by John Robertson
Training on 2nd August was an introduction to the new iZone truck. This is a vehicle for use, on request, either by Auxiliaries or Rurals in iZone incidents. It looks like a small version of 52. The special feature is a high pressure pump (in addition to the normal pump) to produce a ‘water mist’. Water mist is now the standard firefighting method in hazardous enclosed spaces, e.g. tunnels, ships’ engine rooms or oil refineries. The principle behind water mist of very small droplets is that all the water used is evaporated rather than just running as liquid onto the ground. When water evaporates (boils off as steam) it absorbs far more heat than if it merely heats up as liquid. The increased heat absorption is very large – a factor of around 100:1. This means that the water is vastly more effective in removing one of the three elements of the fire triangle, i.e. heat. It is a very effective protection for the person on the branch from radiant heat. All the water vapour produced at the fire front has another effect in that it partly excludes oxygen from the fire. This further reduces fire intensity. Flow rates around 5 litres per minute do more to quell a fire than 100 lpm in a conventional jet. There is nothing toxic or environmentally damaging. Water mist has a very important part to play in future bush fire fighting.
Peter Mason was master of ceremonies and gave each person present, Rural and Auxiliary, a go both on the branch and the high pressure pump.
When that had all been done Rurals and Auxiliaries had a further joint training exercise in which both units showed the other the features of their trucks. This knowledge will stand all of us in good stead as and when we have to operate jointly in the iZone.