United States
Environmental Protection
Agency
Environmental Monitoring and
Support Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S4-86/015 May 1986
4»ER& Project Summary
EPA Method Study 33:
Ignitability Characteristics of
Solids
Robert W. Handy, Larry C. Michael, Caroline E. McLaughlin,
and Edo D. Pellizzari
i /;-~mm«nfi| Protection Agency
P^OIOI V. Ijorary
2,vG souti. D*dfaom Straat
Chicago, Illinois 60604
The full report describes the interlab-
oratory method study that was per-
formed to evaluate three potential
methods for determining the ignitabil-
ity characteristics of solids. The analy-
ses were conducted using specially de-
signed and built ignitability test
chambers. In the radiant heat ignition
test a radiant heat source is placed 6 cm
from the surface of a waste material.
Ignition is detected by a thermocouple
sensor placed above the sample surface
and the time required for ignition is
recorded on a strip chart recorder. The
rate of flame propagation is measured
by recording the time required for a
flame to burn a premeasured distance
between two thermocouple sensors
placed at a fixed distance above the
sample surface. Results are then ex-
pressed as cm/sec. The extinguishabil-
ity characteristic is measured by ignit-
ing the material and, when the surface
of the sample is completely aflame, ex-
tinguishing with a calibrated spray of
water, the volume of which is used as
the measure of extinguishability. The
first phase involved replicate measure-
ments of two well-characterized test
materials and a reference material by
nine laboratories. The second phase in-
cluded similar replicate measurements
of seven test materials by up to five lab-
oratories. For each laboratory and
waste material, the traditional means
and standard deviations of daily tripli-
cate measurements were used to
calculate values for single-laboratory
precision. To characterize the multi-
laboratory performance of the meth-
ods, the overall mean X, the overall pre-
cision S, and the percent relative
standard deviation (%RSD) were calcu-
lated.
This report was submitted in fulfill-
ment of Contract 68-03-3099 by Re-
search Triangle Institute, Inc. It covers
work performed from February 1984 to
September 1984.
This Project Summary was devel-
oped by EPA's Environmental Monitor-
ing and Support Laboratory, Cincinnati,
OH, to announce key findings of the re-
search project that is fully documented
in a separate report of the same title
(see Project Report ordering informa-
tion at back).
Introduction
The United States Environmental Pro-
tection Agency (USEPA) has specified in
the Federal Register that a solid waste
exhibits the characteristic of ignitability
if "it is capable of causing fire through
friction, absorption of moisture or spon-
taneous chemical changes and, when
ignited, burns so vigorously and persis-
tently that it creates a hazard." Pres-
ently, there are no suitable, validated
procedures for determining the ig-
nitability characteristics of solid (non-
liquid) wastes.
Results and Discussion
The data gathered in Phase II of the
study is summarized in Table 1. Exami-
nation of the data in Table 1 indicates
considerable variation in both single-
laboratory and overall precisions for all
three tests. Because of this and the
small data set, the most reliable evalua-
tion of methods was qualitative rather
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than quantitative. As part of the study,
participants were encouraged to submit
narratives of their experiences with the
test apparatus, and to provide com-
ments as to the applicability of the
methods to waste characterization. One
laboratory observed, while conducting
the radiant heat ignition test, that the
relationship between the rheostat set-
ting and the source temperature was
not constant. As a result, replicate radi-
ant heat measurements were highly
variable even at the same rheostat set-
ting. Another laboratory noted that the
interior temperature of the chamber
changed as a function of the length of
time the instrument was in use and soot
deposited on the chamber walls and
heat source. It was further noted that
fluctuations in interior chamber temper-
ature resulted when the chamber door
was opened to introduce samples.
Since ignition times are dependent on
chamber temperature at the beginning
of the test, a second heat source should
be introduced to the chamber accompa-
nied by automatic activation of 1) the
radiant heat source at a predetermined
chamber temperature and 2) a timing
device that would measure and record
time elapsed between activation of the
heat source and a signal from the flame-
detecting thermocouple. This would
eliminate the need for a strip chart
recorder, which in this study was itself
the source of considerable error. The
test procedure requires a chart speed of
0.5 inches/minute (0.02 cm/sec). Since
the chart distances recorded in the
study were commonly in the 0.2-0.4 cm
range, a possible 10-20% error was in-
troduced by the recording step alone.
Operational difficulties were also ex-
perienced in the flame propagation test.
The leading cause for the small amount
of data was non-propagation of the
flame or non-ignition. One laboratory
reported that the propagation rate for
some samples depended on the depth
of the sample in the trough. One analyst
reported that flames had a tendency to
propagate erratically or in the opposite
direction of the second thermocouple. A
narrower trough would minimize the
possibility of misdirected propagation.
Some false starts were reported when
ignition of the sample was attempted.
This problem could be solved by length-
ening the trough so that the sample can
be ignited without activating the first
thermocouple.
In the water extinguishability test,
several factors undoubtedly contributed
to the overall error of the measure-
ments. Perhaps the greatest source of
error was the confusion over whether
extinguishment of only visible flames or
also the embers constituted the end-
point of the analysis. If the-latter end-
point is assumed, larger amounts of
water would be used. Modifications in
the water delivery system would solve
some problems which were reported by
analysts. The system is designed to de-
liver a cone-shaped spray, the diameter
of which is the same as that of the sam-
ple dish. More accurate results might be
achieved by using a spray pattern that
delivers water to the entire surface of
the sample. Direct measurements by
weight of the amount of water delivered
to the flaming sample would be prefer-
able to calculating the value from time
and delivery rate, both of which con-
tribute separately to the total error of
the extinguishability measurement.
Conclusions and
Recommendations
The three ignitability tests studied in
this collaborative effort are potentially
useful and precise techniques for deter-
mining the possible ignition hazard of
solid wastes. Before the methods, par-
ticularly the water extinguishability test,
can be considered fully reliable, sub-
stantial modifications and refinements
of the test chamber itself are manda-
tory. Many of those modifications are
discussed below, but only further test-
ing on actual waste samples will deter-
mine the extent of the changes ulti-
mately required.
Based on the study results, observa-
tions regarding the methodology, and
comments from study participants, the
following recommendations are pre-
sented for future work:
For the radiant heat ignition test,
develop an automated system
which activates the radiant heat
source when the chamber interior
reaches the desired temperature.
Introduce an elapsed time device to
accurately measure beginning and
end points of the radiant heat and
flame propagation tests.
To avoid false starts, lengthen the
sample trough used in the flame
propagation test so that the sample
may be ignited without activating
the first thermocouple. A narrower
trough would also minimize misdi-
rected propagation, giving more
consistent results.
Develop a mechanism for generat-
ing a uniform spray pattern for the
water extinguishability test. Auto-
mate the spray pulsing system to
the maximum extent possible. In-
corporate a more accurate means
of measuring water delivery vol-
ume.
Define the exact endpoint of the ex-
tinguishability test.
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Table 1. Phase II Statistical Summary
Radiant Heat Ignition
Test Material
No.
No.
No.
No.
No.
No.
No.
3 Cotton Fiber
Day 1
Day 2
X (Sec)
ND
ND
Sr
S
%RSD
4 Polyurethane Foam
Day 1 ND
Day 2 ND
5 Paint Waste
Day 1
Day 2
6 Waste Oil
Day 1
Day 2
7 Waste Oil/Sand
Day 1
Day 2
8 Waste Solvent
Day 1
Day 2
98(n=5)
104(n=4)
119(n=4)
151(n=4)
151(n=4)
127(n=4)
61(n=5)
49(n=4)
9 Sawdust/Kerosene
Day 7 16(n=5)
Day 2 14(n=4)
52
25
17
23
39
6
14
6
6
3
56
63
38
152
68
63
23
9
6
3
58
60
32
101
45
50
38
19
35
24
Flame Propagation
X (cm/sec) Sr S %RSD
4.3
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R. W. Handy, L. C. Michael, C. E. McLaughlin, and £. D. Pellizzari are with
Research Triangle Institute, Research Triangle Park, NC 27709.
Terence M. Grady is the EPA Project Officer (see below).
The complete report, entitled "EPA Method Study 33: Ignitability Characteristics
of Solids," (Order No. PB86-166 303/A S; Cost: $11.95. subject to change) will
be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Enivronmental Monitoring and Support Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S4-86/015
0000329 PS
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