30 CFR § 75.310
Installation of main mine fans.
(a) Each main mine fan shall be--
(1) Installed on the surface in an incombustible housing;
(2) Connected to the mine opening with incombustible air ducts;
(3) Equipped with an automatic device that gives a signal at the mine
when the fan either slows or stops. A responsible person designated by the
operator shall always be at a surface location at the mine where the signal
can be seen or heard while anyone is underground. This person shall be
provided with two-way communication with the working sections and work
stations where persons are routinely assigned to work for the majority of a
shift;
(4) Equipped with a pressure recording device or system. Mines
permitted to shut down main mine fans under §75.311 and which do not have a pressure recording device installed
on main mine fans shall have until June 10, 1997 to install a pressure
recording device or system on all main mine fans. If a device or system
other than a circular pressure recorder is used to monitor main mine fan
pressure, the monitoring device or system shall provide a continuous graph
or continuous chart of the pressure as a function of time. At not more than
7-day intervals, a hard copy of the continuous graph or chart shall be
generated or the record of the fan pressure shall be stored electronically.
When records of fan pressure are stored electronically, the system used to
store these records shall be secure and not susceptible to alteration and
shall be capable of storing the required data. Records of the fan pressure
shall be retained at a surface location at the mine for at least 1 year and
be made available for inspection by authorized representatives of the
Secretary and the representative of miners;
(5) Protected by one or more weak walls or explosion doors, or a
combination of weak walls and explosion doors, located in direct line with
possible explosive forces;
(6) Except as provided under paragraph (e) of this section, offset by
at least 15 feet from the nearest side of the mine opening unless an
alternative method of protecting the fan and its associated components is
approved in the ventilation plan.
(1) If an electric motor is used to drive a main mine fan, the
motor shall operate from a power circuit independent of all mine power
circuits.
(2) If an internal combustion engine is used to drive a main mine
fan--
(i) The fuel supply shall be protected against fires and
explosions;
(ii) The engine shall be installed in an incombustible housing and
be equipped with a remote shut-down device;
(iii) The engine and the engine exhaust system shall be located out
of direct line of the air current exhausting from the mine; and
(iv) The engine exhaust shall be vented to the atmosphere so that
the exhaust gases do not contaminate the mine intake air current or any
enclosure.
(c) If a main mine fan monitoring system is used under
§75.312, the system shall--
(1) Record, as described in paragraph (a)(4) the mine ventilating
pressure;
(2) Monitor bearing temperature, revolutions per minute, vibration,
electric voltage, and amperage;
(3) Provide a printout of the monitored parameters, including the mine
ventilating pressure within a reasonable period, not to exceed the end of the
next scheduled shift during which miners are underground; and
(4) Be equipped with an automatic device that signals when--
(i) An electrical or mechanical deficiency exists in the monitoring
system; or
(ii) A sudden increase or loss in mine ventilating pressure
occurs.
(5) Provide monitoring, records, printouts, and signals required by
paragraphs (c)(1) through (c)(4) at a surface location at the mine where a
responsible person designated by the operator is always on duty and where
signals from the monitoring system can be seen or heard while anyone is
underground. This person shall be provided with two-way communication with
the working sections and work stations where persons are routinely assigned
to work for the majority of a shift.
(d) Weak walls and explosion doors shall have cross-sectional areas at
least equal to that of the entry through which the pressure from an explosion
underground would be relieved. A weak wall and explosion door combination
shall have a total cross-sectional area at least equal to that of the entry
through which the pressure from an explosion underground would be
relieved.
(e) If a mine fan is installed in line with an entry, a slope, or a
shaft--
(1) The cross-sectional area of the pressure relief entry shall be at
least equal to that of the fan entry;
(2) The fan entry shall be developed out of direct line with possible
explosive forces;
(3) The coal or other solid material between the pressure relief entry
and the fan entry shall be at least 2,500 square feet; and
(4) The surface opening of the pressure relief entry shall be not less
than 15 feet nor more than 100 feet from the surface opening of the fan
entry and from the underground intersection of the fan entry and pressure
relief entry.
(f) In mines ventilated by multiple main mine fans, incombustible doors
shall be installed so that if any main mine fan stops and air reversals
through the fan are possible, the doors on the affected fan automatically
close.
[61 FR 9829, Mar. 11, 1996; as amended at 61 FR 20877, May 8, 1996]