2.11. Self-heating substances and mixtures
2.11. Self-heating substances and mixtures
2.11.1.1. A self-heating substance or mixture is a liquid or solid substance or mixture, other than a pyrophoric liquid or solid, which, by reaction with air and without energy supply, is liable to self-heat; this substance or mixture differs from a pyrophoric liquid or solid in that it will ignite only when in large amounts (kilograms) and after long periods of time (hours or days).
2.11.1.1. A self-heating substance or mixture is a liquid or solid substance or mixture, other than a pyrophoric liquid or solid, which, by reaction with air and without energy supply, is liable to self-heat; this substance or mixture differs from a pyrophoric liquid or solid in that it will ignite only when in large amounts (kilograms) and after long periods of time (hours or days).
2.11.1.2. Self-heating of a substance or a mixture is a process where the gradual reaction of that substance or mixture with oxygen (in the air) generates heat. If the rate of heat production exceeds the rate of heat loss, then the temperature of the substance or mixture will rise which, after an induction time, may lead to self-ignition and combustion.
2.11.2. Classification criteria
2.11.2.1. A substance or mixture shall be classified as a self-heating substance or mixture of this class, if in the tests performed in accordance with the test method given in the
►M4
UN RTDG ◄ , Manual of Tests and Criteria, Part III, sub-section 33.3.1.6:
(a)
a positive result is obtained using a 25 mm cube sample at 140 oC;
(b)
a positive result is obtained in a test using a 100 mm sample cube at 140 oC and a negative result is obtained in a test using a 100 mm cube sample at 120 oC and the substance or mixture is to be packed in packages with a volume of more than 3 m3;
(c)
a positive result is obtained in a test using a 100 mm sample cube at 140 oC and a negative result is obtained in a test using a 100 mm cube sample at 100 oC and the substance or mixture is to be packed in packages with a volume of more than 450 litres;
(d)
a positive result is obtained in a test using a 100 mm sample cube at 140 oC and a positive result is obtained in a test using a 100 mm cube sample at 100 oC.
2.11.2.2. A self-heating substance or mixture shall be classified in one of the two categories for this class if, in a test performed in accordance with test method N.4 in Part III, sub-section 33.3.1.6 of the
►M4
UN RTDG ◄ , Manual of Tests and Criteria, the result meets the criteria according to Table 2.11.1:
2.11.2.1. A substance or mixture shall be classified as a self-heating substance or mixture of this class, if in the tests performed in accordance with the test method given in the ►M4 UN RTDG ◄ , Manual of Tests and Criteria, Part III, sub-section 33.3.1.6:
a positive result is obtained using a 25 mm cube sample at 140 oC;
a positive result is obtained in a test using a 100 mm sample cube at 140 oC and a negative result is obtained in a test using a 100 mm cube sample at 120 oC and the substance or mixture is to be packed in packages with a volume of more than 3 m3;
a positive result is obtained in a test using a 100 mm sample cube at 140 oC and a negative result is obtained in a test using a 100 mm cube sample at 100 oC and the substance or mixture is to be packed in packages with a volume of more than 450 litres;
a positive result is obtained in a test using a 100 mm sample cube at 140 oC and a positive result is obtained in a test using a 100 mm cube sample at 100 oC.
2.11.2.2. A self-heating substance or mixture shall be classified in one of the two categories for this class if, in a test performed in accordance with test method N.4 in Part III, sub-section 33.3.1.6 of the ►M4 UN RTDG ◄ , Manual of Tests and Criteria, the result meets the criteria according to Table 2.11.1:
Table 2.11.1
Criteria for self-heating substances and mixtures
|
Category |
Criteria |
|
1 |
A positive result is obtained in a test using a 25 mm sample cube at 140 oC |
|
2 |
(a) a positive result is obtained in a test using a 100 mm sample cube at 140 oC and a negative result is obtained in a test using a 25 mm cube sample at 140 oC and the substance or mixture is to be packed in packages with a volume of more than 3 m3; or (b) a positive result is obtained in a test using a 100 mm sample cube at 140 oC and a negative result is obtained in a test using a 25 mm cube sample at 140 oC, a positive result is obtained in a test using a 100 mm cube sample at 120 oC and the substance or mixture is to be packed in packages with a volume of more than 450 litres; or (c) a positive result is obtained in a test using a 100 mm sample cube at 140 oC and a negative result is obtained in a test using a 25 mm cube sample at 140 oC and a positive result is obtained in a test using a 100 mm cube sample at 100 oC. |
Note
The test shall be performed on the substance or mixture in its physical form as presented. If, for example, for the purposes of supply or transport, the same chemical is to be presented in a physical form different from that which was tested and which is considered likely to materially alter its performance in a classification test, the substance shall also be tested in the new form.
2.11.2.3. Substances and mixtures with a temperature of spontaneous combustion higher than 50 oC for a volume of 27 m3 shall not be classified as a self-heating substance or mixture.
2.11.2.4. Substances and mixtures with a spontaneous ignition temperature higher than 50 oC for a volume of 450 litres shall not be assigned to Category 1 of this class.
2.11.3. Hazard Communication
Label elements shall be used for substances or mixtures meeting the criteria for classification in this hazard class in accordance with Table 2.11.2.
Table 2.11.2
Label elements for self-heating substances and mixtures
|
Classification |
Category 1 |
Category 2 |
|
GHS Pictograms |
|
|
|
Signal Word |
Danger |
Warning |
|
Hazard Statement |
H251: Self-heating; may catch fire |
H252: Self-heating in large quantities; may catch fire |
|
Precautionary Statement Prevention |
P235 P280 |
P235 P280 |
|
Precautionary Statement Response |
|
|
|
Precautionary Statement Storage |
P407 P413 P420 |
P407 P413 P420 |
|
Precautionary Statement Disposal |
|
|
2.11.4. Additional Classification Considerations
2.11.4.1. For detailed schemes for the decision logic for classification and the tests to be carried out for ascertaining the different categories, see Figure 2.11.1.
2.11.4.2. The classification procedure for self-heating substances or mixtures need not be applied if the results of a screening test can be adequately correlated with the classification test and an appropriate safety margin is applied. Examples of screening tests are:
(a)
The Grewer Oven test (VDI guideline 2263, Part 1, 1990, Test methods for the Determination of the Safety Characteristics of Dusts) with an onset temperature 80 K above the reference temperature for a volume of 1 l;
(b)
The Bulk Powder Screening Test (Gibson, N. Harper, D.J. Rogers, R.Evaluation of the fire and explosion risks in drying powders, Plant Operations Progress, 4 (3), 181-189, 1985) with an onset temperature 60 K above the reference temperature for a volume of 1 l.
2.11.4.1. For detailed schemes for the decision logic for classification and the tests to be carried out for ascertaining the different categories, see Figure 2.11.1.
2.11.4.2. The classification procedure for self-heating substances or mixtures need not be applied if the results of a screening test can be adequately correlated with the classification test and an appropriate safety margin is applied. Examples of screening tests are:
The Grewer Oven test (VDI guideline 2263, Part 1, 1990, Test methods for the Determination of the Safety Characteristics of Dusts) with an onset temperature 80 K above the reference temperature for a volume of 1 l;
The Bulk Powder Screening Test (Gibson, N. Harper, D.J. Rogers, R.Evaluation of the fire and explosion risks in drying powders, Plant Operations Progress, 4 (3), 181-189, 1985) with an onset temperature 60 K above the reference temperature for a volume of 1 l.
Figure 2.11.1.
Self-heating substances and mixtures
