30 CFR § 75.344
Compressors.
(a) Except compressors that are components of equipment such as
locomotives and rock dusting machines and compressors of less than 5
horsepower, electrical compressors including those that may start
automatically shall be:
(1) Continuously attended by a person designated by the operator who
can see the compressor at all times during its operation. Any designated
person attending the compressor shall be capable of activating the fire
suppression system and deenergizing or shutting-off the compressor in the
event of a fire; or,
(2) Enclosed in a noncombustible structure or area which is ventilated
by intake air coursed directly into a return air course or to the surface and
equipped with sensors to monitor for heat and for carbon monoxide or smoke.
The sensors shall deenergize power to the compressor, activate a visual and
audible alarm located outside of and on the intake side of the enclosure, and
activate doors to automatically enclose the noncombustible structure or area
when either of the following occurs:
(i) The temperature in the noncombustible structure or area reaches
165°F.
(ii) The carbon monoxide concentration reaches 10 parts per million
above the ambient level for the area, or the optical density of smoke reaches
0.022 per meter. At least once every 31 days, sensors installed to monitor
for carbon monoxide shall be calibrated with a known concentration of carbon
monoxide and air sufficient to activate the closing door, and each smoke
sensor shall be tested to determine that it functions correctly.
(b) Compressors, except those exempted in paragraph (a), shall be equipped
with a heat activated fire suppression system meeting the requirements of
75.1107-3 through 75.1107-16.
(c) Two portable fire extinguishers or one extinguisher having at least
twice the minimum capacity specified for a portable fire extinguisher in
§75.1100-1(e) shall be provided for each
compressor.
(d) Notwithstanding the requirements of §75.1107-4, upon activation of any fire suppression system used under
paragraph (b) of this section, the compressor shall be automatically
deenergized or automatically shut off.