Cool pressurised gas containers

Control Measure Knowledge

Responders should understand that as cylinders heat up in a fire the pressure inside them increases, direct flame contact will also weaken the cylinder wall. If heat continues to be applied then the maximum safe working pressure of the cylinder may be exceeded and eventually the cylinder will burst or fail in a violent manner, resulting in the release of a considerable amount of energy. Subsequent events will depend on the gas type. The most effective way to safely control the hazards at cylinder incidents is to stop the heat source and cool the cylinder shell. Water sprays are the most effective way of achieving this.

It should be noted that in the particular case of hydrogen, gas escaping under pressure can reignite so that consideration may have to be given to allowing the flame to burn or managing it with a narrow cone of water.

Any cylinder found to be physically damaged or heated by fire should be treated with caution after the fire has been extinguished as it may have been weakened, increasing the risk of cylinder failure.

Gas leak

If there is a gas leak from a valve, a simple operation to isolate could be carried out by closing the valve. If the leak cannot be stopped, as a cylinder only holds a finite amount of gas, after a period of time the gas will have escaped and will no longer present a hazard.

Personnel should understand the properties of the gases involved, which includes that:

Hazardous materials may be flammable, oxidant, asphyxiant, toxic or corrosive
Some will be heavier than air, some lighter than air, which will affect their behaviour if released
If released as a liquid, the liquid will fall to the ground and will usually quickly convert to a gas. The gas, if lighter than air, will then rise into the atmosphere.
There is a large change in the volume between a liquid and a gas. There will be a much greater quantity of gas formed.

For further information refer to Hazardous materials: Release or spill of hazardous material

Strategic Actions

Fire and rescue services should

Have procedures and support arrangements for the hazards that may be encountered and actions to take when dealing with incidents involving cylinders
Have procedures and support arrangements regarding the hazards that may be encountered and actions to take for a potential BLEVE
Ensure that all personnel can recognise the situations and indicators of a potential BLEVE situation
Provide appropriate means to enable the safe and effective delivery of firefighting media, without the requirement for physical resources

Tactical Actions

Incident commanders should

Gather relevant information from all available sources regarding the substance involved and its potential for BLEVE
Recognise potential BLEVE situations and exercise extreme caution when approaching them
Extinguish the fire and apply cooling sprays directly on to any affected cylinders
Establish ground monitors and branch holding equipment to minimise the deployment of personnel in the risk area
Leave damaged or heated cylinders in situ and refer to specialist agencies for safe disposal
Treat all fire affected cylinders as if they contain acetylene if their contents cannot be identified
Approach potential BLEVE situations, where safe to do so, from an upwind direction and from the side of the tank (avoiding the 45-degree zones at each tank end)
Consider evacuating the potential blast zone and give evacuation or shelter-in-place guidance to those within range of projectiles
If a BLEVE is imminent, consider adopting defensive tactics where there is no risk to life. If there is a risk to life, defensive tactics may be the only option.
Consider ‘flame bending’ to prevent flame contact with pressurised tanks/containers
Consider using heavy, coarse sprays to afford protection to personnel
Consider positioning firefighting jets to prevent firespread using branch holders and ground monitors
In the case of hydrogen, extinguish surrounding fires and apply cooling sprays to cylinder
Consider managing jet flame with narrow spray cones of water without extinguishment