Program Policy Manual - VOLUME V - Mine Safety and Health ...

MSHA PROGRAM POLICY MANUAL VOLUME V
have a 2A 10 BC minimum rating. The letters "A," "B," "C" refer
to the class of fire for which the dry chemical is effective, and
the numerals "2" and "10" refer to the size of the standard fire
for which the extinguisher is effective.
Class A fires are those occurring in solids such as coal, wood,
rubbish, textiles and rubber. Class B fires are those occurring
in flammable and combustible liquids such as fuel oils,
lubricating oils, grease, paint, varnish and lacquer. Class C
fires are those which involve energized electrical equipment
where the electrical nonconductivity of the extinguishing medium
is of importance. Where electricity is involved in a fire, the
electric circuit should be broken or deenergized as soon as
possible.
Fire hose suitable for use in coal mines must meet specific
requirements. The lining material shall pass MSHA's test
outlined in Schedule 2G to limit the flammability. Generally,
the lining will be a synthetic rubber. The jacket shall be
polyester or its equivalent. When subject to flame, the polyester
jacket will melt and burn somewhat; however, the polyester is
more vermin-resistant than other jacket materials. The
flammability characteristics of the polyester jacket can be
reduced by chemical treatment or by an impregnation of synthetic
rubber of the type used for the liner. Such hose is highly
recommended but is not necessary to meet the minimum
specifications. The bursting pressure of the hose shall be at
least four times the static pressure at the hose inlet. The hose
coupling should also be designed to withstand the required
bursting pressure. Couplings approved for fire hoses by the
Underwriters’ Laboratories, Inc., or Factory Mutual Research
Corp. are recommended. Short shank couplings (of the type
ordinarily used on water or air hose) will blow off at pressures
ranging from 300 to 600 psig even if fastened with two hose
clamps. Short shank couplings are not recommended for fire
hoses; however, in a few instances, where the static pressure is
less than 120 psig, they might meet the minimum requirements of
the regulations, provided the water flow rate of 50 gpm through
the nozzle is obtained. Short shank couplings cause excessive
pressure loss; therefore, it is important to ensure that the
minimum quantity of 50 gpm is met.
Fire hose purchased prior to December 30, 1970, may be used if it
meets all requirements except those for flammability. An
inspector having reason to doubt the acceptability of a specific
fire hose should obtain all available manufacturer's
specifications and refer such information to his supervisor. The
supervisor should request clarification from the MSHA Approval
February 2003 (Release V-33) 92