There have been numerous explosions resulting from the use of gas
refrigerators with naked flames on petrol-powered boats. The low level
permanent flame of a pilot light or burner could be the prime source of ignition
for any stray petrol fuel or vapour. To prevent this happening the pilot lights and
burners on LPG or paraffin refrigerators installed in boats with a petrol engine
must be completely enclosed by a suitable flame trap.

When starting to re-fuel, a flash explosion occurred that blew out the cabin windows and injured a woman, though fortunately no fire started. It was determined that even with the petrol pump nozzle fully inserted into the deck fuel connection, sufficient petrol vapour was produced to rise over the 175mm coaming, travel along the cockpit floor and into the cabin to be ignited by the permanent low-level burner flame on a LPG fridge. Before starting to fill, the pump attendant had asked specifically if any appliances were operating on board and was told “no”. [8.2]

Combustion air and combustion products must be drawn and expelled through
a suitable flame trap. Alternatively, combustion air can be piped to the appliance
from outside the vessel, or from a point inside the vessel above the level of any
opening to the outside air. [8.2]