Hazardous Area Approval Explanations

Intrinsic Safety: This method of protection limits the energy passing into the hazardous area. The energy limitation is provided by the use of safety barriers which are mounted in the safe area. Because of the energy limitation, regardless of the fault in the hazardous area, sufficient energy cannot be released to ignite the explosive atmosphere.

Approval Methods: There are approval methods used by approval authority to assure an intrinsically safe system.

System Approval: The system approval method is one in which specific field devices are examined in combination with specific barriers. No other field device or barriers may be substituted unless specifically examined by the approval authority.

Entity Approval: The entity approval method is one in which each piece of equipment is evaluated separately and assigned a set of safety parameters.

Nonincendive: A device may be installed in division 2 locations if it has been approved as nonincendive. Nonincendive equipment is incapable of releasing sufficient electrical or thermal energy to ignite flammable gases or vapors under NORMAL operation and environmental conditions. Nonincendive devices need no special enclosure or other physical safeguard.

Explosion Proof: This is the most popular method of protection. When an explosive gas enters an enclosure containing electrical equipment an explosion could occur. With the enclosure properly installed, and the tight tolerance between the enclosure and the cover, the flame will cool sufficiently by the time it reaches the outside atmosphere.