46 CFR §182.480

1. (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.
2. (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.
3. (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.
4. (d)A flammable vapor detection system must provide a visual and audible alarm at the operating station.
5. (e)A sensor must be located above the expected bilge water level in the following locations:
   1. (1)The lowest part of a machinery space;
   2. (2)The lowest part of a space containing a fuel tank when separate from the machinery space; and
   3. (3)Any other location when required by the cognizant OCMI.
6. (f)A flammable vapor detection system must be installed so as to permit calibration in a vapor free atmosphere.
7. (g)Electrical connections, wiring, and components for a flammable vapor detection system must comply with part 183 of this chapter.
8. (h)An operation and maintenance manual for the flammable vapor detection system must be kept onboard.