46 CFR § 182.480 - Flammable vapor detection systems.
(a) A flammable vapor detection system required by § 182.410(c) must meet UL 1110 (incorporated by reference; see 46 CFR 175.600) or be approved by an independent laboratory.
(b) Procedures for checking the proper operation of a flammable vapor detection system must be posted at the primary operating station. The system must be self-monitoring and include a ground fault indication alarm.
(c) A flammable vapor detection system must be operational for 30 seconds prior to engine startup and continue sensing the entire time the engine is running.
(d) A flammable vapor detection system must provide a visual and audible alarm at the operating station.
(e) A sensor must be located above the expected bilge water level in the following locations:
(1) The lowest part of a machinery space;
(2) The lowest part of a space containing a fuel tank when separate from the machinery space; and
(3) Any other location when required by the cognizant OCMI.
(f) A flammable vapor detection system must be installed so as to permit calibration in a vapor free atmosphere.
(g) Electrical connections, wiring, and components for a flammable vapor detection system must comply with part 183 of this chapter.
(h) An operation and maintenance manual for the flammable vapor detection system must be kept onboard.