Class 4.3 Substances which, in contact with water, emit flammable gases
Criteria
The heading of Class 4.3 covers substances which react with water to emit flammable gases liable to form explosive mixtures with air, and articles containing such substances.
Substances and articles of Class 4.3 are subdivided as follows:
W Substances which, in contact with water, emit flammable gases, without subsidiary hazard, and articles containing such substances:
W1 Liquid;
W2 Solid;
W3 Articles;
WF1 Substances which, in contact with water, emit flammable gases, liquid, flammable;
WF2 Substances which, in contact with water, emit flammable gases, solid, flammable;
WS Substances which, in contact with water, emit flammable gases, solid, self-heating;
WO Substances which, in contact with water, emit flammable gases, oxidizing, solid;
WT Substances which, in contact with water, emit flammable gases, toxic:
WT1 Liquid;
WT2 Solid;
WC Substances which, in contact with water, emit flammable gases, corrosive:
WC1 Liquid;
WC2 Solid;
WFC Substances which, in contact withwater, emit flammable gases, flammable, corrosive.
Properties
Certain substances in contact with water may emit flammable gases that can form explosive mixtures with air. Such mixtures are easily ignited by all ordinary sources of ignition, for example naked lights, sparking handtools or unprotected lamps. The resulting blast wave and flames mayendanger people and the environment. The test method referred to in2.2.43.1.4 below is used to determine whether the reaction of a substance with water leads to the development of a dangerous amount of gases which may be flammable. This test method shall not be applied to pyrophoric substances.
Classification
Substances and articles classified in Class 4.3 are listed in Table A of Chapter 3.2. Theassignment of substances and articles not mentioned by name in Table A of Chapter3.2 to the relevant entry of 2.2.43.3 in accordance with the provisions of Chapter 2.1 shall be based on the results of the test procedure in accordance with the Manual of Tests and Criteria, PartIII, Section 33.4; experience shall also be taken into account when it leads to a more stringent assignment.
When substances not mentioned by name are assigned to one of the entries listed in 2.2.43.3 on the basis of the test procedure in accordance with the Manual of Tests and Criteria, PartIII, Section33.4, the following criteria shall apply:
A substance shall be assigned to Class 4.3 if:
(a)spontaneous ignition of the gas emitted takes place in any step of the test procedure; or
(b)there is an evolution of flammable gas at a rate greater than 1 litre per kilogram of thesubstance to be tested per hour.
NOTE: Since organometallic substances can be classified in Class 4.2 or 4.3 with additional subsidiary hazards, depending on their properties, a specific classification flow chart for these substances is given in 2.3.5.
If substances of Class 4.3, as a result of admixtures, come into different categories of hazard from those to which the substances mentioned by name in Table A of Chapter 3.2 belong, these mixtures shall be assigned to the entries to which they belong on the basis of their actual degree of danger.
NOTE: For the classification of solutions and mixtures (such as preparations and wastes) see also 2.1.3.
On the basis of the test procedures in accordance with the Manual of Tests and Criteria, Part III, Section 33.4, and the criteria set out in paragraph 2.2.43.1.5, it may also be determined whether the nature of a substance mentioned by name is such that the substance is not subject to the provisions for this Class.
Assignment of packing groups
Substances and articles classified under the various entries in Table A of Chapter 3.2 shall be assigned to packing groups I, II or III on the basis of test procedures of the Manual of Tests and Criteria, Part III, section 33.4, in accordance with the following criteria:
(a) Packing group I shall be assigned to any substance which reacts vigorously with water at ambient temperature and generally demonstrates a tendency for the gas produced to ignite spontaneously, or one which reacts readily with water at ambient temperatures such that the rate of evolution of flammable gas is equal to or greater than 10 litres per kilogram of substance over any one minute period;
(b) Packing group II shall be assigned to any substance which reacts readily with water at ambient temperature such that the maximum rate of evolution of flammable gas is equal to or greater than 20 litres per kilogram of substance per hour, and which does not meet the criteria of packing group I;
(c) Packing group III shall be assigned to any substance which reacts slowly with water at ambient temperature such that the maximum rate of evolution of flammable gas is greater than 1 litre per kilogram of substance per hour, and which does not meet the criteria of packing groups I or II.
Substances not accepted for carriage
Water-reactive solids, oxidizing, assigned to UN No. 3133 shall not be accepted for carriage unless they meet the requirements for Class 1 (see also 2.1.3.7).
List of collective entries
_____________________
a Metals and metal alloys which, in contact with water, do not emit flammable gases and are not pyrophoric or self-heating, but which are readily flammable, are substances of Class 4.1. Alkaline-earth metals and alkaline-earth metal alloys in pyrophoric form are substances of Class 4.2 Dust and powders of metals in pyrophoric form are substances of Class 4.2. Metals and metal alloys in pyrophoric form are substances of Class4.2. Compounds of phosphorus with heavy metals such as iron, copper, etc. are not subject to the provisions of ADR.
b Metals and metal alloys in pyrophoric form are substances of Class 4.2.
c Chlorosilanes, having a flash-point of less than 23 °C and which, in contact with water, do not emit flammable gases,aresubstances of Class 3. Chlorosilanes,having a flash-point equal toor greater than 23°Cand which, incontact with water, donot emitflammable gases, are substances of Class8.
Class 5.1 Oxidizing substances
Criteria
The heading of Class 5.1 covers substances which, while in themselves not necessarily combustible, may, generally by yielding oxygen, cause or contribute to the combustion of other material, and articles containing such substances.