What should be done before applying water to gas cylinders in a fire?

Before applying water to gas cylinders in a fire, it is essential to shut the valve or ensure that the fuel has been consumed. This practice is critical for several reasons. Firstly, if the valve is still open, applying water could lead to an explosion or further release of flammable gas when it is cooled with water. Shutting the valve eliminates the risk of additional gas escaping into the environment.

Secondly, ensuring the fuel has been consumed can mitigate the potential for re-ignition. If gas is still present, applying water may only cool the cylinder without addressing the core issue of dangerous, flammable gas being released. Cooling a gas cylinder effectively is vital, but it must be done safely, which involves controlling fuel release as a priority.

While applying foam or moving the cylinder might seem like viable options, they do not address the immediate risk of the cylinder itself releasing flammable gas. Immediate application of water without controlling the valve may compound the danger rather than mitigate it. Thus, containing the gas source first helps establish a safer working environment for firefighters and prevents escalation of the fire hazard.