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(See 30 CFR 1.8 (a), as amended)

(Applicant is not to write in this space.) Bureau's Computation

Give full information as indicated below, attaching additional sheets if necessary for completing answers.

(1) Serial numbers and dates of the applicant's contracts to purchase helium from the Bureau now in effect:

(2) Dates of applications the applicant has submitted to purchase helium, notice of the acceptance of which has not been received:

(3) Type and number of containers and number of tractors the applicant wishes the Bureau to supply, and the applicant's estimate of the period the containers and tractors will be in service for the applicant: (a)

standard-type cylinders for an average of

months each. (b)

helium tank cars for an everage of

days each. (c)

helium semi-trailers for an average of

days each. (d)

multiple-cylinder units for an average of -----

days each. (e)

tractors to haul hellum semitrallers for an average of

days each, traveling total of ----- miles hauling a semi-trailer and

miles without semitraller.

(4) Point to which filled containers are to be shipped:

Applicants Computation ..standard-type cylinders at $0.90 each.

helium tank cars at $300 each.. ...helium semi-trailers at $50 each. ...multiple-cylinder

units at $30 each.. ....tractors at $150 each. $ Total...


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The Bureau may require an advance larger than the total shown in this table, especially if it is materially less than the estimate of total charges for use ol containers. COMPUTATION OF CASH DEPOSIT OR ROND AS GUARANTEE

(See 30 CFR 1.8 (b), as amended)

(Applicant is not to write in this space.) Bureau's Computation


(See 30 CFR 1.3 (e) to (e), as amended)



Applicant's Computation ...standard-type cylin.

ders at $20 each. ...standard-type cylin. ders at $10 each :

belium tank cars at $50,000 each.

helium semi-trailers at $10,000 each..

multiple-cylinder units at $4,000 each...



3 Only the number of cylinders in excess of 500 may be entered at $10 each.

The undersigned hereby:

1. Makes application to use containers supplied by the Bureau in numbers and under conditions as above described.

2. Certifies that he has read the act approved September 1, 1937 (50 Stat. 885; 50 U. S. C. 161-166), and regulations issued pur. suant thereto (30 CFR I, as amended); that the use to be made of the helium containers applied for is not in violation of said act and regulations; and that all statements and answers hereinabove set forth are true.

3. Agrees that if this application is accepted by the Bureau it shall thereupon be come a contract for the furnishing by the Bureau and use by the applicant of hellum containers of the number and type and upon the terms and conditions herein set forth; that the applicant will use, care for, and return sald containers and make payments according to said terms and conditions and fully comply therewith, and will abide and be bound by the terms of said act and regulations,

(Applicant is not to write in this space.) Bureau's Estimate

Applicant's Estimate

standard-type cylinders at $0.45 each per month, for ... months. $

helium tank cars at $100 each, for first 5 days...

helium tank cars at $20 each per day, for ... additional days..

helium semi-trailers at $10 each, for first 2 days..

helium semi-trailers at $5 each per day, for

additional days... $ multiple-cylinder units at $9 each, for first 3 days...

multiple-cylinder units at $3 each per day, for ... additional days. $

tractors: At $30 each per day, for

days.. At $0.10 per mile for

miles pulling semi-trailer At $0.06 per mile for

miles without semi-trailer....


1 In filling out this table, a fraction of a time period (1 month, 5 days, 2 days, 3 days, and i day) is to be counted as a whole period. (See 30 CFR 1.3 (e), as amended.)

4. Agrees that if this application becomes & contract, no Member of or Delegate to Congress or Resident Commissioner shall be admitted to any share or part of such contract or to any benefit that may arise therefrom, but this provision shall not be construed to extend to such contract if made with a corporation for its general benefit.


applicant, was then of said corporation; that said application was duly signed for and in behalf of said corporation by authority of its governing body, and is within the scope of its corporate powers.


(The following portions of the form are to be filled in by the Bureau.)

CHECK AND BOND RECEIVED Certified check in the amount of.----Bond as guarantee for containers and


The foregoing application is hereby accepted.


Director, Bureau of Mines.

(The certificate below is to be executed 11 the applicant is a corporation.) I,

--, certify that I am the

secretary of the corporation named as the applicant herein; that who signed this application on behalf of the

Subchapter E-Electrical Equipment, Lamps, Methane Detectors; Tests

for Permissibility; Fees


Sec. 18.2 Conditions under which approvals may

be granted. (Amended] 18.3 Detailed requirements for Class 1 parts.

(Amended) 18.6 Character of tests. (Amended] 18.7 Inspection and test of parts supplied

by other manufacturers. (Revised] AUTHORITY: $$ 18.2 to 18.7, appearing in this Supplement, issued under 37 Stat. 681, as amended; 30 U.S.C. 3.

(4) Drawings and specifications required. The Bureau will not undertake the inspection and test of equipment until a set of legible drawings, bill of ma-, terial, and specifications suficient in number and detail to identify the parts fully have been delivered to the Supervising Engineer, Electrical-Mechanical Section, at the Central Experiment Station. The nature of the drawings and specifications required is described in subsequent paragraphs of this section. 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 records. The complete rating of each motor shall be specified, and the capacity of all fuses and the setting of overload protective devices shall be given. All drawings are to be handled as strictly confidential by the Bureau.

The set of drawings shall include the following: (Introductory text amended]

SOURCE: $$ 18.2 to 18.7, appearing in this Supplement, contained in Regulation, Director, Bureau of Mines, approved by the Assistant Secretary of the Interior, effective Oct. 21, 1947, 12 F.R. 7285.

$ 18.2 Conditions under which approvals may be granted-(a) Preliminary steps.

(3) Fees charged.
(v) Tests of portable cable.
(a) Run-over tests (complete): $25.00.

(b) Development run-over tests will be charged for at the rate of $2.50 for each five runs over the cable, with a minimum charge of $5.00.

(c) Flame-resistance tests (complete): $15.00.

(d) Development flame-resistance tests will be charged for at the rate of $3.00 per test sample, with a minimum charge of $6.00. (Subdivision (v) amended]

(ii) A drawing or drawings that shall specify the material and detailed dimensions of all parts that make up explosionproof enclosures for units included under Class I, § 18.2 (b) (1), also of those parts that form any portion of the joints through which possible flames might escape. Upon request, the manufacturer shall specify the material and dimensions for such other parts as the Bureau considers necessary for proper record. (Subdivision (ii) amended]

(v) The following exception is made concerning the type of drawings required for squirrel-cage induction motors:

cable should be kept to the minimum necessary for feasible operation of the machine.

Suitable provision shall be made to facilitate disconnection of portable cables quickly and conveniently for replacement. (First paragraph amended)

(b) If full detailed dimensions are not given for all parts, this drawing (or drawings) may show the assembled motor in section, Provided, The section or sections show the parts in their correct proportions and location with respect to each other. A skeleton drawing shall not cover more than one motor-frame diameter. It is recommended that information covering the ratings, range of voltages, speeds, and frequencies for which the motor will be available in this frame be included on the skeleton drawing. Each frame shall have a suitable designation for purposes of reference and identification. (Inferior subdivision (6) amended]

(b) General requirements. (8) Grounding.

When the grounding conductor is one of several making up a portable cable or a connecting cable, the size (cross-sectional area) of the grounding conductor (or conductors) shall be determined in accordance with the following:

(i) If the size of the power conductor is No. 6 or larger, the cross-sectional area of the grounding conductor shall not be less than 50 percent of that of the power conductor, except that in no case shall the grounding conductor be less than No. 8.

(ii) If the size of the power conductor is smaller than No. 6, the cross-sectional area of the grounding conductor shall not be less than that of the power conductor. (Subparagraph (8) amended]

$ 18.3 Detailed requirements for Class 1 parts-(a) Enclosure casings.

(2) Joints and machining tolerances.

The surfaces comprising a flange joint need not be all in one plane. For enclosures having an unoccupied volume (air space) of more than 60 cubic inches, the total width of joint measured along the shortest path from inside to outside of the enclosure shall not be less than 1 inch, except as follows: A rabbet joint having a total width of 34 inch may be 'accepted if neither the cylindrical nor the plane fit is less than Yo inch wide. If the unoccupied volume (air space) is 60 cubic inches or less, a minimum width of 34 inch may be accepted for plane joints, but a 1-inch width of plane or rabbet joint is recommended. The diametrical clearance for cylindrical fits in rabbet joints shall not exceed 0.004 inch if the plane fit is less than 1/4 inch wide. If the plane fit is 1/4 inch or more in width, the diametrical clearance for cylindrical fits shall not exceed 0.008 inch. The edge of a rolled-steel plate forming part of an explosion-proof enclosure may be used as a plane flange, provided the width does not fall short of the previously specified flange widths by more than 164 inch. (Undesignated paragraph amended)

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(10) Portable cables. Every machine operated from an external source of power shall have a portable cable of adequate length and current-carrying capacity. This cable shall have an outer sheath of rubber or equivalent material that is highly resistant to abrasion, moisture, and flame. The cable shall meet the flame-resistance test outlined in $ 18.6 (c). The conductors shall have high-grade insulation of rubber or its equivalent. The use of colored insulation or other suitable markers is recommended for identifying individual conductors to facilitate proper connections and splicing according to polarity. The number of conductors in the portable

(7) Lead entrances. All electrical conductors that pass through the walls of explosion-proof enclosures shall be provided with adequate insulation and guards at the point of entrance to the enclosure in accordance with one or more of the following:

(1) If stuffing-box lead entrances are used, the packing material shall be untreated asbestos, such as woven valvestem packing, and it shall be not less than 316 inch in diameter. The size and kind shall be specified on the drawings or bills of material. The amount of packing material in each stuffing box shall be such that, when compressed, it will completely surround the wire or cable

for not less than 1/2 inch measured along Stuffing boxes and the fittings conthe wire or cable.

nected to them shall be so placed or The stufing-box design and the

guarded that they are not likely to be "amount of packing used shall be such

damaged in derailments and other that, with the packing properly com

accidents. (Subdivision (i) amended) pressed, the gland still has a clearance distance of 16 inch or more to travel (b) Special requirements for Class 1 without meeting, interference by parts parts. other than packing. The glands shall be (8) Distribution boxes. secured against loosening. The use of

Each branch circuit shall be plainly insulating bushings in stufing boxes is

and permanently marked to show the recommended, especially for voltages

maximum current that can be taken that exceed 250. When an outer braid

from it, and plugs that are not of insulation covering is used on wires and

identical rating shall be polarized or cables passing through stuffing boxes, it

otherwise arranged to prevent inserting should be made of asbestos or slow-burn- them in the wrong socket. (Fourth uning material.

designated paragraph amended) The width of space for packing mate

$ 18.6 Character of tests. rial shall not exceed the diameter or

(c) Portable cable run-over test. The width of the uncompressed material by

following run-over test has been estabmore than 50 percent. At other points

lished for determining the durability of small clearances shall be maintained be

portable cables for use with permissible tween the stuffing-box parts and the equipment, and cables that pass this test cables or wires passing through them. A will be listed for this service. diametrical clearance greater than 146 The cable will be placed across the two inch will not be accepted if packing ma- rails of a track, and a four-wheeled car of terial less than 14-inch diameter is used. 7 tons gross weight will be run over it 50 If untreated, woven packing material of times. The speed of the car shall be 14-inch or greater nominal diameter is approximately 342 miles per hour, and used, a diametrical clearance not greater

potential shall be applied to the cable than 18 inch will be accepted.

during tests. The cable will be shifted

after each passage of the car, thus giving To minimize deviation from accept- 100 places in the cable over which two able clearances in stuffing boxes, the wheels have passed. If the cable fails cables used in them should conform to by short-circuiting or grounding to the the following standardized dimensions: rails or wheels at 11 or more places, it Two-CONDUCTOR-ROUND CABLES

will not be listed by the Bureau. [Par

agraph (c) amended) Cond. Con


(d) Portable cable flame-resistance Single

3size Twisted!

toler. cond.icond.

test. The following test has been estabtric

lished for determining the flame-resist

ant properties of portable cables: Inches Inches Inches Inches Inches Inches No. 8. 0. 65 0.81 0.91 0.99

£0.03 A 6-foot sample of the cable in the No. 6... 51 .77 1.01 1.10


form of a closed U shall be mounted No. 5..

1.01 1. 10 1. 19 5.03 NO. 4.. 57 84 1.08 1.17 1. 27 3.03

horizontally and heated electrically, usNo. 3. 63 .89

1. 34 No, 2..

ing a current that is 500 percent of the 66 .94 1. 27 1.34 1. 48

E. 03 No.1.. 1.05 1.44 1. 51

+03 following conductor ratings: No.1/0.. 1.10 1.52 1. 65

£.04 No. 2/0. .82 1. 18 1.65 1.75

£.04 No.3/0. 87 1. 24 1.77 1. 89 2.07 Ł05 No. 4/0..

1. 33
2. 26

SIZE, A. W. O,
#. 05



A. W. G. cond.

ance 1





1. 17

1. 24



1. 93




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explosion-proof and suitable for use on permissible assemblies. Such label shall not be used without prior written authorization from the Director. Authorization will be granted only upon request addressed to the Director providing the conditions applying thereto have been met. The label shall contain the following: “Explosion-Proof Mine MotorBuilt to Bureau of Mines Schedule-Bureau of Mines File X/P ------." The Bureau will assign an identifying file number in the letter authorizing the use of a label. The label can be in the form of a separate plate or else combined with the standard motor nameplate. A sample of the plate adopted shall be sent to the Supervising Engineer, Electrical. Mechanical Section, at the Central Experiment Station in Pittsburgh, Pa. The Bureau reserves the right to rescind for cause, at any time, any authorization granted under this section.

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the adjacent legs of the sample is 350° F. The flame of a Tirrill gas burner adjusted to give an over-all free flame height of 5 inches and a 3-inch inner cone shall be applied directly underneath the sample at a point 372 inches from the terminal ends of the sheath for 60 seconds, the top of the burner being 3 inches below the lower surface of the sample.

With the gas flame and heating current cut off simultaneously, burning of the sheath shall not spread over more than 14 inches of the folded sample.

At least 5 samples of a given cable will be tested to determine its resistance to flame. If 4 of the 5 samples pass this test, the cable will be listed as “flame resistant" and shall be suitably marked at intervals not exceeding 12 feet with an identifying number assigned by the Bureau of Mines. (Paragraph (d) added]

8 18.7 Inspection and test of parts supplied by other manufacturers. All the accessory parts for an approved machine need not be made by the manufacturer requesting the approval. If parts are obtained from other manufacturers, these accessories may be submitted for inspection and test, either by the builder of the permissible machine or directly by the manufacturer of the accessory. All the requirements to be met under either option are identical. Application for such inspection and test by an accessory manufacturer shall be made by a letter addressed to the Director, Bureau of Mines, Washington, D. C., and shall be accompanied by the required fee (see § 18.2 (a) (3)). When the accessory has successfully met all the requirements the Bureau, upon request, will give the manufacturer thereof a letter stating that further test or inspection of the accessory will not be required if it is constructed in strict accordance with the specifications on file at the Bureau. This letter may be cited to the builder of the complete approved machine. Since the Bureau of Mines does not sanction the words “permissible" or "approved” except as applying to complete assemblies, advertising or labeling such accessories as permissible or approved by the Bureau will not be sanctioned. However, motors' may be advertised and labeled as

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Sec. 25.0 Compliance with the requirements for

obtaining approval. 25.1 Purpose. 25.2 Fees charged. 25.3 Instructions on making applications. 25.4 Conditions governing investigations. 25.5 General requirements. 25.6 Specific requirements, 25.7 Material required for Bureau of Mines

records. 25.8 How approvals are granted. 25.9 Wording, purpose, and use of approval

plate. 25.10 Instructions handling future

changes in design. AUTHORITY: $ $ 25.0 to 25.1C, inclusive, issued under sec. 311, 47 Stat. 410; 30 U. S. C. 7; E. O. 6611, Feb. 22, 1934.

SOURCE: 88 25.0 to 25.10, inclusive, contained in Regulations, Director, Bureau of Mines, approved by the Secretary of the Interior, effective Apr. 16, 1947, 12 F.R. 2650.

$ 25.0 Compliance with the requirements necessary for obtaining approval. To receive approval of the Bureau of Mines for any multiple-shot blasting units a manufacturer must comply with the requirements specified in this part.

§ 25.1 Purpose. The purpose of investigations under this part is to promote the development of suitable multipleshot blasting units for use under special conditions where the firing of several

1 Under this amendment, authorization to advertise and label motors will be limited to those motors which are not combined with switches, resistors, starters, or other auxiliary apparatus.

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