THINK DETAILS FOR EXPLOSIVITY

                      Is there time to respond?

One method of response is to ventilate and/or to knock down the explosive vapour or gas cloud using a water spray.  The air entrained in the water spray dilutes the cloud, lowers the gas concentration and reduces the extent of the hazardous zone (refer to TREE 4 - Think Details  - Is there time to respond?).

Part of the response should be to remove all ignition sources.  Although the temperature of an ignition source must be higher than the ignition temperature of the gas or vapour, only a small amount of energy is required to ignite an explosive/flammable gas or vapour.  Naked flames, the arc of a short circuit, hot surfaces, sparks, static discharges could be potential sources of ignition and should be removed.

Operating diesel engines are known to have been ignition sources of several explosive/flammable gas clouds.  A ship’s diesel driven emergency fire pumps could be a source of ignition.  The discharge of CO₂ from a fire extinguisher into the air intake of a diesel engine will stop it.  Furthermore, non-sparking hand tools and explosive proof equipment and working methods that do not produce sparks should be used.