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for safe, durable, and practical devices which will meet not only the demands of the existing situations but also the demands of potential and anticipated situations for which filter-type respirators are designed. However, with the continued adaptation of these devices to new situations and conditions it is possible that instances might arise where the protection afforded would be inadequate. The Bureau of Mines, with the cooperation of both the manufacturers of respirators and the users of respirators, endeavors to be on the alert to these new situations. When any situation arises in which the inadequacy of protection or unusual hazard attending the use of an approved device is established, the manufacturer or manufacturers of any devices involved are requested to affix caution statements, or, if necessary, to cease marketing the device for the particular situation or condition until such changes or provisions as will provide adequate protection are made, it being understood that any provisions or changes made must be submitted to the Bureau of Mines and have this Bureau's approval before they are adopted. Should the situation require a change in the basic requirements and/or tests provided in this part such changes will be issued as a supplement to the current schedule (this part) and later incorporated in a revision.**

Subchapter C—Explosives, Blasting Devices: Tests for

Permissibility; Fees

PART 15—EXPLOSIVES USED IN METAL MINES AND

OTHER ENGINEERING OPERATIONS

Sec.

Sec. 15.0 Compliance with the requirements 15.4 Test requirements of explosives

necessary for obtaining approval, used in metal mines, tunnels, 15.1 Nature of tests.

quarries, and other engineering 15.2 Fees.

operations. 15.3 Conditions under which tests will 15.5 Remittances.

be made.

Section 15.0 Compliance with the requirements necessary for obtaining approval. To receive approval of the Bureau of Mines for any explosives used in metal mines and other engineering operations a manufacturer must comply with the requirements specified in this part.****

**88 15.0 to 15.5, inclusive, issued under the authority contained in sec. 5, 37 Stat. 682, sec. 311, 47 Stat. 410; 30 U.S.C. 7: E.O. 4239, June 4, 1925; E.O. 6611, Feb. 22, 1934.

**The source of $8 15.0 to 15.5, inclusive, is Schedule 1B, Secretary of Commerce, Apr. 3, 1926. Amendments are noted in brackets following sections affected.

15.1 Nature of tests. Official tests of an explosive for its suitability for use in metal mines, tunnels, quarries, and other engineering operations shall involve the following: (a) physical examination, (b) chemical analysis (to manufacturer only), (c) unit deflective charge, (d) gaseous products of explosion, (e) rate of detonation,

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**For statutory and source citations, see note to 14.0.

$90

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(f), pendulum friction, (g) freezing test by crusher board (for explosives marked low freezing), (h) explosion by influence. ,

In addition the Bureau will carry out at the request of the manufacturer or applicant the Trauzl lead-block test, small lead-block test, small impact test (usually applicable only to explosives of very fine granulation), large impact test, maximum pressure test by Bichel gage, calorimeter test, ignitibility test, and fire-setting capacity test, for which additional fees will be charged in accordance with this schedule.** [As amended, Secretary of Commerce, Jan. 12, 1932, Secretary of the Interior, May 13, 1935]

15.2 Fees. The following schedule of fees has been established: (a) For a complete official test of each explosive to determine its suit

ability for use in metal mines, tunnels, quarries, and other engi

neering operations (b) Physical examination (for each size of cartridge). (c) For three experimental small lead-block tests (d) For three rate of detonation tests (e) For three experimental shots in ballistic pendulum, to determine the unit deflective charge

20 (f) Explosion by influence (halved cartridge method). (g) For one gage test to determine the gaseous products of explosion.

15 (h) For pendulum friction test to determine sensitiveness to frictional

impact---(i) Freezing test by crusher board. (j) For three experimental shots in Trauzl lead blocks

10 (k) For three experimental shots to determine the calories developed.- 13 (1) For small-impact test to determine sensitiveness to direct impact-(m) For large-impact test to determine sensitiveness to direct impact.. (n) For maximum pressure by Bichel pressure-gage test-

25 (0) Ignitibility tests (p) Fire-setting capacity test

4 (g) Other tests at estimated cost. ** [As amended, Secretary of Commerce, Jan. 12, 1932, Secretary of the Interior, May 13, 1935]

15.3 Conditions under which tests will be made. (a) Tests will be made at the Explosives Experiment Station of the Bureau of Mines, Bruceton, Pa.

(b) Application for tests shall be addressed to the Director, Bureau of Mines, Washington, D. C.

(c) The manufacturer or applicant desiring tests to be made shall consign to the Explosives Engineer, Explosives Experiment Station, Bureau of Mines, Bruceton, Pa., each explosive in cartridge size and quantities as requested and send the original bill of lading to the Èxplosives Engineer, Bureau of Mines, 4800 Forbes Street, Pittsburgh, Pa. For complete tests for suitability 50 pounds of each explosive is required.

Physical tests will start not less than 60 days after shipment of the explosives, as evidenced by the bill of lading. The applicant will be notified of the date of starting tests in ample time to have a representative present to witness the tests.

(d) No one is to be present at or participate in these tests except the necessary Government officers at the experiment station, their

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**For statutory and source citations, see note to 8 15.0.

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assistants, and the representatives of the manufacturer of the explosives or the applicant desiring tests to be made. The last shall be present in the capacity of observers only.

(e) The conduct of the tests shall be entirely in the hands of the Bureau's representatives in charge of the investigation.

(f) These tests will be made in the order of the receipt of the applications for them, provided the necessary quantity of the explosive has been received at the experiment station by the date set, of which due notice will be given by the Bureau of Mines.

(g) A list of the explosives that pass certain requirements satisfactorily may be furnished to the State mine inspectors in the several States and may be made public in such manner as is considered desirable.

(h) The results of tests are to be considered confidential within the applicant's organization and are not to be made public prior to official publication by the Bureau. Tests for a manufacturer are limited to samples of explosives which are his own product.**

15.4 Test requirements of explosives used in metal mines, tunnels, quarries, and other engineering operations. Each charge shall be fired with an electric detonator of not less efficiency than a No. 6 consisting by weight of 80 parts of mercury fulminate and 20 parts of potassium chlorate (or their equivalent); an electric igniter may be used with slow-burning explosives.

The failure of two or more charges to detonate or explode completely in the course of the official tests will be considered an unfavorable result when fired with a suitable detonator under confinement equal to or greater than 1 atmosphere.

An explosive must pass a pendulum friction test, on the Bureau of Mines pendulum friction device, of 10 trials with the steel anvil and the fiber-faced steel shoe, the latter falling from a height of 11/2 meters (59.1 inches) and carrying an added weight of 20 kilograms (44 pounds), without showing any more unfavorable results than an almost indistinguishable crackling.

The explosive must be in such condition that the chemical and physical tests do not show any unfavorable results. An explosive will be considered unsatisfactory if it is not chemically stable, if it shows leakage of liquid-explosive ingredient, or if it is in such condition that exudation of liquid-explosive ingredient would occur in handling or transportation.

An explosive will be considered unsatisfactory for use in metal mines, tunnels, quarries, and similar operations if, on detonation in the gages, it evolves poisonous gases in quantities that may be considered harmful to the health of the miners.**

15.5 Remittances. Applicants who submit an explosive for tests will be required to send to the Director, Bureau of Mines, Washington, D. C., check or bank draft, made payable to the Treasurer of the United States, covering the total fee required for the complete tests. Such fees must be received at least 3 weeks prior to the date set for beginning the tests.**

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**For statutory and source citations, see note to $ 15.0.

PART 16-EXPLOSIVES USED IN COAL MINES

Sec.

Sec.
16.0 Compliance with the require- 16.10 Complete detonation.

ments necessary for obtaining 16.11 Unit deflective charge.
approval.

16.12 Pendulum friction test.
16.1 Definition of a permissible explo- 16.13 Gallery tests.
sive,

16.14 Experimental tests. 16.2 Prescribed conditions for use of 16.15 Fees. permissible explosives.

16.16 Conditions under which tests will 16.3 Conditions under which a per

be made. missible explosive should not be 16.17 Remittances. used.

16.18 Tolerance for permissible explo16.4 Explosives not to be considered

sives. permanently permissible.

16.19 Chemical analysis. 16.5 Complete official test.

16.20 Products of explosion determined 16.6 Special tests.

by Bichel-gage tests. 16.7 Test requirements of explosives 16.21 Physical tests.

for admittance to permissible 16.22 Application of tolerances.
list.

16.23 Pendulum friction test. 16.8 Poisonous gases.

16.24 Field samples of permissible ex16.9 Grade of electric detonator.

plosives.

CROSS REFERENCE

Regulations of the Geological Survey relating to the storage, transportation, and use of explosives. See 88 211.79–211.91.

Section 16.0 Compliance with the requirements necessary for obtaining approval. To receive approval of the Bureau of Mines for any explosives used in coal mines a manufacturer must comply with the requirements specified in this part.**

*88 16.0 to 16.24, inclusive, issued under the authority contained in sec. 311, 47 Stat. 410; 30 U.S.C. 7; E.O. 6611, Feb. 22, 1934.

*The source of $$ 16.0 to 16.24, inclusive, is Schedule 17C, Secretary of the Interior, Mar. 21, 1935.

16.1 Definition of a permissible explosive. A permissible explosive is an explosive which is similar in all respects to the sample which has passed certain tests prescribed by the Bureau of Mines to determine its safety for use in coal mines, and when used in accordance with the conditions prescribed by the Bureau.

While permissible explosives are designed especially for use in coal mines, they are suitable for use in many other blasting operations.*+

16.2 Prescribed conditions for use of permissible explosives. (a) That the explosive is in all respects similar to the sample submitted by the manufacturer for test.

(b) That electric detonators are used of not less efficiency than those prescribed, namely, those consisting by weight of 80 parts of mercury fulminate and 20 parts of potassium chlorate (or their equivalents).

(c) That the explosive, if frozen, shall be thoroughly thawed in a safe and suitable manner before use.

(d) That the quantity used for a shot does not exceed 11/2 pounds (680 grams) and that it is properly confined with clay or other incombustible stemming.**

**For statutory and source citations, see note to § 16.0.

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16.3 Conditions under which a permissible explosive should not be used. After an explosive has passed the required tests and its brand name has been published in a list of permissible explosives, it is not used in a permissible manner if one or more of the following conditions prevail:

(a) If stored under improper conditions until it undergoes a change in character.

(b) If used in a frozen or partly frozen condition.
(c) If used in excess of 112 pounds (680 grams) per shot.

(d) If the diameter of the cartridge is less than that designated in the column “Smallest permissible diameter."

(e) If fired with an electric detonator of less efficiency than that prescribed.

(f) If fired with fuse. (g) If fired without stemming. (h) If fired with combustible stemming. (i) If fired in the presence of a dangerous percentage of firedamp.

If the shot is a depending shot or is bored into the solid or has a burden so heavy that the shot obviously is liable to blow out.

(k) If the shot is fired by a nonpermissible type of blasting unit.**

16.4 Explosives not to be considered permanently permissible. Moreover, even when all of the prescribed conditions have been met, no explosive on the permissible list should necessarily be considered as being permanently a permissible explosive, for the Bureau reserves the right, on fuller information concerning the conditions that lead to safety, to revise this list; but any permissible explosive when used under the prescribed conditions may properly continue to be considered a permissible explosive until notice of its withdrawal or its removal from the list has been officially published, or until its name is omitted from a later list published by the Bureau of Mines.

Furthermore, the manufacturers of a permissible explosive may withdraw it at any time. Manufacturers are urged to do so when replacing a permissible explosive by one of superior qualities.

Permissible explosives will be placed on an inactive list at the request of the manufacturer, or if they have not been manufactured during any calendar year. The distinction between the inactive list and the active list of permissible explosives is that the inactive list is not published. The Bureau will transfer explosives from the inactive list to the active list of permissible explosives upon the request of the manufacturer, in accordance with the regulations then in force, and without cost to him.

After further experiments and conferences the Bureau of Mines may find it advisable to adopt additional and more severe tests to which all permissible explosives may be subjected, in the hope that through the use of only such explosives as pass the more severe tests the lives of miners may be better safeguarded.*+

16.5 Complete official test. A complete official test of an explosive for its permissibility for use in coal mines shall involve the following: (a) physical examination; (b) chemical analysis; (c) unit deflective charge; (d) gallery tests 1 and 4; (e) gaseous products of

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**For statutory and source citations, see note to s 16.0.

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