[Code of Federal Regulations]
[Title 30, Volume 1]
[Revised as of July 1, 2002]
From the U.S. Government Printing Office via GPO Access
[CITE: 30CFR15.20]
[Page 84-85]
TITLE 30--MINERAL RESOURCES
CHAPTER I--MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR
PART 15--REQUIREMENTS FOR APPROVAL OF EXPLOSIVES AND SHEATHED EXPLOSIVE UNITS--Table of Contents
Subpart B--Requirements for Approval of Explosives
Sec. 15.20 Technical requirements.
(a) Chemical composition. The chemical composition of the explosive
shall be within the tolerances furnished by the applicant.
(b) Rate-of-detonation test. The explosive shall propagate
completely in the rate-of-detonation tesst. The test is conducted at an
ambient temperature between 68 and 86 deg.F. Nongelatinous explosives
are initiated with a test detonator only, while gelatinous explosives
are initiated with a test detonator and a 60-gram tetryl pellet booster.
The test is conducted on--
(1) A 50-inch column of 1\1/4\ inch diameter cartridges; and
(2) A 50-inch column of the smallest diameter cartridges less than
1\1/4\ inches submitted for testing.
(c) Air-gap sensitivity. The air-gap sensitivity of the explosive
shall be at least 2 inches at the minimum product firing temperature and
3 inches at a temperature between 68 and 86 deg.F, and the explosive
shall propagate completely.
(1) Air-gap sensitivity of the explosive is determined in the
explosion-by-influence test using the 7-inch cartridge method. The air-
gap sensitivity is determined for 1\1/4\ inch diameter cartridges and
each cartridge diameter smaller than 1\1/4\ inches. Explosives are
initiated with a test detonator.
(2) The 7-inch cartridge method is conducted with two 8-inch
cartridges. One inch is cut off the end of each cartridge. The
cartridges are placed in a paper tube, the cut ends facing each other,
with the appropriate 2-inch or 3-inch air gap between them. The test is
conducted at a temperature between 68 and 86 deg.F and at the minimum
product firing temperature proposed by the applicant, or 41 deg.F,
whichever is lower. The test temperature at which the explosive
propagates completely will be specified in the approval as the minimum
product firing temperature at which the explosive is approved for use.
(d) Gallery Test 7. The explosive shall yield a value of at least
450 grams for the lower 95 percent confidence limit (L95) on
the weight for 50 percent probability of ignition (W50) in
gallery test 7 and shall propagate completely. The L95 and
W50 values for the explosive are determined by using the
Bruceton up-and-down method. A minimum of 20 trials are made with
explosive charges of varying weights, including wrapper and seals. Each
charge is primed with a test detonator, then tamped and stemmed with one
pound of dry-milled fire clay into the borehole of a steel cannon. The
cannon is fired into air containing 7.7 to 8.3 percent of natural gas.
The air temperature is between 68 and 86 deg.F.
(e) Gallery Test 8. The explosive shall yield a value of at least
350 grams for the weight for 50 percent probability of ignition
(WCDG) in gallery test 8 and shall propagate completely. The
(WCDG) value for the explosive is determined using the
Bruceton up-and-down method. A minimum of 10 tests are made with
explosive charges of varying weights, including wrapper and seals. Each
charge is primed with a test detonator, then tamped into the borehole of
a steel cannon. The cannon is fired into a mixture of 8 pounds of
bituminous coal dust predispersed into 640 cubic feet of air containing
3.8 to 4.2 percent of natural gas. The air temperature is between 68 and
86 deg.F.
[[Page 85]]
(f) Pendulum-friction test. The explosive shall show no perceptible
reaction in the pendulum-friction test with the hard fiber-faced shoe.
Ten trials of the test are conducted by releasing the steel shoe from a
height of 59 inches. If there is evidence of sensitivity, the test is
repeated with the hard fiber-faced shoe.
(g) Toxic gases. The total volume equivalent to carbon monoxide (CO)
of toxic gases produced by detonation of the explosive shall not exceed
2.5 cubic feet per pound of explosive as determined in the large chamber
test. The explosive shall propagate completely.
(1) The large chamber test is conducted with a one-pound explosive
charge, including wrapper and seal, primed with a test detonator. The
explosive charge is loaded into the borehole of a steel cannon, then
tamped and stemmed with one pound of dry-milled fire clay. The cannon is
fired into the large chamber and the gaseous products resulting from
detonation of the explosive are collected and analyzed for toxic gases.
At least two trials are conducted.
(2) The equivalent volume of each toxic gas produced, relative to
CO, is determined by multiplying the measured volume of the gas by a
conversion factor. The conversion factor is equal to the threshold limit
value, time weighted average (TLV-TWA) in parts-per-million for CO
divided by the TLV-TWA for the toxic gas. The TLV-TWA conversion factor
for each gas for which MSHA shall test is specified in Table I of this
subpart. The total volume equivalent to CO of the toxic gases produced
by detonation of the explosive is the sum of the equivalent volumes of
the individual toxic gases.
Table I--Conversion Factors for Toxic Gases
[For Equivalent Volume Relative to Carbon Monoxide]
------------------------------------------------------------------------
Toxic Gas
----------------------
Conversion TLV-TWA
Factor (PPM)
------------------------------------------------------------------------
Ammonia.......................................... 2 25
Carbon Dioxide................................... 0.01 5000
Carbon Monoxide.................................. 1 50
Hydrogen Sulfide................................. 5 10
Nitric Oxide..................................... 2 25
Nitrogen Dioxide................................. 17 3
Sulfur Dioxide................................... 25 2
------------------------------------------------------------------------
(h) Cartridge diameter and length changes. (1) For proposed changes
to an approved explosive involving only cartridge diameter or length,
MSHA will determine what tests, if any, will be required.
(2) When a proposed change to an approved explosive involves a
smaller diameter than that specified in the approval, the rate-of-
detonation and air-gap sensitivity tests will be conducted.
(3) No test will be conducted on cartridges with diameters the same
as or smaller than those that previously failed to detonate in the rate-
of-detonation test.
(i) New technology. MSHA may approve an explosive that incorporates
technology for which the requirements of this subpart are not applicable
if MSHA determines that the explosive is as safe as those which meet the
requirements of this subpart.