4.6.2 Fire fighting

Fires involving hydrogen should not be approached without appropriate flame detection equipment due to the low visibility of hydrogen flames. Hydrogen fires should not be extinguished until the supply of hydrogen is shut off because of the danger of re-ignition or explosion of an accumulation of unburnt hydrogen. The recommended way of handling a hydrogen fire is to let it burn under control until the hydrogen flow can be stopped.  Small hydrogen fires can be extinguished by dry chemical extinguishers or with carbon dioxide, nitrogen, and steam.   Water in large quantities is the best way of extinguishing anything other than a small hydrogen fire, and is required for spraying adjacent plant to keep it cool and preventing fire spread.  Water spray systems should be provided for hydrogen storage containers, grouped piping, and pumps where potential fire hazards exist. The system(s) shall be arranged to deliver a uniform spray pattern over 100 per cent of the container surface, pumps, and adjacent piping.  Manual control stations shall be located outside the hazardous area, but within effective sight of the facility protected.

No attempt should be made to extinguish fires involving hydrogen or other flammable gas cylinders, unless they are in the open or in a well-ventilated area free of combustibles and ignition sources. Even if located in open or well-ventilated areas, extreme care should still be taken in attempting to extinguish the fire, as this may create a mixture of air and escaping gas that, if re-ignited, might explode. Under no circumstances should firefighters attempt to remove a burning cylinder. An appropriate exclusion zone should be set-up and the burning cylinder(s), and any surrounding cylinders and combustibles, should be kept cool by spraying them with water until the gas escape ceases and the fire extinguishes.