Some Interesting Results on the Effectiveness of Foam and Carbon Dioxide Gas

WHEN a manufacturer conducts a test to determine the effectiveness of two of his different types of fire extinguishing appliances on a particular type of fire, the results are apt to be of particular interest, for the element of bias is entirely absent. For that reason the following data on the use of foam and carbon dioxide gas in extinguishing airplane wreck fires contain some really useful figures.

What happens when an airplane crashes and takes fire was graphically demonstrated on Monday, September 16, at the Utica, N. Y., testing grounds and experimental station of the American-LaFrance and Foamite Corporation of Elmira, N. Y.

The tests, which were conducted on two actual airplanes purchased by the American-LaFrance Company especially for the occasion, were witnessed by Wing Commander L. S. Breadner and Squadron Leader Herbert Edwards of the Canadian Royal Air Force and were arranged by the American-LaFrance Company in cooperation with the Canadian Department of National Defense.

Extinguishing a Blaze in an Airplane Crash During a Test the cone shaped nozzles are discharging carbon dioxide gas from the eight cylinders shown at left. The white smoke shown is from the gas, the shower of sparks is from the doped surface of the airplane wings.just before the discharge from two small foam generators was turned on the fire. Approximately 20 seconds later the intensity of the fire had been lessened while inside of three minutes the burning plane had been extinguished.

Realizing that the danger of fire constitutes one of the most serious problems in the development of aviation, the Canadian Government arranged for the Royal Air Force flyers to attend the demonstrations so that they might gain first hand information about fire hazards in airplanes and about airports and the most effective methods for extinguishing them in the quickest possible time.

In order that the tests should represent actual conditions as closely as possible, each plane was set-up as follows: Fuselage resting on the ground; lower wings draped from lower part of plane to ground; upper wings supported by frames and elevated above the cockpit in practically a horizontal position; 50-gallon steel drums placed in the nose of each plane, perforated at the bottom and filled with about 12 gallons of high-test gasoline. When a plane crashes the gas and oil tanks usually rupture. Therefore, to duplicate these conditions between 20 and 30 gallons of high-test gasoline and about three gallons of oil were thrown over the ground and into the motor compartment of each plane.

Fire in the first plane was fought with carbon dioxide gas, contained in eight 50 lb. Alfite cylinders in two batteries of four cylinders each. The two batteries were manifolded together and four flexible metal high-pressure hose lines connected the manifold to the four discharge nozzles. The fire was started and when it had progressed to the fuselage and wings, the gas was directed toward the fire by four men, each operating a discharge nozzle. It was difficult for the men to approach close enough to the burning plane to do effective work, due to the intense heat generated by the burning wings. In a few seconds the inflammable wing fabric had burned away, however, and it was then possible for the operators to advance directly toward the gasoline fire which was by this time concentrated under the forward part of the fuselage. The first battery of four cylinders, which was discharged in less than a minute, was not sufficient to extinguish the fire. The second four cylinders were then utilized and the operators succeeded in completely extinguishing the fire. They had scarcely retired, however, when a reflash occurred which reignited the exposed gasoline on the ground. It was necessary to extinguish this reflash with foam equipment.

The second plane fire was fought with foam, generated by two small Foamite generators. This fire was a more serious one with which to contend because of the fact that the plane was larger and that more gasoline was used than for the first test. Within a few seconds after the firefoam was introduced, the two operators were able to cut down the intensity of the fire to such an extent that they could approach in close proximity to it without taking punishment from heat. The fire was well under control within 20 seconds and completely extinguished within three minutes.

In both cases, before the respective extinguishing mediums were introduced, the fires burned with great intensity, for. in addition to the high-test gasoline involved, the doped wings and fuselage coverings burned with a fierce white light and showered sparks about the vicinity.

Conclusions drawn from these tests were, that while Alfite (carbon dioxide) gas might, in some cases, be sufficient to extinguish a particular airplane fire, firefoam is the better extinguishing medium when considered from every angle and may be used with greater safety to the operators. The problem resolves itself basicly to the fact that unless the entire zone of fire can be completely enveloped with the suffocating gas, the fire will not be extinguished and will reflash with all of its original intensity.

The advantage of foam in fighting such fires is that it may be discharged by an operator from a distant point because of the range of the stream. In addition, wherever it is applied it is effective in cutting down the heat of the fire and will adhere to any surface to which it is applied, rendering that material uninflammable.

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