Page images
PDF
EPUB

explosion; (f) rate of detonation; (g), pendulum friction; (b) freezing test by crusher board (for explosives marked low-freezing)'; (i) explosion by influence.*+

16.6 Special tests. In addition the Bureau will carry out, at the request of the manufacturer or applicant, the Trauzl lead-block test, small lead-block test, flame test, large-impact test, maximum-pressure test by Bichel pressure gage, and calorimeter test, for which additional fees will be charged in accordance with this part.**

16.7 Test requirements of explosives for admittance to permissible list. All explosives submitted for admittance to the permissible list of explosives must pass the following chemical and physical tests without showing 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.**

16.8 Poisonous gases. A 680-gram (112-pound) charge of explosive and original wrapper must not evolve 158 liters (54/2 cubic feet) or more of poisonous gases. The poisonous gas that is likely to be evolved on detonation of a permissible explosive is carbon monoxide. Under special conditions hydrogen sulphide and oxides of nitrogen may be evolved.**

16.9 Grade of electric detonator. Each charge shall be fired with the grade of electric detonator recommended by the manufacturer for use with the explosive, but the detonator shall be not less than a No. 6.**

16.10 Complete detonation. 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 the charges are fired with a suitable detonator under a confinement equal to or greater than 1 atmosphere. **

16.11 Unit deflective charge. The unit deflective charge is that weight of an explosive in grams which gives the same swing on the ballistic pendulum as 227 grams (12 pound) of Pittsburgh testing station standard 40-percent straight nitroglycerin dynamite.

The Bureau requires that this unit deflective charge of said explosive shall not exceed 454 grams (1 pound), as tests have shown that explosives whose unit deflective charge exceeds 454 grams (1 pound) will require on account of the lack of strength more than 680 grams (14/2 pounds) in a single charge to blast down coal satisfactorily, and when so used are not permissible in accordance with the requirement in § 16.2 (d) under the prescribed conditions of use.**

16.12 Pendulum friction test. An explosive must pass a pendulum friction test on the Bureau of Mines pendulum friction device 10 trials on the steel anvil with the fiber-faced steel shoe falling from a height of 112 meters (59.1 inches) and carrying an added weight of 20 kilograms (44 pounds) --without showing any more unfavorable result than an almost indistinguishable crackling. A charge of 7 grams of explosive is used in each trial.*+

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

Page 83

16.13 Gallery tests. An explosive before admittance to the Bureau of Mines permissible list must pass without a single ignition the following tests in gallery No. 1 of the Bureau of Mines :

Test 1. Ten trials with a charge equal to the unit deflective charge, each charge being tamped with 1 pound of dry fire-clay stemming, fired into a mixture of natural gas and air containing 8.0=0.3 percent methane and ethane at a temperature of 68° to 86°

F. Test 4. Five trials with a 11/2-pound charge of the explosive fired without stemming into a mixture of natural gas and air containing 4.050.2 percent of methane and ethane and 20 pounds of bituminous-coal dust, 18 pounds of which is to be placed on shelves along the sides of the first 20 feet of the gallery and 2 pounds to be so placed that it will be stirred up by an air current in such a manner that all or part of it will be suspended in the first division of the gallery, at a temperature of 68° to 86° F.**

16.14 Experimental tests. The Bureau will carry out on request any one or more of the tests comprising the complete official tests for permissibility as well as any of the special tests listed in this schedule. Special application should be made for such experimental tests and fees submitted in accordance with this part.**

16.15 Fees. The following schedule of fees has been established: (a) For a complete official test of each explosive to determine its permissibility for use in coal mines--

$250 (b) In case an explosive is withdrawn or fails to pass any of the official

tests, charges will be made for all the tests made up to the time of
withdrawal or failure, plus handling charge of $5 and a charge of
$25 for chemical analysis of the explosive if made. The balance of

the fee submitted will be returned to the applicant. (c) Physical examination (for each size of cartridge)

1 (d) For tbree experimental small lead-block tests_

9 (e) For three rate-of-detonation tests.

5 (f) For three experimental shots in flame-test apparatus_

10 (g) For each experimental shot in gallery : Test 1_

5 Test 4

18 (b) For three experimental shots in ballistic pendulum.

20 (i) Explosion by influence (halved-cartridge method) -(j) For one gage test to determine the gaseous products of explosion- 15 (k) For pendulum-friction test to determine sensitiveness to frictional

impact (1) For freezing test by crusher board.

7 (m) For three experimental shots in Trauzl lead blocks_

10 (n) For three experimental shots to determine calories developed-

13 (0) For large-impact test to determine sensitiveness to direct impact 22 (p) For maximum pressure by Bichel pressure-gage test-

25 (q) Other tests at estimated cost. **

16.16 Conditions under which tests will be made. The conditions under which the Bureau of Mines will test explosives under this part are as follows:

(a) Tests will be made at the Explosives Testing Station of the Bureau of Mines at Bruceton, Pa.

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

4

Page 84

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

(c) The manufacturer or applicant desiring tests to be made shall ship, prepaid, to the Explosives Engineer, Explosives Testing Station, Bureau of Mines, Bruceton, Pa., each explosive in cartridge sizes and quantities as requested, together with the original bill of lading (and/or copies thereof). For complete official tests for permissibility, it is requested that the manufacturer ship each explosive in sizes and quantities as follows:

(1) Fifty pounds of each in 114- by 8-inch cartridges, but if the cartridge count is less than 150 then 150 cartridges is the minimum quantity required.

(2) Fifty cartridges of each in the smallest diameter in which it is desired the explosive shall become permissible, except when this smallest diameter is 114 by 8 inches.

(3) Ten cartridges of each in any diameter other than those covered by subparagraphs (1) and (2), and in which it is desired the explosive shall become permissible.

Should the manufacturer later desire to market other diameters, the Bureau will without charge establish the basic data for grams of wrapper and apparent specific gravity for those diameters,

Physical tests will start not less than 60 days after shipment of the explosive, as evidenced by the bill of lading, or 60 days after manufacture, when this date is properly certified. The applicant will be notified of the date of starting tests in ample time to have a representative present to witness them.

(d) No one is to be present at or participate in these tests except the necessary Government officers at the testing station, their 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) The tests will be made in the order of the receipt of the applications for them, provided the necessary quantity of explosive has been received at the testing station by the date set, of which due notice will be given by the Bureau of Mines. (g) On any

application, not more than five explosives will be tested to determine their permissibility for use in coal mines, nor will more than five explosives be tested for any manufacturer during a fiscal year so long as there are other manufacturers desiring tests who have not had five explosives tested during that fiscal year.

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

(i) 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.

(j) From time to time field samples of permissible explosives will be collected, and tests will be made of these explosives as they are supplied for use in coal mines in the various States. Field samples

Page 85

[225]

per

collected from original shipping cases will be tested for their missibility and will be analyzed. The results of this chemical analysis and these physical tests of the explosive must agree, within the tolerances as promulgated by the Bureau of Mines, with the chemical analysis and physical tests of the original sample submitted for tests.

(k) The chemical analysis of the explosive and the analysis of the gaseous products will be furnished only to the manufacturer.**

16.17 Remittances. Applicants for tests will be required to send the Director of the Bureau of Mines, Washington, D. C., check or bank draft, made payable to Treasurer of the United States, covering the total fee as set forth in above table. Such fees must be received at least 3 weeks prior to the date set for beginning the tests.**

16.18 Tolerance for permissible explosives. The tolerances promulgated by the Bureau of Mines provide for reasonable limits of variation in the results of analyses and tests of field samples and manufacturers' samples of permissible explosives. These tolerances as now existing and as stated below are quoted, except as amended November 15, 1920, and February 26, 1921, from Bulletin 96, in which they were published after having been established and made effective July 1, 1915.

In order to define more exactly what is meant by the phrase "similar in all respects” in the definition of a permissible explosive, namely, “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”, the tolerances in the following sections are established for field samples or manufacturers' samples of explosives, beyond which such lot of explosives cannot vary and still be considered permissible for use in coal mines.**

16.19 Chemical analysis-(a) Moisture. To be fixed by a sliding, scale from 142 percent at zero to 4 percent at 10 percent of moisture in original sample, this tolerance being on total percentage of moisture in the explosive.

(b) Other ingredients or their equivalents. In quantities not exceeding 60 percent, according to curve shown in figure 1, except that the chemical tolerance for carbonaceous combustible material is changed to plus or minus 3 percent regardless of the amount of carbonaceous combustible material reported as present. For ingredients in quantities of 60 percent or more, the tolerance shall be plus or minus 3 percent: Provided, That the ingredients of a permissible explosive shall be considered to be those substances reported as found by the Bureau of Mines in the original sample of that explosive submitted for tests as to its permissibility; and, Provided further, That an equivalent shall be considered to be a substance which would not materially alter the properties of the explosive and which would produce the same result as the original substance.

6

Storm, C. G., The Analysis of Permissible Explosives: Bull. 96, Bureau of Mines, 1916, 88 pp.

Page 86

**For statutory and source citations, see note to 8 16.0.

[ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small]

FIGURE 2.—Curve of limit variation in composition of permissible explosives.

For the purpose of applying the chemical tolerance for explosives containing ammonium nitrate, the commercial ammonium nitrate will be reported as the sum of the ammonium nitrate, ammonium chloride, and ammonium sulphate reported as present, and the tolerance applied to this figure.

The sum of the ammonium chloride and the ammonium sulphate will be reported separately in a note, and the tolerance applied to their sum will be 4 percent of the commercial ammonium nitrate reported as present in the basic sample, except in those cases where the tolerance thus applied would be less than for a separate ingredient, when the tolerances for "other ingredients” would apply.**

16.20 Products of explosion determined by Bichel-gage tests. The volume of poisonous gases from 680 grams of the explosive, including its wrapper, must be less than 158 liters, except that in case the first test yields 158 liters or more poisonous gases per 680 grams of the explosive, including its wrapper, the average result of three determinations is made and the average accepted if the average deviation of the mean (A. D.) is less than plus or minus 1.25 percent. Otherwise, further determinations will be made until the above criterion is satisfied or until a total of six determinations has been obtained.***

16.21 Physical tests. In making determinations of rate of detonation and of unit deflective charge by the ballistic pendulum, three

* In the case of a doubtful result, the mean and average deviation from the mean (A. D.), omitting the doubtful observation, are found; then the difference between the doubtful observation and the mean is determined, and if this is equal to or greater than 4 A. D., it is rejected, and the remaining results are averaged.

'For the method of making the test see Munroe, C. E., and Tiffany, J. E., Physical Testing of Explosives at the Bureau of Mines Explosives Experiment Station, Bruceton, Pa.: Bull. 346, Bureau of Mines, 1931, 148 pp.

**For statutory and source citations, see note to 8 16.0.

Page 87

« PreviousContinue »