Self defense spray systems

Some of the vehicles involved in burnover incidents had functioning hand held or fixed self defense spray systems in operation. The survival of the Geelong City Tanker, and the loss of the Geelong West Tanker, at Linton in 1998 graphically indicated the potential benefit of such systems. In this incident, 2 essentially similar tankers were overrun by fire on a trail in heavy bush following a wind change. The crew of the Geelong City Tanker took shelter in their truck, operating fog lines for self defense. Their available 1000 litres of water was exhausted just after the fire passed, and the truck and crew survived with superficial damage. The Geelong West Tanker, however, was out of water and was destroyed in the fire, and all 5 crew were killed (Figure 5). Earlier in the day, the Snake Gully Tanker crew exhausted their available 700 litres during their appliance burnover at the same fire, though the vehicle survived with severe scorching.

Engine 3473, patrolling a back burn at the 1997 Logan fire, survived being overun by fire when changing conditions produced spotting in a forest. Two crew defended the truck with a fogline from the wheel arch as the fire burned past. The truck was externally scorched but there were no injuries. When the Glen Park Tanker was overrun, 2 crew sheltered under a blanket in the cabin whilst the other 3 sheltered in the rear crew haven, operating hoselines for protection whilst the fire passed over. All survived uninjured, though the remaining water supply of approximately 1000 litres was exhausted in the burnover and the rear tyres caught fire, subsequently destroying the truck. When Glendale Engine 24 was overrun by fire in California, one crew member remained with the vehicle, using a hose to knock the fire down in the trees as it went past. He survived without injury. Three others ran for their designated safety zone in a nearby house. One was critically burned and the other 2 sustained minor burns as they ran.

The Bridgewater Tanker destroyed at Longwood on Ash Wednesday 1980 was reversing down a road away from the fire crossing in front. It ran off onto the road shoulder, hit a small tree and stopped. A branch from the tree struck the pump throttle, disabling the on board sprinkler system. The crew of 5 all sheltered within the truck cabin during the burnover, but all 5 sustained moderate burns contacting hot metal bailing out after the fire. The crew of the Isuzu Tanker burned over at Ridgeway in 1990 pumped their entire 3600 litre water supply through their self defense sprinklers as the fire passed, then bailed out to shelter behind a house for the remainder of the burnover.

Conclusions :
The incidents detailed above suggest that water spray systems, either fixed or hand held, do have the potential to provide significant protection during a burnover incident. The Linton fire, however, also illustrated the risks of relying on such a system for crew protection, for the benefit is only realised if the pump continues to operate during the burnover, and there is an adequate supply of water.

In 4 real world burnovers, the crews exhausted 700, 1000, 1000 and 3600 litres of water defending their appliances.