30 CFR § 77.201-1
Tests for methane; qualified person; use of approved device.
Tests for methane in structures, enclosures, or other facilities, in which
coal is handled or stored shall be conducted by a qualified person with a
device approved by the Secretary at least once during each operating shift,
and immediately prior to any repair work in which welding or an open flame is
used, or a spark may be produced.