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This part sets out requirements for MSHA approval of certain equipment and materials for use in underground mines whose product testing and evaluation does not involve subjective analysis. These requirements apply to products listed in the subparts following this Subpart A. After the dates specified in the following subparts, requests for approval of products shall be made in accordance with this Subpart A and the applicable subpart.
The following definitions apply in this part.
Applicant. An individual or organization that manufactures or controls the assembly of a product and that applies to MSHA for approval of that product.
Approval. A document issued by MSHA which states that a product has met the requirements of this part and which authorizes an approval marking identifying the product as approved.
Authorized company official. An individual designated by applicant who has the authority to bind the company.
Critical characteristic. A feature of a product that, if not manufactured as approved, could have a direct adverse effect on safety and for which testing or inspection is required prior to shipment to ensure conformity with the technical requirements under which the approval was issued.
Equivalent non-MSHA product safety standards. A non-MSHA product safety standard, or group of standards, that is determined by MSHA to provide at least the same degree of protection as the applicable MSHA product technical requirements in the subparts of this part, or can be modified to provide at least the same degree of protection as those MSHA requirements.
Extension of approval. A document issued by MSHA which states that the change to a product previously approved by MSHA under this part meets the requirements of this part and which authorizes the continued use of the approval marking after the appropriate extension number has been added.
Post-approval product audit. Examination, testing, or both, by MSHA of approved products selected by MSHA to determine whether those products meet the applicable technical requirements and have been manufactured as approved.
Technical requirements. The design and performance requirements for a product, as specified in a subpart of this part.
Test procedures. The methods specified in a subpart of this part used to determine whether a product meet the performance portion of the technical requirements.
(a) Application. Requests for an approval or extension of approval shall be sent to: U.S. Department of Labor, Mine Safety and Health Administration, Approval and Certification Center, 765 Technology Drive, Triadelphia, WV 26059.
(b) Fees. Fees calculated in accordance with part 5 of this title shall be submitted in accordance with § 5.40.
(c) Original approval. Each application for approval of a product shall include—
(1) A brief description of the product;
(2) The documentation specified in the appropriate subpart of this part;
(3) The name, address, and telephone number of the applicant's representative responsible for answering any questions regarding the application;
(4) If appropriate, a statement indicating whether, in the applicant's opinion, testing is required. If testing is not proposed, the applicant shall explain the reasons for not testing; and
(5) If appropriate, the place and date for product testing.
(d) Subsequent approval of a similar product. Each application for a product similar to one for which the applicant already holds an approval shall include—
(1) The approval number for the product which most closely resembles the new one;
(2) The information specified in paragraph (c) of this section for the new product, except that any document which is the same as one listed by MSHA in prior approvals need not be submitted, but shall be noted in the application;
(3) An explanation of any change from the existing approval; and
(4) A statement as to whether, in the applicant's opinion, the change requires product testing. If testing is not proposed, the applicant shall explain the reasons for not testing.
(e) Extension of an approval. Any change in the approved product from the documentation on file at MSHA that affects the technical requirements of this part shall be submitted to MSHA for approval prior to implementing the change. Each application for an extension of approval shall include—
(1) The MSHA-assigned approval number for the product for which the extension is sought;
(2) A brief description of the proposed change to the previously approved product;
(3) Drawings and specifications which show the change in detail;
(4) A statement as to whether, in the applicant's opinion, the change requires product testing. If testing is not proposed, the applicant shall explain the reasons for not testing;
(5) The place and date for product testing, if testing will be conducted; and
(6) The name, address, and telephone number of the applicant's representative responsible for answering any questions regarding the application.
(f) Certification statement. (1) Each application for original approval, subsequent approval, or extension of approval of a product shall include a certification by the applicant that the product meets the design portion of the technical requirements, as specified in the appropriate subpart, and that the applicant will perform the quality assurance functions specified in § 7.7. For a subsequent approval or extension of approval, the applicant shall also certify that the proposed change cited in the application is the only change that affects the technical requirements.
(2) After completion of the required product testing, the applicant shall certify that the product has been tested and meets the performance portion of the technical requirements, as specified in the appropriate subpart.
(3) All certification statements shall be signed by an authorized company official.
(a) All products submitted for approval under this part shall be tested using the test procedures specified in the appropriate subpart unless MSHA determines, upon review of the documentation submitted, that testing is not required. Applicants shall maintain records of test results and procedures for three years.
(b) Unless otherwise specified in the subpart, test instruments shall be calibrated at least as frequently as, and according to, the instrument manufacturer's specifications, using calibration standards traceable to those set by the National Bureau of Standards, U.S. Department of Commerce or other nationally recognized standards and accurate to at least one significant figure beyond the desired accuracy.
(c) When MSHA elects to observe product testing, the applicant shall permit an MSHA official to be present at a mutually agreeable date, time, and place.
(d) MSHA will accept product testing conducted outside the United States where such acceptance is specifically required by international agreement.
(a) An applicant shall not advertise or otherwise represent a product as approved until MSHA has issued the applicant an approval.
(b) MSHA will issue an approval or a notice of the reasons for denying approval after reviewing the application, and the results of product testing, when applicable. An approval will identify the documents upon which the approval is based.
(a) Each approved product shall have an approval marking, as specified in the appropriate subpart of this part.
(b) For an extension of approval, the extension number shall be added to the original approval number on the approval marking.
(c) Applicants shall maintain records of the initial sale of each unit having an approval marking. The record retention period shall be at least the expected shelf life and service life of the product.
Applicants granted an approval or an extension of approval under this part shall—
(a) Inspect or test, or both, the critical characteristics in accordance with the appropriate subpart of this part;
(b) Unless otherwise specified in the subparts, calibrate instruments used for the inspection and testing of critical characteristics at least as frequently as, and according to, the instrument manufacturer's specifications, using calibration standards traceable to those set by the National Bureau of Standards, U.S. Department of Commerce or other nationally recognized standards and use instruments accurate to at least one significant figure beyond the desired accuracy.
(c) Control production documentation so that the product is manufactured as approved;
(d) Immediately report to the MSHA Approval and Certification Center, any knowledge of a product distributed with critical characteristics not in accordance with the approval specifications.
(a) Approved products shall be subject to periodic audits by MSHA for the purpose of determining conformity with the technical requirements upon which the approval was based. Any approved product which is to be audited shall be selected by MSHA and be representative of those distributed for use in mines. The approval-holder may obtain any final report resulting from such audit.
(b) No more than once a year except for cause, the approval-holder, at MSHA's request, shall make an approved product available at no cost to MSHA for an audit to be conducted at a mutually agreeable site and time. The approval-holder may observe any tests conducted during this audit.
(c) An approved product shall be subject to audit for cause at any time MSHA believes that it is not in compliance with the technical requirements upon which the approval was based.
(a) MSHA may revoke for cause an approval issued under this part if the product:
(1) Fails to meet the applicable technical requirements; or
(2) Creates a hazard when used in a mine.
(b) Prior to revoking an approval, the approval-holder shall be informed in writing of MSHA's intention to revoke approval. The notice shall:
(1) Explain the specific reasons for the proposed revocation; and
(2) Provide the approval-holder an opportunity to demonstrate or achieve compliance with the product approval requirements.
(c) Upon request, the approval-holder shall be afforded an opportunity for a hearing.
(d) If a product poses an imminent hazard to the safety or health of miners, the approval may be immediately suspended without a written notice of the agency's intention to revoke. The suspension may continue until the revocation proceedings are completed.
(a) MSHA will accept non-MSHA product safety standards, or groups of standards, as equivalent after determining that they:
(1) Provide at least the same degree of protection as MSHA's applicable technical requirements for a product in the subparts of this part; or
(2) Can be modified to provide at least the same degree of protection as those MSHA requirements.
(b) MSHA will publish its intent to review any non-MSHA product safety standard for equivalency in the Federal Register for the purpose of soliciting public input.
(c) A listing of all equivalency determinations will be published in this part 7. The listing will state whether MSHA accepts the non-MSHA product safety standards in their original form, or whether MSHA will require modifications to demonstrate equivalency. If modifications are required, they will be provided in the listing. MSHA will notify the public of each equivalency determination and will publish a summary of the basis for its determination. MSHA will provide equivalency determination reports to the public upon request to the Approval and Certification Center. MSHA has made the following equivalency determinations applicable to this part 7.
(1) MSHA will accept applications for motors under Subpart J designed and tested to the International Electrotechnical Commission's (IEC) standards for Electrical Apparatus for Explosive Gas Atmospheres, Part 0, General Requirements (IEC 60079-0, Fourth Edition, 2004-01) and Part 1, Electrical Apparatus for Explosive Gas Atmospheres, Flameproof Enclosures “d” (IEC 60079-1, Fifth Edition, 2003-11) (which are hereby incorporated by reference and made a part hereof) provided the modifications to the IEC standards specified in § 7.10(c)(1)(i) through (ix) are met. The Director of the Federal Register approves this incorporation by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. The IEC standards may be inspected at the U.S. Department of Labor, Mine Safety and Health Administration, Electrical Safety Division, Approval and Certification Center, 765 Technology Drive, Triadelphia, WV 26059, or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. These IEC standards may be obtained from International Electrical Commission, Central Office 3, rue de Varembé, P.O. Box 131, CH-1211 GENEVA 20, Switzerland.
(i) Enclosures associated with an electric motor assembly shall be made of metal and not have a compartment exceeding ten (10) feet in length. External surfaces of enclosures shall not exceed 150 °C (302 °F) in normal operation.
(ii) Enclosures shall be rugged in construction and should meet existing requirements for minimum bolt size and spacing and for minimum wall, cover, and flange thicknesses specified in paragraph (g)(19) of § 7.304 Technical requirements. Enclosure fasteners should be uniform in size and length, be provided at all corners, and be secured from loosening by lockwashers or equivalent. An engineering analysis shall be provided for enclosure designs that deviate from the existing requirements. The analysis shall show that the proposed enclosure design meets or exceeds the mechanical strength of a comparable enclosure designed to 150 psig according to existing requirements, and that flamepath clearances in excess of existing requirements will not be produced at an internal pressure of 150 psig. This shall be verified by explosion testing the enclosure at a minimum of 150 psig.
(iii) Enclosures shall be designed to withstand a minimum pressure of at least 150 psig without leakage through any welds or castings, rupture of any part that affects explosion-proof integrity, clearances exceeding those permitted under existing requirements along flame-arresting paths, or permanent distortion exceeding 0.040-inch per linear foot.
(iv) Flamepath clearances, including clearances between fasteners and the holes through which they pass, shall not exceed those specified in existing requirements. No intentional gaps in flamepaths are permitted.
(v) The minimum lengths of the flame arresting paths, based on enclosure volume, shall conform to those specified in existing requirements to the nearest metric equivalent value (e.g., 12.5 mm, 19 mm, and 25 mm are considered equivalent to
1/2 inch,
3/4 inch and 1 inch respectively for plane and cylindrical joints). The widths of any grooves for o-rings shall be deducted in measuring the widths of flame-arresting paths.
(vi) Gaskets shall not be used to form any part of a flame-arresting path. If o-rings are installed within a flamepath, the location of the o-rings shall meet existing requirements.
(vii) Cable entries into enclosures shall be of a type that utilizes either flame-resistant rope packing material or sealing rings (grommets). If plugs and mating receptacles are mounted to an enclosure wall, they shall be of explosion-proof construction. Insulated bushings or studs shall not be installed in the outside walls of enclosures. Lead entrances utilizing sealing compounds and flexible or rigid metallic conduit are not permitted.
(viii) Unused lead entrances shall be closed with a metal plug that is secured by spot welding, brazing, or equivalent.
(ix) Special explosion tests are required for electric motor assemblies that share leads (electric conductors) through a common wall with another explosion-proof enclosure, such as a motor winding compartment and a conduit box. These tests are required to determine the presence of any pressure piling conditions in either enclosure when one or more of the insulating barriers, sectionalizing terminals, or other isolating parts are sequentially removed from the common wall between the enclosures. Enclosures that exhibit pressures during these tests that exceed those specified in existing requirements must be provided with a warning tag. The durable warning tag must indicate that the insulating barriers, sectionalizing terminals, or other isolating parts be maintained in order to insure the explosion-proof integrity for either enclosure sharing a common wall. A warning tag is not required if the enclosures withstand a static pressure of twice the maximum value observed in the explosion tests.
(2) [Reserved]
(d) After MSHA has determined that non-MSHA product safety standards are equivalent and has notified the public of such determinations, applicants may seek MSHA product approval based on such non-MSHA product safety standards.
This subpart establishes the specific requirements for approval of brattice cloth and ventilation tubing. It is effective August 22, 1988. Applications for approval or extension of approval submitted after August 22, 1989, shall meet the requirements of this part.
The following definitions apply in this subpart:
Brattice cloth. A curtain of jute, plastic, or similar material used to control or direct ventilating air.
Denier. A unit of yarn size indicating the fineness of fiber of material based on the number of grams in a length of 9,000 meters.
Film. A sheet of flexible material applied to a scrim by pressure, temperature, adhesion, or other method.
Scrim. A substrate material of plastic or fabric laminated between or coated with a film.
Ventilation tubing. Rigid or flexible tubing used to convey ventilating air.
(a) Brattice cloth. A single application may address two or more products if the products differ only in: weight of the finished product; weight or weave of the same fabric or scrim; or thickness or layers of the same film. Applications shall include the following information:
(1) Trade name.
(2) Product designations (for example, style and code number).
(3) Color.
(4) Type of brattice (for example, plastic or jute).
(5) Weight of finished product.
(6) Film: type, weight, thickness, supplier, supplier's stock number or designation, and percent of finished product by weight.
(7) Scrim: Type, denier, weight, weave, the supplier, supplier's stock number or designation, and percent of finished product by weight.
(8) Adhesive: type, supplier, supplier's stock number or designation, and percent of finished product by weight.
(b) Flexible ventilation tubing. Applications shall include the product description information in paragraph (a) of this section and list the type of supporting structure, if applicable; inside diameters; and configurations.
(c) Rigid ventilation tubing. A single application may address two or more products if the products differ only in diameters, lengths, configuration, or average wall thickness. Applications shall include the following information:
(1) Trade name.
(2) Product designations (for example, style and code numbers).
(3) Color.
(4) Type of ventilation tubing (for example, fiberglass, plastic, or polyethylene).
(5) Inside diameter, configuration, and average wall thickness.
(6) Suspension system (for example, metal hooks).
(7) Base material: type, supplier, the supplier's stock number, and percent of finished product by weight.
(8) Resin: type, supplier, the supplier's stock number, and percent of finished product by weight.
(9) Flame retardant, if added during manufacturing: type, supplier, the supplier's stock number, and percent of finished product by weight.
(a) Brattice cloth shall be flame resistant when tested in accordance with the flame resistance test in § 7.27.
(b) Flexible ventilation tubing shall be manufactured using an MSHA-approved brattice cloth. If a supporting structure is used, it shall be metal or other noncombustible material which will not ignite, burn, support combustion or release flammable vapors when subjected to fire or heat.
(c) Rigid ventilation tubing shall be flame resistant when tested in accordance with the flame resistance test in § 7.28.
A sample of each batch or lot of brattice cloth and ventilation tubing shall be flame tested or a sample of each batch or lot of the materials that contribute to the flame-resistance characteristic shall be inspected or tested to ensure that the finished product will meet the flame-resistance test.
The principal parts of the apparatus used to test for flame-resistance of brattice cloth and ventilation tubing shall be constructed as follows:
(a) A 16-gauge stainless steel gallery lined on the top, bottom and both sides with
1/2 inch thick Marinite or equivalent insulating material yielding inside dimensions approximately 58 inches long, 41 inches high, and 30 inches wide;
(b) Two
3/8 -inch diameter steel J hooks and a
9/16 -inch diameter steel rod to support the sample located approximately 2
3/16 -inches from the front and back ends of the test gallery, 1
1/2 -inches from the ceiling insulation and centrally located in the gallery along its length. Samples shall be suspended to preclude folds or wrinkles;
(c) A tapered 16-gauge stainless steel duct section tapering from a cross sectional area measuring 2 feet 7 inches wide by 3 feet 6 inches high at the test gallery to a cross-sectional area 1 foot 6 inches square over a length of 3 feet. The tapered duct section must be tightly connected to the test gallery;
(d) A 16-gauge stainless steel fan housing, consisting of a 1 foot 6 inches square section 6 inches long followed by a 10 inch long section which tapers from 1 foot 16 inches square to 12 inches diameter round and concluding with a 12 inch diameter round collar 3 inches long. A variable speed fan capable of producing an air velocity of 125 ft./min. in the test gallery must be secured in the fan housing. The fan housing must be tightly connected to the tapered duct section;
(e) A methane-fueled impinged jet burner igniting source, measuring 12 inches long from the threaded ends of the first and last jets and 4 inches wide with 12 impinged jets, approximately 1
3/8 -inches long and spaced alternately along the length of the burner tube. The burner jets must be canted so that they point toward each other in pairs and the flame from these pairs impinge upon each other.
(a) Test procedures. (1) Prepare 6 samples of brattice cloth 40 inches wide by 48 inches long.
(2) Prior to testing, condition each sample for a minimum of 24 hours at a temperature of 70 ±10 °F (21 ±5.5 °C) and a relative humidity of 55 ±10%.
(3) For each test, suspend the sample in the gallery by wrapping the brattice cloth around the rod and clamping each end and the center. The brattice cloth must hang 4 inches from the gallery floor.
(4) Use a front exhaust system to remove smoke escaping from the gallery. The exhaust system must remain on during all testing, but not affect the air flow in the gallery.
(5) Set the methane-fueled impinged jet burner to yield a flame height of 12 inches as measured at the outermost tip of the flame.
(6) Apply the burner to the front lower edge of the brattice cloth and keep it in contact with the material for 25 seconds or until 1 foot of material, measured horizontally, is consumed, whichever occurs first. If the material shrinks during application of the burner flame, move the burner flame to maintain contact with 1 foot of the material. If melting material might clog the burner orifices, rotate the burner slightly during application of the flame.
(7) Test 3 samples in still air and 3 samples with an average of 125 ft./min. of air flowing past the sample.
(8) Record the propagation length and duration of burning for each of the 6 samples. The duration of burning is the total burning time of the specimen during the flame test. This includes the burn time of any material that falls on the floor of the test gallery during the igniting period. However, the suspended specimen is considered burning only after the burner is removed. Should the burning time of a suspended specimen and a specimen on the floor coincide, count the coinciding burning time only once.
(9) Calculate the average duration of burning for the first 3 samples (still air) and the second 3 samples (125 ft./min. air flow).
(b) Acceptable performance. The brattice cloth shall meet each of the following criteria:
(1) Flame propagation of less than 4 feet in each of the six tests.
(2) An average duration of burning of less than 1 minute in both groups of three tests.
(3) A duration of burning not exceeding two minutes in each of the six tests.
(a) Test procedures. (1) Prepare 6 samples of ventilation tubing 48 inches in length with all flared or thickened ends removed. Any sample with a cross-sectional dimension greater than 24 inches must be tested in a 24-inch size.
(2) For each test, suspend the sample in the center of the gallery by running a wire through the 48-inch length of tubing.
(3) Use a front exhaust system to remove smoke escaping from the gallery. The exhaust system must remain on during all testing but not affect the air flow in the gallery.
(4) Set the methane-fueled impinged jet burner to yield a flame height of 12 inches as measured at the outermost tip of the flame.
(5) Apply the burner to the front lower edge of the tubing so that two-thirds of the burner is under the tubing and the remaining third is exposed to allow the flames to curl onto the inside of the tubing. Keep the burner in contact with the material for 60 seconds. If melting material might clog the burner orifices, rotate the burner slightly during application of the flame.
(6) Test 3 samples in still air and 3 samples with an average of 125 ft./min. of air flowing past the sample.
(7) Record the propagation length and duration of burning for each of the 6 samples. The duration of burn is the total burning time of the specimen during the flame test. This includes the burning time of any material that falls on the floor of the test gallery during the igniting period. However, the suspended specimen is considered burning only after the burner is removed. Should the burning time of a suspended specimen and a specimen on the floor coincide, count the coinciding burn time only once.
(8) Calculate the average duration of burning for the first 3 samples (still air) and the second 3 samples (125 ft./min. air flow).
(b) Acceptable performance. The ventilation tubing shall meet each of the following criteria:
(1) Flame propagation of less than 4 feet in each of the 6 tests.
(2) An average duration of burning of less than 1 minute in both groups of 3 tests.
(3) A duration of burning not exceeding 2 minutes in each of the 6 tests.
(a) Approved brattice cloth shall be legibly and permanently marked with the assigned MSHA approval number at intervals not exceeding ten feet. If the nature of the material or method of processing makes such marking impractical, permanent paint or ink may be used to mark the edge with an MSHA-assigned color code.
(b) Approved ventilation tubing shall be legibly and permanently marked on each section with the assigned MSHA approval number.
(c) An approved product shall be marketed only under a brand or trade name that has been furnished to MSHA.
Upon request by MSHA but no more than once a year except for cause, the approval-holder shall supply to MSHA at no cost up to fifty feet of each approved design of brattice cloth and ventilation tubing for audit.
MSHA may approve brattice cloth and ventilation tubing that incorporates technology for which the requirements of this subpart are not applicable, if the Agency determines that the product is as safe as those which meet the requirements of this subpart.
This subpart establishes the specific requirements for MSHA approval of battery assemblies intended for incorporation in approved equipment in underground mines. It is effective August 22, 1988. Applications for approval or extensions of approval submitted after August 22, 1989, shall meet the requirements of this part.
The following definitions apply in this subpart:
Battery assembly. A unit or units consisting of cells and their electrical connections, assembled in a battery box or boxes with covers.
Battery box. The exterior sides, bottom, and connector receptacle compartment, if any, of a battery assembly, excluding internal partitions.
(a) An application for approval of a battery assembly shall contain sufficient information to document compliance with the technical requirements of this subpart and include a composite drawing with the following information:
(1) Overall dimensions of the battery assembly, including the minimum distance from the underside of the cover to the top of the terminals and caps.
(2) Composition and thicknesses of the battery box and cover.
(3) Provision for securing covers.
(4) Documentation of flame-resistance of insulating materials and cables.
(5) Number, type, and rating of the battery cells.
(6) Diagram of battery connections between cells and between battery boxes, except when connections between battery boxes are a part of the machine's electrical system.
(7) Total weight of the battery, charged and ready for service.
(8) Documentation of materials and configurations for battery cells, intercell connectors, filler caps, and battery top:
(i) If nonmetallic cover designs are used with cover support blocks; or
(ii) If the cover comes into contact with any portion of the cells, caps, filler material, battery top, or intercell connectors during the impact test specified by § 7.46.
(b) All drawings shall be titled, dated, numbered, and include the latest revision number.
(a)(1) Battery boxes and covers constructed of AISI 1010 hot rolled steel shall have the following minimum thicknesses based on the total weight of a unit of the battery assembly charged and ready for service:
Weight of battery unit
Minimum required thickness
1,000 lbs. maximum
10 gauge or 1 ⁄ 8 ″ nominal
1,001 to 2,000 lbs
7 gauge or 3 ⁄ 16 ″ nominal
2,001 to 4,500 lbs
3 gauge or 1 ⁄ 4 ″ nominal
Over 4,500 lbs
0 gauge or 5 ⁄ 16 ″ nominal
(2) Battery boxes not constructed of AISI 1010 hot rolled steel shall have at least the tensile strength and impact resistance of battery boxes for the same weight class, as listed in paragraph (a)(1) of this section.
(3) Battery box covers constructed of materials with less than the tensile strength and impact resistance of AISI 1010 hot rolled steel or constructed of nonmetallic materials shall meet the acceptable performance criteria for the impact test in § 7.46. Nonmetallic covers shall be used only in the battery assembly configuration in which they pass the impact test.
(4) Nonmetallic materials for boxes and covers shall—
(i) Be accepted by MSHA as flame-resistant material under part 18 of this chapter; and
(ii) Meet the acceptable performance criteria for the deflection temperature test in § 7.47.
(b) All insulating material shall have a minimum resistance of 100 megohms at 500 volts d.c. and be accepted by MSHA as flame resistant under part 18 of this chapter.
(c) Battery box and cover insulating material shall meet the acceptable performance criteria for the acid resistance test in § 7.48.
(d) Covers shall be lined with insulating material permanently attached to the underside of the cover, unless the cover is constructed of insulating material.
(e) Covers, including those used over connector receptacle housings, shall be provided with a means of securing them in a closed position.
(f) Battery boxes shall be provided with vent openings to prevent the accumulation of flammable or toxic gases or vapors within the battery assembly. The size and location of openings shall prevent direct access to cell terminals and other uninsulated current carrying parts. The total minimum unobstructed cross-sectional area of the ventilation openings shall be no less than the value determined by the following formula:
N = Number of cells in battery box.
R = Rated 6 hour battery capacity in ampere hours.
M = Total minimum ventilation area in square inches per battery box.
(g) Battery boxes shall have drainage holes to prevent accumulation of water or electrolyte.
(h) Battery cells shall be insulated from the battery box walls, partitions and bottom by insulating material, unless such part of the battery box is constructed of insulating material. Battery box wall insulating material shall extend to the top of the wall.
(i) Cell terminals shall be burned on, except that bolted connectors using two or more bolts may be used on end terminals.
(j) Battery connections shall be designed so that total battery potential is not available between adjacent cells.
(k) Cables within a battery box shall be accepted by MSHA as flame resistant under part 18 of this chapter or approved under subpart K of this part. The cables shall be protected against abrasion by insulation, location, clamping, or other effective means.
(l) When the battery plug and receptacle are not located on or within the battery box, strain on the battery terminals shall be prevented by a strain-relief device on the cable. Insulating material shall be placed between the strain-relief device and cable, unless the device is constructed of insulating material.
(m) At least a
1/2 -inch air space shall be provided between the underside of the battery cover and the top of the battery, including the terminals and connectors.
The following critical characteristics shall be inspected or tested on each battery assembly to which an approval marking is affixed:
(a) Thickness of covers and boxes.
(b) Application and resistance of insulating material.
(c) Size and location of ventilation openings.
(d) Method of cell terminations.
(e) Strain relief devices for cables leaving boxes.
(f) Type, location, and physical protection of cables.
(a) Test procedures. (1) Prepare four covers for testing by conditioning two covers at −13 °F (−25 °C) and two covers at 122 °F (50 °C) for a period of 48 hours.
(2) Mount the covers on a battery box of the same design with which the covers are to be approved, including any support blocks, with the battery cells completely assembled. If used, support blocks must contact only the filler material or partitions between the individual cells. At the test temperature range of 65 °F-80 °F (18.3 °C-26.7 °C), apply a dynamic force of 200 ft. lbs. to the following areas using a hemispherical weight with a 6″ maximum radius:
(i) The center of the two largest unsupported areas;
(ii) The areas above at least two support blocks, if used;
(iii) The areas above at least two intercell connectors, one cell, and one filler cap; and
(iv) Areas on at least two corners. If the design consists of both inside and outside corners, test one of each.
(3) Record the condition of the covers, supports, intercell connectors, filler caps, cell covers, and filler material.
(b) Acceptable performance. Impact tests of any of the four covers shall not result in any of the following:
(1) Bent intercell connectors.
(2) Cracked or broken filler caps, except plastic tabs which extend from the body of the filler caps.
(3) Cracks in the cell cover, cells, or filler material.
(4) Cracked or bent supports.
(5) Cracked or splintered battery covers.
(a) Test procedures. (1) Prepare two samples for testing that measure 5 inches by
1/2 inch, by the thickness of the material as it will be used. Prior to testing, condition the samples at 73.4 ±3.6 °F (23 ±2 °C) and 50 ±5% relative humidity for at least 40 hours.
(2) Place a sample on supports which are 4 inches apart and immersed in a heat transfer medium at a test temperature range of 65 °F−80 °F (18.3 °C−26.7 °C). The heat transfer medium must be a liquid which will not chemically affect the sample. The testing apparatus must be constructed so that expansion of any components during heating of the medium does not result in deflection of the sample.
(3) Place a temperature measuring device with an accuracy of 1% into the heat transfer medium within
1/8 inch of, but not touching, the sample.
(4) Apply a total load, in pounds, numerically equivalent to 11 times the thickness of the sample, in inches, to the sample midway between the supports using a
1/8 inch radius, rounded contact. The total load includes that weight used to apply the load and any force exerted by the deflection measurement device.
(5) Use a deflection measuring device with an accuracy of ±.001 inches to measure the deflection of the sample at the point of loading as the temperature of the medium is increased at a uniform rate of 3.6 ±.36 °F/min. (2 ±0.2 °C/min.). Apply the load to the sample for 5 minutes prior to heating, to allow compensation for creep in the sample due to the loading.
(6) Record the deflection of the sample due to heating at 180 °F (82 °C).
(7) Repeat steps 2 through 6 for the other sample.
(b) Acceptable performance. Neither sample shall have a deflection greater than .010 inch at 180 °F (82 °C).
(a) Test procedures. (1) Prepare one sample each of the insulated surfaces of the battery box and of the cover that measure at least 4 inches by 8 inches, by the thickness of the sample which includes the insulation plus the battery cover or box material. The insulation thickness shall be representative of that used on the battery box and cover. If the insulation material and thickness of material are identical for the battery box and cover, only one sample need be prepared and tested.
(2) Prepare a 30 percent solution of sulfuric acid (H 2 SO 4 ) by mixing 853 ml of water with 199 ml of sulfuric acid (H 2 SO 4 ) with a specific gravity of 1.84. Completely cover the samples with the acid solution at the test temperature range of 65 °F−80 °F (18.3 °C−26.7 °C) and maintain these conditions for 7 days.
(3) After 7 days, record the condition of the samples.
(b) Acceptable performance. At the end of the test, the insulation shall not exhibit any blistering, discoloration, cracking, swelling, tackiness, rubberiness, or loss of bond.
Each approved battery assembly shall be identified by a legible and permanent approval plate inscribed with the assigned MSHA approval number and securely attached to the battery box.
Upon request by MSHA, but no more than once a year except for cause, the approval-holder shall make an approved battery assembly available for audit at no cost to MSHA.
Each battery assembly bearing an MSHA approval plate shall be accompanied by a description of what is necessary to maintain the battery assembly as approved.
MSHA may approve a battery assembly that incorporates technology for which the requirements of this subpart are not applicable, if the Agency determines that the battery assembly is as safe as those which meet the requirements of this subpart.
This subpart establishes the specific requirements for MSHA approval of multiple-shot blasting units. It is effective January 22, 1990. Applications for approval or extensions of approval submitted after January 22, 1991 shall meet the requirements of this subpart.
The following definitions apply in this subpart:
Blasting circuit. A circuit that includes one or more electric detonators connected in a single series and the firing cable used to connect the detonators to the blasting unit.
Blasting unit. An electric device used to initiate electric detonators.
Normal operation. Operation of the unit according to the manufacturer's instructions with fully-charged batteries, with electric components at any value within their specified tolerances, and with adjustable electric components set to any value within their range.
(a) Each application for approval of a blasting unit shall include the following:
(1) An overall assembly drawing showing the physical construction of the blasting unit.
(2) A schematic diagram of the electric circuit.
(3) A parts list specifying each electric component and its electrical ratings, including tolerances.
(4) A layout drawing showing the location of each component and wiring.
(5) The model number or other manufacturer's designation of the blasting unit.
(b) All drawings shall be titled, numbered, dated, and include the latest revision number. The drawings may be combined into one or more composite drawings.
(c) The application shall contain a list of all the drawings submitted, including drawing titles, numbers, and revisions.
(d) A detailed technical description of the operation and use of the blasting unit shall be submitted with the application.
(a) Energy output. Blasting units shall meet the acceptable performance criteria of the output energy test in § 7.66.
(b) Maximum blasting circuit resistance. The maximum value of the resistance of the blasting circuit that can be connected to the firing line terminals of the blasting unit, without exceeding its capacity, shall be specified by the applicant. The specified maximum blasting circuit resistance shall be at least 150 ohms.
(c) Visual indicator. The blasting unit shall provide a visual indication to the user prior to the operation of the firing switch when the voltage necessary to produce the required firing current is attained.
(d) Firing switch. The switch used to initiate the application of energy to the blasting circuit shall—
(1) Require deliberate action for its operation to prevent accidental firing; and
(2) Operate only when the voltage necessary to produce the required firing current is available to the blasting circuit.
(e) Firing line terminals. The terminals used to connect the blasting circuit to the blasting unit shall—
(1) Provide a secure, low-resistance connection to the blasting circuit as demonstrated by the firing line terminals test in § 7.68;
(2) Be corrosion-resistant;
(3) Be insulated to protect the user from electrical shock; and
(4) Be separated from each other by an insulated barrier.
(f) Ratings of electric components. No electric component of the blasting unit, other than batteries, shall be operated at more than 90 percent of any of its electrical ratings in the normal operation of the blasting unit.
(g) Non-incendive electric contacts. In the normal operation of a blasting unit, the electric energy discharged by making and breaking electric contacts shall not be capable of igniting a methane-air atmosphere, as determined by the following:
(1) The electric current through an electric contact shall not be greater than that determined from Figure D-1.
(2) The maximum voltage that can be applied across an electric contact that discharges a capacitor shall not be greater than that determined from Figure D-2.
(3) The electric current through an electric contact that interrupts a circuit containing inductive components shall not be greater than that determined from Figure D-3. Inductive components include inductors, chokes, relay coils, motors, transformers, and similar electric components that have an inductance greater than 100 microhenries. No inductive component in a circuit with making and breaking electric contacts shall have an inductance value greater than 100 millihenries.
(h) Maximum temperature. In the normal operation of the blasting unit, the maximum temperature of any electric component shall not exceed 302 °F (150 °C).
(i) Capacitor discharge. The blasting unit shall include an automatic means to dissipate any electric charge remaining in any capacitor after the blasting unit is deenergized and not in use.
(j) Construction. Blasting units shall meet the acceptable performance criteria of the construction test of § 7.67.
(k) Locking device. The blasting unit shall be equipped with a locking device to prevent unauthorized use.
(l) Enclosure. The blasting unit enclosure shall be protected against tampering by—
(1) Sealing the enclosure, except the battery compartment, using continuous welding, brazing, soldering, or equivalent methods; or
(2) Sealing the electric components, other than batteries, in a solidified insulating material and assembling the enclosure with tamper-resistant hardware.
(m) Battery charging. Blasting units that contain rechargeable batteries shall have the following:
(1) A blocking diode, or equivalent device, in series with the battery to prevent electric energy in the battery from being available at the charging connector.
(2) The charging connector recessed into the enclosure.
The following critical characteristics shall be inspected or tested on each blasting unit to which an approval marking is affixed:
(a) The output current.
(b) The voltage cut-off time.
(c) The components that control voltage and current through each making and breaking electric contact.
(d) Operation of the visual indicator and the firing switch.
(a) Test procedures. The blasting unit shall be tested by firing into each of the following resistive loads, within a tolerance of ±1%:
(1) The maximum blasting circuit resistance.
(2) Any resistive load between 3 ohms and the maximum blasting circuit resistance.
(3) One ohm.
(b) Acceptable performance. (1) The voltage shall be zero at the firing line terminals 10 milliseconds after operation of the firing switch.
(2) The electric current from the blasting unit shall be:
(i) Less than 50 milliamperes except during firing of the blasting unit.
(ii) Available only through the firing line terminals.
(iii) At least an average of 2 amperes during the first 5 milliseconds following operation of the firing switch.
(iv) Not exceed an average of 100 amperes during the first 10 milliseconds following operation of the firing switch.
The construction test is to be performed on the blasting unit subsequent to the output energy test of § 7.66.
(a) Test procedures. (1) The blasting unit shall be dropped 20 times from a height of 3 feet onto a horizontal concrete floor. When dropped, the orientation of the blasting unit shall be varied each time in an attempt to have a different surface, corner, or edge strike the floor first for each drop.
(2) After the blasting unit has been drop tested in accordance with paragraph (a)(1) above, it shall be submerged in 1 foot of water for 1 hour in each of 3 tests. The water temperature shall be maintained within ±5 °F (±2.8 °C) of 40 °F (4.4 °C), 70 °F (21.1 °C) and 100 °F (37.8 °C) during the tests.
(3) Immediately after removing the blasting unit from the water at each temperature, the unit shall be operated first with the firing line terminals open circuited, then operated again with the firing line terminals short circuited, and last, the output energy tested in accordance with the output energy test of § 7.66.
(b) Acceptable performance. (1) The blasting unit shall meet the acceptable performance criteria of the output energy test in § 7.66 each time it is performed.
(2) There shall be no damage to the firing line terminals that exposes an electric conductor.
(3) The visual indicator shall be operational.
(4) The batteries shall not be separated from the blasting unit.
(5) There shall be no water inside the blasting unit enclosure, except for the battery compartment.
(a) Test procedures. (1) The contact resistance through each firing line terminal shall be determined.
(2) A 10-pound pull shall be applied to a No. 18 gauge wire that has been connected to each firing line terminal according to the manufacturer's instructions.
(b) Acceptable performance. (1) The contact resistance shall not be greater than 1 ohm.
(2) The No. 18 gauge wire shall not become disconnected from either firing line terminal.
Each approved blasting unit shall be identified as permissible by a legible and permanent marking securely attached, stamped, or molded to the outside of the unit. This marking shall include the following:
(a) The assigned MSHA approval number.
(b) The maximum blasting circuit resistance.
(c) A warning that the unit's components must not be disassembled or removed.
(d) The replacement battery types if the unit has replaceable batteries.
(e) A warning placed next to the charging connector that the battery only be charged in a fresh air location if rechargeable batteries are used.
(f) A warning that the unit is compatible only with detonators that will—
(1) Fire when an average of 1.5 amperes is applied for 5 milliseconds;
(2) Not misfire when up to an average 100 amperes is applied for 10 milliseconds; and
(3) Not fire when a current of 250 milliamperes or less is applied.
Upon request by MSHA, but not more than once a year except for cause, the approval holder shall make an approved blasting unit available for audit at no cost to MSHA.
Each blasting unit bearing an MSHA approval marking shall be accompanied by a description of what is necessary to maintain the blasting unit as approved.
MSHA may approve a blasting unit that incorporates technology for which the requirements of this subpart are not applicable if the Agency determines that the blasting unit is as safe as those which meet the requirements of this subpart.
Subpart A general provisions of this part apply to this subpart E. Subpart E establishes the specific engine performance and exhaust emission requirements for MSHA approval of diesel engines for use in areas of underground coal mines where permissible electric equipment is required and areas where non-permissible electric equipment is allowed. It is effective November 25, 1996.
In addition to subpart A definitions of this part, the following definitions apply in this subpart.
Brake Power. The observed power measured at the crankshaft or its equivalent when the engine is equipped only with standard auxiliaries necessary for its operation on the test bed.
Category A engines. Diesel engines intended for use in areas of underground coal mines where permissible electric equipment is required.
Category B engines. Diesel engines intended for use in areas of underground coal mines where nonpermissible electric equipment is allowed.
Corrosion-resistant material. Material that has at least the corrosion-resistant properties of type 304 stainless steel.
Diesel engine. Any compression ignition internal combustion engine using the basic diesel cycle where combustion results from the spraying of fuel into air heated by compression.
Exhaust emission. Any substance emitted to the atmosphere from the exhaust port of the combustion chamber of a diesel engine.
Intermediate speed. Maximum torque speed if it occurs between 60 percent and 75 percent of rated speed. If the maximum torque speed is less than 60 percent of rated speed, then the intermediate speed shall be 60 percent of the rated speed. If the maximum torque speed is greater than 75 percent of the rated speed, then the intermediate speed shall be 75 percent of rated speed.
Low idle speed. The minimum no load speed as specified by the engine manufacturer.
Maximum torque speed. The speed at which an engine develops maximum torque.
Operational range. All speed and load (including percent loads) combinations from the rated speed to the minimum permitted engine speed at full load as specified by the engine manufacturer.
Particulates. Any material collected on a specified filter medium after diluting exhaust gases with clean, filtered air at a temperature of less than or equal to 125 °F (52 °C), as measured at a point immediately upstream of the primary filter. This is primarily carbon, condensed hydrocarbons, sulfates, and associated water.
Percent load. The fraction of the maximum available torque at an engine speed.
Rated horsepower. The nominal brake power output of a diesel engine as specified by the engine manufacturer with a specified production tolerance. For laboratory test purposes, the fuel pump calibration for the rated horsepower must be set between the nominal and the maximum fuel tolerance specification.
Rated speed. Speed at which the rated power is delivered, as specified by the engine manufacturer.
Steady-state condition. Diesel engine operating condition which is at a constant speed and load and at stabilized temperatures and pressures.
Total oxides of nitrogen. The sum total of the measured parts per millions (ppm) of nitric oxide (NO) plus the measured ppm of nitrogen dioxide (NO 2 ).
(a) An application for approval of a diesel engine shall contain sufficient information to document compliance with the technical requirements of this subpart and specify whether the application is for a category A engine or category B engine.
(b) The application shall include the following engine specifications—
(1) Model number;
(2) Number of cylinders, cylinder bore diameter, piston stroke, engine displacement;
(3) Maximum recommended air inlet restriction and exhaust backpressure;
(4) Rated speed(s), rated horsepower(s) at rated speed(s), maximum torque speed, maximum rated torque, high idle, minimum permitted engine speed at full load, low idle;
(5) Fuel consumption at rated horsepower(s) and at the maximum rated torque;
(6) Fuel injection timing; and
(7) Performance specifications of turbocharger, if applicable.
(c) The application shall include dimensional drawings (including tolerances) of the following components specifying all details affecting the technical requirements of this subpart. Composite drawings specifying the required construction details may be submitted instead of individual drawings of the following components—
(1) Cylinder head;
(2) Piston;
(3) Inlet valve;
(4) Exhaust valve;
(5) Cam shaft—profile;
(6) Fuel cam shaft, if applicable;
(7) Injector body;
(8) Injector nozzle;
(9) Injection fuel pump;
(10) Governor;
(11) Turbocharger, if applicable;
(12) Aftercooler, if applicable;
(13) Valve guide;
(14) Cylinder head gasket; and
(15) Precombustion chamber, if applicable.
(d) The application shall include a drawing showing the general arrangement of the engine.
(e) All drawings shall be titled, dated, numbered, and include the latest revision number.
(f) When all necessary testing has been completed, the following information shall be submitted:
(1) The gaseous ventilation rate for the rated speed and horsepower.
(2) The particulate index for the rated speed and horsepower.
(3) A fuel deration chart for altitudes for each rated speed and horsepower.
(a) Fuel injection adjustment. The fuel injection system of the engine shall be constructed so that the quantity of fuel injected can be controlled at a desired maximum value. This adjustment shall be changeable only after breaking a seal or by altering the design.
(b) Maximum fuel-air ratio. At the maximum fuel-air ratio determined by § 7.87 of this part, the concentrations (by volume, dry basis) of carbon monoxide (CO) and oxides of nitrogen (NO X ) in the undiluted exhaust gas shall not exceed the following:
(1) There shall be no more than 0.30 percent CO and no more than 0.20 percent NO X for category A engines.
(2) There shall be no more than 0.25 percent CO and no more than 0.20 percent NO X for category B engines.
(c) Gaseous emissions ventilation rate. Ventilation rates necessary to dilute gaseous exhaust emissions to the following values shall be determined under § 7.88 of this part:
Carbon dioxide
−5000 ppm
Carbon monoxide
−50 ppm
Nitric oxide
−25 ppm
Nitrogen dioxide
−5 ppm
A gaseous ventilation rate shall be determined for each requested speed and horsepower rating as described in § 7.88(b) of this part.
(d) Fuel deration. The fuel rates specified in the fuel deration chart shall be based on the tests conducted under paragraphs (b) and (c) of this section and shall ensure that the maximum fuel:air (f/a) ratio determined under paragraph (b) of this section is not exceeded at the altitudes specified in the fuel deration chart.
(e) Particulate index. For each rated speed and horsepower requested, the particulate index necessary to dilute the exhaust particulate emissions to 1 mg/m
3 shall be determined under § 7.89 of this part.
The following critical characteristics shall be inspected or tested on each diesel engine to which an approval marking is affixed—
(a) Fuel rate is set properly; and
(b) Fuel injection pump adjustment is sealed, if applicable.
TESTING BY APPLICANT OR THIRD PARTY (U.S.C.). Retrieved via LawPlayer, https://lawplayer.com/us/act/cfr-title-30-part-7
United States government works (U.S. Code, Code of Federal Regulations) are in the public domain under 17 U.S.C. § 105.
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