Definitions cont'd - hdbk10920267

DOE-HDBK-1092-98

operating conditions, in quantities sufficient to produce explosive or ignitable mixtures.

Combustible dusts which are electrically nonconductive include dusts produced in the handling

and processing of grain and grain products, pulverized sugar and cocoa, dried egg and milk

powders, pulverized spices, starch and pastes, potato and woodflour, oil meal from beans and

seed, dried hay, and other organic materials which may produce combustible dusts when

processed or handled. Dusts containing magnesium or aluminum are particularly hazardous and

the use of extreme caution is necessary to avoid ignition and explosion.

ii. Class II, Division 2. A Class II, Division 2 location is a location in which:

a. combustible dust will not normally be in suspension in the air in quantities sufficient to

produce explosive or ignitable mixtures, and dust accumulations are normally insufficient

to interfere with the normal operation of electrical equipment or other apparatus; or

b. dust may be in suspension in the air as a result of infrequent malfunctioning of handling or

processing equipment, and dust accumulations resulting therefrom may be ignitable by

abnormal operation or failure of electrical equipment or other apparatus.

NOTE: This classification includes locations where dangerous concentrations of suspended dust

would not be likely but where dust accumulations might form on or in the vicinity of electric

equipment. These areas may contain equipment from which appreciable quantities of dust would

escape under abnormal operating conditions or be adjacent to a Class II Division 1 location, as

described above, into which an explosive or ignitable concentration of dust may be put into

suspension under abnormal operating conditions.

Class III locations--Class III locations are those that are hazardous because of the presence of easily

ignitable fibers or flyings but in which such fibers or flyings are not likely to be in suspension in the

air in quantities sufficient to produce ignitable mixtures. Class III locations include the following:

Class III, Division 1. A Class III, Division 1 location is a location in which easily ignitable fibers

or materials producing combustible flyings are handled, manufactured, or used.

NOTE: Such locations usually include some parts of rayon, cotton, and other textile mills;

combustible fiber manufacturing and processing plants; cotton gins and cotton-seed mills; flax-

processing plants; clothing manufacturing plants; woodworking plants, and establishments; and

industries involving similar hazardous processes or conditions.

Easily ignitable fibers and flyings include rayon, cotton (including cotton linters and cotton waste),

sisal or henequen, istle, jute, hemp, tow, cocoa fiber, oakum, baled waste kapok, Spanish moss,

excelsior, and other materials of similar nature.

ii. Class III, Division 2. A Class III, Division 2 location is a location in which easily ignitable fibers

are stored or handled, except in process of manufacture.

Collector ring--A collector ring is an assembly of slip rings for transferring electrical energy from

a stationary to a rotating member.

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