(a) Each compressor building in a compressor station must have a fixed gas detection and alarm system, unless the building is:
(1) Constructed so that at least 50 percent of its upright side area is permanently open; or
(2) Located in an unattended field compressor station of 1,000 horse power (746 kW) or less.
(b) Except where shutdown of the system is necessary for maintenance under subdivision (c) of this section, each gas detection and alarm system required by this section must:
(1) continuously monitor the compressor building for a concentration of gas in air of not more than 25 percent of the lower explosive limit; and
(2) if that concentration of gas is detected, warn persons about to enter the building and persons inside the building of the danger.
(c) Each gas detection and alarm system required by this section must be maintained to function properly. The maintenance must include performance tests.