Groups of Gases, Vapours & Dusts
- Category: Hazardous Locations
Substances are categorized into natural groups based primarily on the similarity of their MESG and MIC values.
MESG (Maximum Experimental Safe Gap):
|The distance through which an explosion can propogate if the gap between two machined surfaces exceeds a certain value.|
MIC (Minimum Igniting Current):
The minimum level of current at which each gas or vapour will ignite when tested in a standard intrinsic safety apparatus.
Other factors include explosion pressure and time to peak pressure.
GROUP A GASES/VAPOURS:
GROUP B GASES/VAPOURS:
Butadiene, Ethylene Oxide, Acrolein (inhibited), Hydrogen, Propylene Oxide, manufactured gases containing more than 30% Hydrogen (by volume)
GROUP C GASES/VAPOURS:
Acetaldehyde, Allyl Alcohol, N-Butyraldehyde, Carbon Monoxide, Crontonaldehyde, Cyclopropane, Diethyl Ether, Djiethylamine, Epichlorohydrin, Ethylene, Ethylenimine, Hydrogen Sulphide, Morpholine, 2-Nitropropare Tetrahydrofuran, Isoprene, Unsymmetrical Dimethl Hydrazinc (UDMH)
GROUP D GASES/VAPOURS:
Acetic Acid (Glacial), Acetone, Acrylonitrite, Ammonia, Bensene, Butane, 1-Butanol (Butyl Alcohol), 2-Butanol (Secondary Butyl Alcohol), N-Butyl Acetate, Isobutyl Acetate, Di-Isobutylene, Ethone, Ethonol (Ethyl Alcohol), Ethyl Acetate, Ethyl Acrylate (inhibited), Ethylene Diamine (Anhydrous), Ethylene, Dichloride, Gasoline, Heptanes Hexanes, Isoprene, Isopropyl, Ether, Mesityl Oxide, Methane (Natural Gas), Methanol (Methyl Alcohol), 3-Methyl-1-Butanol (ISO-Amyl Alcohol), Methyl Ethyl Keytone, Methyl, Isobutyl Keytone, 2-Methyl-1-Propanol (Isobutyl Alcohol), 2-Methyl-2-Propanol (Tertiary Butyl Alcohol), Petroleum Naphtha, Pyridene, Ocianes, Pentanes, 1-Pentanol (Amyl Alcohol), Propane, 2-Propanol (Isopropyl Alcohol), Propylene, Styrene, Tolvene, Vinyl Acetate, Vinyl Chloride, Xylenes
GROUP E DUSTS:
Powdered metals such as Aluminum, Magnesium and their commercial alloys
GROUP F DUSTS:
Dusts such as Carbon Black, Coal or Coke dust
GROUP G DUSTS:
Dusts such as Flour, Starch or Grain dust