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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.
- 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