30 CFR § 27.32 Tests to determine performance of the system.
(a)Laboratory tests for reliability and durability. Five
hundred successful consecutive tests2 for gas detection, alarm
action, and power shutoff in natural gas-air mixtures3 shall be
conducted to demonstrate acceptable performance as to reliability and
durability of a methane-monitoring system. The tests shall be conducted as
2 Normal replacements and adjustments shall not constitute a
3 Investigation has shown that, for practical purposes, natural gas
(containing a high percentage of methane) is a satisfactory substitute for
pure methane in these tests.
(1) The methane detector component shall be placed in a
test gallery into which natural gas shall be made to enter at various rates
with sufficient turbulence for proper mixing with the air in the gallery. To
comply with the requirements of this test, the detector shall provide an
impulse to actuate an alarm at a predetermined percentage of gas and also
provide an impulse to actuate a power shutoff at a second predetermined
percentage of gas. (See §§27.21, 27.22, 27.23, and 27.24.)4
4 At the option of MSHA, these tests will be conducted with dust or
moisture added to the atmosphere within the gallery.
(b)Field tests. MSHA reserves the right to conduct tests, similar to
those stated in paragraph (a) of this section, in underground workings to
verify reliability and durability of a methane-monitoring system installed in
connection with a piece of mining equipment.