NEC – National Electrical Code:
CID2 Class I, Division 2 (Hazardous Environments) – a location (1) in which volatile flammable liquids or flammable gases are handled, processed, or used, but in which the liquids, vapors, or gases will normally confined within closed containers or closed systems from which they can escape only case of accidental rupture or breakdown such containers or systems, or in case of abnormal operation of equipment; which ignitable concentrations of vapors are normally prevented by mechanical ventilation, and which become hazardous through failure operation of the ventilating equipment; that is adjacent to a Class I, Division location, and to which ignitable concentrations gases or vapors might occasionally communicated unless such communication prevented by adequate positive-pressure ventilation from a source of clean air, safeguards against ventilation failure pro-vided.
Applies to AHP-XP models
Groups (A-D) Atmospheres containing following: acetylene, hydrogen, fuel, combustible process gases containing 30% hydrogen by volume, or gases of equivalent hazard such as butadiene, ethylene oxide, propylene oxide, acrolein, ether, ethylene, or gases or vapors equivalent hazard such as acetone, ammonia, benzene, butane cyclopropoane, gasoline, hexane, methanol, methane, naphtha, propane, or gases or vapors equivalent hazard.
Applies to AHP-XP models
Source: NEC 2005, Article 500