correction factor versus the percent O2 in the
sample:
-------
25.109
O2 correction factor = 1.0 —
(A - B)
B
CHEMILUMINESCENCE »N»LY2ER
where: A = HC response in N2/O2 blends
B = HC response in air
(5) Check the effect of O2 using a propane concentration of 50 ppmC. If
it is significantly different from the 30 ppmC correction data, establish a curve
and apply the O2 correction on a prorated basis as a function of HC concen-
tration.
(6) If the O2 correction factor is less than 0.96 over the normal O2 range
encountered in CVS sampling, see paragraph 3.5.2.
(7) It is recommended that a different detector be obtained if the oxygen
correction factor is less than 0.90 for the O2 range found in CVS samples.
(b) Modal Analysis—Undiluted Exhaust Gas
(1) Set flows as determined in paragraph 3.4.1.1 and ignite the burner.
Wait for stabilization. Normally, the burner is operated continuously to avoid
the stabilization problem.
(2) Zero the analyzer with N2.
(3) Determine the oxygen response by introducing propane gas at a
concentration of approximately 300 ppmC in the following diluents: 100% N2,
95% N2/10% O2, 85% N,/15% O2, and 100% air.
(4) Using the propane in N2 (0% O2) as the baseline for no O2 correction,
plot a curve of the oxygen correction factor versus the percent O2 in the
sample, where:
HC response with propane in 100% N,
O, corr factor =
HC response with propane in O2 blends
(5) If the O.j correction factor is greater than 1.05 over the range of
0-10% O2, see paragraph 3.5.2.
(6) It is recommended that a different detector be obtained if the oxygen
correction factor is greater than 1.10 for the O2 range found in the undiluted
exhaust gas samples.
3.4.1.3 Dtlermint Linearity of FID Response
(a) Set up the FID as determined in paragraphs 3.4.1.1 and 3.4.1.2. Set the
sample flow rate at a low value (approximately 5 ml/min) consistent with
good signal to noise ratio.
(b) Using propane in air, or N2, vary the concentration of HC over the
expected HC range. If the response is linear, a sample linear calibration factor
can be used. If the response is not linear, prepare a calibration curve.
3.4.1.4 Optimize Performance of ND1R—After adjusting the analyzers for
optimum performance using the manufacturer's recommended procedures, a
calibration curve must be generated for the ranges of the instrument that will
be used. All emission measuring instruments are comparative devices. The
generation of the calibration curves using standard gases (paragraph 3.5.1)
should be as accurate as possible. Since many analyzers are connected to
computers, a variety of curve-fitting techniques are being used. No specific
technique will be recommended here. Polynomial and Lagrangian curve
fitting techniques are widely used. It is recommended to examine carefully an
accurate plot of the calibration curve to verify that a smooth curve was
generated, rather than a curve that has only high correlation at the data
points.
3.4.1.5 Optimize Performance of Ctiemitummescence NO Analyzer—Using the
manufacturer's recommended procedures, adjust the analyzer for optimum
performance. In addition, determine the efficiency of the NO2 to NO con-
verter, at the converter temperature recommended by the manufacturer,
using the flow system shown schematically in Fig. 4. A suggested procedure is
given in Appendix A.
If the converter efficiency is below 90%, the converter temperature should
be increased and the efficiency rechecked. Converter temperature should be
set at a minimum required for near 100% conversion efficiency.
Care must be used to prevent condensation due to pressure buildup in the
NO, sample train between the sample pump and the analyzer. This has been
found to be a critical area of the NO, sample train, since condensation causes
a lowering of the measured NO, concentration and, therefore, an incorrect
NO, emission measurement.
3.4.2 MONTHLY—The following checks are to be made monthly^or more
frequently if there is any doubt regarding the accuracy of the analyses.
3.4.2.1 Calibrate the NDIR analyzers using the same gas flow rates as
when sampling exhaust.
(a) Allow 2 h warmup of analyzers.
(b) Tune analyzer.
(c) Set zero and span using prepurified N2 and the 100% range calibration
gas.
(d) Recheck zero and repeat step 3.4.2. l(c), if necessary.
(e) Calibrate each analyzer with calibrating gases that are approximately
15, 30, 45, 60, 75, and 90% of each range used. The concentration of the
standard gases should be known with at least ±2% accuracy. If the analyzer
proves to be non-linear, use an eight point calibration with a set of calibration
COMPONENT DESCRIPTION
Ci O> supply connection
Ci NO SUPPLY CONNECTION
C, CHEMILUMINESCENCE ANALYZER CONNECTION
MV, OXYGEN SUPPLY FLOW CONTROL VALVE
MV, NITRIC OXIDE SUPPLY FLOW CONTROL VALVE
Vi ON OFF FLOW SOLENOID VALVE
V. CONVERTER BYPASS VALVE
FM, FLOWMETER TO MEASURE 0, FLOW RATE
FM, FLOWMETER TO MEASURE NO FLOW RATE
NO SUPPLY 150-250 PPM NO IN NITROGEN
FIG. 4—FLOW SCHEMATIC OF CONVERTER
ANALYSIS SYSTEM
EFFICIENCY
gases spread approximately uniformly over the analyzer range in question.
(f) Compare values with previous curves. Any significant change reflects
some problem in the system. Locate and correct the problem and recalibrate.
3.4.2.2 Check FID analyzer O., response and HC response.
(a) Ignite the burner and then set the fuel, air. and sample flow rates as
determined in paragraphs 3.4.1.1 and 3.4.1.2.
(b) Introduce HC free air zero gas (CVS bag analysis) or N2 (Modal-undi-
luted exhaust gas analysis) and zero analyzer.
(c) Check O2 effect on the response by introducing the calibration gases of
propane in air, propane in N2, and propane in 90% No/ 10'tf O;,.
(d) Compare the O2 response values with the previous curves. Any signifi-
cant change (:± 10%) indicates a change in the burner operating characteris-
tics. Check the burner system and measure the Hows. If the change in the
response cannot be resolved, establish a new O2 response curve as per para-
graph 3.4.1.2.
(e) Check the calibration curve or response data as per paragraph 3.4.1.3.
3.4.2.3 Calibrate chemiluminesccnt analyzer using same flow rates as
when sampling exhaust.
(a) Set the sample flow and oxygen flow to the recommended settings.
(b) Turn the ozone generator on and allow a 10 min warmup period.
(c) Using nitrogen, zero the meter on the most sensitive range or the range
to be used by means of the dark current suppression adjustment.
(d) Set the span, using IOO'/! range calibration gas on the range to be used.
(e) Calibrate the analyzer with gases blended in N.j that are approximately
25, 50, 75, and 100% of the range being used.
(f) Check the values with the previous curves. Any significant change
reflects some problem in the system. Locate and correct the problem and
recalibrate.
(g) Caution. The correct standby position for the NO, converter is depend-
ent on the converter type. See manufacturer's instructions.
(h) Caution. Some NO2 to NO converters can be rendered useless for many
hours if they are allowed to sample exhaust gas (even momentarily) from over
rich vehicles where high levels of CO, low levels of O2, and free H2 are
produced.
3.4.3 WEEKLY—Check the converter of the chemiluminescent analyzer
using the procedure outlined in paragraph 3.4.1.5.
3.4.4 DAILY—Prior to daily testing carry out the following:
3.4.4.1 NDIR Analyzers—Normally, power is left on the NDIR analyzers
continuously. Only the chopper motors are turned off. In some cases, more
dependable performance has been achieved by leaving the chopper motors on.
(a) Zero on prepurified N2.
(b) Introduce span gas and set the gain to match the calibration curves.
Use the same flow rate for calibration, span gas, and exhaust gas to avoid
correction for the sample cell pressure change. Use span gas having a concen-
tration of the constituent being measured that will result in 75-95% of full-
scale deflection. If the gain has shifted significantly, check the tuning; if
necessary, check the calibration.
(c) Check nitrogen zero and repeat steps 3.4.4.1(a) and 3.4.4.1(b), if neces-
sary.
(d) Repeat steps 3.4.4.l(a) through 3.4.4. l(c) prior to each exhaust gas
analysis.
(e) Span and zero should be rechecked after bag measurements.
-------
25.110
3.4.4.2 FID Analyzer
(a) Ignite the burner and then set the fuel. air. and sample flow rales as
determined in paragraphs 3.4.1.1 and 3.4.1.2.
(b) Introduce zero gas (HC-free air lor CVS analyzers. .V, lor undiluted
exhaust gas analyzers) and zero analyzer.
(c) Introduce HC span gas (propane in HC-free air for CVS analyzers.
propane in No for undiluted exhaust gas analyzers) of appropriate concentra-
tion to result in a response of at least 50'v of full-scale on the range anticipated
for use. If the calibration curve and span value disagree adjust the span
potentiometer of the FID. Sample How for zero and span must be the same as
that used for analyzing exhaust sample.
(d) Repeat steps 3.4.4.2(a) through 3.4.4.3(c) prior to each exhaust gas
analysis.
(e) Span and zero should be rechecked after bag measurements.
3.4.4.3 C/iemiluminrsrent Analyzer—Normally power is left on continuously.
Operate converter in standby mode as recommended by the manufacturer.
Vacuum pumps arc normally kept on continuously on those model analyzers
using vacuum pumps. The ozonator should not be left on continuously for
safety reasons. Vacuum pump and ozone problems can be minimized by
replacing the pump oil with pertluorinated polyether fluid.
(a) Turn on the sample pumps.
(b) Set CX (in some models air is used) and sample Hows using nitrogen.
(c) Turn on ozone generator and allow a 10 min warmup.
fd) With the converter in the NO mode, adjust the dark current suppres-
sion to zero the meter on the most sensitive range or the range to be used.
using prepunlied N...
(el Introduce span gas and set gain to match the calibration curves. Use a
span gas having an NO concentration (hat will result in 73-95'''' of full-scale
deflection.
(f) Check dark current suppression and repeat steps 3.4.4.3(dl and
3.4.4.3(e) if necessary.
(g) Span and zero should be rechecked after bag measurements.
3.4.4.4 Oxygen Analyser
(a) Introduce oxygen-free nitrogen and set zero.
(b) Introduce air and set O2 span. This is usually done concurrently when
setting the zero on the FID analyzer.
(c) Sample flow for zero and span must be the same as that used when
analyzing exhaust gas samples.
3.5 Supplementary Discussion
3.5.1 CALIBRATION GASES—There are several suppliers of calibration gases
in the ranges used in this procedure. These can be obtained wiih an analysis
accuracy of ±2'^ or better. Slated gas analysis accuracies should be explicitly
defined in terms of traccability to NBS standard reference gases or applicable
gravimelric standards. It is recommended that all working gases be renamed
using NBS standard reference gases or in-house primary reference gases. If a
reference gas cylinder value does not fall on a smooth calibration curve, then
that cylinder must not be used.
The CO and CO2 gas can be purchased as a mixture in nitrogen. NO
calibrating gas should be diluted with oxygen-free nitrogen and must not be
mixed either with CO or CO2. Propane calibrating gases are purchased with
HC-free air as the diluent for use in CVS bag analysis and with N2 as the
diluent for use in undiluted exhaust gas analysis.
Zero gas impurity concentration should not exceed 1 ppm for HC, 1 ppm
for CO. O.I ppm for NO, 400 ppm (0.04%) for CO2, and 3 ppm for H2O.
3.5.2 REDUCING THE OXYGEN EFFECT ON RESPONSE—The oxygen correction
for FID should be reduced to attain the limits described in paragraph 3.4.1.2.
The oxygen effect on response for a particular FID burner design may depend
upon (a) the type of burner fuel used, for example H2, 40% H2/60% N2, or
40% H2/60% He; (b) on the sample flow rate into the burner; and (c) the air
and fuel rate to the burner.
3.6 Tailpipe Connections—To obtain a good constant volume sample of
exhaust gas it is imperative that no leakage, either into or out of the sampling
system, occur at the tailpipe connection between the vehicle and the CVS
sampler. The CVS sampler must be provided with dual inlets to accommo-
date vehicles with dual exhaust systems. When a vehicle with a single exhaust
is being tested, the second sampler inlet must be tightly capped to prevent
leakage.
Piping between the sampler and the vehicle should be kept to a minimum
length and be of adequate diameter. (See Section 4 for more detail on this
subject.) The actual connection between the vehicle tailpipe and the flexible
tubing of the CVS can be made in one of two ways:
(a) A flanged fitting such as a Marmon coupling. One end of this cou-
pling is welded to the flexible piping from the CVS and a mating section is
welded to the exhaust pipe(s) of each vehicle to be tested.
(b) A silicone rubber boot clamped to the exhaust pipe and inlet plumb-
ing to the CVS.
The first method, a flanged fitting, should be used whenever possible.
However, when fittings cannot be welded to each vehicle to be tested, the
silicon boot alternative has to be used. The main drawback of the silicone boot
is that the hot exhaust gas causes rapid deterioration of the silicone. When
vehicles with advanced control devices are tested, the very hoi exhaust gases
produced by these systems may cause the boot to crack internally after a single
test.
3.7 Chassis Dynamometer
3.7.1 PROCEDURE FOR DYNAMOMETER ABSORBED HORSEPOWER CALIBRA-
TION — The following procedure describes one method for determining the
absorbed horsepower of a chassis dynamometer. The measured absorbed
horsepower includes the dynamometer frictional horsepower as well as the
power absorbed by the power absorption unit. The dynamometer is driven
above the lest speed range to 60 mph (96 km/h). The device used to drive the
dynamometer (in most cases a vehicle) is then disengaged from the dyna-
mometer and the roll(s) allowed to coast down. The kinetic energy of the
system is dissipated by the dynamometer friction and absorption unit. This
method neglects the variations in roll bearing friction due 10 the drive axle
weight of ihe vehicle and also neglects the variations in friction due to
different inertia weights. The difference in coastdown time of the free (rear)
roll relative to the drive (from) roll may be neglected in the case of dyna-
mometers with paired rolls.
3.7.1.1 Equipment
(a) Fifth wheel, tachometer generator, or other device to measure the speed
of the front roll.
(b) Hydraulic jack or other equipment to lift vehicle's drive wheels from
ihc rolls.
(c) Stop watch or other liming device to measure the lime ii lakes the rolls
speed to decrease from 55 lo 45 mph (88.5 lo T1A km/h).
id) Pair of chocks, vehicle tie-downs, and other safely devices used lo assure
safe operation of a vehicle on the rolls.
3.7.1.2 Preparation
(a) Place the vehicle on the dynamometer rolls and set chocks against the
front wheels. Tie-downs should be slack enough to allow the vehicle to be
lifted from the rolls.
(b) Verify the calibration of the fifth wheel, tach generator, or other speed
monitoring equipment.
(c) Position the lifting device at the rear of vehicle.
(d) Place the lift pads under the rear bumper, adjacent to the bumper
brackets.
(e) Practice lift technique in disengaging the rear wheels to develop a
familiarity with the lifting device's response.
(f) When satisfied, raise the lift pads until they are in contact with the
bumpers so that there is sufficient tension to keep the lift pads in place until
ready to use.
(g) Set dynamometer inertia 10 4000 Ib (1816kg) or to the more common
weight class to be tested.
3.7.1.3 Test hocedure
(a) Drive the dynamometer with the lest vehicle lo 50 mph (80.5 km/h).
(b) Adjust the dynamometer power absorption unit to an indicated 2.5 hp
(1.9kW).
(c) Accelerate the dynamometer test vehicle to 60 mph (96 km/h). At this
point, disengage the drive wheels from the rolls by means of the lifting device.
(d) Record the time for the dynamometer to coast down from 55 to 45 mph
(88.5 to 72.4 km/h).
(e) Repeat steps 3.7. l.3(c) and 3.7.l.3(d) two more times.
(f) Calculate an average from ihe three coastdown times.
(g) Repeal steps 3.7. 1.3(a) through 3.7.1.3(0 for 5.0, 7.5, and 10.0 indicated
hp (3.7, 5.6, and 7.4 kW) and calculate the average coastdown limes for each.
3.7.1.4 Calculations — Calculate actual absorbed road horsepower from:
HP«, = -^
(V* _
2 32.2
550(
0.06073
/
where: Wi = equivalent inertia, Ib
C, = initial velocity, ft/s (55 mph = 80.67 ft/s)
Cj = final velocity, ft/s (45 mph = 66.00 ft/s)
( = elapsed time for rolls to coast down from 55 to 45 mph (88 to
72 km/h)
3.7.1.5 Bell Drive Dynamometers—The procedure outlined above has been
applied extensively to belt drive dynamometers. The next step is to plot the
indicated road load horsepower at 50 mph (80 km/h) versus the actual road
horsepower at 50 mph (80 km/h). Fig. 5.
The Federal Register advises running coastdowns at the inertia weight most
frequently used. Common practice is to run coastdowns at either all inertia
weight settings of a dynamometer or at least all inertia weights that are used
for testing.
3.7.1.6 Direct-Drive Dynamometers—The same procedure can be used for
direct-drive dynamometers as for belt drive dynamometers and should be used
for manual loading calibration of these units. However, automatic loading
-------
25.111
15
10
t-O
QOC
0
O
O
O
O
10
15
20
ABSORBED HORSEPOWER AT 50 MPH
FIG. 5—DYNAMOMETER CALIBRATION CURVE
features of (he new direct-drive dynamometers can improve the coastdown
procedure. An outline of a direct-drive dynamometer procedure is given in
Appendix C.
The direct-drive dynamometer procedure sets up the dynamometer for
operation at the desired operating points rather than finding a linear range for
each inertia weight. This procedure is rapid and reproducible in both running
coastdowns and in operation: It is recommended that a plot of frictional
horsepower versus inertia weight be made for each set of coastdown data.
These plots can aid in determination that the coastdown data is valid.
In Fig. 6, the frictional power is plotted as a function of inertia weight for
nine automatic loading direct-drive dynamometers. The data show that the
frictional powers are confined to an approximate 1 hp (745 VV) band. On these
plots, the "over 5500" values are plotted at 6000 for convenience.
An example of the effect of recalibration is shown in the frictional power
versus inertia weight plot in Fig. 7. A dynamometer recalibration indicated a
shift of over 0.5 hp (0.3 kW) friction. A recalibration showed that a speed
calibration error had been made. After correction, a typical shift of less than
0.5 hp (0.3 kW) was observed.
3.7.2 DYNAMOMETER PROCEDURE
3.7.2.1 The vehicle shall be tested from a cold start. Engine startup and
operation over the driving schedule make a complete test run. Exhaust emis-
sions are diluted with air to a constant volume and a portion is sampled
continuously during each of the three test phases. The composite samples.
collected in three bags, are analyzed for HC. CO. NO,, and CO... Three
parallel samples of dilution air are similarly analyzed. CO., is measured
because it is needed in determining the carbon balance fuel economy.
3.7.2.2 A Hxed-speed cooling fan with a nominal capacity of 5300 ft '/min
(150 nv'/min) is positioned during dynamometer operation so as to direct
cooling air to the vehicle in an appropriate manner with the engine compart-
ment cover open. In the case of vehicles with front engine compartments, the
fan is squarely positioned between 8 and 12 in (200 and 300 mm) in front of
the cooling air inlets (grill). In the case of vehicles with rear engine compart-
ments (or if special designs make the above impractical), the cooling fan or
fans should be placed such that engine/vehicle temperatures normally en-
countered during road operation are approximated. The vehicle should be
nearly level when tested in order to prevent abnormal fuel distribution.
3.7.2.3 Flywheels, electrical, or other means of simulating inertia as
shown in Table 2 should be used. If the equivalent inertia spccilicd is not
available on the dynamometer being used, the next higher equivalent inertia
available, not exceeding 250 Ib (113kg), should be used.
3.7.2.4 t'uwtr Ahsor/ition (mil Adjustment
(a) The power absorption unit is adjusted to reproduce absorbed horse-
power at 50 mph (80km/h) road load. The relationship between absorbed
power and indicated power for a particular dynamometer .should be deter-
mined by the procedure previously outlined.
(b) The absorbed power listed in Table 2 is used or the vehicle manufac-
8
g
° *-•
ISO 00
300.00 350.00 400 00 JSO 00 SOO 00
INERTIA WEIGHT 10
FIG. 6—TYPICAL FRICTIONAL HORSEPOWERS
-------
25.112
a CALIBRATION OF DYNAMOMETER
O RECAUBRATION OF DYNAMOMETER A ONE MONTH LATER SHOWING APPARENT SHIFT
• IMMEDIATE RECAL AFTER FINDING AND CORRECTING A SPEED CALIBRATION ERROR
«-
-f:
30O.OO 3SO.OO 40000
INERTIA WEIGHT 10
-..__. I ._
50000 55000
FIG. 7—EFFECT OF RECAUBRATION
turer may determine (he absorbed power by the following procedure and
request its use:
(i) Measure the absolute manifold vacuum of a representative vehicle of
the same equivalent inertia weight, when operated on a level road under
balanced wind conditions at a true speed of 50 mph (80 km/h).
(ii) Note the dynamometer indicated power setting required to repro-
duce the manifold vacuum, when the same vehicle is operated on the dyna-
mometer at a true speed of 50 mph (80 km/h). The tests on the road and on
the dynamometer should be performed with the same vehicle ambient abso-
lute pressure (usually barometric), that is, within ±5 mm of Hg.
(iii) The absorbed power values are listed in Table 2.
3.7.2.5 The vehicle speed must be measured by a tachometer generator
installed on the rear (or idler) roll. A tachometer generator installed on the
front (or drive) roll is used to measure coastdown speed. Even though most
tests conducted integrating front and rear tachometer generator speeds over
the test cycle have shown only small differences in total distance, the rear (or
idler) roll must be used to measure vehicle speed because of tire distortions
that occur on accelerations which change the rolling radius.
3.7.2.6 The Federal Register recommends that minimum throttle action
should be used to maintain the proper speed-time relationship. When using a
two-roll dynamometer, a truer speed-time trace may be obtained by minimiz-
ing the rocking of the vehicle in the rolls. The rocking of the vehicle changes
the tire rolling radius on each roll. The rocking may be minimized by re-
straining the vehicle horizontally (or nearly so) by using a cable and winch.
Care must be used to prevent tightening this cable too much as this could
cause vehicle to be pulled off rolls.
TABLE 2—EQUIVALENT INERTIA WEIGHT AND ABSORBED POWER
loaded Vehicle Weight
Ib
Up to II 25
1126 lo 1375
1376 to 1625
1626 to 1875
1876 to 2125
2126 to 2375
2376 to 2625
2626 to 2875
2876 to 3250
3251 to 3750
3751 to 4250
4251 to 4750
4751 to 5250
5251 to 5750
575 1 or more
kB
Up to 511
512 to 624
625 to 738
739 to 851
852 to 975
976 to 1085
1 086 lo 1 1 95
II 96 to 1 306
1307 to 1475
1476 to 1700
1701 to 1930
1931 to 2150
2151 to 2380
2381 to 2610
26 1 1 or more
Equivalent
Inertia Weight
Ib
1000
1250
1500
1750
2000
2250
2500
2750
3000
3500
4000
4500
5000
5500
5500
kg
454
568
681
895
908
1022
1135
1250
1362
1590
1816
2045
2270
2500
2500
Abtorbed Power at 50 mph
(80 km/h) Without and
With Air Conditioning
load Simulation
Without
hp
5.9
6.5
7.1
7.7
8.3
8.8
9.4
9.9
10.3
11.2
12.0
12.7
13.4
13.9
14.4
kw
4.4
4.8
5.3
5.7
6.2
6.6
7.0
7.4
7.7
8.4
8.9
9.5
10.0
10.4
10.7
With
hp
6.5
7.2
7.8
8.5
9.1
9.7
10.3
10.9
11.3
12.3
13.2
14.0
14.7
15.3
15.8
kw
4.8
5.4
5.8
6.3
6.8
7.2
7.7
8.1
8.4
9.2
9.8
10.4
11.0
11.4
11.8
:i.7.2.7 Drive wheel tires must be inflated to a cold gage pressure of 40 psi
(280 kPa). This recommended practice acknowledges that all is not fully
understood regarding the rolls-tire interaction. Recent tests using vehicles
having engines of 100-450 in:1( 1.6-7.4 x 10":1 nr') displacement show that the
average drive wheel tire pressure increased from gage pressure of 40 psi
(280 kPa) to 47 ± 3 psi (320 ± 21 kPa) after running the 1975 Federal Test
Procedure. When the 75 FTP was immediately followed by a Highway
Driving Cycle, the average gage pressure at the end of the test was 50 ± 3 psi
(340i20kPa). These observed tire pressure increases are approximately
twice those observed when vehicles are run on the road, confirming that the
lire deflections on rolls probably generate more heat and thereby increase the
tire pressure. Further study is needed in this area. The cold gage pressure
recommended above is an initial step to minimize tire variations.
3.7.2.8 Warmup oj Dynamometer—If the dynamometer has not been oper-
ated during the 2h period immediately preceding (he test, it should be
warmed up for 15 min by operating it at 30 mph (48 km/h) using a nontcst
vehicle.
•f. Calibrating and Operating Procedure
4.1 Calibration Procedure—The purpose of this procedure is to provide
a reliable method for calibrating CVS systems.
A detailed discussion of the major requirements lor conducting an accurate
CVS calibration follows. The individual sections are arranged in proper
sequential order and provide detailed instructions for conducting the neces-
sary checks that must be performed for satisfactory results.
4.1.1 PREPARATION OF CVS SYSTEM FOR CALIBRATION
4.1.1.1 Installation of Sampling Taps and Lines—For measurement of the
pressure differential across the CVS pump, install static pressure taps of (he
type shown in Fig. 8 at the top and bottom of the CVS pump drive head
plate, centering on the inlet and outlet pump cavities. The same static pres-
sure taps used for CVS calibration should be used for vehicle emission testing.
The location should provide at least one diameter of straight pipe up and
downstream from the tap to minimize flow disturbances. If a straight length of
pipe is not available, a piezometer ring from which a single gage connection is
led may be used.
4.1.1.2 If the straight section of pipe is vertical, the static tap can be
installed anywhere around the periphery. If the pipe is horizontal, the tap
should be located in the periphery of the upper half (above the pipe center-
line). The pump inlet pressure tap should be located downstream from the gas
sample probes.
The diameter and hole edge rounding of the pressure tap should conform
with the recommendations shown in Table 3.
NOTE: It is realized that it will seldom be practical and, generally, it will be
impossible actually to measure the radius of the hole-edge rounding. However,
if any dulling or rounding is done, the values in Table 3 offer a guide for
estimating the maximum desirable degree of edge rounding.3
All burrs and irregularities should be removed from the inner wall surface
near the static tap.
•' "Static Pressure Cups and Fluid Meters—Theory and Application, " Fifth Chapter, Section
A!i. pp. 18-19. American Society of Mechanical Engineers. 345 East 47lh Street, New
York, New York 10017.
-------
25.113
STATIC PRESSURE TAP
SAMPLE PROBE
LFE INLET DEPRESSION
ACCURACY 0 1
-1 •
r:
/
SIDE
VIEW
_*»
^
~
^
FRONT
VIEW
^— '• 00 S S.
FIG. 8—srATIC PRESSURE TAP FITTINGS AND PROBE DESIGN
4.1.1.3 The sample probes should be made of stainless steel and be of the
design shown in Fig. 7. They should be faced upstream directly into the flow.
All sample lines leading from the probes should be routed upward. This will
allow any water which may condense to drain out of the lines and thereby
prevent hydraulic blockage. (Similar precautions should be taken when in-
stalling static pressure lines.)
4.1.2 FLANGE GASKETS—When installing the plumbing on the inlet side of
the pump, compression of the gasket may cause a decrease in its inside
diameter. If this occurs, it will affect the restriction on the pump and may
affect the accuracy of the static pressure reading if the gasket protrusion is
upstream of the static tap. Therefore, when assembling the plumbing insure
that the gasket ID as installed is not smaller than the pipe ID.
The placement of modal analysis probes relative to the bag sample probe
can also disrupt sampling. It has been shown that the backflushing of a modal
analysis cart through a probe can significantly affect the bag sampling probe
sample during a CVS calibration verification with propane injection.
4.1,3 PRIMARY CVS CALIBRATION WITH LAMINAR FLOW ELKMKNT
4.1.3.1 This procedure utilizes a laminar flow element and a variable
restriction device to generate a pump performance curve (flow rate as a
function of pressure differential). Fig. (J is a schematic of the test layout and
instruments required to perform this calibration. The volumetric flow is
determined by a laminar flow clement (LFE) placed upstream of the CVS
pump (as shown in Fig. 9) to avoid introducing flow disturbances in the LFE.
A straightener section of 10 times the exit diameter is added to the outlet of
the LFE. This is followed by an adjustable restriction valve. Since the LFE
and the pump are in series, it is necessary that all connections between these
two items be free of leakage. It is advisable to plug all openings and pressure
test the system to insure that the system is free of leaks.
Some LFE have straightener sections built into the device. This obviates the
use of a straightener section. However, these LFEs are subject to calibration
shifts if they are disassembled for cleaning. If these units are cleaned, they
should be recalibrated.
When conducting calibration, the restriction device should be used to
generate data points above and below the normal CVS system operating
pressure. Data should be obtained beginning with the piimp inlet depression
TABLE 3—PRESSURE TAP HOLES
Nominal Inside Pip*
Dia
in
Under 2
2 to 3
4 la 8
10 +
cm
Under 5
5 to 7.5
10 to 20
25 +
Pr«tsur« Holt
Dia
in
1/4 i 1/8
3/8 ± 1/8
1/2 - 1/8
+ 1/4
3/4 ±: 1/4
mm
6.4 ± 3.2
9.5 i 3.2
12.7 - 3.2
+ 6.4
19.0 ± 6.4
HoU-Edg* Rounding
Radius
in
About 1/64
Leu 1/32
Lest 1/32
Lest 1/16
mm
About 0.4
Leil 0.8
Less 0.8
Lew 1.6
DELIA P LF€
LINED OR MICROMANOMETER
.CCURACY 0005 IN H..O
NGE 08 IN H,0
VARIABLE RESTRICTION DEVICE
LFE INLET TEMPERATURE
ACCURACY 05F
RANGE 60 -100 F
PUMP INLET DEPRESSION
ACCURACY 0 I IN H,0
RANGE 0 fiO IN M,0
PUMP INLET TEMP
ACCURACY 05F
RANGE 60 '170 F
DELTA P PUMP
ACCURACY 01 IN M..Q
RANGE 0-90 IN H,0
KIG. !)-(.:VS CALIBRATION WITH LAMINAR FLOW ELEMENT -
SCHEMATIC
corresponding to LFE as ihe only restriction. Pump inlet depression should be
increased by increments of 2-5 in H.jO (500-1250 Pa) until 6-8 data points
are determined. Usually, it is difficult to get points below the normal CVS
system operating pressure unless the heal exchanger is removed from the
system. Most calibrations are done with the heat exchanger in the system.
The following listing of the data to be recorded, unit conversions, and
calculations will be followed by a sample calculation and a computer print-
out.
4.1.3.2 Data Recorded
(a) LFE inlet depression, in H..O (Pa).
(b) Delta P LFE, in H2O (Pa)"
(c) LFE inlet temperature, °F (°C).
(d) Pump inlet depression, in H.jO (Pa).
(e) Pump inlet temperature, °F (°C).
(f) Delta P pump, in H2O (Pa).
(g) Barometric pressure, in Hg (Pa).
(h) Pump rpm.
4.1.3.3 Conversion of Units
(a) Convert in H._,O to in Hg pressure:
LFE inlet depression (in Hg) = LFE inlet depression (in H..O)
X 0.07355 in Hg/in H._.(.)
Pump inlet depression (in Hg) = Pump inlet depression (in Hg)
X 0.07355 in Hg/in H,O
(b) Convert from degrees Fahrenheit to degrees Rankinc:
LFE inlet temperature (R) = LFE inlet temperature (°F) + 460
Pump inlet temperature (R) = pump inlet temperature ("F) + 460
(c) Conversion to absolute pressure:
Absolute pressure (in Hg) at LFE inlet = barometric pressure (in Hg)
- LFE inlet depression (in Hg)
Absolute pressure (in Hg) at pump inlet = barometric pressure (in Hg)
— pump inlet depression (in Hg)
4.1.3.4 Calculations
(a) Determine air viscosity correction factor for LFE inlet air temperature
from LFE correction curve obtained from LFE manufacturer.
(b) Determine pressure correction factor for LFE inlet pressure from LFE
correction table obtained from LFE manufacturer.
(c) Determine uncorrected volume flow rate from curve supplied by LFE
manufacturer and pressure drop. Then determine corrected volume flow rate
by multiplying uncorrected volume flow rate X air viscosity correction fac-
tor X pressure correction factor.
(d) Using Ideal Gas Law, convert the volume flow rate at LFE standard
conditions (530 R, 29.92 in Hg) to the volume flow rate at the pump inlet
temperature and pressure: pump in,e,
29.92 temperature (R)
Pump ftVmin = LFE ftVmin X X —
pump abs inlet 530
pressure (in Hg)
(e) Determine pump ft3/rev by dividing ft3/min by the pump rpm.
(f) Plot pump ft3/rev versus the square root of pump delta P. Determine
the first degree equation of the line by the least squares method.
4.1.3.5 Example of Calculations for LFE CVS calibration, using typical data
from a 400 ftVmin LFE.
-------
25.114
Data Recorded
(a) LFE inlet depression = 1.00 in H2O.
(b) Delta P of LFE = 6.520 in H2O.
(c) LFE inlet temperature = 75.5°F.
(d) Pump inlet depression = 37.8 in H2O.
(e) Pump inlet temperature = 78.0° F.
(f ) Delta P pump = 60.0 in H2O.
(g) Barometric pressure = 29.34 in Hg.
(h) Pump rpm = 1421.
Conversion of Units:
(a) LFE inlet depression = 0.07355 in Hg.
(b) Pump inlet depression = 2.78 in Hg.
(c) LFE inlet temperature = 535.5 R.
(d) Pump inlet temperature = 538 R.
(e) LFE inlet, absolute pressure = 29.27 in Hg.
(f) Pump inlet, absolute pressure = 26.56 in Hg.
Calculations:
(a) Air viscosity correction factor at 75.5°F (from LFE manufacturer's
curve) = 1.006.
DILUTION AIR FILTER
(b) Pressure correction factor =
= 0.9783.
(c) Uncorrected flow rate (from LFE manufacturer's curve) = 342.8
ff'/min.
Id) Corrected volume How rate = 342.8 x I .006 x 0.9783 = 337.4.
(e) Pump ff'/min = 337.4 x ^--^- X -^— = 3858.
26.56 530
(f) Pump IV'/rev =
_ 0.2715.
4.1.4 GAS STRATIFICATION CHECK
4.1.4.1 With the CVS operating in its testing configuration, introduce a
tracer gas, such as 100'^ propane, into the vehicle exhaust inlet of the CVS
system as shown in Fig. 10. The tracer gas should be introduced at a rate that
will give a bag sample which produces at least a % full-scale deflection on the
HC range normally used for reading bags. The use of a continuous HC
analyzer on the dilute continuous sampling probe makes this rate determina-
tion simple. The continuous analyzer is needed for the profile determination
of paragraph 4.1.4.2.
4.1.4.2 Starting with the sample probe inlet opening at one side of the
dilute streo-n, run a cross-sectional profile of the pipe, sampling at 0.5 in
(13 mm) intervals (wall to wall). Record the concentration at each sampling
point location. Conduct a second cross-sectional profile at 90 deg to the first
profile. If concentrations from wall to wall vary more than 1%, there is
incomplete mixing.
4.1.5 INDEPENDENT CVS SYSTEM VERIFICATION
4.1.5.1 Introduction — The system verification technique involves the intro-
duction of a measured quantity of a tracer such as propane (or CO) at the
tailpipe sampling location. If all components of the system are functioning
properly, the quantity of tracer calculated from that collected in the sample
bag should agree closely with the quantity which was injected. A measured
amount of tracer gas partially diluted with air from a small auxiliary blower
(Fig. 1 1) is then mixed with dilution air in the main stream of the CVS. To
avoid possible leakage, the tracer gas should be introduced downstream of the
auxiliary blower. The auxiliary blower is needed to aid mixing of the 0.02 ft3
PUMP MOTOR
EIHAUST TO ATMOSPHCP.E
MEASURED
AMOUNT OF
PROPANE
AUXILIARY
BLOWER
TAILPIPE
CONNECTION
FIG. II—CVS SYSTEM VERIFICATION
(0.56 L) of propane that is used in a test. When propane is used as the tracer
gas, it may be necessary to remove the charcoal filter from the CVS. This will
equalize the HC background in the two dilution air streams.
4.1.5.2 Equipment
(a) CVS system to be checked.
(b) A container of instrument grade tracer gas.
(c) Analytical balance with a capacity to weigh the charged gas container
and flow regulator with a resolution of 0.01 g.
Instead of the weighing technique. How measurement techniques can be
used to determine the amount of tracer gas injected into the CVS. These
include: wet test meter, rotometer, and critical flow orifice.
(d) A tracer gas flow regulator which is capable of adjustment to yield bag
concentrations which are normally encountered during testing.
(e) An auxiliary blower of 10-30 fWmin (0.005-0.014 m:l/s) capacity.
(f) Analyzers to measure tracer gas.
4.1.5.3 Proctdure
(a) Turn on CVS and allow stream pressure and temperature to stabilize.
(b) Weigh gas container with the flow regulator connected and record
weight.
(c) Purge the gas sample bags with dilution air.
(d) Simultaneously, activate CVS mixture and dilution air bag sampling
and the positive displacement pump revolution counter.
(e) After 30 s, begin injecting tracer gas into the CVS. Set tracer gas flow
rate to yield sample stream concentrations approximating those encountered
during vehicle testing.
(f) Record CVS data during tracer gas injection:
Average pump inlet temperature, °F (°C).
Average pump inlet pressure, in H2O (Pa).
Average pump differential pressure, in H2O (Pa).
(g) After 14 min 30 s total elapsed time, stop the tracer gas injection.
(h) After 15 min total elapsed time, stop the CVS mixture and dilution air
bag samples and the pump revolution counter simultaneously. Record total
CVS pump revolutions.
(i) Analyze gases in the CVS mixture and dilution air sample bags. Record
concentrations.
(j) Weigh tracer gas container and record weight.
(k) Determine the injected weight of tracer gas by subtracting weight
measured in step 4.1.5.3(j) from weight measured in step 4.1.5.3(b). Record
difference.
4.1.5.4 Calculations
(a) Determine the mass of injected tracer gas indicated by the CVS using
the following formula:
Calculated mass = fmll X density X cone
where:
= ff, X
"x-^f
'p
528 R
FIG. 10—EXHAUST GAS SAMPLING SYSTEM
29.92 in Hg
-------
25.115
K0 = volume of gas pumped by the positive displacement pump,
ft3/rev at ambient conditions. This volume is dependent on
(he pressure differential across the positive displacement
pump
A' = number of revolutions of the positive displacement pump
during the test while samples are being collected
Pp = absolute pressure of the dilute exhaust entering the positive
displacement pump, that is, barometric pressure minus the
pressure depression below atmospheric of the mixture en-
tering the positive displacement pump
Tf — average temperature of dilute exhaust entering positive
displacement pump during test while samples are being
collected, R
Density = density of tracer gas, g/ft3 at 68°F and 29.92 in Hg pres-
sure.
Example: Propane = 51.91 g/ft3
CO = 32.97 g/ft3
Cone = concentration of gas in sample bag minus concentration of
gas in background bag.
(b) Compare the measured tracer gas weight to the calculated tracer gas
weight and determine the percent difference, based upon the measured weight.
(c) If the difference is greater than :t2% investigate possible sources of
error and repeat the verification.
4.1.5.5 Critical Flow Orifice—A simpler alternative to the gravimetric
procedure described above for CVS system verification is the use of a critical
flow orifice (CFO). The advantage of a calibrated CFO is that the weighing
steps are replaced by a single determination of a high pressure level reading.
Appendix D is an example of a data and calculation sheet for use with a CFO.
The CVS measurement is compared to the CFO measurement using the CFO
measurement as the standard. Again, if the percent difference is greater than
±2%, investigate possible sources of error and repeat the verification.
4,2 Operating Procedure—A wide variety of CVS configurations are
currently available. The detailed operating procedure for each configuration
will be unique, and will depend upon the nature of the test being performed.
Requirements for hot and cold, weighting and inclusion of multiple back-
ground bags all necessitate changes in the detailed operating procedure.
Furthermore, the required degree of operator attention to the CVS console
during performance of an emission test varies from installation to installation.
Fully automated systems require almost no attention to detail. Once the test is
initiated, all functions including the diverting of exhaust gas into the appro-
priate sample bags at the correct times and even changing of the paper filters
are all accomplished automatically. Other units may require the operator to
perform each of these operations manually. As a result of these many factors
(configuration of equipment, interfacing equipment for automatic control,
and test procedure), no attempt will be made here to provide a detailed
step-by-step procedure. Any such procedure would be specific for a particular
unit and test objective, rather than of universal value. Each operator should,
of course, follow the instructions of the CVS manufacturer and/or system
designer as well as the test procedure outlined in the appropriate governmen-
tal regulations. The remainder of this section will be devoted to items which
may be best described as "good operating practice" and are more universally
applicable.
First, it should be pointed out that the concept of CVS sampling is still
evolving. Areas of uncertainty still exist. Such an area is that of defining the
acceptable "tailpipe depression" at idle or positive pressure during modes
such as acceleration and cruise, which the CVS may exert upon the vehicle
during the performance of an emissions test. The objective of the operator
should be to employ his given CVS unit in a way which will minimize its
effect upon vehicle operation. Actual CVS design has a large impact on
tailpipe depression or pressurization. Above and beyond this the operator can
minimize effects by insuring that connections between the vehicle and the
CVS are relatively short (5-6 ft (1.5-1.8 m)), of large enough diameter (4 in
(100mm) or larger) and that the inside wall of this flexible connection is
relatively smooth (interlock type tubing).
A second area which deserves attention is that of preventing moisture
condensation in the CVS or sampling lines. Condensation may remove soluble
gas species from the sample stream and interfere with the accuracy of NO,
measurements. The dew point of concentrated exhaust gas is typically 120-
130°F (49-54°C). Therefore, it is essential that the exhaust temperature not
approach this range before dilution in the CVS mainstream. The use of a
short (5-6 ft (1.5-1.8m)) connection between the vehicle tailpipe and the
CVS inlet will help prevent condensation in the connecting line. If the CVS
configuration is such that the exhaust gas is cooled prior to mixing with the
dilution air, it will be necessary to insure that condensation does not occur
before dilution. Dilution of the exhaust gas should be sufficient to preclude
condensation of moisture in the main flow stream.
Condensation of the dilute exhaust sample may occur in sample lines.
pumps, filters, and meters, particularly when the relative humidity of the
dilution air exceeds 50%. Unless bubbles appear in the How meters, this
condensation may be difficult to detect. Dampness in the paper filters in the
sample streams is an indication that condensation is occurring. If condensa-
tion is a problem, it may be necessary to install drain lines to divert the
condensation back into the main flow path of the CVS upstream of the
positive displacement pump. Better approaches to avoid the condensation
problem are to match the sample pump capacity more closely to the sampling
system and to use back-pressure regulated sample pumps to reduce the maxi-
mum pressure to which the sample is exposed and thus reduce the tendency
for condensation to occur. Usually, humidity is added to the test area so that
the relative humidity is maintained near 50%, so that the NO, correction
factor will be near unity.
Deposits will slowly build up in the CVS. These are most likely to occur in
the heat exchanger. Good operating practice dictates regularly scheduled
cleaning. Increase of depression at the pump inlet is a good indicator of
deposit buildup. Even though the CVS flow conditions are corrected for the
changing operating conditions, the deposit buildup is not uniform and conse-
quently can cause stratification at the sample probe. Deposit buildup will be a
function of the number and type of tests. For a very active testing program.
monthly cleaning would be recommended.
CVS pumps have been known to seize. Usually, this is due to deposits and
moisture that remain in a CVS after a scries of intermittent tests. This
problem can be avoided by connecting the CVS outlet to a laboratory exhaust
system that has sufficient capacity to rotate (he blower slowly when the CVS
is off. The laboratory exhaust is effective in removing the moisture.
Foreign objects can enter the CVS inlet and effectively destroy mixing or
cause severe stratification. Large mesh screens have been used effectively to
prevent foreign objects from reaching the mixing area and the heat exchanger.
The dilution air filter is not intended to remove all hydrocarbons from the
inlet air, but rather to stabilize their level. Precautions should be taken to
insure that the dilution air is not contaminated with excessive HC vapor from
spilled gasoline, etc. The dilution air filter package is normally a set of three
24 x 24 in (600 x 600 mm) filters. The first is a dust filter, the second a char-
coal filter, and the third filter to remove charcoal particles from the dilution
air stream. These filters can become loaded with dirt. An acceptable method
for determining the useful life of these filters is to monitor the pressure drop
across the filter when the CVS blower is operating at high speed. When the
pressure drop across the three filters reaches 0.5 in H._,O (125 Pa), the filter set
should be changed. If desired the charcoal could be reactivated and reused.
A detailed calibrating procedure appears in another section. It should be
noted that, while this procedure is intended to uncover mechanical and flow
problems which may exist, it is not a cure-all. Actual operating conditions are
somewhat different from calibrating conditions. For example, the temperature
and flow rate entering the CVS during calibration is different than the
temperature and flow rate of exhaust entering during vehicle emission testing.
The degree of stratification under actual test conditions could differ from that
observed during calibration. Mixing difficulties at other than calibrating
conditions will lead to a situation where, even though a CVS checks out
during the calibration, during actual operation the mass obtained by inte-
grating the continuous diluted exhaust stream concentration does not agree
with that collected in the bags. When a situation like this is observed, it will
be necessary to repeal the stratification check outlined in the calibrating
procedure with exhaust gas supplied by a vehicle operating at 50, 40, and
30 mph (80.5, 64, and 48 km/h) steady-states. If mixing is not complete it may
be necessary to experiment with unique mixing devices to aid or replace those
supplied with the CVS unit. Considerations such as those outlined above
emphasize the importance of paying careful attention to each step of CVS
operation even when the unit is completely automated. Each configuration
has its unique advantages and problems. Furthermore, changes in a given unit
may occur from time to time, so that what is not a problem at one moment
may become one later.
5. Data Analysis—Two types of data analysis are possible, bag and modal.
Bag analysis will yield emission values which are the composite for a complete
test. This kind of analysis is simpler to perform, and is satisfactory for deter-
mining whether a vehicle will pass a given lest. Therefore, bag analysis is used
for surveillance or compliance testing. For development of emission control
systems, modal analysis is necessary to determine the relationships between
emissions and driving mode.
5.1 Bag Analysis—The HC, CO, NO, (NO + NO,), and CO, concen-
trations are measured in the diluted exhaust and the background bags. De-
pending upon the specific cycle used, more than one exhaust and one back-
ground bag may be needed. For the 1975 Federal Test Procedure, separate
exhaust bags are needed for the cold transient, cold stabilized, and hot
transient phases of the driving cycle, thus allowing weighting factors to be
applied to the cold and hot transient phases of the test. It is good practice to
use a separate background bag for each sample bag used, in case the back-
ground concentrations change during a test.
-------
25.116
5.1.1 EXHAUST EMISSION CALCULATIONS—One diluted exhaust sample bag
and one background bag are required for each test phase. The concentrations
of HC. CO. NOX. and CO, in the bags are determined by passing the gases
through the analyzers described in paragraph 3.2.
5.1.1.1 The final reported test results are computed as follows:
J'irm = (x\Yi + x-yy + -V3K3)/7.5 miles
where: Yu.m = weighted mass emissions of each pollutant, that is, HC,
CO. and NO,, g/vehicle mile
A',, A',, A', — 0.43, 1.0, 0.57. respective weighting factors for each test
phase
^i' ^'a- ^3 ~ mass emissions for each phase, g/phase
I = cold transient test phase
2 = cold stabilized test phase
3 = hot transient test phase
5.1.1.2 The mass of each pollutant for each phase of the test is deter-
mined from the following:
(al HC mass:
Hf
HCmas, = Vml, X density,,,, X
(b) CO mass:
c°m«. = v,ni. X density(:o X
1 000000
1 000000
(c) NO, mass:
NO.
= V
„ X densilyNO X
-NQ...,,.,.
I 000000
X Kh
id) CO., mass
»« X dcnsi'yco, X
CO.,
100
5.1.1.3 Meaning of Symbols
HCmls, = hydrocarbon emission, g/'test phase
Dcnsity,,c = density of hydrocarbons in the exhaust gas, assuming an
average carbon-to-hydrogen ratio of 1:1.85 g/ft3 at 68°F
(20°C) and 29.92 in Hg (101 kPa) pressure (16.33 g/ft3)4
HCronc = hydrocarbon concentration of the dilute exhaust sample cor-
rected for background, ppm carbon equivalent, that is equiv-
alent propane X 3
HC,.,
= HC, - HCd(l - I /OF)
HC, = hydrocarbon concentration of the dilute exhaust sample as
measured, ppm carbon equivalent
HC,, = hydrocarbon concentration of the background as measured,
ppm carbon equivalent
C'.OmM, = carbon monoxide emissions, g/test phase
Density,.,, = density of carbon monoxide g/ft:lat 68°F(20°C) and 29.92 in
Hg (101 kPa) pressure (32.97 g/ft3)
CO,.,,nr = carbon monoxide concentration of the dilute exhaust sample
corrected for background, water vapor, and CO2 extrac-
tion, ppm
00ronc = CO, -C0d(l - I /DF)
CO, = carbon monoxide concentration of the dilute exhaust sample
corrected for water vapor and carbon dioxide extraction,
ppm. The calculation assumes the hydrogen-carbon ratio of
the fuel is 1.85:1
CO, = (I - 0.01925 CO2 - 0.000323 R)CO,
(CO, = CO, , if instrument has no CO2 or H2O response)
CO, = carbon monoxide concentration of the dilute exhaust sample
as measured, ppm
CO2 = carbon dioxide concentration of the dilute exhaust sample,
mol %
R = relative humidity of the dilution air, %
CO,, = carbon monoxide concentration of the background air cor-
rected for water vapor extraction, ppm
CO,, = (I - 0.000323 R)CO^
(CO,, = COd , if instrument has no H.X) response)
CO,, = carbon monoxide concentration of the background air sample
as measured, ppm
NO, = oxides of nitrogen emissions, g/test phase
DensityNO = density of oxides of nitrogen in the exhaust gas, assuming
they are in the form of nitrogen dioxide, g/ft:1 at 68°F (20°C)
and 29.92 in Hg (101 kPa) pressure (54.16 g/ft:1)
•Density of emissions are based on Ideal Gas Law. Density is equal to 1.17714 times the
molecular weight.
NO,
NO,
*((
CO,
rriMt
Densityco =
CO, =
Tone
CO, =
"rone
CO2 =
CO, =
"
DF =
oxides of nitrogen concentration of the dilute exhaust sample
corrected for background, ppm
NO, - NO^d - I/Of)
oxides of nitrogen concentration of the dilute exhaust sample
as measured, ppm
oxides of nitrogen concentration of the background as meas-
ured, ppm
carbon dioxide emissions, g/test phase
: density of carbon dioxide g/ft1 at 68°F (20°C) and 29.92 in
Hg (101 kPa) pressure (51.81 g/ft3)
: carbon dioxide concentration of the dilute exhaust sample
corrected for background, %
CO2 -CO2j(l - \/DF)
carbon dioxide concentration of the dilute exhaust sample as
measured, %
carbon dioxide concentration of the background as meas-
ured, %
13.4
CO, + (HC, + CO,) 10-4
Vmi% = total dilute exhaust volume, ft'Vtest phase corrected to
standard conditions (68°F, 29.92 in Hg) (528 R, 101 kPa)
f/mi, = K, X /V x (/>p/29.92)(528/rj
1'0 = volume of gas pumped by the positive displacement pump,
ft3/rev. This volume is dependent upon the pressure differen-
tial across the positive displacement pump
.V = number of revolutions of the positive displacement pump
during the test phase while samples are being collected
Pf = absolute pressure of the dilute exhaust entering the positive
displacement pump, in Hg, that is, barometric pressure
minus the pressure depression below atmospheric of the
mixture entering the positive displacement pump
Tf = average temperature of dilute exhaust entering the positive
displacement pump during test while samples are being
collected
Pt = barometric pressure, in Hg
T^ = wet bulb temperature, °F
Tt = dry bulb temperature, °F
Pw = saturation water vapor pressure, in Hg at wet bulb tempera-
ture
Pw = -4.14438 10-3 + 5.76645 10-X - 6.32788 10-57V +
2.12294 lO-6'^3 - 7.85415 IQ-"^4 + 6.55263 10-"TV1.
This equation is a least squares fit of the Keenan and Keyes
"steam table". It reproduces steam table values within
±0.001 in Hg for temperatures of 20-110°F.
Pt = saturation water vapor pressure in Hg at dry bulb tempera-
ture. Same equation as for Pw except Td is used instead of Ta
A = experimentally derived constant for use in Ferrel's equation
as recommended by NBS
A = 3.67 10-4 (1 + 0.00064) (Ta - 32)
Pv = partial pressure of water vapor, in Hg (found from Ferrel's
equation)
Pw — A P,, (Td — Tw), Ferrel's equation
absolute humidity, grains H2O/lb dry air
4347.8 P.,
/".=
H —
H =
= humidity correction factor
1
I - 0.0047(// - 75)
R = relative humidity, %
/>
R = —- x 100
P*
5.1.1.4 Calculation of Mass Emission Values—Computers are generally used
to determine the mass emission values. To verify computer programs, Appen-
dix E detailing hand calculations can be used.
5.2 Modal Analysis—Modal analysis is necessary for the development of
emission controls because it relates cause and effect. The cause is the particu-
lar engine system at a specific operating point. The effect is the resulting
emissions. Mode of operation can be defined its an idle, cruise, acceleration,
and deceleration. The length of a mode could be several minutes or as short as
1 s. At least two methods of modal analysis are available: continuous analysis
of diluted vehicle exhaust, and continuous analysis of undiluted exhaust using
the CO2 tracer technique.
-------
25.117
5/2.1 CONTINUOUS ANALYSIS USING DILUTED VEHICLE EXHAUST—Any driv-
ing schedule can be broken down into arbitrary modes such as idle, accelera-
tion, cruise, and deceleration. For each mode, the mass emission of each
pollutant can be computed using the equations of paragraph 5.1.1.2 modified
slightly. The modifications are: The HC, CO, and NO, masses will be in
grams per mode. Generally, a computer will be advantageous for performing
the large amount of calculation required for continuous modal analysis.
5.2.1.1 Calculation of Vm^for One Mode—The diluted exhaust volume,
ft3/mode. can be calculated as in paragraph 5.1.1.3, except that N should be
taken as the number of pump revolutions for the individual mode being
calculated. The number of pump revolutions can be sensed with magnetic or
photocell pickups and fed into the computer. For short modes, it may be
necessary to measure partial pump revolutions in order to obtain sufficient
accuracy.
5.2.1.2 Calculation oj HC,.onc, COconc, am/NO, —These quantities have
the same meaning as in paragraph 5.1.1.2, except that they now are the
average concentrations for each mode. The output of the HC, CO, NOX, and
CO., analyzers can be continuously monitored by a computer, with suitable
provisions for time delays between the vehicle driver's mode changes and the
corresponding analyzer output change. The computer can be programmed to
lime average the concentrations for the specified intervals corresponding to
the individual modes, and make the required corrections. However, it is
difficult to measure the background HC. CO, NO,, and CO2 concentrations
continuously in the dilution air unless separate analyzers are available, which
is not usually the case. Therefore, some approximation may be necessary, such
as measuring the background before and after the test and assuming a linear
relation in between, or collecting an average background dilution air sample
for the entire test.
5.2.2 MODAL ANALYSIS USING CO., TRACER METHOD—There are many
inherent difficulties in continuously analyzing diluted vehicle exhaust, pri-
marily because of the very low diluted concentrations obtained for some
modes. These problems can be avoided by continuously measuring the undi-
luted exhaust concentrations of HC, CO, NO,, and CO2. If the undiluted
exhaust CO., concentration is also measured continuously, it is possible to
calculate the vehicle exhaust volume for each mode. From the exhaust volume
and the undiluted exhaust concentrations, the modal mass of each pollutant
can be calculated. Actually, any constituent of the exhaust can be used as the
tracer, but CO., is a good choice because it occurs in the largest and most
"I < >(* HC
I '-0 38?
-i i t ».r
* f.« 2";
: 10 *
CYILI
'.*»ir»E cone
tO NO C02 02 C02P
A?-! 3i 1 82 16 ? 1?
*.M 64 iO OS 6 2 81
(MC 3?? 11. 33 4. 8 2. «2
0»* 218 11. 43 3 0 2. 12
(H^, 107 10 90 33 97
i (ORAHS/MILE>
HC
CO
>E M«SS —
NOX C02 X-VOL D/H
I <-.i
~ --0
: 17
Q 012 T 10 r? c 3 e«
41 •••.*• 301 12. ti 2. e ?. «.*-
5 01? 680 10 87 •• 7 3 10
17 012 18? o 77 72 1 00
CYCI C 2
•:• 010 103 10 69 6. 1 .89
9 0/2 442 IT 37 3. 6 3 il
? (ill 52O 10. 3? 6. 3 I. 92
1 «tt 13O IO O6 6.8 "2
CYCLE 3
T 3 4 Oil 102 10 66 6 1 1. 01
- »V I* :fS 342 12.90 2.3 3. 97
? <4 "; 671 173 11. 43 3. 1 1 11
CYCLE 4 (ORAHS/HILE)
1 IS ? 013 103 10. 70 6 0 "2
•* '/ 19 C./1 362 12 88 2. 3 4 16
: :•/ i 014 337 10 33 6 3 i *3
? M 1 . (>!•> 118 10. OS 68 87
CYCLE 3 (GRAHS/HILE)
Tf f LCMOlll 307. 1
«•••»•» I-»OD«U TEST S
010
134
03?
088
001
3°e
006
11?
031
013
003
001
012
OO2
OO1
044
ooo
013
OO1
099
001
024
001
000
1
2
3
10
3.
2.
2.
16
3.
13
?2
08
04
02
62
06
38
34
06
63
02
63
03
02
Ol
01
24
04
22
03
63
09
02
003
026
429
688
024
2. 037
061
961
4 866
161
3 087
029
. 686
43O
. 043
3 219
012
337
. 061
37.
76
426.
22.
8?7
79
366.
711.
78
«31.
27.
173
78.
*0
944
11.
123.
36.
3. 0331218.
O41
322
627
. 037
39.
169.
106.
28
9
2
9
1
8
9
4
2
0.
6
2
3
3
3
3
9
9
2
6
0
0
6
3
8
7.
12.
71
4.
96.
14
36.
126.
13
212.
3.
27.
14
5.
32.
2.
18.
6.
26.
7.
23.
19.
3.
9
1
9
8
0
8
3
3
2
3
6
0
4
6
8
7
2
4
2
8
0
4
9
3
. O
. O
. 0
0
o
D/M-
O
. 0
. 0
. 0
0/M-
0
. 0
. 0
0
o/n-
. O
0
. o
D.'M-
. O
O
0
0
0 VIOL
0 VIOL
O SEC.
0 SEC
0 VIOL
038 12. 92 2. 738 767 I 37. 8 D/M" O VIOL
0 SEC
O SEC
?fif-.1S
IU.E
ft'TEL
£
r
ll
1
f.
'".'ISC-
>CEL
I'TAl
JIVOLCNl
CRAftS/MI
MC
1 0«2
V 0?6
V 101
054
1 324
M^SS
1. 201
CO
18 64
35.
32.
87
BAO
24.
32
88
23
10
NOX
190
2.
6
9
330
368
310
S9C
C02
237
1037-
1741
196
3211
RESULTS
19
2.
666
892
EX-VOL
47 7
139
2°3
36.
337.
3
6
6
1
o/n
. 0
. 6
' 0
. 4
1. 0
F-ECON
9 30
f. OI_D
MCE
A!CEL
CKUISF
I* TEL
TCTAL
£(: 'IVftLFNI
OftANS/HI
HOT
STAE'XI- I ZED
HC CO NOX C02
. 017 20 273 291
075 372 4388 1373
. O16 81 2.719 1172
. 027 I 18 . 344 418
135 3. 91 7. 924 3237
833
BAO RESULTS
. 034 1. 32 2. 032
IDLE
*CCEL
t-WJISE
W.CCL
I'JTAL
IMT
MC CO NOX C02
133 1. 76 . 172 196
. l»6 18. 99 2. 933 913
122 2.72 6.812 1322
. 016 17 326 197
. 487 23. 64 IO 266 2628
h«.*S. BAO RESULTS
133 6. 37 J 852 730
WE TO! tTED TOTrtL.
COUIVALENT MASS BAO RESULTS
W
-------
25.118
constant concentration and, therefore, is easiest to measure accurately even
after dilution.
5.2.2.1 Exhaust Modal Mass Flow Calculations Using CO-, Tracer Method-
Assume that the modal average undiluted exhaust HC, CO, NO,, and CO2
concentrations are measured, and that the modal average CO2 concentrations
are measured in the diluted exhaust stream. The diluted exhaust volume
ftVmode. Vmil, can be calculated as described in paragraph 5.2.1.1. Assuming
a constant for background CO2, the average exhaust dilution ratio for each
mode can be calculated as follows:
lculated as follows:
CO2 exhaust — CO2 backgroun
~ CO2 CVS - CO2 background
olume ft3mode is:
nd
The undiluted exhaust volume, ft3/mode, is:
Vund = VmlI/DR
The modal mass is given by following:
Hp _ HCconcund X Vund X densityHC
I***-*modal maw ~ IQS ~~
COconcund X Vund x densityco
CO
NO.
I06
modal mass ~~
106
The upper portion of Fig. 12 shows only a hot transient modal mass output.
Several pages may be required for a complete test. The mass emissions for
individual modes can then be summed for the complete test, and these values
compared with the mass emissions computed from the bags. Theoretically, the
total of the modal masses should be equal to the mass emissions calculated
from the bag data. In practice, there will not usually be perfect agreement,
but the bags should agree with the modal total for each phase within a few
percent. Fig. 13 is an example of a computer mass summary. The weighted
mass values of Fig. 13 can be compared to the weighted modal data of Fig. 12.
Fig. 14 shows the results of the bag versus modal NO, comparison when the
chemiluminescent NO, analyzer was used.
5.3 Background—The exhaust dilution inherent in the operation of the
constant volume sampler results in low concentrations of pollutants being
presented to analyzers. Under some conditions, such as testing vehicles with
very low emission levels, the diluted exhaust concentrations are not far above
the background level of pollutants found in the dilution air. Therefore, it is
important that background levels of pollutants be taken into account when
measuring vehicle emissions.
MO
DAO RESLJL-TS »•»•»
HC CO NOX C02
C. T. ZERO IT
v. '1 SPAN !>ttC
C. T. SPAN CK
C. T MID «'fC
C. T. HID-*;" CK
• 1
C. « ZERO t K
C. !i. SPAN SPEC
7. !i. SPAN (:•<
C. S. fllD SPCC
C. S. NID-W CK
•2 (C. s <;rw>>
tr, (C. 5. ftllH)
H '1 ZERO CK
H. T. SPAM SSKCC
H. 1. SPAN CK
HI. mo srer
M. T. MIO-« CK
»'•> (M T SftHP)
H, (H T. ANN)
92.
92.
36.
38.
32.
2.
91.
92
36.
38.
3
2.
92.
92
3*.
38.
7
3.
4
2
S
8
3
6
4
2
2
7
8
4
4
6
4
2
2
8
2
2
0
1.
1980
1378.
450
463.
1337
6.
1.
iseo.
1 370
43O.
466.
42.
3.
1
1380.
1384
130.
466.
36«
4.
3
0
6
O
4
3
7
O
O
9
0
e
3
0
2
0
4
0
2
8
3
80.
80
16
18.
73
80
eo.
16.
18.
43.
8O
80
16.
18
88.
0
0
1
1
0
7
3
0
0
3
|
2
4
3
0
O
3
1
0
8
3
3
3
2
2.
2
3
3
2
2.
1.
3
3
2.
2
2.
03
43
43
13
08
39
07
03
43
41
13
07
63
07
03
43
42
13
06
08
07
<»•«»•• O»A MASS TEST RESUL.TS »•»•»
COLD TRANS
COLD STAR
HC CO NOX
3. 62 1O3 9 10 29
22 51 10 38
33 29 9 12. OO
ORWS/MILI
COCO TNftNS
COLD STAB.
HOT TRAN;>.
W-.IOHTCO lOfAL
HC
I. ou/
037
132
CO NOX
29. 4i 2 8t-O
1 31 2 662
8 03 ' 3. 334
C02
3U6
33O9
2506
C02
879 4
648 6
696 7
279
8 93
2 887 813. 4
EC ON
9 33
10 43
12. 30
10. 71
ECON
COLU• f. HOr-7'.
9 99 11. 34
TOT-7?
10 4-9
• ••»•» TK-.ST
TEJ;T DATE 7-27-7.*
DRV BULB //
VEH NO 4O5
DILUTION FACTOR
Kf.LATIVC HUMIDITY > PRESSU>tt: DIFF. I
AV(> CVS FLOW (CO. FT/REV)
TOTAL CVS VOL (STD <
AVO MODAI. C02 RATIO
TEST NO. 4H 26
UET BLCB 67
MODEL NO. 3D37
COLD TRANS
4. 9O2
60
I. 047
887O
) F) 103
i F) 88
(. F ) 96
)) 8 3
)) 7 1
)) 7 7
120) 14 0
(20) 12. 8
(20) 13. 4
299
•T ) 2411
4 33
6012 TEST
TIME 1887 4
BAROMETER 29. 21
CID
COLD STAD
8. 194
60
1 047
13070 .
104
9O
99
8. 1
7 7
7. 9
13 9
13. 3
13. 7
299
4O72
7 04
360
HOT TRANS.
6. 323
60
1 O47
8800
102
83
93
8. 3
7. 4
7. 9
14 4
13. 3
13. 8
299
2393
3. 20
ODOMETER 13278
TRANS A
FIG. 13-EXAMPLE OF BAG DATA
-------
25.119
2
tr
o
o
z
300 425
5.50
6.75
800
MODAL NOX. GRAMS MILE
FIG. 14 —BAG NO. VERSUS MODAL NO
Fig. 15 is a partial schematic diagram of a constant volume sampler. The
following equations apply:
= v'
(I)
where: VK = volume of vehicle exhaust
VD = volume of dilution air
V'mjx = volume of diluted exhaust
VECE + V,)CD = viuixc:m,x (2)
where: CF = concentration of a given pollutant in the undiluted exhaust
C,, = concentration of same pollutant in the dilution air (back-
ground)
^''cnii = ttmccniration of the same pollutant in the diluted exhaust
Eq. 3 expresses the correct way of calculating the true mass emission of the
test vehicle, which is the quantity, V'pCp. However, the application of Kq. 3
requires that V'K be measured, which is not done in practice. An approxima-
tion to the correct value of V'KCB can be obtained by neglecting the VKCD
term in the right-hand side of Eq. 3. The background concentration is merely
substracted from the diluted exhaust concentration of the same pollutant.
This method may be satisfactory if the background concentration and/or V'F
is small compared to V1I11X. However, for very low emitting vehicles whose
diluted exhaust concentrations approach the background concentrations, it is
necessary to apply Eq. 3 more rigorously, which requires the determination of
either vehicle exhaust or the dilution air flow. The procedure of paragraph
5.1.1 may be used, wherein the exhaust dilution factor is estimated by means
of the empirical equation:
13.4
DF =
10-
CO, + (HC_ + CO,
Then VE is approximately equal to Vlnix divided by DF. With VE known,
Eq. 3 can be used. This technique avoids the need to measure either the
exhaust flow or the dilution air How, and may be satisfactory for all but the
most rigorous testing. Eq. 3 is applicable to continuous modal analysis as well
as to bag samples.
5.4 Fuel Economy Calculation from Exhaust Emissions—It is possible to
calculate fuel economy from a vehicle's exhaust emissions using a form of
carbon balance. The carbon in the fuel can be calculated as follows:
Fuel density, g/gal = 8.331 X 0.7404 x 453.6 = 2798
8.331 Ib/gal = density of water
0.7404 = specific gravity of typical gasoline
453.6 g/lb = conversion factor
Weight fraction of carbon in fuel, assuming fuel of composition CH, sr, =
12.0 II,'(12.011 + (1.85 x 1.008)) = 0.866
12.011 = atomic weight of carbon
1.008 = atomic weight of hydrogen
Grams of carbon per gallon of fuel = (fuel density. g/gal)(wt'/; C in fuel) =
2798 x 0.866 = 2423
The carbon in the exhaust can be calculated as follows:
Mass C in HC = (HC g.'milcl(wt'>; C in HO molecule, assume OH, M)
= (HC g/mile)(0.866)
Mass C in CO = (CO g/mile)(wtV{ C in CO molecule)
= (CO g/mile 1(12.011/12.011 + 16)
= (CO g/mile)(0.429)
Mass C in CO2 = (CO2 g/mile)(wt% C in CO, molecule)
= (CO2 g/mile)( 12.011)/(I2.0M + (2 x 16))
= (CO2 g/mile)(0.273)
Total mass of C in the exhaust, g/mile = 0.866 HC g/mile + 0.429 CO
g/mile + 0.273 CO2 g/mile
The vehicle fuel economy can be calculated as follows:
miles/gal = (g C/gal fuel)/(g/mile C in exhaust)
2423
0.866 HC + 0.429 CO + 0.273 CO,
2798
HC + 0.495 CO + 0.315 CO,
where HC, CO, and CO, represent the grams/mile of these respective exhaust
emissions for the vehicle.
Different values for fuel density and/or fuel H/C ratio will yield a slightly
different equation.
5.4.1 WEIGHTED FUEL ECONOMY—"Weighted" fuel economy is the carbon
balance fuel economy based on weighted emission values found from the 1975
Federal Test Procedure. This weighted fuel economy is identical to the fuel
economy that would be obtained if the fuel economies were calculated for
each of the three phases of the 75 FTP, and then weighted in the same manner
as the emissions. The proof follows: Subscript w refers to the 75 FTP weighted
emissions, subscript 1, 2, and 3, refer to the 75 FTP phase. The distance for
phase 1 and phase 3 is 3.59 miles, and the distance for phase 2 is 3.91 miles.
The weighting factor for phase 1 is 0.43 and for phase 3 is 0.57.
2423
HCU. =
CO,,. =
CO2 =
0.866 HC^ + 0.429 CO^ + 0.273 CO^
0.43(3.59) HC, 4- 3.91 HQ. + 0.57(3.59) HC,
15
0.43(3.59) CO, + 3.91 CO, + 0.57(3.59) CO..,
_
0.43(3.59) CO,, + 3.91 CO,, + 0.57(3.59) CO,.,
_
Substituting Eqs. 2, 3, and 4 into Eq. I and rearranging terms gives:
2423(7.5)
/••£„. =
FIG. 15—CONSTANT VOLUME SAMPLER SCHEMATIC
0.43(3.59)(0.866 HC, + 0.429 CO, 4- 0.273 CO.,,,) +
(3.91)(0.866 HC, + 0.429 CO, + 0.273 CO,,) +
0.57(3.59)(0.866 HC:, + 0.429 CO., + 0.273 CO,:1)
(1)
(2)
(4)
(5)
-------
25.120
The carbon balance formula applied to the emissions lor each test phase is
given by:
0.866 HC, + 0.429 CO, + 0.273 CO.^
where: n indicates the test phase. Substituting Eq. 6 into Eq. 5 gives
7.5
0.43
F
The denominator is simply the gallons for each test phase weighted in the
same manner as emissions.
5.4.2 FUEL ECONOMY CYCLE—The carbon balance fuel economy can be
determined from any cycle, where emissions have been measured and are
expressed in grams/mile. Recently EPA has developed a Highway Driving
Cycle for fuel economy measurements. The driving sequence for this cycle is
shown in Appendix F. This 12.75 min cycle has an average speed of 48.20 mph
(77.6 km/h) and covers 10.24 miles (16.5km).
ft Safety Recommendations
6.1 Dynamometer—The test vehicle should be restrained on the dyna-
mometer by using tie-downs or other suitable means. The maximum speed
and acceleration/deceleration rates of the dynamometer must not be ex-
ceeded.
6.2 Calibration Gas Cylinders
6.2.1 HANDLING—Gas cylinders must not be moved unless the safety cap is
securely screwed on the cylinder. Gas cylinders must always be supported by
chains or other suitable means when in use, transported, or in storage.
6.2.2 Toxic OR DANGEROUS GASES—Gases such as CO and NO, must be
used in an area with adequate ventilation. An ambient CO monitor for the
emissions laboratory area is suggested.
6.3 Vehicle Fuel (Gasoline)—Vehicle fuel must always be contained in
safety containers.
APPENDIX A
NO, CONVERTER EFFICIENCY CHECK
(See Fig. 4)
1. Attach NO/Nj supply to NO inlet on NO, generator at C2 (NO concentration approxi- 6. Turn off ozonator.
mately 95% of full-tcale), O2 or air supply at Cl and efficiency checker to analyzer at C3. Record actual reading .
2. With ozonator of NO, generator off, oxygen or air supply off, and analyzer in bypass 7. Repeat steps 4 through 6 as necessary.
mode, adjust NO 'N2 flow to analyzer. Zero analyzer and adjust span calibration to indicate
approximately 100% of full-scale while flowing NO from NO, generator. 8. Calculate efficiency as follows:
Record actual reading .
% Efficiency = — X 100V.
6—4
% Efficiency =
3. Turn oxygen or air supply of NO, generator and adjust MVI to obtain analyzer reading of
approximately 90% of full-scale.
Record actual reading
Note: Converter efficiency must be greater than 90% and should be greater than 95%.
4. Turn on ozonator power and adjust varioc to obtain approximate 20V. full-scale reading. Check efficiency weekly.
Record actual reading
5. Place analyzer in converter mode.
Record actual reading
Record Test Cell, Analyzer, Date and Operator
APPENDIX B
STANDARD REFERENCE GASES FOR
AUTOMOTIVE EMISSIONS ANALYSIS
The NBS Office of Standard Reference Materials announces the availabil-
ity of Nitric Oxide in Nitrogen SRMs as its fourth series of SRMs for mobile
source emission analysis. These SRMs are individually certified, and are
available at the following nominal concentrations:
SRM 1683—Nitric Oxide in Nitrogen. 50 ppm
SRM 1684—Nitric Oxide in Nitrogen, 100 ppm
SRM 1685—Nitric Oxide in Nitrogen, 250 ppm
SRM 1686—Nitric Oxide in Nitrogen, 500 ppm
SRM 1687—Nitric Oxide in Nitrogen, 1000 ppm
The availability of the first two series. Propane in Air and Carbon Dioxide
in Nitrogen, were announced in February 1973, and consist of the following
nominal concentrations:
SRM 1665—Propane in Air. 2.8 ppm
SRM 1666—Propane in Air, 9.5 ppm $
SRM 1667—Propane in Air, 48 ppm
SRM 1668—Propane in Air, 95 ppm
SRM 1669—Propane in Air. 475 ppm
SRM 1673—Carbon Dioxide in Nitrogen, 0.95%
SRM 1674—Carbon Dioxide in Nitrogen, 7.2%
SRM 1675—Carbon Dioxide in Nitrogen, 14.2%
The availability of the third series. Carbon Monoxide in Nitrogen, was
announced in January 1974, and consists of:
SRM 1677—Carbon Monoxide in Nitrogen, 9.74 ppm
SRM 1678—Carbon Monoxide in Nitrogen, 47.1 ppm
SRM 1679—Carbon Monoxide in Nitrogen, 94.7 ppm
SRM 1680—Carbon Monoxide in Nitrogen, 484 ppm
SRM 1681—Carbon Monoxide in Nitrogen, 957 ppm
The development of these SRMs is a cooperative effort by National Bureau
of Standards and the Environmental Protection Agency to provide standards
that are needed to monitor compliance with automotive emission laws.
These standard reference gases are not to be considered as daily working
standards, but rather as primary standards to be used in the calibration of daily
working standards obtained from commercial sources, and by gas manufac-
turers to help control the quality of the working standards during processing.
Thus, they provide a traceability of all gas standards used in mobile-source
emission analysis back to a central reference point, the National Bureau of
Standards.
These gases are supplied in cylinders with a delivered volume of 31 ft3 at
STP. The cylinders conform to the DOT 3AA-2015 specification.
The certified concentration of gas in each cylinder is given on the certifi-
cates issued at the time of purchase. For propane, carbon dioxide, and nitric
oxide, cylinder labels list only the nominal concentration and these SRMs
should be used only in conjunction with the printed Certificate of Analysis.
Because the Certificate of Analysis may not accompany the cylinders, pur-
chasers are requested to list the name of the actual user on the purchase order
so that the Certificate of Analysis can be mailed directly to the user.
The cost of these SRMs includes the cost of the cylinder: for Propane in Air
(SRMs 1665-1669) and Carbon Dioxide in Nitrogen (SRMs 1673-1675) the
cost is $280 per cylinder; for Carbon Monoxide in Nitrogen (SRMs 1677-
1681) the cost is 8303 per cylinder; and for Nitric Oxide in Nitrogen (SRMs
1683-1687) the cost is S303 per cylinder. Purchase orders for these SRMs
should be sent to the Office of Standard Reference Materials, B311 Chemis-
try, National Bureau of Standards, Washington, DC 20234.
-------
25.121
APPENDIX c:
PROCEDURE FOR AUTOMATIC LOADING
DIRECT-DRIVE DYNAMOMETER
Procedure:
1. Verify dynamometer speed and indicated horsepower calibrations.
2. Use typical weight car to run coastdowns after verifying speed calculation
3. Set inertia weight ta 1750, horsepower to 7.7 (indicated about 6 hp)
4. Run coastdown recording lime between 55 mph and 45 mph
(a) Read horsepower directly with computer if available, or
(b) Determine coostdown time between 55 and 45;
5. If necessary adjust internal pot. on auto. dyno. Repeat coastdowns until horsepower or time (depending upon your system) is within O.I hp or O.I.
6. Repeat coastdown without further pot. adjustment.
7. Record FINAL repeated HORSEPOWER or TIME value.
8. Drive vehicle at 50 mph. Record INDICATED HORSEPOWER as observed on meter.
9. Repeat above for all inertia weights.
10. Check I or 1 coastdowns W AC set paint. Friction should be the same at each inertia weight.
1 1. Find friction horsepower at each inertia weight, plot and compare with previous coastdown results.
LOCATION .
-ROLLS,
.ENGINEER.
ROLLS S/N.
.COASTDOWN DATE.
INERTIA
WEIGHT,
Ib
1750
2000
2250
2500
2750
3000
3500
4000
4500
5000
5500
over
5500
ABS HP
AT SO MPH
WO/AC
7.7
8.3
8.8
9.4
9.9
10.3
11.2
12.0
12.7
13.4
13.9
14.4
COAST
DOWN
TIME
S
13.80
14.63
15.53
16.15
16.87
17.86
18.98
20.24
21.52
22.66
24.03
23.20
FINAL
HP
FROM
Camp.
—
—
—
—
—
—
—
—
—
FINAL
TIME OF
COAST
DOWN
—
—
—
—
—
—
—
INDICATED
HP
AT 50
MPH
—
—
—
—
—
—
—
FRICTION
HP
AT SO
MPH
.
—
—
—
ABS HP
AT SO
MPH
W/AC
8.47
9.13
9.68
10.34
10.89
11.33
12.32
13.20
13.97
14.74
15.29
15.84
Run a sufficient number of coastdowns to verify that W AC switch is increasing horsepower by 10%, as indicated in Table 2.
-------
25.122
APPENDIX D
CRITICAL FLOW ORIFICE (CFO) PROPANE INJECTION
DATA AND CALCULATION SHEET
CVS (MANF.-NUMBER) = DATE
ENGINEER REMARKS
&oro
-------
APPENDIX E
HAND CALCULATION FORM-1975 FEDERAL TEST PROCEDURE
25.123
AMBIENT CONDITIONS
CORRECTED BAG CONCENTRATIONS
Corrected Barometric Prestura (PJ — jn Hg
Wet Bulb Temperature IT | — °r
Dry Bulb Temperature (Td) - °f
CONSTANT VOtUME SAMPLER PARAMETERS
Phase 1 Phaie 2
Average Delta P, in H.O
Average Flow, HJ/r»v
Average P|u, in H,O
Average T,u, °f
TJU, T,0 4- 460. R
Dilution Air Temp, Dry Bulb
Dilution Air T.mp, W.t Bulb
Dilution Air Relative
Humidify (R) %
CVS Revolutions, rev
BAG CONCENTRATIONS
Dilution Bog
HCd, ppm
CO, , V.
V
Samplt Bog
HC , ppm
NO * ppm
CO, , •/.
*t
Facility Date
TEST PHASE CONCENTRATIONS
HCe.nc = HC. - HCdC - '/OF)
COconc=CO, -C0d(l - I/OF)
NO^co,* = NO" - NO" (' - '/OF)
Phase 1 Phase 2
1/DF
(1 _ I/OF)
Hr.
wrjl 1 /OF)
Hf
HC Ppm
CO.
COj ( 1 1 /DF)
CO
NO j
NO j { 1 1 /DF)
NO
NO , , ,,. ppm
CO,
wJd
CO,, n i /Df\
CO,
'.
CO,
'cane
Facility Date—
Dilution Bog COd - ( 1 0.000323 R) CO,
R Phase 1 Phase 2 Phase 3
0.000323 R
Pkmf 1 1 - 0.000323 R
COj
COJr ppm
Sample Bag CO, = (1 - 0.0 1925 CO, - 0.000323 R) CO,
CO,
0.01925 COj
CO
COr. ppm
DILUTION FACTORS
Df 13'4
CO, + (HC, + CO,) 10 '
HC, enters into this equation as ppm carbon equivalent.
HC
CO
HC + CO
CO, 4. (HC + CO ) 10 •
Of
Phase 3
NO« HUMIDITY CORRECTION FACTOR
Phase 1 Phase 2 Phase 3
p
T
T
p
Pj
. . - A
p
4147 8 P
P P
H
0 0047 (H 75)
1 0 0047 (H 75)
*h
p
Facility Do»«
-------
25.124
APPENDIX E
HAND CALCULATION FORM —1975 FEDERAL TEST PROCEDURE (continued)
ABSOLUTE INLET PRESSURE
Phot. 1 Pho.t 2 Phau 3
P,n (absolute) = Pb - P,n, 13.596
Pm
P,n 13.596
Pb
P]n (absolute}
CORRECTED CVS FLOW PER PHASE
CVS Flo. ,V,,,,,, = V0 X X X r.y,
vo
P,n(abs), 29.92
528/T,,,, _
revs
Vmll. Sid ft'
NO, HUMIDITY CORRECTION FACTOR
P, = -4.14438 10 ' 4- 5.76645 10 ' T, - 6.32788 10 ' T.»
-f- 2.12294 10 »TJ - 7.85415 10 ' T,4 + 6.55263 10
A = 3.67 10 4(1 + 0.00064(T. - 32)1
P, = P. - AP,,(Tj-T.)
4347 8 P,
1
" I - 0.0047(H - 75)
P 100
R = where P, from first equation above using T, instead of Tw.
Facility _ . , Date
PHASE MASS
HC,,,,,, = Vm|i x HC „. X 16.33 X 10 «
CO,,,,,, = V,,,,, x CO,.,,,,,. X 32.97 x 10 '
NO,,,,,,, = V x NO,,,,,,,. X 54.16 X 10 » X K,,
CO,,,,,,, = Vml, x CO,,,,,,, X 51.81 X 10 '
Phau 1 Phase 1 Phot* 3
V,,,,,
HC
HC,,,,,,, g
CO,,,,,,.
CO,,,,,,,, g
NO,,,,,,,
NO , 9
CO,,
CO,,,,,,., g
WEIGHTED MASS
Weighted Moss = 0.43 Phase I Mass + Phase 2 Mass + 0.57 Phase 3 Mass
HC CO NO, CO,
0.43 Phase 1 Mass
1.00 Phase 2 Mass
0.57 Phase 3 Mass
Weighted Mass, g
Weighted Emissions,
grams/mile (Hand Calc)
Weighted Emissions,
grams/mile (Comp Calc)
Difference
(Computer — Hand Calculation)
% Difference = X 100
Hand Calculation
Facility , Date
-------
APPENDIX F
EPA HIGHWAY DRIVING CYCLE
TIME-SPEED TRACE
25.125
Tim*
0
I
2
3
4
5
6
7
8
9
10
11
12
13
U
13
16
17
18
19
20
21
22
23
24
IS
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
mph
0.0
0.0
0.0
2.0
4.9
8.1
11.3
14.5
17.3
19.6
21.8
24.0
25.8
27.1
28.0
29.0
30.0
30.7
31.5
32.2
32.9
33.5
34.1
34.6
34.9
35.1
35.7
35.9
35.8
35.3
34.9
34.5
34.6
34.8
35.1
35.7
36.1
36.2
36.5
36.7
36.9
37.0
37.0
37.0
37.0
37.0
37.0
37.1
37.3
37.8
38.6
39.3
40.0
40.7
41.4
42.2
42.9
43.5
44.0
44.3
44.5
44.8
44.9
45.0
45.1
45.4
45.7
46.0
46.3
46.5
46.8
46.9
47.0
47.1
47.7
47.3
47.2
47.1
47.0
46.9
46.9
46.9
47.0
47.1
47.1
47.2
47.1
47.0
46.9
46.5
km/h
0.0
0.0
0.0
3.2
7.9
13.0
18.2
23.3
27.8
31.5
35.1
38.6
41.5
43.6
45.1
46.7
48.3
49.4
50.7
51.8
52.9
53.9
54.9
55.7
56.2
56.5
57.5
57.8
57.6
56.8
56.2
55.5
55.7
56.0
56.5
57.5
58.1
58.3
58.7
59.1
59.4
59.5
59.5
59.5
59.5
59.5
59.5
59.7
60.0
60.8
62.1
63.2
64.4
65.5
66.6
67.9
69.0
70.0
70.8
71.3
71.6
72.1
72.3
72.4
72.6
73.1
73.5
74.0
74.5
74.8
75.3
75.5
75.6
75.8
76.0
76.1
76.0
75.8
75.6
75.5
75.5
75.5
75.6
75.8
75.8
76.0
75.8
75.6
75.5
74.8
Tint*
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
no
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
mph
46.3
46.2
46.3
46.5
46.9
47.1
47.4
47.7
48.0
48.2
48.5
48.8
49.1
49.2
49.1
49.1
49.0
49.0
49.1
49.2
49.3
49.4
49.5
49.5
49.5
49.4
49.1
48.9
48.6
48.4
48.1
47.7
47.4
47.3
47.5
47.8
47.9
48.0
47.9
47.9
47.9
48.0
48.0
48.0
47.9
47.3
46.0
43.3
41.2
39.5
39.2
39.0
39.0
39.1
39.5
40.1
41.0
42.0
43.1
43.7
44.1
44.3
44.4
44.6
44.7
44.9
45.2
45.7
45.9
46.3
46.8
46.9
47.0
47.1
47.6
47.9
48.0
48.0
47.9
47.8
47.3
46.7
46.2
45.9
45.7
45.5
45.4
45.3
45.0
44.0
km/h
74.5
74.4
74.5
74.8
75.5
75.8
76.3
76.8
77.2
77.6
78.1
78.5
79.0
79.2
79.0
79.0
78.9
78.9
79.0
79.2
79.3
79.5
79.7
79.7
79.7
79.5
79.0
78.7
78.2
77.9
77.4
76.8
76.3
76.1
76.4
76.9
77.1
77.2
77.1
77.1
77. 1
77.2
77.2
77.2
77.1
76.1
74.0
69.7
66.3
63.6
63.1
62.8
62.8
62.9
63.6
64.5
66.0
67.6
69.4
70.3
71.0
71.3
71.5
71.8
71.9
72.3
72.7
73.5
73.9
74.5
75.3
75.5
75.6
75.8
76.6
77.1
77.2
77.2
77.1
76.9
76.1
75.2
74.4
73.9
73.5
73.2
73.1
72.9
72.4
70.8
Tim*
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
mod
43.1
42.2
41.5
41.5
42.1
42.9
43.5
43.9
43.6
43.3
43.0
43.1
43.4
43.9
44.3
44.6
44.9
44.8
44.4
43.9
43.4
43.2
43.2
43.1
43.0
43.0
43.1
43.4
43.9
44.0
43.5
42.6
41.5
40.7
40.0
40.0
40.3
41.0
42.0
42.7
43.1
43.2
43.4
43.9
44.3
44.7
45.1
45.4
45.8
46.5
46.9
47.2
47.4
47.3
47.3
47.2
47.2
47.2
47.1
47.0
47.0
46.9
46.8
46.9
47.0
47.2
47.5
47.9
48.0
48.0
48.0
48.0
48.0
48.1
48.2
48.2
48.1
48.6
48.9
49.1
49.1
49.1
49.1
49.1
49.0
48.9
48.2
47.7
47.5
47.2
km/h
69.4
67.9
66.8
66.8
67.8
69.0
70.0
70.7
70.2
69.7
69.2
69.4
69.8
70.7
71.3
71.8
72.3
72.1
71.5
70.7
69.8
69.5
69.5
69.4
69.2
69.2
69.4
69.8
70.7
70.8
70.0
68.6
66.8
65.5
64.4
64.4
64.9
66.0
67.6
68.7
69.4
69.5
69.8
70.7
71.3
71.9
72.6
73.1
73.7
74.8
75.5
76.0
76.3
76.1
76.1
76.0
76.0
76.0
75.8
75.6
75.6
75.5
75.3
75.5
75.6
76.0
76.4
77.1
77.2
77.2
77.2
77.2
77.2
77.4
77.6
77.6
77.4
78.2
78.7
79.0
79.0
79.0
79.0
79.0
78.9
78.7
77.6
76.8
76.4
76.0
Tim*
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
mph
46.7
46.2
46.0
45.8
45.6
45.4
45.2
45.0
44.7
44.5
44.2
43.5
42.8
42.0
40.1
38.6
37.5
35.8
34.7
34.0
33.3
32.5
31.7
30.6
29.6
28.8
28.4
28.6
29.5
31.4
33.4
35.6
37.5
39.1
40.2
41.1
41.8
42.4
42.8
43.3
43.8
44.3
44.7
45.0
45.2
45.4
45.5
45.8
46.0
46.1
46.5
46.8
47.1
47.7
48.3
49.0
49.7
50.3
51.0
51.7
52.4
53.1
53.8
54.5
55.2
55.8
56.4
56.9
57.0
57.1
57.3
57.6
57.8
58.0
58.1
58.4
58.7
58.8
58.9
59.0
59.0
58.9
58.8
58.6
58.4
58.2
58.1
58.0
57.9
57.6
km/h
75.2
74.4
74.0
73.7
73.4
73.1
72.7
72.4
71.9
71.6
71.1
70.0
68.9
67.6
64.5
62.1
60.4
57.6
55.8
54.7
53.6
52.3
51.0
49.2
47.6
46.3
45.7
46.0
47.5
50.5
53.8
57.3
60.4
62.9
64.7
66.1
67.3
68.2
68.9
69.7
70.5
71.3
71.9
72.4
72.7
73.1
73.2
73.7
74.0
74.2
74.8
75.3
75.8
76.8
77.7
78.9
80.0
81.0
82.1
83.2
84.3
85.5
86.6
87.7
88.8
89.8
90.8
91.6
91.7
91.9
92.2
92.7
93.0
93.3
93.5
94.0
94.5
94.6
94.8
95.0
95.0
94.8
94.6
94.3
94.0
93.7
93.5
93.3
93.2
92.7
Tim*
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
mph
57.4
57.2
57.1
57.0
57.0
56.9
56.9
56.9
57.0
57.0
57.0
57.0
57.0
57.0
57.0
57.0
57.0
56.9
56.8
56.5
56.2
56.0
56.0
56.0
56.1
56.4
56.7
56.9
57.1
57.3
57.4
57.4
57.2
57.0
56.9
56.6
56.3
56.1
56.4
56.7
57.1
57.5
57.8
58.0
58.0
58.0
58.0
58.0
58.0
57.9
57.8
57.7
57.7
57.8
57.9
58.0
58.1
58.4
58.9
59.1
59.4
59.8
59.9
59.9
59.8
59.6
59.4
59.2
59.1
59.0
58.9
58.7
58.6
58.5
58.4
58.4
58.3
58.2
58.1
58.0
57.9
57.9
57.9
57.9
57.9
58.0
58.1
58.1
58.2
58.2
km/h
92.4
92.1
91.9
91.7
91.7
91.6
91.6
91.6
91.7
91.7
91.7
91.7
91.7
91.7
91.7
91.7
91.7
91.6
91.4
90.9
90.4
90.1
90.1
90.1
90.3
90.8
91.2
91.6
91.6
92.2
92.4
92.4
92.1
91.7
91.6
91.1
90.6
90.3
90.8
91.2
91.9
92.5
93.0
93.3
93.3
93.3
93.3
93.3
93.3
93.2
93.0
92.9
92.9
93.0
93.2
93.3
93.5
94.0
94.8
95.1
95.6
96.2
96.4
96.4
96.2
95.9
95.6
95.3
95.1
95.0
94.8
94.5
94.3
94.1
94.0
94.0
93.8
93.7
93.5
93.3
93.2
93.2
93.2
93.2
93.2
93.3
93.5
93.5
93.7
93.7
Tim*
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
mph
58.2
58.1
58.0
58.0
58.0
58.0
58.0
58.0
57.9
57.9
58.0
58.1
58.1
58.2
58.3
58.3
58.3
58.2
58.1
58.0
57.8
57.5
57.1
57.0
56.6
56.1
56.0
55.8
55.5
55.2
55.1
55.0
54.
54.
54.
54.
54.
54.
55.0
55.0
55.0
55.0
55.0
55.0
55.1
55.1
55.0
54.9
54.9
54.8
54.7
54.6
54.4
54.3
54.3
54.2
54.1
54.1
54.1
54.0
54.0
54.0
54.0
54.0
54.0
54.0
54.0
54. t
54.2
54.5
54.8
54.9
55.0
55.1
55.2
55.2
55.3
55.4
55.5
55.6
55.7
55.8
55.9
56.0
56.0
. 56.0
56.0
56.0
56.0
56.0
km/h
93.7
93.5
93.3
93.3
93.3
93.3
93.3
93.3
93.2
93.2
93.3
93.5
93.5
93.7
93.8
93.8
93.8
93.7
93.5
93.3
93.0
92.5
91.9
91.7
91.1
90.3
90.1
89.8
89.3
88.8
88.7
88.5
88.4
88.4
88.4
88.4
88.4
88.4
88.5
88.5
S8.5
88.5
88.5
88.5
88.7
88.7
88.5
88.4
88.4
88.2
88.0
87.9
87.5
87.4
87.4
87.2
87.1
87.1
87.1
86.9
86.9
86.9
86.9
86.9
86.9
86.9
86.9
87.1
87.2
87.7
88.2
88.4
88.5
88.7
88.8
88.8
89.0
89.2
89.3
89.5
89.6
89.8
90.0
90.
90.
90.
90.
90.
90.
90.
(Table continued next page)
-------
25.126
APPENDIX F
EPA HIGHWAY DRIVING CYCLE
TIME-SPEED TRACE (continued)
Tim*
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
-561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
mph
56.0
56.0
56.0
56.0
56.0
56.0
56.0
55.9
55.9
55.9
55.8
55.6
55.4
55.2
55.1
55.0
54.9
54.6
54.4
54.2
54.1
53.8
53.4
53.3
53.1
52.9
52.6
52.4
52.2
52.1
52.0
52.0
52.0
52.0
52.1
52.0
52.0
51.9
51.6
51.4
km/h
90.1
90.1
90.1
90.1
90.1
90.1
90.1
90.0
90.0
90.0
89.8
89.5
89.2
88.8
88.7
88.5
88.4
87.9
87.5
87.2
87.1
86.6
85.9
85.8
85.5
85.1
84.7
84.3
84.0
83.8
83.7
83.7
83.7
83.7
83.8
83.7
83.7
83.5
83.0
82.7
Tim*
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
moh
51.1
50.7
50.3
49.8
49.3
48.7
48.2
48.1
48.0
48.0
48.1
48.4
48.9
49.0
49.1
49.1
49.0
49.0
48.9
48.6
48.3
48.0
47.9
47.8
47.7
47.9
48.3
49.0
49.1
49.0
48.9
48.0
47.1
46.2
46.1
46.1
46.2
46.9
47.8
49.0
km/h
82.2
81.6
81.0
80.1
79.3
78.4
77.6
77.4
77.2
77.2
77.4
77.9
78.7
78.9
79.0
79.0
78.9
78.9
78.7
78.2
77.7
77.2
77.1
76.9
76.8
77.1
77.7
78.9
79.0
78.9
78.7
77.2
75.8
74.4
74.2
74.2
74.4
75.5
76.9
78.9
Tim*
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
552
653
654
655
656
657
658
659
mph
49.7
50.6
51.5
52.2
52.7
53.0
53.6
54.0
54.1
54.4
54.7
55.1
55.4
55.4
55.0
54.5
53.6
52.5
50.2
48.2
46.5
46.2
46.0
46.0
46.3
46.8
47.5
48.2
48.8
49.5
50.2
50.7
51.1
51.7
52.2
52.5
52.1
51.6
51.1
51.0
km/h
80.0
81.4
82.9
84.0
84.8
85.3
86.3
86.9
87.1
87.5
88.0
88.7
89.2
89.2
88.5
87.7
86.3
84.5
80.8
77.6
74.8
74.4
74.0
74.0
74.5
75.3
76.4
77.6
78.5
79.7
80.8
81.6
82.2
83.2
84.0
84.5
83.8
83.0
82.2
82.1
Tim*
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
mph
51.0
51.1
51.4
51.7
52.0
52.2
52.5
52.8
52.7
52.6
52.3
52.3
52.4
52.5
52.7
52.7
52.4
52.1
51.7
51.1
50.5
50.1
49.8
49.7
49.6
49.5
49.5
49.7
50.0
50.2
50.6
51.1
51.6
51.9
52.0
52.1
52.4
52.9
53.3
53.7
km/h
82.1
82.2
82.7
83.2
83.7
84.0
84.5
85.0
84.8
84.7
84.2
84.2
84.3
84.5
84.8
84.8
84.3
83.8
83.2
82.2
81.3
80.6
80.1
80.0
79.8
79.7
79.7
80.0
80.5
80.8
81.4
82.2
83.0
83.5
83.7
83.8
84.3
85.1
85.8
86.4
Tim*
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
mph
54.2
54.5
54.8
55.0
55.5
55.9
56.1
56.3
56.4
56.5
56.7
56.9
57.0
57.3
57.7
58.2
58.8
59.1
59.2
59.1
58.8
58.5
58.1
57.7
57.3
57.1
56.8
56.5
56.2
55.5
54.6
54.1
53.7
53.2
52.9
52.5
52.0
51.3
50.5
49.5
km/h
87.2
87.7
38.2
38.5
89.3
90.0
90.3
90.6
90.8
90.9
91.2
91.6
91.7
92.2
92.9
93.7
94.6
95.1
95.3
95.1
94.6
94.1
93.5
92.9
92.2
91.9
91.4
90.9
90.4
89.3
87.9
87.1
86.4
85.6
85.1
84.5
83.7
82.6
81.3
79.7
Tim*
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
mph
48.5
47.6
46.8
45.6
44.2
42.5
39.2
35.9
32.6
29.3
26.8
24.5
21.5
19.5
17.4
15.1
12.4
9.7
7.0
5.0
3.3
2.0
0.7
0.0
0.0
0.0
km/h
78.1
76.6
75.3
73.4
71.1
68.4
63.1
57.8
52.5
47.2
43.1
39.4
34.6
31.4
28.0
24.3
20.0
15.6
11.3
8.0
5.3
3.2
1.1
0.0
0.0
0.0
INSTRUMENTATION AND TECHNIQUES FOR
VEHICLE REFUELING EMISSIONS
MEASUREMENT—SAE J1045
SAE Recommended Practice
Report of Automotive Kmissions and Air Pollution Ixmimmer approved August
Scope—This SAE Recommended Practice describes a procedure for measur-
ing the hydrocarbon emissions occurring during the refueling of passenger cars
and light trucks.'It can be used as a method for investigating the effects of
temperatures, fuel characteristics, etc., on refueling emissions in the labora-
tory. It also can be used for determining the reduction in emissions achieved
with emission control hardware. For this latter use, standard temperatures,
fuel volatility, and fuel quantities are specified.
Central Discussion—Refueling losses are made up of the following indi-
vidual losses:
(a) Displaced fuel tank vapor.
(b) Entrained fuel droplets in the displaced vapor.
(c) Liquid spillage.
(d) Nozzle drip during insertion and removal from the filler neck.
Experience has shown that displaced vapor normally is 90'7o or more of the
total loss. The amount of displaced vapor is known to be affected by a number
of factors, particularly dispensed fuel temperature, Reid vapor pressure, and
the degree to which dispensed fuel and displaced vapor come into contact.
The measurement facility described in this SAE Recommended Practice
includes a sealed enclosure. The enclosure is identical to that described in
SAE J171, except for the minimum length specified and that a refueling hose
and nozzle has been added. The hydrocarbon measuring instrument is iden-
tical to that of SAE Jl 71. This technique is used to measure the total loss for
the four sources listed above.
The recommended practice includes the following sections:
1. Test Fuel
2. Test Facilities and Equipment
3. Measurement Method
4. Information and Data to be Recorded.
/. Test Fuel
1.1 The test fuel should have a Reid vapor pressure of 'J.O ± 0.5 psi
(62 ± 3 kPa). To describe the fuel being used adequately, it should be in-
spected for these properties:
Property
Distillation
IBP
5%
10%
15%
20%
30%
40%
50%
90%
FBP
Reid vapor pressure, psi (Pa)
Hydrogen-carbon ratio0
ASTM Till Method
D 86
D323
0 1018
aThe hydrogen-carbon (H/C) ratio it required for the calculation of lonet uting the enclosure
method. The H/C ratio will be different for vapor louet at compared to liquid lotiei. Therefore,
the H/C ratio thould be meaiured for both condenied vapor and for the teit fuel. Judgment
ihoutd be uied in interpolating between the two valuet for individual lesti. H/C ratio can alter-
nately be meaiured by /3-roy absorption, which it quick and accurate dee Jacobi, et al., Anal
Chem., Vol. 28, March 1956).
-------
25.162
tor signal from a gas chromaiograph. which shows deflections to indicate, for
example, (he presence of individual hydrocarbons.
11.14 Hang-Up—A term to describe the phenomena whereby higher
molecular weight hydrocarbons are retained in the sample train, causing an
initial low analyzer reading, followed by higher readings in subsequent tests.
Excessive hang-up causes errors in the analysis of the hydrocarbons in ex-
haust gas.
O 11.15 Gas Chromalograph—An instrument commonly used to detect
individual gases in complex gaseous mixtures. NOTE: In automobile exhaust
gas analvsis such instruments can be used 10 separate and determine the
concentration of individual hydrocarbon species in a complex hydrocarbon
mixture.
0 11.16 Hexane Equivalent Concentration (ppm hexane)—The concen-
tration of a propane calibrating gas in terms of its hexane equivalent concen-
tration. For .NDIR, hexane equivalent concentration has been established as
propane concentration times 0.52. For FID. hexane equivalent concentration
equals propane concentration times 0.50.
0 11.17 Idle Speed—The engine's low idle speed as specified by the manu-
l.ujurer.
11.19 Intermediate Speed—The peak torque speed or 60'« of the rated
••peed, whichever is higher.
0 11.20 Mode—A particular event (for example, acceleration, deceleration.
i mise. or idle I of a vehicle test cycle.
~c> 11.21 Nondispersive Infrared (NDIR)—Electromagnetic radiation used
.is ilie light source in NDIR instruments capable of measuring CO, CCX. NO.
and unburned hydrocarbons in exhaust gas.
0 11.22 Nondispersive Ultraviolet (NDUV)—Electromagnetic radiation
used as the light source in NDUV instruments capable of measuring NO.,
concentrations in exhaust gas.
0 11.23 Non-Methane Hydrocarbons (N'MHC)—All organic hydrocarbon
i (impounds, excluding methane, present in an exhaust sample.
O 11.24 Smoke Opacimeter—An optical instrument designed to measure
the opacity of diesel- exhaust gases. The full flow of exhaust gases passes
through the optical unit. One such smoke opacimeter is described in SAE
)'-'55 (June. 1971].
11.27 Opacity—The fraction of light transmitted from a source which is
prevented from reaching the observer or instrument receiver, in percent
(Opacity = |1 — Transmittancc| X 100).
& 11.28 Photographic Smoke Measurement—A measurement technique
which relies upon an instrumental or visual comparison of the photograph
image of a smoke plume with an established scale of blackness or opacity |.
determine the opacity of the original smoke plume.
11.29 Probe—A device inserted into some portion of an engine or vehic>
system in order to obtain a representative gas or liquid sample.
11.30 Proportional Sampling—A method of obtaining a composite san-,.
pie of exhaust gas representative of all driving modes in a test cycle. Thj
sample, when analyzed, will represent the average molar concentration of»
constituent properly weighted for mass flow rates.
11.31 Rated Power—The maximum brake power output of an engine, in,
horsepower or kilowatts, as stated by the manufacturer.
11.32 Rated Speed—The engine speed at which the manufacturer specj.,
fics the rated brake power of an engine.
11.33 Rated Torque—The maximum torque produced by an engine, a,
stated by the manufacturer.
11.34 Reid Vapor Pressure—The vapor pressure of gasoline at 100'F,
(37.8°C) determined in a special bomb in the presence of a volume of m
which occupies four times the volume of liquid fuel (ASTM procedure D323i
11.35 Reference Cell—That portion of the NDIR instrument which:
provides the reference signal to the detector.
11.36 Resolution—The minimum distinguishable reading, for a given t
trace width and scale combination, expressed as a percent of full-scale.
11.37 Sample Cell—That portion of the NDIR instrument which con-(
lains (he sample gas being analyzed.
11.38 Sampling—The technique of obtaining an accurate sample of i
exhaust gas for analysis. Sampling may be grab, continuous, or proportional
11.39 Test Cycle—A sequence of an engine or vehicle operating moda(
usually designed to simulate road usage of the vehicle.
11.40 Test Fuel—A fuel for use in a given test and having specifict
chemical and physical properties required for that test.
11.41 Transmitlance—That fraction of light transmitted from a source, t
through a smoke-obscured path, which reaches the observer or ins(rumtm
receiver.
/ Opacity \
ITransmittance = 1 -I
V 100 /
11.42 Variable Dilution Sampling—Use Constant Volume Sampling e
11.43 Variable Rate Sampling—A technique to obtain an exhaust sanvt
pie which takes a specific and constant fraction (for example, '/10oo) °f '^
total exhaust stream at each mode so that when the aggregate sample is
analyzed for its molar constituents, it is weighted in proportion to the averap
flow rate through the cycle.
11.44 Visual Smoke Measurement—A measurement technique which*
relies upon human observation of an engine's smoke plume to rate tna'
plume's appearance agains( an esoblished scale of blackness or opaci(y (usu'
ally a gray scale on eilher a transparent or opaque white base).
METHANE MEASUREMENT USING GAS
CHROMATOGRAPHY—SAE J1151 OCT88
SAE Recommended Practice
Report of (he Automotive Emissions Committee, approved August 1976, completely revised June 1983. and reaffirmed October 1988.
/. Purpote—This SAE Recommended Practice provides a means for
a batch measurement of the methane concentration in light-duty vehi-
cle exhaust samples. Nonmethane hydrocarbon concentration can be
obtained by subtracting the methane concentration from the total hy-
drocarbon concentration obtained by a separate measurement made in
accordance with accepted practices such as SAE J1094, J254, or a" cur-
rent Federal Test Procedure.1
2. Scope—This SAE Recommended Practice describes instrumenta-
tion for determining the amount of methane in air and exhaust gas.
3. Section!—The remainder of this practice is divided into the fol-
lowing sections:
4. Definitions of Terms and Abbreviations.
5. Equipment.
6. Principle of Operation.
7. Instrument Operating Procedure.
8. Instrument Performance Specifications.
9. Maintenance.
1 See Code of Federal Regulations. Title 40 Protection of Rnvironment. Part
86. Subpart B, F.mission Regulations for 1977 and Later Model Year New Light-
Duty Vehicles and New Light-Duty Trucks: Test Procedures (40 CFR 86.101 et
seq.) (as possibly amended by the Federal Register).
4. Definition! of Terms and Abbreviations
4.1 Terms Used
4.1.1 Vehicle emission terms are defined in SAE Jl 145.
4.1.2 CARRIER GAS—A gas that acts as a passive vehicle to transporl
the sample through a gas chromatograph column.
4.1.3 GAS CHROMATOCRAPHV—A separation technique in which a
sample in the gaseous state is carried by a flowing gas (carrier (!'•
through a tube (column) containing stationary material. The stationary
material performs the separation by means of its differential affinity '°
the components of the sample.
4.2 Abbreviations and Symbols
°C —degree(s) Celsius
CH4 —methane
CO —carbon monoxide
COj —carbon dioxide
cm —centimeter(s)
CVS —constant volume sampler
FID —flame ionization detector
Fig. —figure
g —gram
GC —gas chromatograph(ic)
h —hour(s)
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25.163
HC —hydrocarbon(s)
ID —inside diameter
in —inch
kPa —kilopascal
NMHC —nonmethane hydrocarbon(s)
min —minute(s)
m —meter
mm —millimeter(s)
jim —micrometer(s)
Oj —oxygen
OD —outside diameter
ppm —parts per million
ppm C —parts per million carbon
psig —pound(s) per square inch, gage
s —second(s)
scfh —standard cubic foot per hour
SAE —Society of Automotive Engineers. Inc.
SS —stainless steel
7c —percent
5. Equipment
5.1 Safety Precautions—Flammable FID fuel (containing hydro-
gen) and potentially toxic 29J CO in exhaust gas are vented from this
instrument at low flow rates of approximately 80 cmVmin (0.2 scfh).
At these low flow rates, there should not normally be a hazard trom
these gases, but precautions should be observed to insure dilution of
these potentially hazardous vented gas streams.
The instrument uses flammable fuel and the precautions specified by
the manufacturer should be observed.
The sample bypass line in the instrument has a How of about 2000
cmVmin (4 scfh) of automotive exhaust gas. This flow should be dis-
charged outside of the building or into an adequately ventilated area.
5.2 Instrument—A gas chromatograph is used to separate the
methane from the other constituents of an exhaust gas sample. The
concentration of methane is determined with a FID. A typical suitable
gas chromatograph is described in this section.
5.3 Component Description—The schematic diagram in Fig. 1
shows a typical gas chromatograph assembled to routinely determine
methane. The following components are typically used.
5.3.1 VALVE, VI—Sample injection and switching valve, should be
low dead volume, gas tight, and heatable to at least 150°C.
5.3.2 VALVE, V2—Used to provide supplementary fuel to the FID
burner.
OVEN
5.3.3 VALVE. V3—Used to seleci span gas. sample, or no flow.
5.3.4 VALVE, V'4—Used as a restrictor to match the How resistance
of the Porapak N column.
5.3.5 VALVE. V5—Used as a restrictor to match the flow resistance
of the Molecular Sieve column. This valve allows equalizing backflush
and foreflush flow rates through the Porapak column.
5.3.6 VALVE, V6—Used as a restrictor for controlling the rate of
sample flow to fill the sample loop.
5.3.7 PRESSURE REGULATOR. PR1. AND PRESSURE CAGE. Gl—To con-
trol flow rate of the fuel which is also the carrier gas.
5.3.8 PRESSURE REGULATOR. PR2. AND PRESSURE GAGE. G2—Back-
pressure regulator for controlling the rate of sample flow to the sample
loop in conjunction with valve V6. Should be adjusted in the pressure
range from 7 to 34 kPa (I to 5 psig).
5.3.9 GC COLUMN—Porapak N. 180/300 urn (equivalent to 50/80
mesh), 610 mm (2 ft) length X 2.16 mm (0.085 in) ID X 3.18 mm ('/8
in) OD SS, to separate air. CH«, and CO from the other sample constit-
uents. The column is conditioned 12 h or more at 150°C with carrier
gas flowing prior to initial use. Valve VI should be in the fill/backflush
position during the conditioning.
5.3.10 GC COLUMN—Molecular Sieve Type 13X. 250/350 urn
(equivalent to 45/60 mesh), 1220 mm (4 ft) length X2.16 mm (0.085
in) ID, 3.18 mm ('/8 in) OD SS. to separate methane from oxygen, ni-
trogen, and CO. The column is conditioned 12 h or more at 150°C
with carrier gas flow prior to initial use. Valve VI should be in the fill/
backflush position during the conditioning.
5.3.11 -SAMPLE LOOP—A sufficient length of SS tubing to obtain ap-
proximately 1 cmj volume.
5.3.12 OVEN—To maintain columns and valves at a stable tempera-
ture for analyzer operation, and to condition columns at 150°C.
5.3.13 VALVE ACTUATOR—To actuate sample injection and switching
valve.
5.3.14 VALVE PROGRAMMER—Timing unit to control valve actuator.
5.3.15 DRYER—To remove water and other contaminants which
might be present in the carrier gas, a filter dryer containing Molecular
Sieve is used. If it is a visual indicating type, the dryer is replaced when
the need is indicated. Otherwise, it is replaced or reconditioned month-
ly. If the dryer has a metal body, it can be reconditioned after remov-
ing it from the instrument by flowing approximately 50 cmVmin of
dry nitrogen through the dryer while it is heated to 150'C in an oven
for 12 h.
TO
VENTILATED
AREA
FUEL
INLET
VENT
VALVE (VI)
POSITION
• INJECT
- FILL / BACKFLUSH
SAMPLE
SPAN GAS
FIG. 1—INSTRUMENT TO MEASURE METHANE
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25.164
5.3.16 RKSTRICTOR. R3—For controlling the rate of air flow to FID.
p.3.17 PRESSURE REGULATOR. PR3—Used with pressure gage. G3,
and restrictor. R3. to control air flow to FID.
5.3.18 FILTERS Fl. F3. F4—Sintered metal filters to prevent grit
from entering the instrument.
5.3.19 FILTERS F2, F5—Sintered metal filters in the sample stream to
prevent grit from entering the pump or instrument. Should be of suffi-
ciently large area to have a pressure drop of less than 15 kPa (2 psi) at
the bypass flow rate used of approximately 2000 cmVmin (4 scfh).
5.3.20 PLMP—Used to bring sample to gas chromatograph.
5.3.21 VALVE. V7—Used with flowmeter. FM1, to regulate bypass
sample flow rate. The bypass sample flow rate should be fast enough to
flush out the entire sample line in a time less than the GC analysis time
so that while an analysis is being made, the sample loop is filled with
the next sample and is ready for the next analysis cycle. A typical by-
pass flow rate would be 2000 cmVmin (4 scfh).
5.3.22 VALVE, V8—Used with flowmeter. FM1, to equalize bypass
flow rates of span gas and sample.
5.3.23 RECORDER—The recorder or other readout device should
have an input compatible with the FID analyzer output, an accuracy (in-
cluding the effects of deadband and linearity) of ±0.259? of full scale
or better, a span step response time of 0.4 s or less, and a chart speed
of approximately 25 mm/min (1 in/min).
5.3.24 FID—The flame ionization detector generates an electrical
current proportional to the flow rate of methane through the burner.
The associated electrometer amplifier acts as a current to voltage con-
verter and should have an electronic time constant of less than 0.20 s.
6. Principle of Operation—The instrument (Fig. 1) measures the
methane concentration in a sample swept from a fixed volume sample
loop by a carrier gas stream when the valve (VI) is in the inject posi-
tion. The carrier gas can be blended FID fuel. The stream enters the
Porapak N gas chromatographic column which temporarily retains
NMHC. COj, and water, and passes air, methane, and CO to the Mo-
lecular Sieve column. As soon as all of the methane elutes from the
Porapak N column and has passed through valve VI toward the Molec-
ular Sieve column, the Porapak N column is backflushed to waste by
switching the valve (VI) to the fill/backflush position. Switching VI
also starts filling the sample loop with the next sample. The Molecular
Sieve column separates the methane from the air and CO before pass-
ing it to the FID. The FID produces a signal peak proportional to the
methane concentration in the sample. As soon as the methane peak
passes through the FID. valve VI can be switched back to the inject po-
sition to inject the next sample. A complete cycle, from injection of one
sample to injection of a second, can be made in 30 s. Automation of in-
jection and backflush switching assures reproducible peak times and
shapes and is easily accomplished.
7. Instrument Operating Procedure
7.1 In general, the manufacturer's instructions for operation of
the instrument or gas chromatograph should be followed.
7.2 Component Assembly—The assembly of the components for
the instrument is shown in Fig. 1. The sample and switching valve VI.
restrictor valves V4 and V5, sample loop, and the two GC columns are
installed in the oven. The outlet of valve V5 and the outlet from valve
VI. port 8 must discharge directly into an open area at atmospheric
pressure where there can be no effluent build-up. The other compo-
nents are connected outside the oven with all connecting tubing of
minimum length. After all of the connections have been made, as indi-
cated in Fig. 1, leak check the fittings and the instrument is ready for
adjustment of operating parameters.
7.3 Initial Adjustment of Operating Parameters—The timing se-
quence is determined by the flow rates of the carrier gas, the gas hold-
up volume of the system, and the column temperature. Typical flow
rates at several instrument locations identified by the encircled numer-
als in Fig. 1 are given in Table 1. The following procedure would typi-
cally be followed to determine satisfactory flow rates of the assembled
system and the switching times of the valves.
7.3.1 Set the initial operating parameters. Record oven temperature,
gas pressures, and flow rates for later reference.
7.3.1.1 Sample—Adjust the flow of span gas or sample with V8 or
V7 so that the flow discharged to the vent is about 2000 cm'/min (4
scfh). Adjust backpressure regulator PR2 so that gage G2 reads from
7 to 34 kPa (1 to 5 psig). Readjust span gas or sample bypass flow to
2000 cmVmin. With valve VI in the fill/backflush position, adjust
valve V6 so that the flow from port 8 of valve VI is 80-100 cmVmin.
7.3.1.2 Carrier Gas—Mixed fuel is recommended to minimize the
number of gases required for vehicle exhaust measurements since
mixed fuel is also used for total hydrocarbon measurements (see SAE
J1094). Mixtures from 38 to 559? hydrogen with the diluent being heli-
TABIE 1 —TYPICAL FLOW RATES .
Location (Fig. 1)
1 . Sample Bypass Vent
2. Burner Air
3. Total Burner Fuel"
4. Backflush
5. Sample
6. Makeup Fuel0
7. Porapak N Column0
8. Molecular Sieve Column0
Vary* VI Position
Inject
Fill/Bockflush
Flaw Rat* — cm'/min
(room pressure and temperature!
2000
400
100
60
95
30
70°
70°
2000
400
100
60
90
30
60
70°
"Fuel: 40% H,/60% He.
° These flow rates were measured at location 3 with valve V2 closed.
um or nitrogen have been found to be acceptable. The carrier gas mix-
ture should contain less than 0.5 ppm C HC. (The oxygen peak height
(see Fig. 2) is not a direct response to oxygen, but is caused by a syner-
gistic effect of O2 on the HC impurity in the mixed fuel, therefore it
is an approximate indicator of the hydrocarbon concentration in the
fuel.)
With sampling and switching valve (VI) in the inject position and
valve V2 closed, adjust pressure regulator PR1 so that the carrier flow
rate through the columns into the FID burner is about 70 cmVmin.
Typically, the pressure regulator PR1 will be set at approximately 140
kPa (20 psig). The flow is readily measured with a soap bubble flow-
meter. The elapsed time from sample injection to the appearance of
the oxygen peak (Fig. 2) is primarily a function of the carrier flow rate.
Turn valve VI to the fill/backflush position. Adjust valve V4 so that
the carrier flow rate through the Molecular Sieve column and into the
FID burner is the same (within 29c) as when valve VI is in the inject po-
K) 15 20 25 30
TIME (s)
INJECT
FILL/BACKFLUSH
FIG. 2—TYPICAL GAS CHROMATOGRAM
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25.165
sition. Check the backflush flow rate through valve V5 to confirm that
it is approximately equal (within 3090 to the flow rate through the col-
umns into the FID burner.
7.3.1.3 Column Conditioning—With valve VI in fill/backflush posi-
tion and carrier gas flowing, adjust oven temperature to 150°C and
condition columns for a minimum of 12 hours. After conditioning, ad-
just oven temperature to about 55°C.
7.3.1.4 Additional Fuel—Open valve V2 to provide a total hydro-
gen flow to the FID burner of about 40 cmVmin (for example, 100
cmVmin of 40<7C H2/60'7c He fuel).
7.3.1.5 Air (Should Contain Less Than 0.5 ppm C HC)—Set the pres-
sure regulator PR3 so that the air flow to the FID burner is approxi-
mately ten times the hydrogen flow.
7.3.1.6 Column Oven Temperature—The column oven should be
maintained at a constant temperature. A temperature of about 55°C
will allow an analysis time of 30 seconds. The temperature can be ad-
justed between 35 and 75°C in order to give a desired analysis time. Al-
low time for oven temperature to stabilize before making measure-
ments. The temperature control setting that maintains 150°C for use
in conditioning the GC columns should be ascertained before column
installation.
7.3.2 TIMING SEQUENCE—The analysis starts with valve VI in the fill/
backflush position. In this position, the sample loop is flushed and filled
with sample (flow rate 80-100 cmVmin). With a typical instrument, it
was found that if the sample select valve, V3, selected the next sample
at least 6 s before sample injection, the sample loop was fully flushed
and hence a longer flush and fill time gave the same analytical results.
The sample is injected by switching valve VI into the inject position.
The sample passes into the Porapak N column from which air elutes
first and then methane. Carbon dioxide, higher hydrocarbons, and wa-
ter vapor are retained longer in the Porapak N column. It is necessary
to leave valve VI in the inject position only long enough for all the
methane to elute from the Porapak N column. If valve VI is in the in-
ject position too long, CO? will also elute from the Porapak N column,
pass onto the Molecular Sieve column, be absorbed by and gradually
deactivate the Molecular Sieve column. The optimum time for switch-
ing is found by determining the minimum time required for maximum
methane response to be obtained. With a typical instrument at a col-
umn flow rate of 73 cmVmin. it was found that if valve VI was manu-
ally switched from inject to fill/backflush 6 s after injection, the meth-
ane peak height was 539J of its ultimate height measured with a later
valve switching. If valve VI was switched 7 s after injection, the meth-
ane peak height was 959J of its ultimate height, and if valve VI was
switched 8 s after injection, the ultimate peak height was reached. For
this instrument, valve VI was programmed to stay in the inject position
for 9 seconds. The gases in order of elution from the Molecular Sieve
column into the FID are oxygen, which gives a small peak: nitrogen;
methane, which gives the peak that is measured: and CO, which elutes
well before the next methane peak. The FID does not respond to the
nitrogen and carbon monoxide. Fig. 2 shows a gas chromatogram ob-
tained with this system. (In normal use a slower chart speed is used.)
With valve VI in the fill/backflush position, the Porapak N column is
backflushed to waste to clean it out for the next sample. Also during
this time, the sample loop is flushed and filled with the next sample to
be analyzed. After most of the methane peak has eluted into the FID,
valve VI can be switched to inject the next sample. The last traces of
methane can finish eluting while the next sample is being injected. In
a typical instrument, the cycle time was 30 seconds.
7.4 Calibration—Typically, analyzer response is linear (not neces-
sarily passing through the origin) with the methane content of the sam-
ple. However, this should be verified for each analyzer prior to its in-
troduction into service and at monthly intervals thereafter. The
linearity should also be verified whenever the FID burner is serviced
and whenever the fuel carrier gas supply is changed. A series of four
or more calibration gases, containing methane of known concentration
in air, covering the range of concentrations within which sample gases
may be expected to fall, should be used for calibration. Optionally, a
flow blender may be used to blend a single calibration gas with zero
grade air to provide a series of intermediate calibration gases.. The
methane impurity of the zero grade air should be determined and con-
sidered in the calculation of the methane concentration of the interme-
diate gases. Obtain the least-squares straight line regression of the
methane concentration in the calibration gas as a function of methane
peak height (or, if used, peak area). It is recommended that the datum
point obtained with zero grade air should not be included in the regres-
sion. The reason is that if the methane concentration in the zero grade
air is lower than the methane concentration in the carrier gas, the sam-
ple of zero grade air will produce a negative methane peak. Many peak
height or peak area measuring schemes cannot correctly determine the
height or area of the negative peak. For each range calibrated, it the
deviation of the calibration points from the regression line is 2C? or less
or within 0.1 ppm methane of the value of each data point (excluding
zero), then linearity is confirmed and a linear equation may be used to
determine the methane concentration. Otherwise, attempt to find and
correct the cause of the non-linearity. If necessary, the best fit non-
linear equation which represents the data to within 2$ (or 0. 1 ppm
methane) of each point may be used to determine the concentration.
7.5 Emission Measurement Procedure — Each series of sample
and dilution air bags from one vehicle test should be preceded with a
measurement of zero gas and span gas. If the instrument output for
these gases is not the same as during the last calibration, an electrical
or computational correction to the instrument output should be made.
Re-check zero. Six methane analyses can be made in 4 minutes. A mea-
surement of zero gas and span gas following the test series which is
within 2% of full scale from the initial values will confirm that there
was no substantial instrument drift during the measurement of the test
samples. The instrument should be located near the CVS in order to
minimize the length of tubing. Samples are pumped directly from the
bag via a Teflon or stainless steel tube to the sample inlet.
7.6 Data Analysis — The methane peak height is used as a measure
of the amount of methane. Peak height is the distance from the peak
maximum to the peak baseline. The peak baseline is defined as the pla-
teau immediately preceding the peak. (Alternatively, the methane peak
area, as determined with an integrator, can be used as a measure of the
amount of methane.) Methane concentrations are measured directly,
NMHC concentrations can be determined by the difference between an
independent total hydrocarbon concentration measurement and the
methane concentration.
7.6.1 METHANE — The following example for a linear analyzer illus-
trates the method of calculation:
Span — 18.9 ppm C methane — 50.0 chart divisions
Bag Analysis
Methane — 25.0 chart divisions
Bag Concentration Calculation
25.0
Methane — 18.9 X JTJJ-JJ = 9.45 ppm C
For calculating the mass of methane by a method analogous to that
used in the Federal Test Procedure' for hydrocarbons, the methane
density at 20°C (68°F) and 101.32 kPa (760 mm Hg) pressure should
be taken to be 0.667 kg/m3 (18.89 g/ft3).
7.6.2 NONMETHANE HYDROCARBON — NMHC data analysis is accom-
plished with calculation techniques similar to those used for total HC
CVS bag emission data analysis. The following example for a linear an-
alyzer illustrates the method of calculation:
Span — 18.9 ppm C methane — 50.0 chart divisions
Bag Analysis
Methane — 25.0 chart divisions
Total HC — 82.56 ppm C
Bag Concentration Calculations
25.0
Methane — 18.9 X - = 9.45 ppm C
NMHC — (total HC (ppm C) — methane (ppm C))
= 82.56 — 9.45 =73.11 ppm C
The exhaust sample and the dilution-air bags should be analyzed and
the NMHC concentrations used for calculation of mass emissions as di-
rected in the Federal Test Procedure1 for hydrocarbon.
It can be noted that, in general, the sum of the methane mass emis-
sions and the calculated NMHC mass emissions will not exactly equal
the total calculated HC mass emissions. This is because the FID mea-
sures carbon mass and not hydrocarbon mass. The relation between
these two masses depends on the hydrogen/carbon ratio of the hydro-
carbons in the exhaust gas and this is not determined for each sample.
Instead a nominal value for the hydrogen/carbon ratio is assumed in
the Federal Register.
See Code of Federal Regulations, Title 40 Protection of Environment. Part
86, Subpart B, Emission Regulations for 1977 and Later Model Year New Light-
Duty Vehicles and New Light-Duty Trucks: Test Procedures (40 CFR 86.101 et
seq.) (as possibly amended by the Federal Register).
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25.166
S. Instrument Performance Specifications
8.1 Baseline Noise—The instrument shall be run for 20 min with
valve VI remaining in the fill/backflush position. The peak-to-peak
noise and drift of the baseline shall not exceed the equivalent of 0.16
ppm methane. (With a typical instrument, the peak-to-peak noise and
drift was 0.07 ppm methane.)
8.2 Precision—A span gas containing about 20 ppm methane in
air shall be read at least 25 times. Wait one cycle period (typically 30
s) between starting the flow of span gas and trie first rotation of valve
V1 into the inject position. The standard deviation of the series of span
gas readings shall not exceed 0.10 ppm methane. (With a typical instru-
ment the standard deviation of a series of span gas readings was 0.02
ppm methane.) Since the first reading of the series is most apt to show
an offset, the magnitude of the difference between the first determina-
tion of the series and the mean of the series shall be no greater than
0.14 ppm methane or 3.3 standard deviations, whichever is greater.
8.3 Column Resolution—The methane retention time (paragraph
9.2.1) divided by the peak width at half height (paragraph 9.2.2) shall
exceed 10.5. (In Fig. 2 this quotient is 11.5.)
9. Maintenance
9.1 Valve VI Position—Except when actually injecting a sample.
valve VI should be kept in the fill/backflush position so as to minimize
possible contamination of the Molecular Sieve column by effluent from
the Porapak N column.
9.2 Column Performance
9.2.1 The methane retention time, which is the elapsed time from
sample injection (sample injection is when valve VI rotates from thf
fill/backflush position to the inject position) to the appearance of th?
methane peak maximum, should be measured when the instrument is
placed in service and at weekly intervals thereafter. A change in the re-
tention time from its initial value gives an indication that the column
has deteriorated or that the initial conditions have changed. If the rf.
tention time has changed by more than 109£, the cause should be iden-
tified and corrected. Check oven temperature. Check or condition tht
dryer as described in paragraph 5.3.15. Check the carrier gas flow ram
against the flow rates initially measured as described in paragraph
7.3.1.2. Check for leaks. Condition the columns as described in para-
graphs 5.3.9 and 5.3.10.
9.2.2 Time the width of the methane peak at half of its peak height
using a stopwatch or a gas chromatogram obtained with the recorder
running at a fast speed of at least 0.3 m/min (1 ft/min). Perform this
test when the instrument is first placed in service and at monthly inter-
vals thereafter. A change in the peak width at half height of more than
15% suggests that the cause be identified as in paragraph 9.2.1.
9.3 Dryer Conditioning—If an indicating type dryer is used, ii
should be checked monthly and replaced if exhaustion is indicated. If
a non-indicating type dryer is used, it should be replaced or recondi-
tioned monthly. (See paragraph 5.3.15.)
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