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maritime DC & PPE Information Center

aircraft

P-25 Firefighting Vehicle


Image of P-25, painted with FDNY color scheme in                   Image of P-25 (traditional color scheme)
remembrance of those lost 9/11

The P-25 also formally known as the A/S32P-25 is a self-propelled fire-fighting vehicle designed for shipboard flight deck use. The vehicle is a two-wheel drive, diesel powered vehicle with overall dimensions of 64 in. x 70 in. x 190 in. and a gross vehicle weight of 18,850 pounds. A hydrostatic drive system transmits power to the rear wheels, steering is performed by a single hydraulic cylinder and tie rod controlling the front wheels. Dynamic vehicle braking is provided by a hydrostatic drive system when the accelerator pedal is released. The dynamic braking is supplemented by a service/parking brake module mounted between each rear wheel drive motor and planetary. The vehicle’s engine is a turbocharged, two-cycle, six cylinder, liquid cooled, forced air induction diesel engine (Detroit Diesel Model 6V-53TA) with a displacement of 318 cubic inches, 237 BHP at 2,800 RPM. The engine and main hydraulic system are located in the rear of the vehicle. The hydraulic system provides pressure to the drive system, fire-fighting system, proportioning system and steering system. The hydrostatic drive system consists of a variable displacement hydraulic pump supplying flow to a hydraulic motor and planetary drive unit mounted to each of the two rear wheels. Direction and speed are regulated by the F-N-R control lever and accelerator pedal. The fire fighting system consists of two separate tanks within the vehicle’s chassis, the water tank holds 750 gallons and the AFFF tank holds 60 gallons. There are three 20 pound Halon 1211 fire extinguishers stored on the right side of the vehicle. One nursing line connection on each side of the vehicle allows the ships mixed AFFF system to flow directly to the vehicle’s water pump, bypassing the water tank. There is also a service connection with a shutoff valve for quick-filling the vehicles water tank. The fire fighting delivery system consists of a turret with a maximum flow rate of 500 gpm and a 1½ inch, 100 foot handline with a 95 gpm nozzle. The vehicle’s hydraulic water pump system delivers water from the vehicle’s water tank or nursing system to the turret and handline and is controlled by a manually controlled joystick capable of flows from 0 to 500 gpm. The fire fighting system also features an AFFF proportioning system consisting of an AFFF pump, AFFF/water mixing (ratio) controllers, and an AFFF-to-water back pressure regulating valve. The AFFF pump circulates AFFF concentrate from the AFFF tank to the AFFF/water ratio controllers where water and AFFF concentrate are mixed. The back pressure regulating valve balances the amount of AFFF concentrate allowed to flow to the ratio controller to ensure the water/AFFF exiting the turret or handline nozzle is mixed in the proper proportion. The steering system controls direction of the vehicle travel via the front wheels. The system includes a hydraulic steering cylinder attached to a tie rod connecting both front wheels, a steering valve, a dedicated hydraulic pump and hydraulic reservoir and a priority flow control valve.