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4. Flammable / Explosive Limits: For flammable or explosive materials there is a
concentration range in air in which a fire or explosion will occur if a source of ignition is
present. The limits are expressed in percent volume of the gas or vapour in air (parts
gas or vapour per 100 parts air).
 Below the Lower Explosive Limit (LEL) or Lower Flammable Limit (LFL), the
mixture is too lean to burn
 Above the Upper Explosive Limit (UEL) or Upper Flammable Limit (UFL), the
mixture is too rich to burn

For example
Hydrogen Sulphide:
LEL – 4.5%. UEL – 45%

Therefore the flammable range for H2S is between 4.5% and 45% in air.

5. Auto-Ignition Temperature: This is the temperature at which a gas or vapour will
automatically ignite with no ignition source. This is important information in the event
a gas or vapour could be exposed to a high temperature or hot surface, thereby raising
the temperature to this explosive level.

6. Hazardous Combustion Products: If hazardous products could be formed when the
material is burned, those products would be listed.

Examples
1. During the operation of a gasoline engine, carbon monoxide
is formed. 2. The PVC coating (yellow jacket) on piping.
If heat is applied and the PVC burns, toxic fumes are released from the
thermal decomposition of the plastic.

7. Explosion Data – Sensitivity to Impact: Includes information about potential of the
product exploding if it is bumped. We have all heard about the jarring consequences of
nitroglycerine (explosives).

8. Explosion Data – Sensitivity to Static Discharge: A description of the potential for the
product to explode when exposed to static discharge. Often during the transfer of
flammable liquids, static electricity can build up. This is why containers need to be
grounded and bonded during product transfer.

Section 5: Reactivity Data

This section will tell you whether or not the product is stable, and if it’s unstable, under what conditions.
This information impacts handling and storage.

1. Chemical Stability: A chemical is considered unstable if it can undergo a vigorous
polymerization, decompose, or become self-reactive. Some of the results can be:
 Explosion
 Generation of excessive heat and fire
 Production of toxic or corrosive by-products

For example
When acetylene is exposed to pressures over 15 psi is an example of a
product becoming unstable.

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