(a)Two available openings to the surface are required from each seam or stratum of coal worked. In drift or slope mines, such openings provided after August 12, 1949, must be separated by not less than 40 feet of natural strata, and all crosscuts between them shall be closed with stoppings of fireproof material. In shaft mines, such openings provided after August 12, 1949, must be separated by not less than 200 feet of natural strata. The second opening may be made through an adjoining mine. Until these provisions are met, not over five men in a drift, 10 men in a slope, and 20 men in a shaft shall work in the mine at one time, and no additional development shall be permitted until the connection is made to the second opening. In mines wherein final pillar robbing operations necessitate c
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(a) Two available openings to the surface are required from each seam or stratum of coal worked. In drift or slope mines, such openings provided after August 12, 1949, must be separated by not less than 40 feet of natural strata, and all crosscuts between them shall be closed with stoppings of fireproof material. In shaft mines, such openings provided after August 12, 1949, must be separated by not less than 200 feet of natural strata. The second opening may be made through an adjoining mine. Until these provisions are met, not over five men in a drift, 10 men in a slope, and 20 men in a shaft shall work in the mine at one time, and no additional development shall be permitted until the connection is made to the second opening. In mines wherein final pillar robbing operations necessitate closing the second opening, the above limitations as to the number of men permitted to work will apply until the mine is worked out and abandoned.
(b) Both openings shall be kept in good condition and shall at all times be reasonably safe and convenient for entering and leaving the mine. At all points where the passageway to the escapeway or escapement shaft is intercepted by roadways, entries or other passageways, conspicuous signboards shall be placed indicating the direction to the place of exit.
(c) Not more than 80 persons may be assigned or permitted to work on any split of air.
(d) Stations or rooms containing electrical transformers, rectifiers, motor generator sets, battery chargers, permanent pumps or air compressors, control rooms, and such other stationary and semipermanent equipment as would endanger lives of employees in event of equipment fire shall be ventilated by a separate split of air, returning directly to the surface.
(e) Changes in ventilation that may affect the safety of the men shall be made when the mine is idle. Only those men and supervisors engaged in major ventilation changes will be permitted in the mine during the change.
(f) In mines, the doors, other than man doors, used for deflecting and conducting the ventilation shall be installed in pairs in a manner approved by the division. They shall be so spaced as to prevent interruption to the regular coursing of air, and they shall be hung and maintained so that they will be self-closing by gravity or by effective mechanical means. An emergency door, to be used in case of damage to a regular door, shall be provided at all points where doors are in use.
(g) Mine doors in use must not be propped or latched open or by any other means used to be prevented from being self-closing.
(h) Proper breaks-through shall be made in all pillars as necessary to meet ventilation requirements at the working faces. The maximum distance between breaks-through shall be 105 feet and closer when required by the chief of the division. Permission to exceed 105 feet between breaks-through may be granted by the chief of the division only in exceptional conditions and must be in writing. Requests for permission must be initiated by the operator and recommended by the mine inspector.
(i) On entries, stoppings in crosscuts between intakes and returns shall be built solidly, substantially, and of incombustible material.
(j) Dead ending of rooms, slopes, or entries in mines classed as gassy is prohibited unless it is manifestly impracticable to drive crosscuts at or close to faces.
(k) Workings shall not be turned off slopes or entries in by the last crosscut; except, that the places may be necked during development of slopes and entries and when good mining practice justifies the practice in order to establish a main airway.
(l) Line brattice and ventilation tubing used to conduct air to the faces of working places shall be substantially erected and shall be of flame-resistant materials.
(m) In the event that diffuser or auxiliary fans and tubing are used in lieu of or in conjunction with a line brattice system to provide ventilation of the working face:
(1) The fan shall be of a permissible type, maintained in permissible condition, so located and operated to avoid any recirculation of air at any time and inspected frequently by a certified person when in use.
(2) In places where auxiliary fans are used, accumulations of methane resulting from unscheduled stoppage of the main fan shall be removed after restoration of normal mine ventilation by conducting air current into the place with line brattice or equivalent. Auxiliary fans shall not be operated in such place during stoppage of normal mine ventilation and until methane accumulations have been removed.
(3) If the auxiliary fan is stopped or fails and the ventilation of the working face is inadequate, the electric equipment in the place shall be stopped and the power disconnected at the power source until adequate ventilation is restored. During such stoppage the ventilation shall be by means of the primary air current conducted into the place in a manner to prevent an accumulation of methane.
(4) In places where auxiliary fans are used, the ventilation during scheduled idle periods such as weekends and idle shifts shall be by means of the primary air current conducted into the place in a manner to prevent accumulation of methane.
(5) If the air passing through the auxiliary fan or tubing contains one percent or more of methane, the provisions of subsection (b) of Section 25-9-82 shall be applied.
(6) To insure that an adequate volume and velocity of air are supplied continuously to the working face where auxiliary fan and tubing are used for face ventilation, a line brattice or other approved device shall be installed before the auxiliary fan is stopped.
(7) All face ventilation systems using auxiliary fans and tubing or machine-mounted diffusers approved by the Mining Enforcement and Safety Administration shall be filed with the chief of the division.
(8) Any variance in the above diffuser and auxiliary fan and tubing use must be approved in writing by the chief of the division.
(n) Overcasts shall be constructed tightly of incombustible materials and of sufficient strength to withstand falls of roof, or protected against falling roof, and shall be of ample area to pass the required volume of air.