Envoy 1-4 Zone Conventional Fire Alarm Control Panels Specifications download pdf (Page 51)

Hazardous Location

Devices

Initiating Devices p. 46

Notification Appliances p. 47

Classes

Class I - Hazardous Gases. Class I locations are areas in which flammable

gases or vapors are or may be present in the air in quantities sufficient to

produce explosive or ignitable mixtures.

Typical Class I Hazardous Areas

• Spray painting and finishing areas

• Utility gas plants

• Petroleum refining production plants

• Petroleum dispensing locations

• Dry cleaning facilities

• Dip tanks containing combustibles or flammable liquids

• Plant facilities extracting solvents

• Inhalation anesthetics areas

• Process facilities manufacturing pyroxylin type plastics

Class II - Hazardous Dusts. Class II locations represent areas that are

hazardous due to the presence of combustible dust.

Typical Class II Hazardous Areas

• Flour mills

• Feed mills

• Grain elevators and grain handling facilities

• Aluminum manufacturing and storage areas

• Magnesium manufacturing and storage areas

• Coal preparation and handling facilities

• Starch manufacturing and storage areas

• Confectionery plants

• Pulverizer sugar and cocoa manufacturing, and storage plants

• Spice grinding and storage plants

Class III - Hazardous Fibers. Class III locations have easily ignitable fibers

or flyings present, but not likely to be suspended in air in quantities sufficient

to produce ignitable mixtures in the atmosphere.

Typical Class III Hazardous Areas

• Textile mills

• Woodworking plants*

• Furniture manufacturers*

• Cotton gins

• Cotton seed milling plants

• Flax plants

• Carpet manufacturers

* Except if wood flour (dust), which is Class II Group G, is present

Divisions

The Location Classes are broken down by the NFPA into

Divisions 1 and 2, defining different levels of risk. In general, the

risk of there being a hazardous presence of flammable/

combustible/ignitable materials is higher for Division 1 than for

Division 2. The specifics differ between the three classes (I, II and

III). Equipment suitable for Division 1 is also suitable for Division 2

locations.

Groups

Class I and II locations are divided by the NFPA into Group

designations identifying specific gases, vapors and dusts by

characteristic similarities that relate to specific equipment

construction requirements. Class III locations are not divided into

separate group designations.

Class I Groups

Group A. Atmospheres containing acetylene.

Group B. Atmospheres containing hydrogen, fuel and

combustible process gases containing more than 30 percent

hydrogen by volume, or gases or vapors of equivalent hazard

such as butadiene, ethylene oxide, propylene oxide, and

acrolein.

Group C. Atmospheres such as ethyl ether, ethylene, or other

gases or vapors of equivalent hazard.

Group D. Atmospheres containing acetone, ammonia, benzene,

butane, cyclopropane, ethanol, gasoline, hexane, methanol,

methane, natural gas, naphtha (petroleum), propane, or gases or

vapors of equivalent hazard.

Class II Groups

Group E. Atmospheres containing combustible metal dusts,

including aluminum, magnesium, and their commercial alloys, or

other combustible dusts whose particle size, abrasiveness and

conductivity present similar hazards in the use of electrical

equipment.

Group F. Atmospheres containing combustible carbonaceous

dusts, including carbon black, charcoal, coal, or dusts that have

been sensitized by other materials so that they present an

explosion hazard.

Group G. Atmospheres containing combustible dusts not

included in Group E or F, including flour, grain, wood, plastic, and

chemicals.

GE Security hazardous location devices provide reliable life safety protection and emergency signaling in areas

where atmospheres could become harsh or explosive. All hazardous location devices are UL rated under the full

range of classifications set out in the National Electrical Code.

The following classification definitions are an interpretive summary based on the 1996 edition of the National

Electrical Code (NEC, NFPA 70). Refer to the latest editions of NFPA 497M, NFPA 70 and the UL Hazardous Location

Equipment Directory for current and more detailed information. For more information on NEMA classifications, refer

to NEMA Standards Publication No. 250.

Hazardous Location Classifications

Hazardous Location Devices

Hazardous Location

Devices

Door Holders

& Relays

EST3

Hazardous Location Devices

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Envoy 1-4 Zone Conventional Fire Alarm Control Panels Specifications Page 51

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