CFR > Title 30 - Mineral Resources > CHAPTER I—MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR > SUBCHAPTER K—METAL AND NONMETAL MINE SAFETY AND HEALTH (parts 56 to 58) > PART 57—SAFETY AND HEALTH STANDARDS—UNDERGROUND METAL AND NONMETAL MINES > SUBPART T—Safety Standards for Methane in Metal and Nonmetal Mines (§57.22001 to §57.22608) > 57.22220—Air passing unsealed areas (I-A, II-A, III, and V-A mines).

57.22220—Air passing unsealed areas (I-A, II-A, III, and V-A mines).

All mines shall be ventilated mechanically.
(a) Main fans shall be—
(1) Installed on the surface in noncombustible housings provided with noncombustible air ducts;
(2) Except in Subcategory I-A mines, provided with an automatic signal device to give an alarm when the fan stops. The signal device shall be located so that it can be seen or heard by a person designated by the mine operator.
(b) Fan installations shall be—
(1) Offset so that the fan and its associated components are not in direct line with possible explosive forces;
(2) Equipped with explosion-doors, a weak-wall, or other equivalent devices located to relieve the pressure that would be created by an explosion underground. The area of the doors or weak-wall shall be at least equivalent to the average cross-sectional area of the airway.
(c) (1) All main fan-related electrical equipment and cables located within or exposed to the forward or reverse airstream shall be approved by MSHA under the appliable requirements of 30 CFR part 18 ;
(2) Drive belts and nonmetallic fan blades shall be constructed of static-conducting material; and
(3) Aluminum alloy fan blades shall not contain more than 0.5 percent magnesium. [Paragraph (c)(3) of this section does not apply to Subcategory I-C mines].
(d) When an internal combustion engine is used to power a main fan or as standby power, the engine shall be—
(1) Installed in a noncombustible housing;
(2) Protected from a possible fuel supply fire or explosion; and
(3) Located out of direct line with the forward and reverse airstream provided by the fan. Engine exhaust gases shall be vented to the atomsphere so that exhaust cannot contaminate mine intake air.
(e) For Subcategory I-A mines only: Main exhaust fans shall be equipped with methane monitors to give an alarm when methane in the return air reaches 0.5 percent. The alarm shall be located so that it can be seen or heard by a person designated by the mine operator.

Code of Federal Regulations

[52 FR, 24941, July 1, 1987, as amended at 52 FR 41397, Oct. 27, 1987]
Main fans shall be operated continuously while ore production is in progress.
Main fans shall be—
(a) Provided with a pressure-recording system; and
(b) Inspected daily while operating if persons are underground. Certification of inspections shall be made by signature and date. Certifications and pressure recordings shall be retained for at least one year and made available to an authorized representative of the Secretary.

Code of Federal Regulations

[52 FR, 24941, July 1, 1987, as amended at 52 FR 41397, Oct. 27, 1987; 60 FR 33722, June 29, 1995]
In mines ventilated by multiple main fans, each main fan installation shall be equipped with noncombustible doors. Such doors shall automatically close to prevent air reversal through the fan. The doors shall be located so that they are not in direct line with explosive forces which could come out of the mine.
(a) When there has been a main ventilation failure, such as stoppage of main fans or failure of other components of the main ventilation system, tests for methane shall be conducted in affected active workings until normal air flow has resumed.
(b) If a total failure of ventilation occurs while all persons are out of the mine and the failure lasts for more than 30 minutes, only competent persons shall be allowed underground to examine the mine or to make necessary ventilation changes. Other persons may reenter the mine after the main fans have been operational for at least 30 minutes, or after the mine atmosphere has been tested and contains less than 1.0 percent methane. Persons other than examiners shall not reenter a Subcategory II-A mine until the methane level is less than 0.5 percent.
(a) Booster fans shall be approved by MSHA under the applicable requirements of 30 CFR part 18, and be—
(1) Provided with an automatic signal device located so that it can be seen or heard by a person designated by the mine operator to give an alarm when the fan stops or when methane reaches the following levels:
(i) 1.0 percent at the fan in Subcategory I-A, Category III, and Subcategory V-A mines; and
(ii) 0.5 percent at the fan in Subcategory II-A mines.
(2) Equipped with a device that automatically deenergizes power in affected workings should the fan stop; and
(3) Equipped with starting and stopping controls located at the fan and at another accessible remote location.
(b) Booster fan installations, except for booster fans installed in ducts, shall be—
(1) Provided with doors which open automatically when all fans in the installation stop; and
(2) Provided with an air lock when passage through the fan bulkhead is necessary.
(a) Auxiliary fans, except fans used in shops and other areas which have been so designed that methane cannot enter the airway, shall be approved by MSHA under the applicable requirements of 30 CFR part 18, and be operated so that recirculation is minimized. Auxiliary fans shall not be used to ventilate work places during the interruption of normal mine ventilatioin.
(b) Tests for methane shall be made at auxiliary fans before they are started.
Electric auxiliary fans shall be approved by MSHA under the applicable requirements of 30 CFR part 18. Tests for methane shall be made at electric auxiliary fans before they are started. Such fans shall not be operated when air passing over or through them contains 0.5 percent or more methane.
Air that has passed by or through unsealed abandoned or unsealed inactive areas and contains 0.25 percent or more methane shall—
(a) Be coursed directly to a return airway;
(b) Be tested daily for methane by a competent person; and
(c) Not be used to ventilate work places.