There are three main types of gas hazards.
- Flammable Gas – presents a risk of fire and/or explosion
- Toxic Gas – presents a risk of poisoning
- Asphyxiant Gas – presents a risk of suffocation
Flammable gases present a risk of fire and/or explosions. Combustion is a chemical reaction and happens when oxygen is combined rapidly with another substance. This release of energy will appear as heat, and sometimes in the form of heat. A hydrocarbon compound in the form of solid, vapour, gas or liquid can be a common source of ignition substance. High levels of oxygen O2 can also increase the flammability of gases and materials.
The fire triangle helps show the combustion process and includes three causing factors – a source of ignition, oxygen and fuel in the form of a gas or vapour. When Frontline Safety look to designing a fire protection system, we will aim to remove at least one of these factors.
There are certain limits of flammability which produce a combustible gas mixture. This is depicted as three bands with two explosive limits – upper exposure limit (UEL) and lower explosive limit (LEL). Each individual gas or mixture will have its own limits. Gas and air above the UEL is considered too rich and is oxygen deficient. Anything under the LEL is considered too lean as there is insufficient gas to create an explosion. Between the two explosive levels is the flammable range.
Contact us to find out the limiting values for certain gases and vapours and normal conditions of pressure and temperature. The flammability ranges may fluctuate depending on an increase in pressure, temperature or oxygen O2.
It’s important to remember that a concentration in excess of the upper explosive limit may occur in enclosed or unventilated areas.