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(f) Normal operation. The performance by each part of the locomotive of those functions for which each part was designed.

(g) Permissible. Formally approved by the Bureau of Mines. This term shall apply only to completely assembled locomotives identified by an approval plate.

(h) Toxic and objectionable gases. Toxic and objectionable gases present in the exhaust of Diesel engines are carbon monoxide, oxides of nitrogen, carbon dioxide, and aldehydes. The exhaust also will contain oxides of sulfur if the fuel contains sulfur.

(i) Fuel: air ratio. The ratio of fuel to air present in the combustion space of the engine, expressed in terms of weight, as pound of fuel per pound of air. Fuel: air ratio at any operating condition may be calculated from the composition of the exhaust gas and of the fuel.

(j) Gas-air mixtures, explosive mixtures, inflammable mixtures, or inflammable atmospheres. These terms refer to such mixtures created by mixing natural gas with normal air. Natural gas that will be used by the Bureau of Mines in testing Diesel mine locomotives consists chiefly of methane, with smaller proportions of higher hydrocarbons and approximately 1 percent of nitrogen.

§ 31.3 Conditions under which approvals may be granted; preliminary steps-(a) Consultation. Upon appointment, manufacturers, engineers, or their representatives may visit the Central Experiment Station of the Bureau of Mines at 4800 Forbes Street, Pittsburgh, Pa., to discuss the requirements of this Part 31 or to obtain criticisms of proposed designs of equipment to be submitted for test. There is no charge for such consultation.

(b) Application. Before the Bureau of Mines will undertake the active investigation of any equipment, manufacturers shall have filed a written application requesting that the necessary official inspections, tests, and examination of drawings be made.

This application

shall be addressed to the Director, Bureau of Mines, U. S. Department of the Interior, Washington, D. C., and shall be accompanied by a certified check or bank draft payable to Treasurer of the United States to cover all required fees. A copy of the application shall be sent to the Engineer in Charge of Diesel Testing,

Bureau of Mines, 4800 Forbes Street, Pittsburgh, Pa. There are no application blanks to be filled out.

(c) Fees charged for testing.

1. For preliminary review of drawings and specifications and related reports, for each new locomotive....

2. For tests to determine the composition of exhaust gases from the engine under various conditions

$25.00

300.00

3. For tests to determine the effectiveness of engine flame arrester 100.00 4. For detailed inspection of engine flame arrester..

5. For detailed inspection of manifolds, scrubbers, etc., making up the intake and exhaust systems

6. For detailed inspection of each explosion-proof enclosure of

electrical units___. 7. For explosion test of each explosion-proof enclosure of electrical units..

8. For each inspection of a completely assembled locomotive___

9. For the final examination and recording of all the necessary drawings and specifications for a complete locomotive, preparatory to issuing an approval___. 10. For each half day or fraction thereof, spent in the examination and recording of drawings and specifications, preparatory to issuing an extension of approval

EXAMPLE OF FEES

25.00

25.00

25.00

25.00

50.00

50.00

7.50

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detail to identify the parts fully have been delivered to the Engineer in Charge of Diesel Testing. No drawings or specifications should be sent to the Washington office of the Bureau. Drawings should be numbered and dated to facilitate identification and reference in the records.

(2) The drawings and specifications for locomotives that are to be submitted for approval shall include the following:

(i) An assembly drawing or drawings clearly showing the over-all dimensions of the locomotive, the character, size and relative arrangement of the electrical parts and the wiring between them, also the size and position of the fuel tank, engine flame arresters, the exhaust-gas cooling and dilution systems, and other protective features of the engine.

(ii) A drawing or drawings that shall specify the material and detailed dimensions of all parts that make up explosionproof enclosures, also of those parts that form any portion of the joints through which possible flames might escape.

(iii) Any other drawings necessary to identify or explain any feature that is to be considered in the approval of the locomotive.

(iv) A wiring diagram for all electrical equipment and circuits on the locomotive shall be submitted.

(v) The complete rating of each starting motor and charging generator, also the capacity of all fuses, and the setting of overload protective devices shall be given. The size of conductors used in all the various circuits shall be specified.

(3) All drawings are to be handled as strictly confidential by the Bureau of Mines.

(e) Factory inspection form. Each locomotive shall be carefully inspected by the manufacturer before it leaves the factory. The manufacturer will be required to furnish the Bureau of Mines with a copy of the form to be used by him in this inspection. The form shall draw special attention to the points that must be checked in making certain that the safety features of the locomotive are in proper condition, are complete in all respects, and agree in every detail with the drawings and specifications filed with the Bureau.

(f) Instruction manual. The manufacturer shall furnish an instruction manual with each locomotive. This manual shall give complete instructions

covering the operation and servicing of the locomotive, particularly with reference to proper adjustment and maintenance of the engine and its auxiliaries in minimizing the production of smoke and toxic gases in the exhaust, in reducing fire hazards, and maintaining flame arresters and flame-proof equipment in proper condition.

A copy of this manual shall be submitted to the Bureau for review.

(g) Material required for investigation. Unless requested to do so, the manufacturer need not send a complete locomotive for the purposes of inspection and test. Usually one engine with protective equipment, one fuel tank, one motor, starting switch or other electrical unit of a given design need be shipped to the Bureau for the investigation. Any special tools necessary to disassemble any parts for inspection or test shall be furnished with the equipment submitted.

(h) Shipment of material. All shipments must be prepaid and should be plainly marked for the attention of the Engineer in Charge of Diesel Testing. Before making any shipments the manufacturer shall obtain shipping instructions from the Bureau. He shall arrange and pay for any trucking that may be necessary between the freight depot and the testing station. He shall also take care of crating and removal of parts upon completion of the investigation.

Inspection and tests usually are undertaken in the order of receipt of parts, provided that application, fees, and drawings have been received.

(i) Assistance required during investigation. When requested to do so, the manufacturer shall provide one or more men to assist in disassembling parts for inspection and in preparing them for test. These persons may serve as witnesses of the tests.

(j) Witnesses. No one is to be present during the tests of any equipment except the necessary Bureau of Mines engineers, their assistants, the manufacturer's representatives, and such other persons as may be mutually agreed upon by the manufacturer and the Bureau.

$31.4 General requirements—(a) Quality of material, workmanship, and design. The Bureau of Mines reserves the right to refuse to test any equipment that, in the opinion of qualified representatives of that Bureau, is not constructed of suitable materials, or that

gives evidence of faulty workmanship, or that is not designed upon sound engineering principles. This right shall apply to all parts of the equipment, and to the design thereof, whether or not the points in question are covered specifically by the requirements of this Part 31.

(b) Type of engine considered for approval. Only locomotives equipped with engines of the compression-ignition type will be considered for approval. Such engines shall be designed to operate only on liquid fuel of flash point not less than 150° F. The starting mechanism shall consist of an explosion-proof electric. motor or other device considered safe; engines using gasoline or other volatile fuel for starting will not be considered.

(c) Fuel injection. The fuel-injection system of the engine shall be so constructed that the mechanism controlling maximum fuel injection may be fixed definitely, permitting adjustment only by breaking a seal on a locked compartment, or by altering design. Provision shall be made in the fuel-injection system to permit suitable adjustment in maximum fuel injection for engine operation at different barometric pressures.

(d) Engine intake system-(1) Construction of engine intake system. The intake system of the engine (exclusive of the air cleaner) shall be of such construction that it will withstand internal pressures of 125 pounds per square inch, or such internal pressures as may be developed within it in explosion tests with gas-air mixtures, whichever is the greater. All joints in the intake system shall be formed by flanged metal-tometal contacts designed in accordance with requirements for other types of explosion-proof equipment as outlined in paragraph (i) (6) (ii) of this section.

(2) Intake flame arrester. The intake system of the engine shall be equipped with a flame arrester to prevent propagation of flame from the system to a surrounding inflammable atmosphere. The flame arrester shall be so designed and attached to the intake system that it may be removed readily for inspection, repair, replacement, or cleaning. The flame arrester shall be so constructed that it may be cleaned readily. The flame arrester shall be of sufficiently rugged construction to withstand use in its intended application and shall be so situated in the locomotive assembly that it is protected from damage.

The component parts of any flame arrester must be positively positioned. If a flame arrester of the spaced-plate type is used, the thickness of the plates must be at least 0.125 inch; the space between plates must be no greater than 0.02 inch; and the width of plates must be at least 1 inch. The unsupported length of the plates shall be such that deformation in the intended application shall not exceed 0.002 inch. Plates shall be of material not subject to corrosion in the intended application.

(3) Air shut-off valve in engine intake. A valve shall be provided in the engine intake system so that the supply of air to the engine may be shut off. This valve shall be operable from the driver's compartment and shall be so arranged that it may be actuated only when the fuel supply to the engine is shut off.

(4) Air cleaner on engine intake. An air cleaner of automotive type shall be included in the engine intake system. The air cleaner shall be situated in the intake system so that the intake air shall pass through the cleaner before entering the intake flame arrester. size and design of the air cleaner shall be such that resistance to air flow will not increase rapidly in dusty atmospheres.

The

(5) Attachment of gage to engine intake system. A vacuum gage shall be attached to the engine intake system at point suitable for indicating total pressure drop through that system. The gage shall be graduated in inches of water and shall be situated in the driver's compartment.

(e) Engine exhaust system-(1) Construction of engine exhaust system. The exhaust system of the engine shall be of such construction that it will withstand internal pressures of 125 pounds per square inch or such internal pressures as may be developed within it in explosion tests with gas-air mixtures, whichever pressure is the greater. All joints in the exhaust system shall be formed by flanged metal-to-metal contacts designed in accordance with requirements for other types of explosion-proof equipment as outlined in paragraph (i) (6) (ii) of this section.

(2) Exhaust flame arrester. The exhaust system of the engine shall be provided with a flame arrester to prevent propagation or egress of flame or heated particles from the exhaust system to a surrounding inflammable atmosphere.

The flame arrester shall be so designed that it is readily accessible for inspection, repair, replacement, or cleaning. The flame arrester shall be of sufficiently rugged construction to withstand use in its intended application and shall be so situated in the locomotive assembly that it is protected from damage.

The component parts of any flame arrester must be positively positioned. If a flame arrester of the spaced-plate type is used the thickness of the plates must be at least 0.125 inch; the space between plates must be no greater than 0.02 inch; and the width of plates must be at least 1 inch. The unsupported length of the plates shall be such that deformation in the intended application shall not exceed 0.002 inch. Plates shall be of material not subject to corrosion in the intended application.

(3) Exhaust cooling system. A cooling system shall be provided for the exhaust gas of the engine. The heat-dissipation capacity of this cooling system shall be such that the temperature of the undiluted exhaust gas shall not exceed 160° F. at the point of discharge from the cooling system under any condition of operation. A device shall be provided which shall stop the engine automatically and immedaitely if the temperature of the exhaust gas reaches 180° F. at the point of discharge from the cooling system.

Cooling preferably shall be obtained by a water spray entering the exhaust system at a point close to the outlet of the exhaust manifold or by passing the exhaust gas through water in suitable containers, or by a combination of the two. If a water spray is used, the water shall be delivered to the spray nozzle by a pump, and the water shall pass through a filtering device to protect the spray nozzle from clogging by extraneous material. Provision shall be made for draining and cleaning all exhaust cooling boxes included in the locomotive assembly.

If cooling equivalent to that obtained by the use of water can be provided by other means, such means will be considered acceptable.

(4) Control of surface temperature of exhaust systems. Provisions shall be made for limiting the temperature attained by the external surfaces of the exhaust system. The temperature of such surfaces shall not exceed 400° F. under any condition of engine operation.

If water-jacketed parts are used the jackets shall be integral with the parts in question. Insulating coverings that would absorb oil will not be considered acceptable.

If a water spray is employed to reduce the temperature of the exhaust gas, as mentioned in subparagraph (3) of this paragraph (e), the spray shall be situated as closely as possible to the outlet of the exhaust mainfold to aid in reducing surface temperature of this portion of the exhaust system.

Exterior surfaces of the exhaust system shall be designed to minimize accumulation and lodgment of combustible dusts and to permit ready access to these surfaces for cleaning.

(5) Dilution of exhaust gas. Provision shall be made to dilute the exhaust gas with air before it is discharged from the locomotive into the surrounding atmosphere. The quantity of diluting air shall be such that the discharged mixture of exhaust gas and air shall not contain more than 100 parts per million, by volume, of carbon monoxide; 25 parts per million, by volume, of oxides of nitrogen (as equivalent nitrogen peroxide); or 10 parts per million, by volume, of aldehydes (as equivalent formaldehyde) under any condition of operation.

The final (diluted) exhaust of the locomotive shall be discharged in such manner that it is not directed toward the locomotive operator's compartment and shall be deflected downward so that persons alongside the locomotive do not encounter the exhaust at breathing level.

(6) Temperature indicator in exhaust system. A temperature-indicating device shall be provided in the exhaust system to indicate the temperature of the undiluted exhaust gas after its final contact with cooling water. The indicating portion of this device shall be situated in the operator's compartment of the locomotive.

(7) Provision for attachment of gage or gas-sampling equipment to exhaust system. A connection shall be provided in the engine exhaust system for temporary attachment of a gage at a point suitable for measuring the total back pressure in that system. This connection shall be suitable also for temporary attachment of gas-sampling equipment to the exhaust system. This opening into the exhaust system shall be provided with a locking closure.

(f) Composition of exhaust gas. Under normal operating conditions, and within the rated power output range, the undiluted exhaust gas of the engine shall not contain more than 0.25 percent, by volume, of carbon monoxide.

(g) Locomotive fuel-supply system(1) Fuel tank. The fuel tank shall be fuel-tight and shall be of metal at least 1/16 inch thick welded at all seams. The fuel tank shall be provided with a drain plug (not a valve or pet cock) that shall be locked in position when inserted. The fuel tank shall be provided with a vent opening of such design that atmospheric pressure is maintained inside the tank and that discharge of liquid fuel from the vent opening is prevented. Construction of the fuel tank shall be such that fuel may be added to the tank only through a self-closing valve situated at least 1 foot from the exhaust manifold of the engine and preferably below it. The self-closing valve shall constitute a fuel-tight closure when fuel is not being added. Any part of the self-closing valve that would be detached during the addition of fuel shall be secured to the locomotive to prevent loss.

The fuel tank shall be a built-in unit comprising part of the locomotive assembly, and no provision shall be made for attachment of separate or auxiliary fuel tanks to the locomotive.

(2) Fuel lines. All fuel lines to the engine and its accessory parts shall be installed so that they are not subject to damage in ordinary use and shall be designed to resist breakage from vibration.

(3) Valve in fuel line. A shut-off mechanism, operable from the driver's compartment, shall be provided in the fuel system so that the engine may be stopped immediately in an emergency.

(h) Signal or warning devices. All locomotives shall be equipped with a bell, horn, or other suitable warning device. This device shall not be electrically operated.

(i) Electrical equipment—(1) Classification of electrical parts. The electrical parts of a locomotive that may cause ignition of mine gas and coal dust are classified as follows:

(i) Class 1. Class 1 shall include motors, starting switches, fuses and all their parts that may produce sparks or flashes as the result of normal operation. Headlights, motors, rheostats, electromagnets, and similar parts which may become dangerous because of failure of electrical

circuits in them are also included in this class. Parts in this classification shall be enclosed in explosion-proof casings.

(ii) Class 2. Class 2 shall include all parts, such as batteries and external connections and wiring between enclosures, that do not produce sparks or flashes as the result of normal operation but may do so as the result of accident. Parts in this classification shall have adequate shields or guards of a strength and character proportionate to the risk of injury, or else they shall be enclosed in explosion-proof casings.

(iii) Class 3. Class 3 shall include all parts such as plugs and receptacles that may produce sparks or flashes in normal operation, but are not of necessity operated while the locomotive is in a gassy place. Parts in this classification shall be enclosed in explosion-proof or adequately locked casings. If locked casings are used, they shall have adequate mechanical strength.

(2) Type of electrical system. The electrical system on the locomotives shall be completely insulated from the chassis, the engine, and all other metal parts.

(3) Automatic protection of electrical circuits and equipment. On locomotives using storage batteries for starting of engines, each electrical conductor from the battery to the starting motor shall be protected against short circuit by fuses or other suitable automatic circuitinterrupting devices placed at the battery unless conductors of adequate size are provided.

Fuses or other automatic circuit-interrupting devices shall be inserted at the point where branch circuits are connected to the main circuit between the charging generator and battery. Headlight circuits and circuits for instruments and instrument-panel lights are construed as being branch circuits.

Fuses shall be enclosed in explosionproof casings with locked or sealed

covers.

(4) Conductors, conduits. and wiring. Every conductor shall have adequate insulation from "ground" and from conductors of opposite polarity. Insulation shall be selected with special reference to its ability to resist deterioration from engine heat and oil.

It is recommended that all conductors have a carrying capacity of not less than 110 percent of the total current rating of the motor or other load connected to

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