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

MSHA PROGRAM POLICY MANUAL VOLUME V
minutes. In calculating the capacity, the volume of foam
generated need not fill the entry to the roof but must be capable
of filling the entry to the top belt.
Generally, the foam generator should be located on the intake air
side of the belt drive and other components to be protected so as
to take advantage of the ventilating air in moving the foam and
preventing air, contaminated by smoke and hot gases, from entering
into the foaming unit. Smoke and hot gases in the intake air to
the unit decrease the efficiency of foam generation. The warning
device actuated by the sensor or foam generator should be located
where a miner is in constant attendance.
The foaming agent used in most foam generators tend to corrode
metal parts. Therefore, care should be taken to flush out and
clear the unit after operation.
The development of a foam plug in a passageway will affect the
ventilation pattern. If the belt is in a neutral airway, smoke
will be trapped in the entry decreasing visibility and travel.
75.1101-8 Water Sprinkler Systems; Arrangement of
Sprinklers
The installation of a water sprinkler system for fire suppression
at belt drives generally requires two branch lines so that an
effective water discharge pattern can be produced. A single
branch line located at the top belt ordinarily does not offer an
equivalent flow pattern. However, the following single branch
line system can be considered equivalent when the following
conditions are met:
1. The entry width does not exceed 16 feet, and the entry
height is not less than 6 feet.
2. The static water pressure is not less than 250 psig, and
the quantity of water delivered with all nozzles operating
is not less than 1.0 gallon per minute per square foot of
top belt surface area.
3. The nozzles are mounted above the top conveyor belt near
the roof, and reasonable water coverage of the belt
surfaces is achieved by splashing action.
The maximum distance between sprinklers shall not be more than 8
feet to achieve a reasonable water spray pattern. In general, the
sprinklers need not be closer than 6 feet apart. If sprinklers
are too close together, the cooling action of the water from one
sprinkler may affect the operation of another.
October 2003 (Release V-34) 101