Chicago Municipal Airport Gets Crash Truck
On December 22nd, the City of Chicago accepted delivery of a new aircrash fire truck at its municipal airport. The extinguishing agents used in the apparatus are 4,500 pounds of low pressure carbon dioxide and 230 gallons of mechanical foam solution. The truck itself is a modernization of the U. S. Army’s Class 150 and U. S. Navy’s Model 9506, both of which were used in many theatres of war and are still in active service.
Airport protection and particularly aircraft crash fires demand quick extinguishment, which in turn demands quick application of the extinguishing agents upon rapid approach to the scene of the fire. As carbon dioxide extinguishes fire by displacing the oxygen in the area, the faster this is accomplished, the faster the flames are extinguished and rescue can be made. This truck, with its “boom” nozzle, an oscillating ground sweep nozzle, and two hand lines, can if necessary, discharge 3,200 pounds of low pressure carbon dioxide in one minute. This cloud blankets a plane and extinguishment is accomplished in seconds. Mechanical foam solution is employed to cover over areas of flammables that are subject to reflashing.
Although this unit weighs approximately 32,000 pounds with full load, it has cruising speed of 60 miles per hour and can negotiate the first mile in 90 seconds or less. It is 25 feet long and approximately 9 feet high.
Mr. John H. Bell, President of Cardox Corporation, of Chicago, which built the truck, officially turned it over to the Hon. Martin Kennelly, Mayor of Chicago.
A feature of the truck is the new type front bumper mounted boom. This is ten feet long, has a working elevation of 18 feet, and it can be quickly maneuvered into any desired position with accurate control of the direction of discharge of carbon dioxide. The capacity of the boom nozzle is 1,250 pounds of carbon dioxide per minute. This nozzle has an effective discharge range of up to 50 feet. The carbon dioxide, cooled by expansion upon release to 110 degrees below zero, forms a cooling and smothering envelope of inert gas and carbon dioxide “snow” (small particles of solid carbon dioxide) to knock down heat and flame.
A new type ground-sweep nozzle directs 750 pounds of carbon dioxide per minute at the base of the flames. This nozzle oscillates through a wide arc and can cover a large area. It is powered by an air-type motor, driven by carbon dioxide vapor, and is put into action as the truck approaches the fire. It cuts the flames off from their fuel and prevents a break-through of fire beneath the truck. This ground-sweep nozzle permits the truck to be driven almost into the fire for close range fire fighting. It is assisted by two foam makers, mounted on the front bumper, that discharge a total of 60 gallons of foam solution per minute ahead of the truck in two intersecting arcs. All the foam discharge equipment, while in use, is under pressure supplied by the carbon dioxide itself. Exposed gasoline or oil is blanketed against reflash and at the same time the foam helps to cool down the fire zone.
With the boom and ground-sweep carbon dioxide nozzles and the fixed foam makers in operation, the men handling the hand lines go into action. Each of the 1 1/4 inch by 100 foot carbon dioxide lines has a discharge capacity of 600 pounds per minute. The two operators attack the fire around the edges and in those places not directly accessible to the other nozzles. They also assist in clearing an entrance way into the plane for rescue. Two other operators use the 100 foot hand foam lines, each of which releases approximately 45 gallons of foam solution per minute, to blanket gasoline and oil, to cool hot metal and to extinguish any glowing embers that may remain after the rest of the fire has been put out.
Still another nozzle can be brought into play if needed. This is a bayonet type, used to pierce plane compartments, engine nacelles or other enclosed spaces and flood them with carbon dioxide to stop fire or render the enclosed space inert and so prevent explosion.
All discharge equipment except the handlines is controlled from within the cab. A single control mechanism, entirely new to this type of use, activates the boom up, down or sideways, as well as the movement of the boom nozzle itself “in” and “out” in a vertical plane. Control valves on truck’s instrument panel release carbon dioxide and foam from the ground-sweep apparatus. A six man crew is required for full effectiveness—a driver, an operator for the discharge controls within the cab and one for each of the four hose lines, although, in an emergency, fewer men may be used.
SUSANVILLE, LASSEN CO., CALIF.—A call system has been inaugurated by the Susanville Fire Department whereby its units can be dispatched to aid in fighting fire in local lumber mills. The details were worked out by Asst. Fire Chief Bob Davis.