Gas Explosion Properties
So what is an explosion?
Defined as any uncontrolled combustion wave.
All dangerous substances have a flammable range
For any mixture of a combustible gas or vapour with an oxidizer (air) there is a critical ignition energy.
Release less than the critical amount of energy into the mixture and there will not be an explosion, the principle behind intrinsically safe
At a critical concentration called the most easily ignited concentration (MEIC), the amount of energy required to cause ignition is minimal.
The critical energy at the MEIC is called minimum ignition energy (MIE).
For the assessment of the ignition of gases a device defined in EN 60079-11 is used.
This gives the Minimum Ignition Current (MIC) ratio.
It is the means used for classifying gases and vapours into IIA, IIB or IIC.
Examples of Flammable Range
(PD IEC 60079-20)