In 1939, Victoria was one of the first locations in the world to trial the ‘bombing’ of bush-fires using aircraft, and in 1967 the Forests Commission (FCV) made the first operational use of aerial-firebombing in Australia using two fixed-wing agricultural aircraft.
Overseas experience and earlier local trials had suggested that mixing water with chemicals, to create a fire retardant, made operations far more effective. Retardants were subsequently found to be particularly useful in slowing the spread of lightning-caused fires in inaccessible terrain, thereby improving the likely success and safety of follow-up ground crews.
Remote area fire-fighting was a difficult and physical operation for a fire crew in the 1950s and '60s. Several methods used were ‘dry’ fire-fighting techniques using rake-hoes and shovels, and ‘blacking- out’ using a ‘hose relay’ system.
A ‘hose relay’ system was constructed by siting a fire pump at a water source; either a creek or dam, and transferring the water via a delivery hose to a relay tank, previously set up several hundred metres along the fire edge .The water provided would be used by the fire crew to attack the fire edge using a knapsack spray, or a separate pump and hose line connected to the relay tank.
If water was required at a greater distance, a second or third relay tank and pump system would be positioned further along the fire edge, providing additional water access. A pump operator would be positioned with each relay tank transfer pump to maintain its fuel supply and to ensure that a constant water flow was being delivered.
This paper sets out the history of Class A Foam use in Victoria, giving full details of equipment development and the advantages and disadvantages of the various approaches.
The nature of water makes its conservation difficult, since it evaporates, beads up and will not penetrate or stick to vertical surfaces. One method which assists with overcoming these difficulties is adding foam compound to the water.
In Victoria, from the mid 1950's until the early 1980's, water was treated with "wetting agent" to reduce the surface tension of the solution, and allow it to spread and penetrate fuels more effectively. Wetting agent plus water was known as "wet water". Wetting agent was available in powder form in cellophane packs from the mid-fifties, and as a liquid in more serviceable plastic packs from the mid-sixties. It was introduced directly into the water tank, then mixed in by vehicle motion or by pump impeller rotation. Although it was an advance over using plain water, "wet water" could not be made into foam. Also, pump priming problems due to cavitation were frequent. An improvement had to be found, and the answer lay in both equipment development and the introduction of Class A Foam.