Historical information

The Aerial Drip Torch (ADT) was an idea conceived in Canada in the 1970s by John Muraro

It was developed in 1982 by the New Zealand Forest Service to become the Ashley Aphid Helitorch.

Forestry Tasmania acquired one of the machines and modified it in February 1987.

Also known as a dragon helitorch it consisted of a large 135-litre tank containing jellied petrol, a displacement pump, propane ignition system, burner nozzle and fire extinguisher system.

It was first trialled in Victoria at Swifts Creek in 1991 and the Aerial Drip Torch (ADT) has now become standard practice.

Physical description

Two Aerial Drip Torches (ADTs) were built in the 1990's by the Fire Equipment Development Centre at North Altona,

They were developed in conjunction with the Department of Conservation and Land Management in Western Australia.

The first was trialled during the 1991/92 autumn burning season. The machine proved to be successful and a second machine was introduced in 1998 to assist with burning operations across the State.

The ADT's were commonly used for regeneration burning.

The first ADT introduced in 1992 had a dry weight of 160kg and a capacity of 130 litres, providing about an hour of operation. Following initial use, systematic modifications were adapted including improved ignition of gel at the drop tube, installation of an air bleed valve at the pump to assist pump priming and improved mounting brackets for the CO2 bottles and propane canister attached to the machine.

The second, and lightweight ADT, introduced in 1998 had a dry weight of 68kg and a capacity of 200 litres due to a smaller lightweight frame and plastic (Polyfin) tank.

In operation the ADT is suspended below a helicopter via four strops attached to the vessel and a cable to the helicopter cargo hook. Gelled fuel is dispensed via a drop tube which is attached to the pump outlet of the machine, and ignited via a gas torch.

Safety features built into the first ADT were:
a brass melting plug designed to be activated at 200 C
bursting disc designed to burst at170 Kpa should the vessel over pressurise.
a pressure relief valve set to 35 Kpa ( vessel operated between 16 &34 Kpa)
a low pressure sensor designed to shut down the machine should the vessel pressure drop below 15Kpa.
the vessel is filled with CO2 above the gelled fuel to eliminate ignition with in the vessel.
CO2 is used to expel any residue of ignited gel from the drop tube to prevent ignition when flying outside the boundaries of the burning area.