Header:
CODE OF FEDERAL REGULATIONS
TITLE 30 -- MINERAL RESOURCES
CHAPTER I -- MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR
SUBCHAPTER K -- METAL AND NONMETAL MINE SAFETY AND HEALTH
PART 57 -- SAFETY AND HEALTH STANDARDS -- UNDERGROUND ME
Date:
02/28/2013
Document:
§ 57.4760 Shaft mines.
(a) Shaft mines shall be provided with at least one of the following means to control the spread of fire, smoke, and toxic gases underground in the event of a fire: control doors, reversal of mechanical ventilaton, or effective evacuation procedures. Under this standard, "shaft mine" means a mine in which any designated escapeway includes a mechanical hoisting device or a ladder ascent.
(1) Control doors. If used as an alternative, control doors shall be--
(i) Installed at or near shaft stations of intake shafts and any shaft designated as an escapeway under § 57.11053 or at other locations that provide equivalent protection;
(ii) Constructed and maintained according to Table C-3;
(iii) Provided with a means of remote closure at landings of timbered intake shafts unless a person specifically designated to close each door in the event of a fire can reach the door within three minutes;
(iv) Closed or opened only according to predetermined conditions and procedures;
(v) Constructed so that once closed they will not reopen as a result of a differential in air pressure;
(vi) Constructed so that they can be opened from either side by one person, or be provided with a personnel door that can be opened from either side; and
(vii) Clear of obstructions.
(2) Mechanical ventilation reversal. If used as an alternative, reversal of mechanical ventilation shall--
(i) Provide at all times at least the same degree of protection to persons underground as would be afforded by the installation of control doors;
(ii) Be accomplished by a main fan. If the main fan is located underground--
(A) The cable or conductors supplying power to the fan shall be routed through areas free of fire hazards; or
(B) 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
(C) A second fan capable of accomplishing ventilation reversal shall be available for use in the event of failure of the main fan;
(iii) 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
(iv) Be done according to predetermined conditions and procedures.
(3) Evacuation. If used as an alternative, effective evacuation shall be demonstrated by actual evacuation of all persons underground to the surface in ten minutes or less through routes that will not expose persons to heat, smoke, or toxic fumes in the event of a fire.
(b) If the destruction of any bulkhead on an inactive level would allow fire contaminants to reach an escapeway, that bulkhead shall be constructed and maintained to provide at least the same protection as required for control doors under Table C-3.
TABLE C-3 -- CONTROL DOOR CONSTRUCTION
Location Minimum required construction
At least 50 feet from: timbered areas, Control door that meets the
exposed combustible rock, and any requirements for a ventilation door
other combustible material fn1 in conformance with 30 CFR 57.8531.
Within 50 feet but no closer than 20 Control door that serves as a barrier
feet of: timbered areas, exposed to the effects of fire and air
combustible rock, or other combustible leakage. The control door shall
material fn1 Within 20 feet of: any provide protection at least equivalent
timbered areas or combustible rock, to a door constructed of no less than
provided that the timber and oone-quarter inch of plate steel with
combustible rock within the 20 foot channel or angle-iron reinforcement to
distance are coated with one inch of minimize warpage. The framework
shotcrete, one-half inch of gunite, or assembly of the door and the
other material with equivalent fire surrounding bulkhead, if any, shall be
protection characteristics and no at least equivalent to the door in
other combustible material fn1 is within fire and air-leakage resistance, and in
that distance physical strenth.
Within 20 feet of: timbered areas, Control door that serves as a barrier
exposed combustible rock, or other to fire, the effects of fire, and
combustible material fn1 air-leakage. The door 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
twenty-four 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 if
an automatic sprinkler or deluge
system is installed that provides even
coverage of the door on both sides.
fn1 In this table, "combustible material" does not refer to installed wiring or track support.
|