ISA 12.12.01

This standard applies only to equipment, circuits, andcomponents designed specifically for use in Class I and II,Division 2 and Class III, Divisions 1 and 2 hazardous (classified)locations as defined in the National Electrical Code® (NEC®)ANSI/NFPA 70. NOTE Some equipment designed for use in unclassifiedlocations is permitted by the NEC®for installing in Division 2locations. The judgment of acceptability for the installation wouldb e determined by the authority having jurisdiction. Such equipmentwould not have the hazardous location marking or documentationdescribed in this standard. It is anticipated that such equipmentwould comply with the other requirements in this standard and thatthe determination of compliance is elementary (e.g., a nonarcinginstrument inside a NEMA Type 4 or 12 enclosure used in a Class II,Division 2 location).

This standard also applies to certain unclassified locationequipment specifically designed to directly connect to nonincendivefield wiring in Class I and II, Division 2 and Class III, Divisions1 and 2 hazardous (classified) locations as defined in theNEC®.

This standard is primarily intended to provide requirements forelectrical and electroni c test, measuring, and controllingequipment.

This standard is concerned only with equipment construction andtest criteria related to electrical or thermal ignition ofspecified flammable gases, vapors, combustible dusts, fibers, andflyings in air.

This standard is not intended to cover equipment for use inClass I and Class II, Division 1 locations, such as equipmentconstructed to be intrinsically safe, dust ignition-proof, orexplosion-proof. Such equipment is, however, suitable for use inClass I and Class II, Division 2 locations in the same group andtemperature class for which it is suitable in Division 1.

This standard does not cover mechanisms of ignition fromexternal sources, such as static electricity or lightning, that arenot related to the electrical characteristics of the equipment.

This standard is not intended as an instructional manual foruntrained persons. It is intended to promote uniformity of practiceamong those skilled in the area of design, construction, andapplication of equipment suitable for Class I and Class II,Division 2 and Class III, Divisions 1 and 2 locations.

The requirements of this standard are based on consideration ofignition in locations made hazardous by the presence of flammablegases, vapors, combustible dusts, fibers, and flyings under thefollowing ambient conditions:

a) an ambient temperature of -25°C to 40°C

b) an oxygen concentration of not greater than 21 percent byvolume

c) a pressure of 80 kPa (0.8 bar) to 110 kPa (1.1 bar)

NOTE If equipment is specified to operate in conditions outsidethe ranges listed above, the requirements of this standard may notensure the desired level of safety.

This standard covers portable battery-powered equipment otherthan flashlights and lanterns for Class I and Class II, Division 2,and Class III, Divisions 1 and 2 hazardous (classified)locations.

This standard does not cover electric luminaires for use inDivision 2 hazardous (classified) locations.

This standard does not cover electric motors, electric heaters,heat tracing c ables, and similar heat-producing devices, exceptwhere they are an integral part of the equipment under evaluation,for use in Division 2 locations.

This standard does not cover AEx requirements for equipment foruse in Class I, Zone 2 hazardous (classified) locations.

This standard does not cover the requirements for equipment foruse in Zone 20, Zone 21 or Zone 22.

Purpose

The purpose of this standard is to provide minimum requirementsfor the design, construction, and marking of electrical equipmentor parts of such equipment for use in Class I and Class II,Division 2 and Class III, Divisions 1 and 2 hazardous (classified)locations. This equipment, in normal operation, is not capable ofcausing ignition of the surrounding atmosphere under the conditionsprescribed in this standard, although the equipment may containelectronic components that operate at incendive levels and may alsohave field wiring that is incendive. In addition, it is the intentof this document to establish uniformity in test methods fordetermining the suitability of the equipment and associatedcircuits and components as they relate to potential ignition of aspecific flammable gas or vapour-in-air mixture, combustible dust,easily ignitible fibers, or flyings.

Edition:

12

Published:

07/09/2012

ANSI:

ANSI Approved

Number of Pages:

46

File Size:

1 file , 790 KB