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Subchapter 17. Mine Safety Orders
Article 25. Engines-Internal Combustion
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§7070. Permit to Use Diesel Engines Underground.

(a) No diesel engine shall be permitted in an underground mine unless a permit to use diesel engines underground has first been secured from the Division of Industrial Safety.

(b) Application for such permit shall be made in writing to the Division of Industrial Safety, and shall include the following information:

(1) Service for which diesel engines are intended.

(2) Location in mine where engines are to be operated.

(3) Aggregate brake horsepower of all diesel engines to be operated in the mine.

(4) Plans for ventilation of the mine.

(5) Any other information considered pertinent by the Division.

(c) When in the opinion of the Division diesel engines can be operated safely in the mine, a permit may be issued to the applicants specifying the conditions under which the diesel engines must be operated.

(d) When a permit is issued the conditions specified are those believed necessary for the protection of workers. If experience in the operation of the diesel engine indicates that any of the conditions are inadequate or unnecessary, the Division may revise the conditions in the light of such experience.

(e) The permit to use diesel engines underground may be revoked for failure to comply with conditions of the permit.

(f) The following is a list of conditions under which diesel powered equipment will be permitted to operate in underground mines:

(1) Before any diesel engine is permitted underground, the employer shall make sure that it is in good operating condition.

(2) Every diesel engine, which is operated underground, shall be checked daily by a mechanic who is skilled in the operation and maintenance of diesel engines. The diesels shall be maintained in good operating condition.

(3) The exhaust of each diesel shall be passed through a water bath or approved catalytic conditioner prior to its discharge into the atmosphere. Conditioners shall be kept in proper operating condition at all times when equipment is in use underground.

(4) Diesel exhaust gas shall not be directed towards diesel operators and shall be deflected so that persons alongside will not encounter exhaust gas at breathing level.

(5) The diesel fuel shall not contain in excess of .5% of sulphur.

(6) Each diesel unit shall be equipped with a fire extinguisher suitable for control of oil fires.

(7) Before any diesel engine is permitted underground, the mine shall be provided with a mechanically produced and positively controlled system of ventilation.

(8) The main fan shall be installed on the surface and shall be of a type that readily permits the air current to be reversed in direction.

(9) A continuous flow of fresh air shall be maintained in the mine as long as any diesel equipment is operating therein.

(10) The flow of fresh air in any air course shall never be less than 100 cubic feet of air per minute per brake horsepower of the aggregate diesel equipment operating in such air course, plus 200 cubic feet of air per minute for each employee therein.

(11) Positive instructions shall be issued to all workmen that all diesel equipment underground shall be shut down immediately should the air flow stop, and shall remain shut down until the air flow is resumed.

(12) A daily record shall be kept of the condition of the diesels and the amount of ventilation provided. The record shall show:

(A) Condition of each diesel engine

(B) Total horsepower of diesel equipment that operates in the mine

(C) Quantity of air flowing in the air course

(D) Locations at which the air measurements were taken in relation to position of the diesel engines

(E) Name and title of the person who made the measurements

(13) The record shall be signed by the person who made the measurements. A signed copy shall be kept in the office at the mine, and this copy shall be available for inspection by engineers of the Division of Industrial Safety.

(14) Daily air quality tests shall be conducted for nitrogen dioxide and carbon monoxide. Results of such tests shall be kept with the daily diesel engine records. Diesels shall be shut down or ventilation increased if contaminant levels exceed safe threshold limit values.


1. Editorial correction restoring missing text in subsection (f)(10) (Register 91, No. 45).

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