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Flammability - Pyrophoric properties of solids and liquids(contact with water causing fire)
Substances liable to spontaneous combustion.
Self-heating of substances, leading to spontaneous combustion, is caused by reaction of the substance with oxygen (in the air), conduction of the heat developed not being rapid enough to avoid combustion. Spontaneous combustion occurs when the rate of heat production exceeds the rate of the heat loss and the autoignition temperature is reached. Two types of substances can be distinguished with spontaneous combustion properties:
a) Substances, including mixtures and solutions (liquid or solid), which even in small quantities ignite within 5 min of coming into contact with air; these substances are the most liable to spontaneous combustion and are called pyrophoric substances.
b) Other substances which in contact with air, without addition of energy, are liable to self-heating; these substances ignite only when present in large amounts (kilograms) and after long periods of time (hours or days), and are called self-heating substances.
A pyrophoric material can spontaneously ignite in air. The word is derived form Greek for ?fire-bearing? Many pyrophoric materials are also water reactive, reacting vigorously with water or high humidity, often igniting upon contact.
To determine pyrophoric properties of solids see Dir 92/69/EEC (O. J. L383 A)