EVALUATION OF THREE LOW COST
EXHAUST ANALYZERS
by
Charles Urban
for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Ann Arbor, Ml. 48105
May 1984
SOUTHWEST RESEARCH INSTITUTE
SAN ANTONIO HOUSTON
-------
EVALUATION OF THREE LOW COST
EXHAUST ANALYZERS
PROPERTY OF:
NATIONAL VEHICLE AND FUEL EMISSIONS
LABORATORY LIBRARY
2000 TRAVERWOO0 DRIVE
AA'N ARBOR. Ml 48105
by
Charles Urban
for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Ann Arbor, Ml. 48105
Approved:
Karl J. Springer, Director
Department of Emissions Research
Engines, Emissions and Vehicle Research Division
-------
SOUTHWEST RESEARCH INSTITUTE
POST OFFICE DRAWER 28510 6220 CULEBRA ROAD SAN ANTONIO, TEXAS. USA 78284 (512) 684-5111'TELEX 76-7357
ENGINES. EMISSIONS. AND VEHICLE RESEARCH DIVISION
TELEX: 767357
TWX: 910-871-1084
TO:
Robert J. Garbe, Project Officer
William Clemmens, Branch Technical Representative
Control Technology Assessment and Characterization Branch
Environmental Protection Agency
2565 Plymouth Road
Ann Arbor, MI 48105
FROM: Charles M. Urban
Department of Emissions Research
Southwest Research Institute
6220 Culebra Road
San Antonio, Texas 78284
SUBJECT: Submittal of Test Results for work conducted under Work
Assignment No. 18, Contract 68-03-3162, SwRI, Project 03-7338-018.
Contract Title: "Pollution Control Assessment for the Emission
Control Technology Division, Ann Arbor, Michigan"
Assignment No. 18 Title: "Low Cost I/M Analyzer Study"
I.
INTRODUCTION
Three "low cost" exhaust analyzers were provided to SwRI by the
EPA for evaluation under a specific series of tests. This evaluation
involved measuring various concentrations of CO in vehicle exhaust
using a reference analyzer and the three "low cost" analyzers. The
Statement of Work is given in Attachment A-l.
II.
TEST PLAN
The test plan followed was the same as that given in the Work
Plan for Work Assignment No. 18. A copy of the technical approach for that
Work Plan is given in Attachment A-2. Some additional evaluations, over
and above those given in the Work Plan, were conducted.
III. CAR, ANALYZERS, AND MISFIRE UNIT
The car used was a 1981 Ford Mustang with a 2.3 liter engine and a
three-way exhaust catalyst. A commercial grade unleaded gasoline was
used. The air pump was disconnected to enable attaining the higher levels
of exhaust CO requested.
An Electronic Ignition Misfire unit that had been utilized in
several previous EPA projects was used in this work assignment. This
unit was described in the final report EPA-460/3-80-003.
SAN ANTONIO. TEXAS
WITH OFFICES IN HOUSTON. TEXAI
AND WASHINGTON. 0 . C .
-------
The reference analyzer used was a Beckman 315A Infrared Analyzer
appropriately configured for full scale ranges of 6,3 and 1.5 percent
CO. It was determined at the start of the testing that use of the 6
percent range was adequate over all the test points. The use of a
single range greatly facilitated the testing, and was felt to improve
the overall integrity of the results. Use of a single range enabled
concentrating on those items of greater importance and reduced elapsed
time, which minimized drift for all analyzers used. The calibration
curve for the reference analyzer is given in Attachment A-3.
The three exhaust gas analyzers tested included the following:
KAL-EQUIP CO. Model 4089 (Part No. 97-3665)
HEATHKIT Model CI-1080
PEERLESS Model 600
Based on the copyright and other dates on the instructions provided, these
analyzers are from the early 1970's. The sensing element in the Heathkii .
analyzer is a thermistor bead, and it is assumed that the other two analyzers
also utilized thermistor beads. Such instruments using thermistors measure
the overall thermal conductivity of the gas being sampled and compare those
values with the thermal conductivity of air.
In the manuals provided, the accuracy of these analyzers was not
given. However, with the Kal-Equip analyzer, a possible indication of
accuracy was given. In a factory calibration, a tolerance of plus or
minus three divisions of air fuel ratio (i.e., plus or minus 0.3 air
fuel ratio) was allowed. Therefore, the tolerance on CO would be plus
or minus one percent CO (e.g., 2.5 to 4.5 percent CO for a value of 3.5
percent).
Copies of the data sheets developed and used for the evaluations
conducted under this work assignment are given in Attachment A-4.
IV. TEST RESULTS
The specified exhaust CO concentrations of 1, 2, 3 and 5 percent were
obtained by adjusting the carburetor idle air fuel mixture. The air pump
was disconnected throughout these analyses, except when obtaining near zero con-
centrations of CO in the exhaust.
Results of the analyses are summarized in Attachments B-l and B-2.
The averages of the results are resummarized in Table 1 and are shown
graphically in Figure 1.
The Kal-Equip analyzer was evaluated in one series of tests and the
Heathkit and Peerless analyzers were evaluated simultaneously in a separate
series of tests. The odd run number evaluations involved starting at the
one percent CO value,and the even run number evaluations involved starting
at the five percent CO values.
-------
O 4
U
O
u
5
4
2 3
0 1
0 12 345
Ref. Analyzer, %CO
Legend: - W/0 Engine Misfire
- 6% Engine Misfire
Figure 1. Performance o.f. Low Cost Analyzers
-------
TABLE 1. BRIEF. SUMMARY OF RESULTS
Measured CO Values in Percent
Ref.
4..b
0
1
2
3
5
Anal.a
24»b
0
1
2
3
5
Kal-Equip
Base
0.4d
1.5*
2.6d
5.7d
Misfire0
0.5
0.9
1.3
3.0
Heathkit.
Base
1.5
1.9
2.6
3.3
4.9
Misfire0
1.1
1.8
2.4
3.5
Peerless
Base
1.5
1.6
2.1
2.6
3.6
Misfire0
2.1
2.4
2.6
3.3
Set values were generally within plus or minus 0.2 of the values shown.
There were no significant differences between the measured values at the
.two probe locations.
Probe location from end of vehicle exhaust pipe.
,Six percent misfire setting.
Next day repeat values were 0.2, 1.1, 2.1, and 4.7
For the analyses with the reference analyzer probes at 4 inches and
24 inches from the exit of the vehicle exhaust pipe, measurements of the
initial position were repeated. The results were than compensated for
any. drift in the CO concentration. In no case was there any shift in the
value when changing from one probe to the other. There was, of course,
an initial blip with the first switch at each exhaust CO concentration.
The set point shifted or drifted as much as one percent CO with the
Kal-Equip analyzer. A next day repeat evaluation with the Kal-Equip
analyzer produced measured CO values of 0.2, 1.1, 2.1, and 4.7 percent for
1, 2, 3, and 5 percent exhaust concentrations After careful setting of
the control on this analyzer, a 0.5 percent CO drift was observed after
five minutes with the probe in room air.
Not shown on the summaries are the results of some added evaluations
which were conducted. With essentially no CO in the exhaust, the average
readings were 1.5 percent CO with the Heathkit and with the Peerless analyzers.
With a calibration gas containing 9 percent CO in nitrogen, the CO readings
on the Heathkit and Peerless analyzers dropped less than 0.5 percent CO from
the room air set point of 3.5 percent CO (i.e., readings of about 3 percent CO)
-------
It should be pointed out that with room air the analyzers are set to read
3.5 percent CO. With a 10.7 percent CC>2 calibration gas, the CO readings
on these two analyzers were about 1 percent.
V.
CLOSURE
This submission of the test results completes all of the requirements
in Work Assignment 18.
Prepared by:
Charles M. Urban
Senior Research Engineer
Department of Emissions Research
Submitted by:
Charles T. Hare
Manager, Advanced Technology
Department of Emissions Research
Karl J./^prdJnger
Director v
Department of Emissions Research
-------
ATTACHMENTS
A-l Statement of Work
A-2 Statement of Technical Approach
A-3 Calibration Curve for the Reference CO Analyzer
A-4 Data Sheets
B-l Results Without Ignition Misfire
B-2 Results With Ignition Misfire
-------
ATTACHMENT A-l
Statement of Work
The testing will consist of replicate measurements of vehicle
exhaust at several tailpipe CO concentrations at idle,
measuring simultaneously* with three low cost CO analyzers
and a reference analyzer.** The CO exhaust concentrations
should have values near 1%, 2%, 3%, and 5% CO such that each
value can be replicated to within .03% CO (300 ppm) (the
reference CO meter shall be used for determining the CO
level) . The low cost analyzer shall be operated per the
manufacturers instructions. The reference analyzer shall
measure CO at two locations; one at the same location as the
shortest low cost analyzer probe, the other location shall be
at least 20 inches upstream from the end of the vehicle
tailpipe (to avoid tailpipe dilution). The vehicle shall
have a 4- or 6-cylinder engine, and be capa&le of producing
the CO levels indicated (more than one vehicle can be used if
desired). The tests shall be run with a warmed-up vehicle.
Replicate the concentrations serially, starting with
ascending order, then with descending order, and so forth
until five values are recorded at each level. Provide TSS
with the upstream and downstream CO values for the reference
analyzer; CO values from the low cost analyzers; average CO
levels for each level, analyzer, and location; and the CO
standard deviation for each level, analyzer, and location.
Indicate the fuel type used, (Indolene or commerical).
Repeat the above procedure using a misfire generator (6%
misfire) and provide the same data.
*If the tailpipe cannot contain all of the probes without
distributing the flow, reduce the number of analyzers per
test ana repeat tiie test for the analyzers not tested in the
first group.
**The reference analyzer snail conform to and be operatea in
accordance with 40 CFR 86 Subpart D (Heavy-duty raw exhaust) .
-------
Attachment A-2
II. STATEMENT OF TECHNICAL APPROACH
The approach to be taken is as follows:
Receive the three low cost CO analyzers supplied by the EPA
Technical Project Monitor.
Check out the CO analyzers in accord with the manufacturers'
instructions, which are to be provided by the EPA along with
the analyzers. Analyzers meeting the requirements in the manu-
facturers' instructions will be used in this task; any analyzer
not meeting the requirements will be dropped from further evaluation.
Using a vehicle with a 4- or 6-cylinder engine, develop a method
for obtaining tailpipe CO emissions of 1, 2, 3, and 5 percent by
volume (±0.3%, or minimum variation practical). One of the
following methods or a combination will be used:
- Idle mixture adjustment
- Intake restriction (i.e., choking)
- Control of injected air (if and when a catalyst is used)
It is anticipated that an oxidation catalyst-equipped car will
be used for the initial evaluation.
Tailpipe CO readings will first be taken with the low-cost analyzer
having the shortest exhaust probe, and with the reference analyzer.
The reference analyzer will have one probe located the same as
that of the low-cost analyzer, and one probe located at least 20
inches upstream from the outlet of the tailpipe. The procedure
will be as follows:
- Warm-up the engine over an FTP, by operating at 40 mph
for 15 minutes, or by equivalent operation.
- Measure exhaust CO at idle mixtures producing approximately
1, 2, 3, and 5% CO, and then at 5, 3, 2, and 1% CO.
- Clear the engine by operating at increased engine speeds
for a few seconds, and check zero and/or spans on the
instruments.
- Repeat the measurement sequences of exhaust CO.
- Clear the engine, zero, and span.
- Repeat the measurement sequence of exhaust CO from the
1 through 5% values.
- Zero and span the instruments.
Note: Idle is generally not a stable condition, and therefore,
does not generally produce stable or repeatable CO
values, especially,within ±0.3 at the higher CO setting.
-------
ATTACHMENT A-2 (Cont'd)
If the CO values become more stable without clearing
the engine, the clearing will be omitted. The engine
idle speed will not be readjusted at the various CO
levels as long as the speed remains within reasonable
limits (i.e., within ±100 rpm). If found necessary,
the grder in which the idle CO values are measured may
be altered.
Repeat the tailpipe CO reading sequence with the remaining two
low-cost analyzers (simultaneously, if practical to do so).
These evaluations will include measurements with the reference
analyzer at only one probe location: at least 20 inches upstream.
Review the data to assure it appears reasonable and that there are
at least four acceptable data points for each condition.
Install the available misfire generator on a 4- or 6-cylinder
engine that does not have a catalyst (can be a catalyst-equipped
car on which the catalyst has been removed). With a 6 percent
misfire setting, develop a method for obtaining the various tailpipe
CO emission levels. Repeat the tailpipe CO reading sequence with
the low-cost and reference analyzers, and review the data.
Note: The level of effort assumes that the misfire generator
still functions properly (it has not been used in
approximately two years). Hydrocarbon readings may
also be taken if it proves practical to do so, but any
such reading will not be used in determination of
validity of the data.
Tabulate the CO data, and determine the averages and standard
deviations for each combination of CO level-analyzer-probe location.
Record identification data from the cars and the analyzers used,
and determine the probe locations in the exhaust pipe. The fuel
will be identified by type only; no analyses of the fuel will be
conducted.
Return or retain the low cost analyzers as subsequently requested
by the EPA Tehcnical Project Monitor.
-------
CALIBRATION CURVE FOR THE REFERENCE CO ANALYZER
ATTACHMENT Af 3 .
CURVE FIT USING Y=X/(A+B*X+C*X**2+0»X«»3)
C U G/D-2 NDIR CO
5/04/1984 RANGE-1
S/N 201048
0-6 %
DANNY
A= .3140212E+02 B= -.1527510E+00
TABULATION USING EQUATION
C= -.6650272E-04 D= .7999959E-07 FULL SCALE=
6.0
METER
.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
7.50
8.00
8.50
9.00
9.50
10.00
10.50
11.00
11.50
12.00
12.50
13.00
13.50
14.00
14.50
15.00
15.50
16.00
16.50
17.00
17.50
18.00
18.50
19.00
19.50
20.00
CONC
.02 y
.03 y
.05 y
.06 /
.08 y
.10 y
.11 y
.13 /
.15 /
.16 y
.18 y
.20 y
.21 y
.23 >
.25 y
.27 y
.28 y
.30 y
.32 y
.33 y
.35 y
.37 y
.39 y
.41 y
.42 y
.44 /
.46 y
.48 y
*50 y
.52 >
.53 >
.55 >
.57 /
.59 >
.61 >
.63 >
.65 ,
.67 >
.69 >
.71 t
METER CONC
' 20.50 .73
' 21.00 .75
' 21.50 .77
' 22.00 .79
' 22.50 .81
' 23.00 .83
' 23.50 .85
' 24.00 .87
' 24.50 .89
' 25.00 .91
f 25.50 .93
f 26.00 .95
' 26.50 .97
' 27.00 .99
' 27.50
' 28.00
' 28.50
' 29.00
' 29.50
' 30.00
' 30.50
' 31.00
' 31.50
' 32.00
' 32.50
' 33.00
' 33.50
' 34.00
' 34.50
' 35.00
' 35.50
' 36.00
' 36.50
f 37.00
f 37.50
f 38.00
f 38.50
t 39.00
1 39.50
f 40.00
.01
.03
.06
.08
.10
.12
.14
.17
.19
.21
.23
.26
.28
.30
.32
.35
.37
.39
.42
.44
.47
.49
.51
.54
.56
.59
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
METER CONC
40.50
41.00
41.50
42.00
42.50
43.00
43.50
44.00
44.50
45.00
45.50
46.00
46.50
47.00
47.50
.61
.64
.66
.69
.71
.74
.77
.79
.82
.84
.87
.90
.92
.95
.98
48.00 2.01
48.50 2.03
49.00 2.06
49.50 2.09
50.00 2.12
50.50 2.15
51.00 2.17
51.50 2.20
52.00 2.23
52.50 2.26
53.00 2.29
53.50 2.32
54.00 2.35
54.50 2.38
55.00 2.41
55.50 2.44
56.00 2.47
56.50 2.50
57.00 2.53
57.50 2.57
58.00 2.60
58.50 2.63
59.00 2.66
59.50 2.69
60.00 2.73
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
METER
60.50
61.00
61.50
62.00
62.50
63.00
63.50
64.00
64.50
65.00
65.50
66.00
66.50
67.00
67.50
68.00
68.50
69.00
69.50
70.00
70.50
71.00
71.50
72.00
72.50
73.00
73.50
74.00
74.50
75.00
75.50
76.00
76.50
77.00
77.50
78.00
78.50
79.00
79.50
80.00
CONC
2.76
2.79
2.82
2.86
2.89
2.93
2.96
2.99
3.03
3.06
3.10
3.13
3.17
3.21
3.24
3.28
3.32
3.35
3.39
3.43
3.47
3.51
3.54
3.58
3.62
3.66
3.70
3.74
3.78
3.83
3.87
3.91
3.95
3.99
4.04
4.08
4.12
4.17
4.21
4.26
METER
f 80.50
f 81.00
f 81.50
f 82.00
f 82.50
f 83.00
/ 83.50
/* 84.00
/ 84.50
/ 85.00
/ 85.50
/ 86.00
/ 86.50
/ 87.00
/ 87.50
/ 88.00
/ 88.50
/ 89.00
/ 89.50
1 30.00
/ 90.50
/ 91.00
/ 91.50
/ 92.00
/ 92.50
/ 93.00
/ 93.50
/ 94.00
/ 94.50
/ 95.00
/ 95.50
/ 96.00
/ 96.50
/ 97.00
/ 97.50
/ 98.00
/ 98.50
/ 99.00
/ 99.50
/ 100.00
CONC
4.30 /
4.35 /
4.39 /
4.44 /
4.49 /
4.53 /
4.58 /
4.63 /
4.68 /
4.73 /
4.77 /
4.82 /
4.88 /
4.93 /
4.98 /
5.03 /
5.08 /
5.13 /
5.19 /
5.24 /
5.29 /
5.35 /
5.40 /
5.46 /
5.52 /
5.57 /
5.63 /
5.69 /
5.75 /
5.81 /
5.87 /
5.93 /
5.99 /
6.05 /
6.11 /
6.18 /
6.24 /
6.30 /
6.37 /
6.43 /
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-------
ATTACHMENT A-4
Sheet 1 of 2
LOW COST. I/M ANALYZER STUDY
SwRI Project 03-7338-018
Date
By
ANALYZERS:
Calibration Check O.K.:
KAL-EQUIP [""I
. Connect to Battery
.-Adj. Set Control
HEATHKTT
PEERLESS ||
Yes I
AUTOMOBILE:
Year
No I I
Connect to Battery
Balance Meter
Yes | | No 1 |
Balance Meter
Adj. Set Pointer
Turn ON and Balance
. Adj. Set every 15 min.
| Nc| I
Yes
Make
Model
Engine CID Q.,3
Fuel Used: Uj
Catalyst: None | | Oxid.'l | 3- way | X I
G**t>o\ /*.-
CO MEASUREMENTS IN PERCENT:
Misfire Setting: None
6%
. Warm-up engine - 15 minutes at 40 mph, or equivalent.
Set
% CO*
1
2
3
4
5
5
.4
3
2
1
Ref. Anal.
4"
24"
Kal-
Equip
Ref.
24"
Heath-
Kit
Peer-
less
* +_0..3%, or minimum variation practical.
Continued
-------
ATTACHMENT A-4 (Cont'd)
Sheet 2 of 2
Misfire Setting: None
6%
. Clear Engine at increased speed.
. Check calibration of all instruments
Set
% CO*
1
2
3
4
5
5
4
3
2
1
Ref. Anal.
4"
24"
Kal-
Equip.
Ref.
24"
Heath-
kit
Peer-
less
. Clear Engine at increased speed.
. Check calibration of all instruments.
Set
% CO*
I
2
3
4
5
5
4
3
2
1
Hef. Anal.
4"
24"
Kal-
Equip.
Ref.
24"
Heath-
kit
Peer-
less
,
. Check calibration of all instruments.
*+_ 0.3%, or minimum variation practical.
-------
RESULTS WITHOUT IGNITION MISFIRE
ATTACHMENT B-l
LOW COST I/M ANALYZER CO RESULTS
Misfire Setting: None /X /6%/7
Set % CO
Run 1
Run 2
Run 3
Run 4
Run 5
Run 6
Average
Std. Dev.
Ref . Anal, at 4"
1
/. /
0.1
I.D
o.%
/I
I.D
(,D
O.I
2
£.0
2J
2.2
3.0
3.2
£.0
£.1
0. I
3
3.1
3.0
3.0
3.1
3.1
23
3.0
o, 1
5
42
4.1
3.1
f.O
f.!L
f.Si
f.O
o.Z
Ref. Anal, at 24"
1
/./
0.9
1.0
*t
/./
l.t
1.0
O.I
2
3.0
3.1
J..Z
3-°
&*-
2.0
3.1
l
3.1
3.g
3.0
O.I
5
4.9
q.%
/./
f.o
£&
5-.Z
S.o
Q.&
Kal-Equip.
1
0.1
o.f
.o
&.&
$'7
0,^
»
Set % CO
Run 1
Run 2
Run 3
Run 4
Run 5
Run 6
Average
Std. Dev.
Ref. Anal, at 24"
1
Q-*
o.t
1,1
0.9
/./
&.$
0.1
O.I
2
/'$
2-1
J.b
1-9
1.1
2.0
2.0
O.I
3
J.O
3*0
*9
3.0
j,a
3.0
J.o
OJ
5
J.o
f.3
j.O
f>l
f.JU
'f.l
S'/
OJ
Heathkit
1
a.o
1.9
/.1
z.l
l.l*
$.0
1.1
0,0,
2
*1
2-b
J.+
J.b
*₯
*7
2,b
S.I
3
3.*
3.4
3. 1
3.(*
3.2,
3.3
3.5
0.5L
5
*7
J.o
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3
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-------
RESULTS WITH IGNITION MISFIRE
ATTACHMENT B-2
LOW COST I/M ANALYZER CO RESULTS
Misfire Setting: None / /6%/X/
Set % CO
Run 1
Run 2
Run 3
Run 4
Run 5
Run 6
Average
Std. Dev.
Ref. Anal, at 4"
1! 2
3
5
Ref. Anal, at 24"
1
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/.D
1.3.
/.I
1,2
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2
2.1
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3-f
2.3
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5
4.0
4.1
f.a.
4.f
S.I
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£.1
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2
3.C
1.3.
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2.3.
1.9
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/.z
0,^
3
3.0
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2.Z
2.Z
J-2
J.O
2.4
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5
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3,3
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3.4
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z.o
a.o
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3.2
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3.1
O.I
2
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*₯
j-t
J.3
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2.4
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3
a. 7
£.(0
£.(0
3-7
J.b
j.b
Z.I*
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5
3.3
3-3
3.2.
3.3L,
3.ZL
3-3
3.3
0,1
------- |