Current through Register Vol. 41, No. 3, September 23, 2024
A.
Fire doors shall be provided at shaft stations or other appropriate locations
where necessary to prevent the spread of smoke or gas; the doors shall be
equipped with latches operable from both sides. To confine or prevent the
spread of toxic gases from a fire originating in an underground shop where
maintenance work is routinely done on mobile equipment, one of the following
measures shall be taken:
1. Use of control
doors or bulkheads;
2. Routing of
the mine shop air directly to an exhaust system;
3. Reversal of mechanical ventilation;
or
4. Use of an automatic fire
suppression system in conjunction with an alternate escape route.
The alternative used shall at all times provide at least
the same degree of safety as control doors or bulkheads.
B. If used as an alternative,
control doors and bulkheads shall:
1. Be
constructed to serve as a barrier to fire, the effects of fire, and air leakage
at each opening to the shop; and
2.
Be constructed and maintained as follows:
a.
So that, once closed, it will not reopen as a result of a differential in air
pressure;
b. So that it can be
opened from either side by one person or be provided with a personnel door that
can be opened from either side;
c.
To be clear of obstruction;
d.
Provided with a means of remote or automatic closure unless a person
specifically designated to close the door in the event of a fire can reach the
door within three minutes;
e. If
located 20 feet or more from exposed timber or other combustible material, the
control doors or bulkheads shall provide protection at least equivalent to a
door constructed of no less than one-quarter inch of plate steel with channel
or angle-iron reinforcement to minimize warpage. The framework assembly of the
door and the surrounding bulkhead, if any, shall be at least equivalent to the
door in fire and air-leakage resistance and in physical strength; and
f. If located less than 20 feet from exposed
timber or other combustibles, the control door or bulkhead shall provide
protection at least equivalent to a door constructed of two layers of wood,
each a minimum of three quarters of an inch in thickness. The wood grain of one
layer shall be perpendicular to the wood grain of the other layer. The wood
construction shall be covered on all sides and edges with no less than 24-gauge
sheet steel. The framework assembly of the door and the surrounding bulkhead,
if any, shall be at least equivalent to the door in fire and air-leakage
resistance and in physical strength. Roll down steel doors with a fire
resistance rating of 1-1/2 hours or greater, but without an insulation core,
are acceptable, provided that an automatic sprinkler or deluge system is
installed that provides even coverage of the door on both sides.
C. If routing of mine
shop air to exhaust system is used as an alternative, routing the mine shop
exhaust air directly to an exhaust system shall be done so that no person would
be exposed to toxic gases in the event of a shop fire.
D. If mechanical ventilation is used as an
alternative, reversal of mechanical ventilation shall be accomplished by a main
fan. If the main fan is located underground:
1. The cable or conductors supplying power to
the fan shall be routed through areas free of fire hazards; or
2. The main fan shall be equipped with a
second, independent power cable or set of conductors from the surface. The
power cable or conductors shall be located so that an underground fire
disrupting power in one cable or set of conductors will not affect the other;
or
3. A second fan capable of
accomplishing ventilation reversal shall be available for use in the event of
failure of the main fan; and
4. The
mechanical ventilation shall provide rapid air reversal that allows persons
underground time to exit in fresh air by the second escapeway or find a place
of refuge and be done according to predetermined conditions and
procedures.
E. If
automatic fire suppression system and escape route is used as an alternative,
the automatic fire suppression system and alternate escape route shall:
1. Be located in the shop area;
2. Be of the appropriate size and type for
the particular fire hazards involved;
3. Be inspected at weekly intervals and
properly maintained; and
4. In the
case of the escape route, bypass the shop area so that the route will not be
affected by a fire in the shop area.
Statutory Authority
§§ 45.1-161.3, 45.1-161.294 and 45.1-161.305
of the Code of Virginia.
