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I. Introduc t ion
Subtitle C of the Solid Waste Disposal Act, as amended
by the Resource Conservation and Recovery Act of 1976 creates
a comprehensive "cradle-to-grave" management control systea
for the disposal of hazardous waste designed to protect the
public health and the environment from the improper disposal
of such waste. Section 3001 of that Subtitle requires EPA to
identify the characteristics of and list hazardous wastes.
Wastes identified or listed as hazardous will be included in
the management control system created by Sections 3002-3005
and 3010. Wastes not identified or listed will be subject to
the requirements for non-hazardous waste imposed by the States
under Subtitle D. The Agency has determined that reactivity
is a hazardous characteristic because improperly managed
reactive wastes (i.e., explosives, etc.) pose a substantial
present or potential danger to human health and the environment
The purpose of this document is to explain the Agency's
definition of reactive wastes, to discuss the comments received
on the proposed definition of reactive waste (43 FR 58956,
December 18, 1978) and the changes subsequently made.
I1. Proposed Regulation
Reactive waste. (1) Definition - A solid waste is a
hazardous waste if a representative sample of the waste:
(i) Is normally unstable and readily undergoes violent
chemical change without detonating; reacts violently with
water, forms potentially explosive mixtures with water, or
generates toxic gases, vapors, or fumes when mixed with water;
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or is a cyanide or sulfide bearing waste which can generate
toxic gases, vapors, or fumes when exposed to mild acidic or
basic conditions.
(ii) Is capable of detonation or explosive reaction but
requires a strong initiating source or which must be heated
under confinement before initiation can take place, or which
reacts explosively with water.
(iii) Is readily capable of detonation or of explosive
decomposition or reaction at normal temperatures and pressures
(iv) Is a forbidden explosive as defined in 49 CFR
173.51, a Class A explosive as defined in 49 CFR 173.53, or a
Class B explosive as defined in 49 CFR 173.58.
NOTE—Such waste includes pyrophoric .substances,
explosives, autopolymerization material and oxidizing
agents. If it is not apparent whether a waste is a
hazardous waste using this description, then the
methods cited below or equivalent methods can be used
to determine if the waste is hazardous waste.
Identification method. (1) Thermally unstable waste
can be identified using the Explosion Temperature Test cited
in Appendix II of this Subpart (waste for which explosion,
ignition, or decomposition occurs at 125°C after 5 ninutes is
classed as hazardous waste).
(i) Waste unstable to mechanical shock can be identified
using the Bureau of Explosives impact apparatus and the tests
cited in 49 CFR 173.53 (b), (c), (d), or (f), as appropriate.
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Ill. Rationale for Proposed Regulation
A. Rationale for proposing a reactivity characteristic
Reactivity was chosen as a characteristic of hazardous
waste because improperly managed reactive wastes present a
danger to human health and the environment. By definition,
reactive wastes are those which are capable of violently
generating heat and pressure, reacting vigorously with air or
water, reacting with water to generate toxic fumes, etc. The
dangers which these wastes pose to transporters, waste disposal
personnel, and the public are thus for the most part obvious.
In the past, there have been a number of incidents of damage
to persons or property which have resulted from the improper
management of reactive wastes. Some of these damage incidents
are listed and discussed in Appendix I.
Because of their acknowledged danger, reactive materials
are often controlled by federal and state regulations and
suggestions for their safe use or management are often
published by public or private organizations. Some of these
federal and state regulations and the guidelines for reactive
materials prescribed by the National Fire Protection Association
(NFPA) are listed and discussed in Appendix II.
B. Rationale for proposed reactivity definition
Reactive substances can be described as those which:
1) autopolymerize
2) are unstable with respect to heat or shock
3) are explosive
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4) are strong oxidizers
5) react vigorously with air or water
6) react with water to generate toxic fumes
As can be seen from this description, the tern "reactivity"
encompasses a diverse and somewhat loosely conjoined class of
physical properties or effects. These effects are not mutually
exclusive and a particular substance might exhibit several of
the properties mentioned above. For instance, certain
peroxides would fall into four of the above six categories.
Additionally, these categories overlap not only with each
other, but also with the other characteristics. For example,
the difference between flammabi1ity (conflagration) and ex-
plosiveness (deflagration) is only one of degree -- an illustra-
tion of the fact that the properties embraced by the term
"reactivity" are, like the term "reactivity" itself, relative
properties which have meaning only in a relative sense.
The Agency has attempted where possible to define
hazardous waste characteristics in terms of specific,
numerically quantified properties measurable by standardized
and available testing protocols. This has proven difficult
in the case of reactive wastes. The first problen vith
constructing a numerically quantified definition cf reactive
wastes arises from the fact that the term "reactivity" ecbraces
a wide variety of different (though overlapping) effects,
each of which can be triggered by an equally wide variety of
initiating conditions or forces. It would be cumbersome, if
not completely impractical, to construct a numerically
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quantified definition which included all these different
effects and their potential initiating forces. The second
problem arises from the fact, as noted above, that the
properties embraced by the term reactivity are relative
properties. The determination that something "reacts vigorously
with air or water" or is "unstable with respect to heat or
shock" is a relative determination, not an absolute one. The
effects being measured proceed along a continuum. Thus, it
is difficult to draw the line at any particular point.
These problems are reflected in the testing methods
which might be used to identify reactive substances. These
methods suffer from the following generic deficiences:
1. The available tests are too specific and do not
reflect the wide variety of waste management
conditions.
The available tests are used to determine how a specific
aspect or manifestation of waste reactivity behaves under a
special and specific type of stress. For example, DTA
(Differential Thermal Analysis) measures how the rate of
temperature rise of the waste (one specific aspect of waste
reactivity) correlates with the slow input of thermal energy
(one special and specific type of stress). This would not
indicate how the waste reacts to mechanical shock (a drop
test would be necessary to determine that), electrical shock,
whether the waste is a strong oxidizer, or even what is
producing the rate of temperature change (pressure buildup,
toxic or nontoxic fumes, heat of mixing, etc.). The information
derived from the available tests, then, is too specialized
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and does not reflect the wide variety of stresses and initiating
forces likely to be found in a disposal environment.
2. Reactivity of a sample may not reflect reactivity of
the whole waste:
In the case of wastes which are thermally unstable, the
reactivity of the sample may not adequately reflect the
reactivity of the whole waste. The kinetics of reaction are
not only a function of the available initiating sources and
ambient temperature, but are also a function of the mass,
configuration, geometry, etc. of the sample. For a "runaway"
reaction to occur, the system must transcend that steady
state where the energy (heat) produced by reaction is equal
to the energy transferred to the surroundings from the re-
acting mass. When this critical temperature is reached, the
mass experiences catastrophic self-heating. This heat
transfer phenomena is a function of sample size, density, and
geometry. As demonstrated in equation 1:^
Cdt/dt - QVp exp (-E/RT) + hS (T - To) (1)
C = me (m=mass and c = specific heat)
T = Temperature of the material
Q = Heat of decomposition
V = Volume
p = Density
E = Activation energy
R = Gas constant
h => Heat transfer coefficient
S = Surface are of the material
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As can be seen from this equation the rate of temperature
rise will be affected both by the intensive properties of the
waste, such as density, and the extensive properties of the
waste, such as. surface area and geometry. Since the extensive
properties of the sample are likely to be different from the
extensive properties of the whole waste, the reactivity of
the sample may not reflect the reactivity of the whole waste.
3. The test results are in most cases subjective or
not directly applicable.
The ideal test to use in a regulatory program is usually
one which requires minimal interpretation. The majority of
available reactivity testing methods are not of the "pass-
fail" type. Rather, these testing methods usually produce
test results which consist of a first order differential
plotted against time or against a standard, from which relative
reactivity can be assessed. When a test of this sort is run,
it is not run to determine "reactivity" per se but rather to
elicit information concerning how "fast" a material reacts
(i.e. kinetic information) or how vigorously it reacts (thermo-
dynamic information). Thus, the decision as to whether a
waste is reactive requires subjective interpretation of the
test results.
Additionally, the information derived from such tests
may not be directly related to reactivity. For example, the
test results might provide information on the activation
energy - a useful, but potentially misleading bit of information
since it reflects the speed of the reaction rather than the
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reaction's effects. The inapplicability of some of the test
results emphasizes the indefinite meaning of the term
"reactivity", a term which draws its meaning from the context
of its use. A chemist might think of a "reactive" substance
as one with a small activation energy (the energy difference
between the reactive substance's initial and transition
states), i.e., one which reacts easily. The Agency, however,
unlike the hypothetical chemist, is not just interested in
things that react "easily" but also in things which react
vigorously. It consequently needs to take into account not
just the activation energy of a substance but also the heat
of reaction, the molecularity of the reaction and other
factors - information which the available tests often do not
supply. It is, in other words,, not really interested in
performing a thermodynamic measurement, but rather in observing
if a waste behaves in such a way as to pose a danger under
normal handling conditions.
4. The standardized methods that do exist were not
developed for waste testing.
Use of the available testing methods on waste materials
often results in the application of standardized methods to
non-standardized samples and the application of standardized
methods to samples with physical consistencies the method was
not designed for. If such methods are used, there suits
might be difficult to interpret with certainty.
The avai lable reactivity testing methods are individually
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described and evaluated in Appendix 3*. As is evident from
those specific evaluations and from the preceeding discussion
of the generic shortcomings of the available testing methods,
none of these "type" methods are suitable for use to
unequivocally.determine if a waste presents a reactive hazard.
For essentially the same reasons, a numerically quantified
definition of reactive waste is not feasible. This is not as
big a problem as might be thought on initial reflection.
Most generators whose wastes are dangerous because they are
reactive are well aware of this property of their waste.
Reactive wastes present special problems in handling, storage
and transprot. Also, reactive wastes are rarely generated
from unreactive feed stocks or in processes producing unreactive
products or intermediates. Furthermore, the problems posed
by reactive wastes appear to be confined to a fairly narrow
category of wastes. The damage incidents show that the major
problems seem to be the formation of hydrogen sulfide (H2S)
from either soluble sulfides or biological degradation of
sulfur containing wastes, the formation of hydrogen cyanide
(HCN) from soluble cyanides, and the explosion of some
*These evaluations are taken from "A Second Appraisal of
Methods for Estimating Self Reaction Hazards", E. D. Domalski,
Report No. DOT/MTB/OHMD-76-6,"Classification of Test Methods
for Oxidizing Materials", V.M. Kuchta, A. C. Furno, and
A. C. Imof, Bureau of Mines, Report of Investigations 7954 and
"Classification of Hazards of Materials-Water Reactive Materials,
and Inorganic Peroxides", C. Mason and V. C. Cooper, NTIS No.
PB 209-422. The evaluations are slightly modified so as to
determine applicability of test methods to waste materials.
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"unidentified" waste material. It will thus only be in a
rare instance that a generator would be unsure of the reactivity
class of the waste, or would be unable to assess whether the
waste fits a prose definition, ,and would require the application
of testing protocols to determine the reactivity of this
waste. Since the available testing methods are not ideal
for identifying those wastes categorized as hazardous due to
reactivity, the approach chosen is to prescribe a prose
description of reactive waste for self-determination by
generators and to list wastes which meet this description and
have been identified as reactive.
The prose definition chosen is a paraphrase of the top
three of the reactive classes of the National Fire Protection
Association (.NFPA) reactivity classification system. The
other two classes in the NFPA c1 assificat ion scheme are not
included since these would include materials which are inert
under normal handling•conditions. This definition is used
because it includes all aspects and types of reactivity which
present a danger* and is already familiar to persons handling
reactive materials. The Chemical Manufacturers Association^-
uses this definition to classify reactive wastes in its
"Laboratory Waste Disposal Manual". Also, a paraphrase of
this classification system is used by the Navy2 in. their
hazardous waste disposal guide and is used in other hazardous
materials handling guides^>^ as a classification system.
*A11 wastes which have been identified as having caused
damage are identified under this definition as are all
commonly defined types of reactivity.
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Furthermore, the States of California and Oklahoma use this
system to define reactive wastes.
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References
1. "Laboratory Waste Disposal Manual" Chemical Manufacturers
Association (1975).
2. "NEPSS Hazardous Waste Disposal Guide", Naval Environ-
mental Protection Support Service (1976).
3. "Handling Guide for Potentially Hazardous Materials",
Material Safety Management Inc. (1975).
4. Material Data Safety Sheets.
5. E. J. Domalski, "A Second Appraisal of Methods for Estimating
Self-Reaction Hazards", DOT/MTB/OHHO-76/6, G.P.O. (1976).
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IV. Comments Received on the Proposed Characteristics
and the Agency's Response to These Comments
The Agency received approximately forty comment letters
addressing reactivity. These letters contained approximately
sixty discrete recommendations or comments on the proposed
regulation (in some letters more than one point was addressed).
Several of the commenters felt that the proposed reactivity
definition was adequate and provides desirable flexibility
for the generator to use judgement. However, the large
majority of comments expressed concern with the Agency's
reactivity characteristic. These comments have been categorized
by either content or the portion of the regulation addressed.
A discussion of these follows:
A. A large majority of the comments dealt with the asserted
lack of specificity and ambiguity of the prose definition.
0 A number of commenters argued that the prose definition
employed by the Agency is, as a general matter, too
vague and should be replaced by a numerically quanti-
fied definition accompanied by appropriate testing
protocols. This comment has been fully addressed in
Part III above and need not be addressed further here.
0 A number of commenters argued that the inclusion in
the definition of wastes which "generate toxic gases,
vapors, or fumes when mixed with water" and of "cyanide
or sulfide bearing wasteCs] which can generate toxic
gases, vapors, or fumes when exposed to mild acidic
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or basic conditions" needs to be made more specific.
Several of the commenters suggested that a phrase
such as "in harmful quantities" be inserted into the
proposed regulations as follows: "...or generates
toxic gases, vapors, or fumes in hamful quantities
when mixed with water"; "or is a cyanide or sulfide
bearing waste which can generate toxic gases, vapors,
or fumes in harmful quantities when exposed to mild
acidic or basic conditions." The comments on the
cyanide and sulfide bearing wastes all pointed out
that everything contains sulfides and most things
contain cyanides (albeit in trace amounts) and many
of these can generate minute quantities of hydrogen
sulfide or hydrogen cyanide under mildly acidic or
basic conditions. The Agency is sympathetic to these
concerns, and, in anticipation of such problems, had
attempted to make clear in the preamble and background
documents that the Agency Was leaving the determination
of reactivity hazard up to the reasonable judgement
of the generator based upon the generator's past
experience with.the waste. Taking this conmon sense
approach, such material as soil or flyash with sulfides
contamination (examples of sulfide and cyanide bearing
wastes supplied by the commenters) would clearly not
meet the reactivity definition. Despite this, the
point made by the commenters is certainly valid. There-
fore, so that there will be no confusion, the Agency has
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changed the final regulation to make it more specific, as
follows: "...or generates toxic gases, vapors or fumes:
in quantities sufficient to present a danger to public
health or the environment when mixed with water; or is a
cyanide or sulfide bearing waste which can generate toxic
gases, vapors or fumes in quantities sufficient to present a
danger to public health or the environment when exposed..."
This would certainly better reflect our regulatory intent.
e A number of commenters advocated that the Agency specify
what is meant by mildly acidic or basic conditions. One
commenter specified a pH range (5 to 9), but offered no
rationale as to why this particular range should be used.
Since a substantal percentage of the commenters found the
phrase "mildly acidic or basic" to be rather nebulous, the
Agency has decided that a specific pH range should be speci-
fied. The pH range chosen is that which is considered non-
hazardous by the corrosivity characteristic (2 < pH <12.5).
This range was chosen because any liquid outside the range
is hazardous and requires management within the Subtitle C
regulations. Only liquid wastes inside this range can be
landfilled without regard to the strictures on compatibility
imposed by the Subtitle C regulations and co-disposed with
wastes containing soluble cyanides or sulfides. These are
then the most stringent pH conditions which a waste could be
subjected to outside of a Subtitle C facility. (Natural
waters are unlikely to be outside this pH range).
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0 Several commenters suggested that the definition of
cyanide bearing waste should distinguish between "free
cyanide" and ferro cyanide" since the latter would not
be available to generate hydrogen cyanide under mild
acidic or basic conditions. The Agency beleives that
such a clarification is not necessary. If the cyanide
is unavailable under the specified acidic or basic
conditions then toxic hydrogen cyanide fumes.cannot be
generated and the wastes containing these unavailable
cyanides are not reactive. To specify these as exemp-
tions would be redundant and by implication might lead
generators to conclude that other unavailable sulfides
or cyanides NOT specifically exempted, do meet the
reactivity characteristic.
0 A number of commenters advocated specifying the concen-
tration of sulfide or cyanide needed to make cyanide
or sulfide bearing wastes hazardous. As explained above,
the identity of wastes which generate toxic gases under
the conditions specified in the Definition should be
obvious to the generator and thus, this level of sophi-
stication is unnecessary.
0 One commenter suggested that the Agency specify a
rate of evolution of toxic gas, but included no sugges-
tions as to how to do so. The Agency is unsure of how
a laboratory test method measuring gas evolution rate
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could be developed which could then be meaningfully
related to field conditions. Therefore, an evolution
rate of toxic gas will not be included in the final
regulat ions.
One comtnenter argued that sulfides and cyanides should
not be singled out in the regulations and further
stated that all other potential toxic fume generators
be included or, alternatively, that no toxic fume gen-
erators be included. The Agency disagrees. According
to information which the Agency has in its possession
(see Appendix I), the primary vastes implicated in the
generation of toxic gas are sulfides and cyanides. Thus,
the Agency would be remiss if it did not specify thase
types of wastes. If others are identified, they will
be included also.
B. A number of commenters argued that the test protocols
proposed in Section 250.13 (c)(2) of the regulations were
expensive, unreliable and not specific enough. Additionally,
several other commenters had problems with specific test
protocols. (For instance, some commeaters argued that the
125°C temperature adopted for the Explosion Temperature Test
was not a reasonable temperature and that decomposition, as
used in this test, needs to be defined.)
As a result of some preliminary work undertaken by the
Agency on the Explosion Temperature Test* and after revieving
*Evaluation of Solid Waste Extraction ?rocedures and Various
Hazard Identification Tests (Final Report)", NUS Corporation,
September, 1979, (see Appendix IV).
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the comments received on these test protocols* (and in view of the
generic problems with such tests, discussed above and in Appendix
III), the Agency has decided to remove the test protocols from
§261.23 of the regulations. The Agency agrees in general that
they are are unsuitable in defining a "reactive" waste for RCRA
regulatory purposes. The Agency has accordingly removed the des-
ignated test protocols from the regulations except to the extent
that the Department of Transportation's definition of Class A
explosiv.es -requires use of the shock instability test. As a result
of this decision, the Agency does not believe it is necessary to
discuss the individual concerns on the various test protocols.
C. A number of commenters argued that only under landfill con-
ditions will a waste be subjected to strong initiating sources
or heated under confinement. Therefore, they stated that since
no landf.illing of explosive waste is permitted, these conditions
will never occur and Section 250.13(c)(1) (ii ) is unnecessary.
This argument is completely circular. If Secti'on 250.13
(c)(l)(ii) were removed from the regulations, explosive wastes
would not be considered hazardous and could be disposed of in
a sanitary landfill, thus subjecting the wastes to the very
conditions which the commenters contend will cause the waste
to explode. In any event, the'Agency.does' not agree that a
landfill is the only place in which strong initiating forces
*Comments were received from.the public on the proposed
reactivity test protocols both during the 90-dav comment
period on the proposed §3001 regulations (43 FR 58956) and
in response to the solicitation of corn-merits on the NUS report
(Evaluation of Solid Waste Extraction Procedures and Various
Hazard Identification Tests) which was noticed in the Federal
Register on December 28, 1979. (44 FR 75827-76828)
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or heating under pressure can occur. Pressure increase can
be caused by confinement (e.g., a drum) together with
temperature increase (e.g., caused by mixing) or gas generation
(e.g., desolubilization of gases or deconposit ion into gases).
D. A number of commenters advocated exempting emergency
situations (i.e., homemade bombs) from coverage of RCRA so
that emergency teams can dispose of these explosive materials
as expeditiously as possible without delay (i.e., without
requiring a manifest, etc.).
The regulation already makes accommodation for cases of
imminent hazard in §263.30. Thus, emergency handling of
explosive wastes would be exempted by this section.
E. Other Comments
A number of commenters advocated that all the character-
istics be made as flexible as the reactivity character-
istic.
The Agency disagrees with these comments; the broad
meaning and generic character of the reactivity "uni-
verse" requires a flexible characteristic. The Agency
would have preferred to define, reactivity by specific
test protocols. However, this is not possible. The
other characterisitics, (except ignitable solids) can
be delineated or gauged by measurement of one (or a
few) specific chemical/physical properties; therefore,
the Agency will continue to define the ignitable,
corrosive, and toxicity characteristic as proposed.
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0 One commenter argued that just because a waste may
undergo a violent chemical change with another waste
is no reason to consider a waste hazardous. To illu-
strate this point, the commenter pointed out that an
acid and base when mixed will undergo violent chemical
change, but that such mixing (neutralization) is a
necessary part of many treatment systems and should
not be prohibited.
The Agency believes this commenter to be under a mis-
apprehension about the scope of the reactivity defi-
nition. The definition of reactivity refers to wastes
which undergo violent change in an uncontrolled raanner
either by themselves, or when mixed with water. There-
fore, the example of neutralization given by the commente;
is inappropriate, in as much as that example involves the
mixing of wastes. Furthermore, the Agency does not
believe that the example given by the commenter is a fair
representation of the hazards posed by wastes capable
of undergoing a violent chemical change. The example
given involves the controlled interaction between two
wastes which is a treatment technique and thus does not
reflect the hazards presented by uncontrolled violent
chemical change characteristic of waste management
situations.
0 One commenter suggested that the definition of reactive
waste be subdivided into sections which might be later
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indexed into a compatibility chart.
The primary purpose of Section 3001 is to identify
hazardous wastes, and not to dictate management tech-
niques. Section 3004 will address the various management
techniques including incompatible wastes (see §265.17
of the regulations). An appendix to the regulations
(Appendix 5 in Part 265) is provided with just such infor-
mat ion.
One commenter suggested that the Agency allow a genera-
tor to use any test that is believed appropriate for
determining reactivity. Similarly, one commenter
suggested that Appendix III to this background document
be removed because it might discourage use of a suitable
test .
This comment must be evaluated in light of the
Agency's decision not toprescribe any tests for mea-
suring reactivity. Ordinarily, when the Agency pre-
scribes a specific test for measuring a characteristic,
the generator is free to employ a different test if he
can demonstrate, in accordance with the equivalency
procedurees set forth in Subpart E, that his test is
equivalent to the Agency-prescribed test. Since the
Agency has elected not to prescribe any test protocols
for measuring reactivity, the question of equivivalent
test methods is. largely mooted: test results are no
longer determinative of whether a waste is reactive
and there is nothing against which to measure equivalency.
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This is not to say, however, that the use of tests by
the generators is precluded. The generator is free
to conduct any tests which aid him in assessing whether
his waste fits within the prose definition of reactivity.
However, the Agency is not bound in any way by these
tests and will make its assessment of whether a waste
is reactive by reference to the prose definition.
If a generator devises a test method which he be-
lieves adequately measures the reactivity of a waste, he
should submit that test method to the Agency for evalua-
tion.
One commenter suggested that the Agency address reacti-
vity over time in the definition since a material may
undergo physical and chemical changes as it ages and
become extremely reactive, whereas it might not be
reactive when first generated.
The Agency agrees with the comraenter that some
materials, such as certain ethers, can become more re-
active with time. However, the Agency has no information
(such as damage incidents) concerning any was te s which
might present this type of problem. Additionally, the
Agency is not aware of any testing method by which such
wastes might be identified. Therefore, the final regula-
tion will not address reactivity over time per s e; as
these wastes are identified by the Agency they will be
listed in Subpart D of Part 261 of the regulations.
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One commenter objected to the Agency defining as reactive
those wastes which are capable of detonation or explosive
reaction if subjected to a strong initiating source or
heated under confinement. The commenter asserted that
many inert, non-reactive materials, including tap water,
can be triggered to detonate or explode under confinement
when subjected to strong, heat, pressure, or a combination
of these and other initiating sources.
The Agency disagrees with this coTamenter and takes
specific issue with the assertion that many relatively
inert substances could be made to explode when subjec-
ted to extreme heat and pressure. In any event, even
if relatively inert substances could be made to explode
when subjected to strong heat and pressure, these sub-
stances would not be considered reactive under the pro-
posed definition. The Agency is only concerned with
substances capable of exploding under reasonable confine-
ment conditions -- i.e., those confinement conditions
likely to be encountered in disposal environments.
V . Promulgated Regulations
As a result of EPA's review of the comnents regarding
the reactivity characteristic, EPA is promulgating a reactivity
characteristic which significantly differs from the proposed
regulations in two aspects: the thermal instability and shock
instability test protocols cited in the proposed regulation
has been removed and the sect ion • relative to generation of
toxic gas, hydrogen cyanide and hydrogen sulfide has been
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made more specific. The thermal instability test protocol
was removed because the Agency determined that its interpre-
tation was too subjective for use in a regulatory program*.
(See Appendix IV) .
§261.23 Characteristic of reactivity
(a) A solid waste exhibits the characteristic of reactivity
if a representative sample of the waste has any of the following
properties:
(1) It is normally unstable and readily undergoes violent
change without detonating.
(2) It reacts violently with water.
(3) It forms potentially explosive mixtures with water.
(4) When mixed with water, it generates toxic gases, vapors
or fumes in a q'uantity sufficient to present danger to
human health or the environment.
(5) It is a cyanide or sulfide bearing waste which, when ex-
posed to conditions of pH between 2 and 12.5, can gen-e
erate toxic gases, vapors or fumes in a quantity suffi-
cient to present danger to human health or the environ-
ment .
(6) It is capable of detonation or explosive reaction if sub-
jected to a strong initiating source or if heated under
confinement.
(7) It is readily capable of detonation or explosive decompo-
sition or reaction at standard temperature and pressure.
*"Evaluation of Solid Waste Extraction Procedure and Various
Hazard Identification Tests" , (Final Report), NUS Corporation,
September, 1979, (Appendix IV)
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(8) It is a forbidden explosive as defined in 49 CFR 173.51
or a Class A explosive as defined in 49 CFR 173.53, or
a Class B explosive as defined in 49 CFR 173.88.
(b) A solid waste that exhibits the characteristic of
reactivity, but is not listed as a hazardous waste in Subpart
D, has the EPA Hazardous Waste Number D003.
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APPENDIX I
SELECTED DAMAGE INCIDENTS INVOLVING LAND DISPOSAL
OF REACTIVE WASTE
1. Santa Cruz, California - A bulldozer operator was overcome
by hydrogen sulfide (H2S) fumes generated while mixing tanning
wastes with other wastes. (Four deaths have occured in
California between 1963-1976 from inhalation of H2S from
waste tanning sludge.
2. Baltimore County, Maryland - Six nen were hospitalized
due to the inhalation of hydrogen sulfide gas liberated from
salts being landfilled.
3. Edison Township, New Jersey - A bulldozer operator was
killed at a landfill when a barrel of unknown waste exploded.
4. Crosby, Texas -Residentsin-the area were subjected to
sore throats, nauseau, and headaches when toxic fumes were
released from the reaction between oily wastes and acids,
dumped in an abandoned sand pit (twenty-six wells were closed
by this incident).
5. Edison Township, New Jersey - Cases of conjunctivetis ,
eye irritation, burn on cornea, and chemical burns resulted
from reactive wastes being landfilled.
6. Northern California - A drum of toluene ciisocyanate
(TDI) exploded, spreading extremely toxic toluene diisocyanate
throughout the area.
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7. Los Angeles, California - In Los Angeles County, a tank
truck emptied several thousand gallons of cyanide waste onto
refuse at a sanitary landfill. Another truck subsequently
deposited several thousan'ds gallons of acid waste at the sane
location. Reaction between the acid and the cyanide evolved
large amounts of toxic hydrogen cyanide gas. A potential
disaster was averted when a local chlorine dealer was quickly
called to oxidize the cyanide with chlorine solution.
8. California - Sulfide waste was added to s.oluble oil
waste in a tanker and subsequently added to other oily wastes
in a tank. Later treatment fo the oil with acid to break the
emulsified oil resulted in the evolution of hydrogen sulfide.
Two operators were briefly affected by the gas. There was
also an explosion in the tank.
9. Dundalk, Maryland - At a. sanitary landfill near Dundalk,
Maryland^ a 2,000-gallon liqu.id industrial waste load containing
iron sulfide, sodium sulfide, sodium carbonate and sodium
thiosulfate along with smaller quantities of organic compounds
was discharged into a depression atop an earth-covered area.
of the fill. When it reached eight to ten feet below the
point of discharge, the liquid started to bubble and fume
blue smoke. The smoke cloud quickly engulfed the truck driver
and disabled him. Several nearby workers rushed to his aid
and were also felled. During the clean-up operation, one of
the county firefighters collapsed. All six of the injured
were hospitalized and treated for hydrogen sulfide poisoning.
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It was not determined whether the generation of hydrogen
sulfide was due to the instability of the waste or the
incompatibility of the waste with some of the landfill
materials. (The pH of the waste was 13 when measured before
it left the plant).
10. Los Angeles, California - When the laboratory drain at a.
Los Angeles hospital was being cleaned by scraping, the drain
pipe exploded scattering fragments of aetal from the pipe.
Two subsequent attempts to remove the residual piping with
screwdriver and hacksaw resulted in explosions in both
instances. Fortunately, no one was injured in these explosions.
The cause was later attributed to shock, sensitive lead azide
formed in the lead pipes. A test solution, containing sodium
azide as a preservative, was routinely poured into the sewer
drain line after use. This chemical accumulated in the pipes
and reacted with the lead in the pipe to forn shack-sensitive,
explosive crystals of lead azide.
11. Riverside County, California - Several drums of phosphorus
oxychloride, phosphorus thiochloride and thionyl chloride
(all oxidizing agents) were improperly dropped off at1 a dump.
Later, during a flood, the drums were unearthed, ruptured, •
and washed downstream, releasing highly toxic hydrogen chloride
gas and contaminated the water.
12. California - A disposal site in central California
accepted a load of solid dichroaate salts (oxidizing agents)
and dumped it into a pit along with pesticide formulations
and empty pesticide conainers. For several days thereafter,
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snail fires erupted in the pit due to the oxidation of the
pesticide formulations by the dichromate. Fortunately, the
site personnel were able to extinguish these fires before
they burned out of control.
13. Southern California - A company using toluene diisocyanate
(TDI) in the manufacture of plastic and foam rubber automobile
products collected and stored its TDI wastes on-site in 55-
gallon metal drums with clamp type lids. After an extended
period of time during which thirty such drums had been
collected, a hauler was contacted to transport the wastes to
a Class I site in Southern California. The hauler stored
these drums in an open area at his facility for approximately
two weeks. Heavy rainfall occurred during this period. Upon
arrival at the disposal site a violent explosion ruptured one
of the drums. There were no injuries associated with this
incident. During storage some water apparently condensed or
leaked into the drums through the clamp-type lids. Transportation
of the drums then provided the agitation to accelerate the
reaction between water and TDI. The rapid production of C02
caused extreme pressure build-up on one of the drums and
subsequent violent rupture.
14. Southern California - In 1972 at a disposal site in
Southern California, reaction of sodium chlorate (oxidizing
agent) with refuse started a fire which lasted for two hours.
There were no injuries associated with the incident.
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Dirt contaminated with NaC104 (oxidizing agent) was drummed
and tranported as "Nad" to the sanitary landfill. The drums
were emptied onto re.fuse. The contents of the drums were wet
but reacted with the refuse to cause a fire upon dumping out.
A similar incident involving NaC104 and refuse producing a
fire occured in 1973. This incident involved containerized
material that reacted with refuse when a container ruptured
during the covering operation.
15. Southern California - A' standard procedure at a Southern
California disposal site for handling cyanide-bearing liquid
wastes and spent caustic solutions was to inject these loads
into covered wells dug into a completed section of a sanitary
landfill. Routine air sampling in the vicinity of the wells
defected low levels of HCN. No cyanide was detected during
addition of the spent caustic to a new well. On the basis of
these discoveries, use of the wells was discontinued. The
cyanide gas was apparently formed in the well as a result of
lowering of the pH of the waste by carbon dioxide and organic
acids produced in the decomposition of refuse.
16. A delayed reaction between phosphorus oxychloride (oxidizing
agent) and water in a 55 gallon drum caused violent rupture
of the durm and killed a plant; operator. The steam and
hydrogen chloride gas generated by the reaction caused the
explosion which propelled the bottom head of the drum
approximately 100 yards from the scene.
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APPENDIX II
STATE, FEDERAL AND NFPA REGULATIONS AND GUIDELINES
1 . Texas
The Texas Water Quality Board uses the following definition:
"Industrial Hazardous Waste" means any waste or mixture of
waste which ... generates sudden pressure by decomposition,
heat or other means and would therefore be likely to cause
substantial personnel injury..." - in combination with a listing
of 40 compounds.
2. State of Washington
Defines explosive using a 5" drop test, or class A explosive
(see DOT) definition.
3. P ennsyIv an i a
Combines Flammables and Explosives and uses only the following
list:
(1) Munit ions
(2) Blasting Materials
(3) Pressurized Cans
(4) Paint Thinners
(5) Solvents
(6) Kerosene
(7) Oils
(8) Petrochemical Waste Sludges
(9) Petroleum Waste Sludge
4 . California
Uses the following definition:
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"A waste, or component of waste is considered pressure
generating or reactive if it:
1) Is a Forbidden or class A, B, or C explosive as de-
fined in Title 49 CFR, Sect ions 173 . 51, 173.88,
and 173.100 respectively (see DOT).
2) Is a water reactive material.
3) Is in NFPA category 2, 3, or 4 (see NFPA)".
5 . Illinois
Uses the following definitions:
"Explosives" - Any waste having concentration of 1 % or
more of a substance described as an explosive (high, low, or
permissible) by Sax (Dangerous Properties of Hazardous Materials
by N. Irving Sax, Van Nostrand Reinhold) shall be considered
as explosive "per se".
"Reactives" - Any waste having a composition of 5% of more
of a substance that (as described by Sax) readily reacts
with air, water, or other substances to produce heat and/or
toxic fumes shall be considered a reactive waste. The definition
includes oxidizing agents.
6. NFPA
Category 0 - Materials which in themselves are nor-
mally stable, even, under fire exposure
conditions, and which are not reactive
with wat er.
Category 1 - Materials which themselves are normally
unstable and readily undergo violent
chemical change but do not detonate.
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Also materials which may react violently
with water or which may form potentially
explosive mixtures with water.
Category 3 - Materials which in themselves are capable
of detonation or explosive reaction but
require a strong initiating source or
which must be heated under confinement
before initiation or which react explo-
sively with water.
Category 4 - Materials which in themselves are
readily capable of detonation or of
explosive composition or reaction at
normal temperatures, and pressures.
7 . DOT
The Department of Transportation lists explosive wastes (these
are typically propellants, explosives, initiating compounds
etc.) and also specifies testing methods for liquids and
solids unstable to thermal and mechanical stresses. (See 49
CFR 173.53) .
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Appendix III
The testing methods examined in this section* are
separated into tests for thermal instability, (Tests I thru
X) tests for impact mechanical shock instability (Tests XI a
and b) tests identifying oxidizing agents, (Tests XII thru
XIV) and a test identifying water reactive materials (Test
XV).
1. Most of the information contained in this Appendix was
taken from "A Second Appraisal of Methods for Estimating Self
Reaction Hazards" E.S. Domalski Report No. DOT/MTB/OHMO-76/6.
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A. Tests Identifying Wastes Unstable to Thermal Stress
I. JANAF (Joint Army Navy Air Force) Thermal Stability Test
Number Six for Liquid Propellants.
1. Purpose of Test:
To determine the maximum temperatures to which thermally
unstable liquids can be subjected for short periods of time
without danger of explosive decomposition.
2. Operating Principle:
Under confinement in a microbomb, a liquid sample is either
heated rapidly and held at a pre-determined temperature for
an arbitrary time interval, or heated at a constant rate until
evidence of rapid decomposition appears. Spot immersion is
also possible, where th'e microbomb containing the sample is
immersed into the bath at some elevated temperature.
3. Test Description;
A microbomb which is drilled and tapped for a thermocouple
and burst disc fitting, has an internal volume of 1.3 cm^. A
liquid sample of 0.5 ml volume is used and burst diaphrams
ranging from 300 to 8400 psi failure pressure can be used. The
microbomb is immersed in a bath containing a bismuth-lead alloy,
which melts in the range of 65.6°C(150°F) to 12 1 . 1 °.C ( 25 0 ° F ) .
Maintenance of the bath around 93 .3°C (200"F) and of the
.heating rate at -6.7eC (20°F) per minute, allows detection
of the rate of decomposition of -16.7°C (2" F) to -1'5'C (5°F)
per minute. An air-vibrator is used to agitate the bath and
the sample in order to establish the desired.heat transfer
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between bath and sample. The sample temperature and the
temperature difference between the bath and sample are recorded
as a functions of time. The temperature at which self-decompo-
sition begins and the rate of decomposition can be derived.
4. Test Evaluation:
This test utilizes small samples of material in good thermal
contact with thermostated suroundings. The temperature of the
sample can be increased with time at such a slow rate that
quasi-steady states are maintained.
Rates of decomposition can be estimated from plots of the
sample temperature vs. time, and from plots of the temperature
difference between the sample and bath vs. time. The slope of
the temperature differential curve represents the rate of heat
transfer between the sample and the bath. Factors which need
to be taken into account are the rate at which the bath is being
heated, heat ing from the self-reaction of the sample, and
temperature gradients in the microbomb. From a plot of the
self-heating rate of the sample vs. the reciprocal of the
temperature, a linear slope proportional to the activation
energy should result. The precision of activation energies
derived in this manner is about +_ 15 percent.
5. Applicability, of Test as an Index of Waste Reactivity:
The activation energy of the reaction in quest ion, while
certainly an important parameter in assessing waste reactivity
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(as discussed previously) is not the only parameter.
Also important are heat of reaction, waste geonetry,
density; the heat transfer etc. To indicate a particular
activation energy as a cut-off for waste reactivity would
result in many false positives and negatives.
II. ASTM \(_Am_erican So^ie_ty f^or JTe_s_t ing_and_Mater ials) Standard
Method of Test E-476-73^ Thermal I_ns tability_of Con-
fined Co_nde_nse_d ^hase Sys_te_ms_( Confinement T^est)
1. Purpos^e of T_est:
To determine the temperature at which a checical mixture will
commence reaction, liberating appreciable heat or pressure,
when subject to a pro-grammed temperature rise. This method
applies to solids or liquids in a closed system in air or some
other atmosphere present initially under normal laboratory
conditions.
2 . Ope_rat_ing_Pr i ncip_lej
The sample to be tested is confined in a closed vessel
equipped with a burst diaphram, pressure transducer, and
thermocouple. The apparatus is equilibrated in a bath at
room temperature and subsequently heated at a constant rate.
The temperature difference between the bath and sample, the
pressure in the closed vessel, and the bath temperature are
recorded continuously during the course of the test.
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3 . Test Description;
This apparatus is a modification of that described under
the JANAF Thermal Stability Test. The sample (300 rag.) is
placed in the test cell or vessel (volume 1 cm') and is in
intimate contact with a thermocouple. The apparatus also has
a burst diaphram-vent tube system to release gases formed during
decomposition if the pressure reaches too high a value, and a
pressure transducer to provide measurement of the total pressure
inside the vessel as heat is supplied from a bath at a. constant
rate. The nominal heating rate of the bath is 8 *C (46.4°F)
to 10°C (50"F) per minute. Silicone oil is used in the
range 0" C (32*F) to 370°C (698°F) and a low-melting alloy
(i.e., Wood's metal) in the range 100°C (212eF) to 500°C (932°F).
Recorders are used to ..monitor, firs.t, the difference between
the sample temperature, (T) and bath temperature, (Tg) as a
function of bath -temperature, and, second, pressure, (P) as a
function of bath temperature. No agitation is used so as to
minimize thermal lag.
4 . Test Evaluation:
The threshold temperature is the lowest temperature at the
left hand base of the positive peak which appears in the plot
of (T)-(TQ) vs TO . The threshold temperature is an indication of
the onset of thermal instability in the sample. A potential
hazard exists, therefore, when the temperature of the sample
exceeds this value. The instantaneous rate of pressure versus
bath temperature, the maximum pressure generated and the rate
of pressure rise are useful hazard parameters related to rough
approximations of reaction time, and damage potential.
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Examination of the rate of temperature rise of the
sample, (dT/dt) and rate of temperature rise of the bath '(dT0/dt)
not only allows an evaluation of the Arrhenius constants, but
also provides for arbitrary scaling of the process. A simpler,
and probably preferable procedure, may be to record only TQ
corresponding to a runaway condition (e.g.. a. specified value
dT/dt dTo/dt, or rupture of a pressure disk (there is some
arbitrariness in the definition of the runaway criterion, but
this feature may not be serious)), and then repeat the experiment
with a different sample diameter, d. The Frank-Kamenetskii
condition then gives the value of E from
(dl/d2)2 = (Toi/To2)2 exP (E/R) (1/Tol~1To2U-
This procedure obviates the necessity of evaluating A and IN , and
allows immediate seal-ing to any size.
5. App_licab_il_ijty of_Tej_t_ a_s_ an _Ind_ex_of_Waste_ Reactivity:
This test suffers from the same drawbacks as the JANAF
test, i.e., the activation energy obtained from the test
is not a definitive indicator of waste reactivity.
III. SELF HEATIN£ ApIABATI_C_T_EST__
This test is run under adiabatic conditions. Conditions of
this sort do not correspond to normal waste management conditions,
and thus the test results are not likely to be reflective of actual
waste reactivity. Since different information cannot be obtained
from this test than is already available from tests I and II, a_n_d
the test conditions correspond less to waste management conditions
than do tests I and II, no further evaluation of this test is
presented here.
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IV. THERMAL SURGE TEST
1. Purpjpse of Test1.
To determine explosion temperature (temperatures for
which there is a delay time of 250 sec before explosion).
2. Operating Principle:
The discharge of a capacitor across a thin-walled tube
provides the thernal stimulus to initiate explosive decomposition.
The time-temperature profile of the decomposition is obtained
from oscillographic records. Although the tubes are thin-walled
(0.089 mm), they have considerable strength and provide a state
of heavy confinement for the explosive or unstable material.
3. Test_Description:
A test sample is loaded into hypodermic needle tubing which
is heated, essentiall-y instantaneously, by a capacitor discharge.
The temperature and time of the explosive event are recorded
from a continuous measurement of the electrical resistance of
the tubing by means of an oscilloscope. The test is particularly
suited to liquid material but solids can also be accomodated
by melting prior to their insertion into the hypodermic needle
tubing. Materials are subject to temperatures in the range of
260°C (500°F) to 1100°C .(2012°F) and delay times of 50 in
sec. to 50 sec. The delay time, T is given by A exp (B/RT)
where A and B are constants (somewhat related to the Arrhenius
pre-exponential factor and activation energy), R is the gas
constant, and T is the absolute temperature.
4. J_es_t Ev au 1 j_t_i on :
The thermal surge test supplies data on explosion
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temperatures which represent conditions of minimal heat transfer.
This test measures the true induction tine of an explosive rather
than the time required to heat up the sample. Wenograd 15
was able to show a correspondence between the temperature of the
system 250 sec prior to explosion and impact test data. The
activation energy parameter obtained in thermal surge test
measurements under dynamic conditions are considerably lower
than those determined in other measurements under isothermal
conditions. This test is probably one of the best available
approximations to a point source heat initiation of an unstable
material in a multicomponent system.
5. Applicability of Test aj_ an Index of Was_te Reactivity
The high temperatures the test materials are subjected
to in this test do not correspond to the temperatures which
wastes might be subject to during management (unless the
waste is subject to a strong electric discharge). For this
reason, this test is unacceptable.
V . ADJ. A_B AT! 1C STORAGE TEST
Like test III, this test is run also under adiabatic
conditions, and therefore no further evaluation is presented.
VI. ISOTHERMAL STRONG TEST
This test determines the heat generation rate as a function
of time and estimates the induction period at a given temperature
for a material. This test is run under isothermal conditions
and takes anywhere from weeks to months to complete. For these
reasons, no further evaluation is presented.
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VII. EXPLOSION TEMPERATURE TEST
1. Purpose of T_est
To determine the temperature at which a material explodes,
ignites, or decomposes after a five second immersion in a Wood's
metal bath.
2. Operating_Principle
This test gives an estimate of how close the explosion
temperature is to ambient condition for a material, and, hence
provides a measurable indication of thermal instability.
3. Te£t Description: •
The material to be tested (25 mg.) is placed in a copper
test tube (high thermal conductivity) and immersed in a Wood's
metal bath. This test is made at a. series of bath temperatures,
and the time lag prior to explosion at each temperature is recorded.
The bath temperature is lowered until a temperature is reached a-c-—-"
which explosion, ignition, or apparent decomposition does not occur.
The bath temperature working range is from about 125°C (257°F)
to 400°C (752°F). The sample is removed from the bath after
5 minutes if no explosion has occurred at 3608C (680°F).
4. Test Eva_luji_t^on:
The explosion time is very nearly independent of sample
size provided, the sample size is in the range 10 to 40 mg.
Particle size is also important in providing consistent re-
sults for a group of materials. Rapid equilibration of the
sample upon contact with the high tenperature bath will depend
upon the heat capacity and thermal conductivity of the material,
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and could be a major uncertainty in the test. Explosion tempera-
ture data is a' function of time and serves as useful indicators
to assist in maintaining safe thermal conditions during handling
.and transport.
5. Applicability of Test as an Index of Waste Reaetivity:
This test would seem the most suitable for our purposes.
The test results are pass-fail, either an explosion, ignition,
decomposition etc. takes place or not.
Problems do arise out of distortion of thermal transport
from sample size. However, this is a problem with all tests.
Also the Woods Metal Bath results in Cadmium fumes being generated
and should only be operated in a hood. A sand bath or nonflammable
oil bath might be more suitable for our purposes.
Field testing of this method indicate that it is unsuitable
for use without other modifications (see Appendix IV).
VIII. EXOTHERMIC DECOMPOSITION METER TEST
1. Purpose of Test;
To determine the self-heating of a sample at small to
moderate heat generation rates as a function of temperature
or t ime.
2 . Operating Principle:
A cylindrical aluminum block contains a cavity which has
a Peltier element attached at the bottom and a sample is placed
on the Peltier element. Heat flow from the block to the sample
is measured by means of the Pe1tier e1ement which provides
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an'electrical signal to a recording device.
3. Test Description:
A sample vessel constructed of stainless steel (volume,
2 cm^) is positioned over a Peltier element, and both are
housed inside the cavity of a cylindrical aluminum block.
This central block is surrounded by mantles containing elec-
trical heating elements in addition to an insulating layer.
The electrical input to the block and mantles is maintained
in such a manner as to keep the temperature difference between
the block and mantles as small as possible while the block is
heated linearly at about 108C (50°F) per hour. The heat flow
from the aluminum block to the sample is measured by the
Peltier element. As soon as the sample begins self-reaction
the heat flux to the sample starts to decrease. From a plot
r*
of the heat generation of the sample vs. the reciprocal of
the absolute temperature, the activation energy can be calculated.
4. Test EvaJUiatij3n_:_
Changes in the heat capacity of the aluminum block over the
temperature range 20°C (68°F) to 200°C (392°F) will cause the
temperature increase over this range to be slightly non-linear.
The Peltier element is temperature dependent, and calibration
using a pure copper sample having known thermal properties is
recommended.
5 . Ap p Li_c_ab_il_ity of T_es t_as an _Index_o_f_Waste Re a c t i v i t y
This test yields activation energy and is, as a result,
subject therefore to the same drawbacks as tests I and II.
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IX Homogeneous Explo_sion_Test
1. Purpose of Tes_t:
To determine the pressure-time profile of the thermal
explosion of solid or liquid materials.
2. Operating Principle:
A sample is heated under adiabatic conditions in a closed
vessel until explosion occurs. The maximum rate of pressure rise
and the maximum overpressure are measured as a function of
time at different heat input rates.
3. Test__Description_:_
About 100 ml of a sample is introduced into the lower part
of a stainless steel vessel. The lower section is sealed off
from a larger upper section above by a membrane (breaking
pressure 1 bar). The larger upper section serves as a free
space for the expansion of reactant or product vapors.
During the main part of the induction period, pressure equali-
zation is accomplished by a capillary tube connecting the
upper and lower sections of the vessel. The two-compartment
vessel is placed inside a larger vessel of 20 liter capacity
which seals the former from the external surroundings. A
heating mantle around the latter vessel allows heating of the
inner vessel to take place as near to adiabatic conditions
as possible. Around the sample vessel there is also an
auxiliary heater which heats the sample at a constant (but
adiabatic) rate until explosion occurs. When explosion
takes place, the membrane is ruptured and expansion into the
larger volume takes place. A piezo-electric pressure transducer
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records the pressure prior to, during, and after explosion.
4. Test Evaluation:
Differentiation of materials which give large rates of
pressure rise and overpressures can be singled out from those
which give low values. Subsequent precautions for management
can be taken.
5. Applicability of Test as an Index of Waste Reactivity;
This test identifies those wastes which react under
thermal stress to produce la.rge pressure gradients. This
information could be of use to identify potentially reactive
wastes, hazardous due to pressure generation. This type of
reactive waste would also be identified by the explosion
temperature test since some part of degradation or change in
the sample would be apparent for the samples failing this test.
X. Differential Thermal Analysis (DTA) Test
1. P_urj>jos_e_ of Test:
To determine exothermic and eadothermic reactions in a
material as heat is applied at a particular input rate.
2. Operating-Principle; l
The material under test and a stable reference material
are heated simultaneously at the same rate. Exothermic and
endothermic traces are measured using a recorder providing a
temperature-time plot of the reaction process.
3. Test Description:
The material to be tested (5 to 25 mg) and a. reference
material (such as alumina or glass beads) are placed into
identical compartments in an aluminum block. Heat is supplied
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to both compartments at the same constant rate of input.
Temperatures are measured using therno-cocples in conjunction
with automatic recording devices so that a plot of temperature
vs. time is obtained. A shift in the base line results from a
change in the heat capacity or mass of the naterial under test.
Particular care must be given to the type of temperature sensor
used and to the choice of its location, in the conpartment inside
the aluminum block. The geometry of the sanple and thermal
characteristics (such as thermal conductivity) of the sample
will affect the shape of the DTA curve.
4. Test_Ev_a_luation_:_
From the exotherms and endotherzs of the DTA curve,
decomposition temperatures corresponding to various rates of
temperature rise can ~be obtained. Kinetic parameters can be
calculated as a result of properly varying the heating rates
and assuming a constant degree of conversion of reactant when
a specific thermal event (such as the peak temperature of a
given exotherra) takes place. When the temperature sensors are
placed in the path of the heat flow the DTA apparatus can
measure the enthalpies of processes such as heats of deconposition
or transition. .
5. Applicability of Test as an Index of Waste Reactivity:
This test will give information as to how a waste reacts,
thermally, to thermal stress. There are several problems beyond
those normally associated with test's of this kind:
(1) The stress is specialized, as is the reactivity
inf orinat ion.
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(2) The test must be interpreted, and is sometimes
ambiguous (as in the case where several reactions are
taking place, one of which is eadothermic e.g. decomposition
of NH4N03).
(3) Usually very small samples are used, which makes
getting a representative sample even more difficult.
On the other handj this is a .standardized procedure which is
familiar to industry, widely known and often used.
B. Tests for Reactive Wastes Sensitive to Mechanical S_tr_e_ss
A great many sensitivity tests using mechanical stimuli
have been devised, mostly by the military, hence generally
intended for the rating of sensitive energetic materials
(explosives and propellants). Since we are interested mostly
in waste commercial materials or b--?roducts of lower sensitivity
(although handled in larger amounts), the raain problem is to
select a few suitable tests from the large number of existing
ones.
XI . Impa_c_t_Te_s_t
1. Purpose of .Te_s_t ^
To determine the minimum drop height of a falling weight
which strikes an explosive material and produces either a mild
or violent decomposition reaction. Both falling weight and
explosive material have a fixed and constant mass.
2. Operating Principle:
Impact energy is supplied to an explosive by a weight, of
constant mass which is dropped fron varying heights to establish
the minimum height to provide•detonation, decomposition, or
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charring. The impact provides rapid compression and crushing
of the sample (which may involve a frictional component of
crystals rubbing against crystals) and detonation ensues.
3. T_est De_sc^rj.jrtion :
The two most prevalent impact tests are those by Picatinny
Arsenal (PA) (Test XI a) and the Bureau of Mines (3M)(Test XI b).
In the PA apparatus a sample is placed in the recess of a
small steel die cup, and capped with a thin brass cover. A
cylindrical steel plug is placed in the center of the cover,
which contains a slotted-vent and the impact of the 2 kiram
weight is transferred to the steel plug.
In the BM apparatus a. 20 rag. weight is always employed while
the PA sample size may be varied for each experiment. The explosive
sample is held betwee'n two flat parallel plates made of hardened
steel and impact is transmitted to the sample by means of the
upper plate. Sample decomposition is detectable by audible,
visual or other sensory means.
In an apparatus used by the Bureau of Explosives (part
of the Association of American Railroads) and cited in Title
49 CFR (DOT Hazardous Materials Regulations) a falling weight
is guided by a pair of rigid uprights into a haamer-anvil
assembly containing a 10 mg. sample of explosive. Reproduci-
bility can become a problem here because of a non-ideal
collision between the drop weight and the impact hantaer since
only a fraction of the drop-weight energy is transmitted to
the sample.
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4. Test Evaluation:
Greater confinement of the sasple will limit the translational
component of the impulse to a smaller area as is the case with
the PA apparatus. Factors which play an influential role in
the test are: materials of construction, sample thickness, sample
density, hammer geometry, mass of drop weight, impact area,
surface finish, the surrounding atnosphere, temperature, and
pressure. Modifications can also be made to accomodate cast
and liquid samples.
5. Applicability of These Tests^as^Indicies of Waste Reactivity;
Impact tests suffer from the drawback that the fundamental
processes leading to energy release are complicated and poorly
understood. Failure of good agreement between various impact
tests shows that these tests contain uncontrolled parameters.
On the other hand, (1) partial correlations do exist, (2) the
history of the test indicates rough agreement with field
experience, (3) the stimulus is of reasonable severity, (4) the
tests are widely known and realtivelj easy to use. These facts
make them useful for a partial definition of hazards.
C. Tests Identifying Oxidizing Wastes^
XII . Burning Rate Test for Solid Oxidizers^
1. . j? ur_p_oj_e of Tes tj_
To determine the relative fire hazard present when in-
organic oxidizers are heated in the presence of wood or cellulosic
subs tances.
2 Most~o~fthe information contained in this section was taken
from "Classification Test Methods for Oxidiz.ing Materials"
by J. M. Kutcha, A. I,. Furno, and A. C. Imhof, Bureau of
Mines, Report of Investigations 7594.
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2. Operating Principle:
A set sample size and ratio of dried sawdust (12-50 nesh)
and oxidizer is ignited and the burning rate is determined by
measuring the time for the burning to propogate at least 5 inchest
3. Test Description
For the test, sawdust is initially screened to provide
particles ranging in size from 12 to 50 mesh (Tyler screen
series). The sawdust is dried in an oven at 101.5°C (215°F)
+ -15°C (5°F) for about six hours, and then test mixtures
having various concentrations of the oxidizers are prepared.
To obtain a uniform mixture, the materials are agitated for
10 minutes or more in a closed container. Generally, fine
oxidizers are used "as received" but coarse oxidizers can be
pulverized and screened to obtain sanples at least as fine
as the wood sawdust. For most of the oxidizers, a particle
size range of about 20 to 100 mesh appears to be adequate
for determining their hazard classification by this proposed
test. However, where the hazard level of such materials is
uncertain because of particle size considerations, the burning
rates of the mixtures should also be determined using oxidizer
samples that have fractions finer than 100 mesh.
Burning rates are measured using a rectangular rack that
was mounted horizontally and equipped with a 60-nesh steel screen
to support the sample. The sample bed is separated fron the side
rack nounts to insure unrestricted .burning along the sides of the
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sample. To form the sample bed, the sawdust-oxidizer mixture
is placed on a rack between a pair of spacer bars vhich fixed the
bed size and which are removed before ignition. The bed can also
be formed in a U-shaped wire screen channel which is transferred
onto the burning rack; the wire screen channel is then removed
before ignition. The sample is ignited by a. propane torch or
similar flame source and the burning rate determined by
measurements made with two fuse wire (0.5 anp) stations
and an electric timer, although slow-burning nixtures can be
followed visually and timed with a stoowatch. The sample bed
was normally 7 inches long and the rates are measured over a
distance of 5 inches and at least 1 inch from the ooint of
ignition.
4. Test Evaluation:
This proposed test method permits classification of solid
oxidizers into two or more groups based on their relative
burning rates with a cellulose-type cotnbustible such as wood
sawdust. The least hazardous class includes those oxidizers that
burn at low rates «10 in/min) when aixed with the select-grade,
red oak sawdust. A second class consists of oxidizers, such as
the alkali nitrates and chlorates, which burn at relatively high
rates (>10 in/min) when mixed with this sawdust. A third, more
hazardous class should include those oxidizers, which when un-
mixed or mixed with a combustible, might ignite spontaneously
and burn vigorously if moisture is present or if they are heated
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slightly. This class would include sodium peroxide and calcium
hypochlorite (69.5 percentage C12) which gives very high burning
rates with the sawdust. A fourth class is also required for those
oxidizers, such as ammonium perchlorate, which may detonate
when heated under confinement or when exposed to shock.
5. Applicability of Test a_s_ a_n Index of Waste Oxidizing
Strength
This method is designed to provide a relative measure of
the increased ignition or burning hazard that may exist when
inorganic oxidizers are mixed with an organic substance such
as sawdust. They are not applicable to organic peroxides or
to inorganic oxidizers that may detonate when heated with or
without a combustible.
In the application of this test method, it must be recog-
nized that a reliable hazard rating may not be possible for
all oxidizers using a single reference combustible. If the
adjacent material is not cellulosic in nature, (and in a
landfill this may or maynot be the case) it is conceivable
that an oxidizer may display a greater level of hazard than
observed with the select-grade, red oak sawdust used in the
present study.
XIII. Ignition Hazard Test for Liquid Oxidizers:
1. Purpose of Test:
To determine the relative fire hazard by exothermic reaction
of liquid inorganic oxidizers with other substances or by
decomposition to products which ignite or sustain a fire.
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Generally, these liquids react with nany organic substances and
some are capable of producing spontaneous ignition when nixed
with the combustible at normal or slightly elevated temperatures;
some may also ignite spontaneously when heated in the absence
of a combustible material.
2. Operating Principle;
In this proposed test, the ignitability or reactivity of
the oxidizer sawdust mixtures is determined in an open reaction
vessel using small quantities of the reactants. Temperatures
up to at least 87.8°C (190°F) are used to compare the oxidizers,
depending upon their reactivity. Such temperatures are not
necessarily unrealistic, considering particularly the possibility
of over-heating from the reaction of liquid oxidizers with
contaminants. The reaction vessel in these experiments is a
200-cm^' Pyrex beaker that is equipped with insulated heating
tapes and which rested on a flat ceramic heater; however, a stain-
less steel beaker can also be used. Because of possible violent
reactions, the reaction vessel is placed in a larger vessel of
heavy-duty steel and the experiments are to be performed in a
prot ected area.
3 . Test Description;
In a trial, a predetermined quantity of the sawdust (12 to
50 mesh) is added to the reaction vessel and brought to the
desired temperature. The liquid oxidizer is then cautiously
injected with a long hypodermic syringe ( 12 inches) fron behind
a protective shield, and the extent of reaction is determined
from continuous temperature measurements and visual observations.
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The mixture temperature is measured with a 30-gage iron-
constantan thermocouple protected against corrosion by a thin-
walled glass sheath and located near the center of the reacting
mass. Ignitions are confirmed visually since the flame reactions
does not necessarily occur in the immediate area of the
thermocouple; in many ignitions, the sawdust-oxidizer mixture
is scattered or the flames occurred primarily near the top or
outside of the test vessel. Generally, evidence of ignition
is observed for periods of at least 15 minutes. If no significant
temperature increase occurred, experiments are made at higher
temperatures and with various sawdust-oxidizer quantities.
Preliminary trials are always made with a small quantity of
oxidizer «1 ml), particularly in the case of an oxidizer of
unknown reactivity.
4. Test Evaluation:
This method is not applicable to detonable liquid oxidizers,
such as concentrated hydrogen'peroxide (90 percent) or perchloric
acid (72 percent). A shock sensitivity or thermal stability test
(Test XIV) is required for evaluating these types.
5. Applicability of Test as an Index of Waste Oxldizing Strength
(see Test XII, No. 5).
XIV. Self-Heating Test for Organic Peroxides*
1. Purpose of Test;
To determine the minimum ambient temperatures for self-
heating to explosion of thermally unstable compounds in charges
of specified shape but varying size.
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2. Operating Principle:
The thermal decomposition of organic peroxides is observed
from studying temperature-tine plots to obtain the critical
temperatures for explosion, heat transfer coefficient data, and
apparent activation energies.
A circulating fan located within the working space of the
furnace provides temperature control to within 0.5°C.
3. Test Description:
A cylindrical tube furnace is constructed of steel housed and
an aluminum open-topped cylindrical container which could hold 40
to 60 grams of organic peroxide. The furnace was heated elec-
trically over the range of 50°C (122°F) to 350°C (662°F) and
could be maintained at a fixed temperature to within 0.3°C.
The progress of selfheating in the peroxide sample relative
to the furnace was observed by using a differential thermocouple
at the center of the sample. A second thermocouple attached
to the side of the container monitored the surface temperature.
Temperature-time plots were recorded for different cylindrical
diameters for the samples and critical temperatures were
calculated.
Explosion studies were carried out with sample amounts
as large as 800 grams using a somewhat modified apparatus,
and similar parameters examined.
4 . Test Evaluation:
The chief disadvantage of the method is the long period
over which readings must be recorded and the long time required
for the furnace to stabilize following a large change in
operating temperature.
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5. Applicability_of_T_est as an Index of Waste Oxidizing
Strength:
This test can be used to identify detonable oxidizers, but
does not give any additional information other than that provided
by the explosion temperature test.
D. Tests for Identifying Water Reactivity3
XV. Test Method for Water Reactivity3
1. £u..rJL° ^ of Test:
To identify materials which react so violently with
water and provide a danger from ignition of nearby combustables,
generation of flammable gases or generation of toxic fumes.
2. Operating Principle:
Water reactivity of a substance is determined either
by adding a given weight of water, to a given weight of material
or vice versa. In either case, the rate of temperature rise
and the gross temperature rise are recorded, and the gases
evolved are sampled for analysis.
3. Test Description:
The sample container is a Pyrex tube, 1-3/8 inches in
diameter by 10 inches long, imbedded to a depth of 3-1/2
inches in a block of insulating foam (polyurethane or poly-
styrene) 3 inches square by 5 inches high. A thin piece of
copper 3/8 inch square and weighing 0.5 gram (about 0.025
inch thick) is silver-soldered to the tip of a chromel-
al.umel thermocouple which measures the temperature rise. This
Test XV is taken from "Classification of Hazards of Materials--
Wat er-React ive Materials and Organic Peroxides", C. Mason and
J. C. Cooper, NTIS Number PB-209 422.
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thermocouple is placed in the Pyrex tube in such a way that the
copper square is near enough to the bottom to be covered by
the sample. The output of the thermocouple is fed to a
suitable recorder.
An initial estimate of the severity of the reaction is
made by adding 5 grams of water slowly to 0.5 gram of material
with, the apparatus behind a protective shield. Since either
toxic or flammable gases may be evolved, the test must be
carried put in a suitable fume hood. The temperature rise
is measured by adding 10 grams of water slowly (10-20 sec) from
behind a protective shield to 1, 2, 5, 10, and 20 grams,
successively, of the sample. Measurements are continued
until the temperature reaches a peak and then begins to drop.
If 1, 2, and 5 grams of the material give virtually no temper-
ature increase in 4 minutes, 10 grams of water are added to
10 grams of sample and the temperature is monitored for 1
hour to determine whether a slow reaction occurs. If the
reaction is not too violent, 10 grams of water are added
to 20 grams of the material to see whether a greater rise in
temperature results. The procedure may be reversed by adding
the material to the water in the container. The best method
to determine whether a flammable or toxic gas is evolved is
by chemical analysis of the gas. If a gas is evolved, a
sample from the reacting material is collected through a.
flexible needle inserted into .the reaction container to with-
in about an inch of the reacting mixture. The.sample is then
analyzed on a. chromatograph for flammable and/or toxic gas.
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4. Test
The test is reproducible to within 10 percent. The test
results for known reactives like the hydules of the alkali
metals are positive. There seems to be little difference in
the results caused by the order of mixing.
5. Applicability of Test as an Index of Waste Reactivity:
A test such as this could be used to identify pyrophoric
wastes, wastes which generate toxic gases when contacted with water
etc.
The test method appears to define the activity of the
various materials tested. Classification of the water reactivity
hazard could be based on the temperature rise which is a
measure of the heat released by reaction with water. The
release of flammable and/or toxic gases would create an
additional hazard which could be covered by a classification
such as the following:
t ive Wastes:
Wastes which react with water to give
temperature rises of 60°C (140°F) a_nd_
evolve toxic or flammable gases.
Wastes which react with water to give
temperature rises greater than 60°C (140°F)
or evolve toxic or flammable gases.
Simplified methods of analysis for toxic gas, (particu-
larly HCN and H2S) must be developed before this test could
be considered.
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APPENDIX IV
The information contained in this Appendix was extracted
from "Evaluation of Solid Waste Extraction Procedures and
Various Hazard Identification Tests (Final Report)", NUS
Corporation, September 1979.
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1. Reactivityt Explosion Temperature Test Testing Method
The Explosion Temperature Test, which is described in
Attachment A to this Appendix, was used by two independent.
laboratories (Safety Consulting Engineers, Inc. of Rosemont,
Illinois and United States Testing Cotapany, lac.) to determine
reactivity. The purpose of this test is to determine the
temperature at which a material explodes, ignites, or deconposes
in a Wood's metal bath after being immersed for five minutes.
Table IV-I gives the testing results obtained from the Explosion
Temperature Test.
2. Conclusions and Recommendations of the Explosion
Temperature test
The proposed Explosion Temperature Test is unacceptable
on the basis of the testing results. Interpretation of the
testing results is too subjective.
As a replacement for the Explosion Temperature test, it
is recommended that differential temperature methods be
considered. For example, differential .scanning calorimeter
testing (i.e., differential temperature analysis) is a quick
and accurate means for objectively determining the temperature
at which a material will decompose or react with other materials
'This system is composed of a sensitive array of temperature
sensors, an adiabatic chamber, several small heating elements,
and a data processing and recording system.
To determine the amount of energy absorbed or given up
by a substance, a 0.1 to 5.0 mg sample is placed into the
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TABLE IV-I
EXPLOSION TEMPERATURE TEST RESULTS
Sample
Ferromanganese Dust
Ammonium Nitrate
Laboratory
K
L
K
Testing Results
5 min. at 350°C, no reaction
207°C, slignt reaction
Between 300°C and 325eC,
major reaction (sample de-
composed, smoke visible)
210°C, major reaction
IV-3
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adiabatic chamber and the temperature Is increased via the
heating elements. The data are recorded on a strip chart.
This is a very sensitive method. It can detect changes
such as loss of water of hydraticn, phase changes, etc.
It will give indications of innocuous events as well as severe
ones. Endo- or exothermic reactions are clearly indicated
by changes in the recorded temperature curves.
3. Supplemental General Comments (These comaents are those
provided by the two laboratories participating in the
testing program)
1) Wood's metal is composed of bismuth (50.09%), lead (25%),
tin (12.5%), and cadmium (12.5%). The use of a molten
metal bath could re'sult in potential OSHA violations
because of the toxic nature of the metal fumes.
2) The proposed method is archaic and the results are highly
subjective rather than objective. The nethod is time
consuming. A thermal analysis (i.e., differential tem-
perature analysis) is rapidly performed and the thermal
properties are easily identified. Testing results are
reproducible and many commercial laboratories provide
these analytical services at reasonable fees.
3) Determining if a reaction has taken place by visual
observations is very subjective. One laboratory sealed
the copper tubes with vise-grip pliers and immersed the
tubes in the bath. A reaction was judged to have taken
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place If bubbles were observed in the molten bath. The
test procedure gives no standard nethod for sealing the
tubes to prevent molten metal for contacting the sample,
and determining if a reaction has taken place is the
opinion of the analyst.
IV-5
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Attachment A
EXPLOSION TEMPERATURE TEST
(March 17, 1978 Draft)
1. Purpose of Test
To determine the temperature at which material explodes,
ignites, or decomposes after a five minute immersion in
a Wood's metal bath.
2. Operating Principle
This test gives an estimate of how close the explosion
temperature is to ambient conditions for a material, and
hence, provides a measurable indication of theraal insta-
bility.
3. Test Description
The material to be tested (25 mg.) is placed ia a copper
test tube (high thermal conductivity) and immersed in a
Woodf's metal bath. This test is made at a series of bath
temperatures , and the tine lag prior to explosion at each
temperature is recorded. The bath temperature is lowered
until a. temperature is reached at which explosion, ignition,
or apparent decomposition does not occur. The bath temp-
erature working range is from about 125 to 400'C. Tbe
sample is removed from the bath after 5 ninutes if no
explosion has occured at 360°C.
Taken from "A Second Appraisal of Methods for Estimating Self
Reaction Hazards," E.S. Domalski, Report No. DOT/MTB/OHMO-76/6.
Department of Transportation.
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