Division 1 and / or Zone 1: An area, location, or atmosphere, which is known to contain concentrations of ignitable or flammable vapor, gas, liquid, and / or dust during normal operation and will exist frequently because of equipment failure, breakdown, or service and maintenance.

Division 1 and / or Zone 0: An area, location, or atmosphere, which is known to contain concentrations of ignitable or flammable vapor, gas, liquid, and / or dust, which is present continuously or for long periods of time.


Types of Purging Definitions

Type Z - Purge: Type Z purging reduces the classification within a protected enclosure from Division 2 and / or Zone 2 to nonhazardous. Failure to maintain pressure within the protected enclosure shall be detected by an alarm or indicator. The dilution purge time can be a manual operation and once the enclosure has been purged of ignitable or flammable concentrations, only positive pressure is required to be maintained within the enclosure and it is not necessary to remove power from the protected equipment upon the loss of purge pressure.

Type Y - Purge: Type Y purging reduces the classification within the protected enclosure from Division 1 and / or Zone 1 to Division 2 and / or Zone 2. All equipment in the protected enclosure shall be approved for Division 2 and / or Zone 2 locations. Failure to maintain pressure within the protected enclosure shall be detected by an alarm or indicator. The dilution purge time can be a manual operation and once the enclosure has been purged of ignitable or flammable concentrations, only positive pressure is required to be maintained within the enclosure and it is not necessary to remove power from the protected equipment upon the loss of purge pressure.