In last month’s newsletter, we opened the can of worms marked “hazardous gasses” and started to scratch the surface of classification, fire hazards and more. Now, let’s pick up where we left off and take a closer look at flammable substances and temperature classes.
In terms of fire hazards, hazardous areas are defined by four main criteria:
- The type of hazard
- The likelihood of the hazard being present in flammable concentrations
- The auto ignition temperature of the hazardous material
- The type of hazard – gas, vapour, dust or fibre.
Let’s zoom in on gases and vapours (Group I/II)
Gases and vapours are categorised in terms of their ignition energy or the maximum experimental safe gap, in respect of flameproof protection. Through this categorization, we have the following gas groups:
Please note that the gases noted in the table are typical gases for each group. MIE = Minimum ignition energy.
Now, let’s look at temperature classes
A temperature class is not the operating temperature range of the equipment, but the maximum permissible surface temperature of the equipment, in relation to + 40°C ambient temperature on any surface area. The maximum surface temperature must remain below the ignition temperature of the surrounding medium at all times.
Explosion proof equipment, installed within the Ex area, is divided into 6 temperature classes – T1 to T6. Let’s take a closer look:
Stay tuned as we look at dust explosions in next month’s newsletter!
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