30 CFR § 75.320
Air quality detectors and measurement devices.
(a) Tests for methane shall be made by a qualified person with MSHA
approved detectors that are maintained in permissible and proper operating
condition and calibrated with a known methane-air mixture at least once every
(b) Tests for oxygen deficiency shall be made by a qualified person with
MSHA approved oxygen detectors that are maintained in permissible and proper
operating condition and that can detect 19.5 percent oxygen with an accuracy
of ±0.5 percent. The oxygen detectors shall be calibrated at the start of
each shift that the detectors will be used.
(c) Handheld devices that contain electrical components and that are used
for measuring air velocity, carbon monoxide, oxides of nitrogen, and other
gases shall be approved and maintained in permissible and proper operating
(d) An oxygen detector approved by MSHA shall be used to make tests for
oxygen deficiency required by the regulations in this part. Permissible flame
safety lamps may only be used as a supplementary testing device.
(e) Maintenance of instruments required by paragraphs (a) through (d) of
this section shall be done by persons trained in such maintenance.