On-Board Fire Suppression System!

This material first appeared in the I-CAR Advantage Online, which is published and distributed free of charge. I-CAR, the Inter-Industry Conference on Auto Collision Repair, is a not-for-profit international training organization that researches and develops quality technical education programs related to collision repair. To learn more about I-CAR, and to subscribe to the free publication, visit www.i-car.com.

Since the 2005 model year, the Ford Crown Victoria Police Interceptor (police car) has had an optional fire suppression system designed to help reduce the risk of fire in high-speed rear impacts.

Fire suppression systems were initially developed and tested for use in military and aerospace applications. The system on the Crown Victoria is a first for the automotive industry, and so far the only factory-installed system available. The fire suppression system was developed for these vehicles because police vehicles are more likely to be involved in high-speed/high energy rear collisions than other vehicles. Also, police vehicles are frequently parked along highways during traffic stops.

Operation

The fire suppression system is designed to sense a high-speed, high-energy rear impact and discharge the fire suppressant material underneath the vehicle and onto the fuel tank, slowing the spread of a fire, or potentially extinguishing a fire. The system is not deployed immediately, but when the vehicle comes to a stop, or at six seconds, whichever occurs first. Development testing showed that the best time for deploying the fire suppressant is near the point of rest, which may be more than 60 m (200 ft) away from the point of impact. The system can also be discharged manually with a button on the front headliner. The ignition must be in the RUN position for the manual button to operate.

The actual discharging operation uses a hybrid (nitrogen and CO2) gas generator, similar to that used to deploy an airbag. Also similar to an airbag operation, the system uses two impact sensors. In order to determine the most appropriate time to deploy the foam, the system also measures post-impact vehicle movement.

The system cannot be retrofitted to pre-2005 police vehicles. The frame had to be modified to support additional weight at the mounting locations. Also, the electronics monitoring and deploying the system had to be integrated throughout the vehicle.

Main Parts

Main system parts include the fire suppression module, fire suppressors, fire suppressor manifolds, a manual activation switch, and a system indicator lamp on the instrument panel.

The fire suppression module, or electronic control module, is mounted under the rear seat cushion. This is the computer for the system and contains the impact sensors. It also receives information from the anti-lock brake module to help sense how far the wheels have moved and when the vehicle is coming to a rest. This information is used to signal the suppressors to deploy. The fire suppression module also monitors the system for faults. A large capacitor in the module provides backup system power in case vehicle electrical power is lost.

The fire suppressors contain the fire suppressant material. These are two stainless steel containers and gas generators mounted above the rear axle on the number four cross-member. Mounted on the fire suppressors are the fire suppression manifolds. The manifolds contain the nozzles that spread the fire suppressant material. There are two manifold assemblies with nozzles pointed toward the ground and an additional manifold mounted higher which sprays fire suppressant material up and into the body.

The manual activation switch is located on the headliner between the sun visors and is covered by a clear plastic door. The indicator lamp on the instrument panel normally turns on for about six seconds when the ignition is cycled ON and then goes out. Again similar to an airbag system, a lamp that stays lit or starts flashing is an indication that there is something wrong with the system.

After deployment of the system, the main system parts must be replaced. There are no repairs permitted of any of the parts or recharging of the suppressor material. Replacement parts include the fire suppression module, the fire suppressors, and the fire suppressor manifolds.

So What’s a Crown Victoria Police Interceptor? ...the Gospel According to Ford In the United States, the police cruiser you see is likely to be a Ford Crown Victoria Police Interceptor. Kevin Fitzpatrick, Ford Motor Company State and Local Government sales manager, says Ford owns about 80 percent of total annual sales in the United States police vehicle market and is on track to sell about 50,000 Police Interceptors this year. Fitzpatrick says the reason is simple: Ford is the only manufacturer that has continuously offered a police package in its carline since 1950. While other manufacturers have come and gone with police entries applied to front-wheel-drive cars and unibody rear-wheel-drive cars, Ford continues to offer the market’s only standard V-8, rear-wheel-drive and body-on-frame vehicle. Fitzpatrick also cites Ford’s commitment to its police customers, evidenced by a strong dealer support network and the early establishment of the Police Advisory Board. “We were the first in the industry to establish this,” he says of the board, which works to help Ford provide for the needs of law-enforcement customers. Michael Blackmer, Ford Police Package chief engineer, says having rear-wheel-drive, body-on-frame construction is important to this segment. “The predictable handling of rear-wheel drive is a benefit,” says Blackmer. In addition, body-on-frame means the car’s chassis components (steering, suspension) are mounted to a frame, not to the car’s body. This is important for the heavy-duty driving often associated with police work. The frame is there to take the chassis loads instead of sending them through the body, Blackmer says. This, in turn, helps keep repair costs down and contributes to the longevity of the vehicle. The Dodge Charger and the Chevrolet Impala police sedans do not offer this form of construction. The 4.6-litre V-8 makes 250 horsepower by incorporating the airbox from the performance-oriented Mercury Marauder. The package includes a high-output, 200-amp alternator, an engine oil cooler, heavy-duty shock absorbers, a heavy-duty front suspension, speed-sensitive steering with power steering oil cooler, a transmission oil cooler and heavy-duty steel wheels. All Police Interceptors feature rack-and-pinion steering for improved handling and an available Fire Suppression System and ballistic door panels. The Crown Victoria Police Interceptor also features a large, 20.6-cubic-foot trunk with a full-size spare; spacious, 106.4 cubic feet of interior passenger volume; and an exemplary safety record that includes dual five-star frontal crash ratings for driver and front passenger in the National Highway Traffic Safety Administration’s test every year since 1996. The Crown Victoria Police Interceptor is tested in a 75-mph rear-end crash, something no other car manufacturer publicly claims. 2007 Crown Victoria Specifications BODY Construction Steel body on fully boxed frame Final Assembly Location St. Thomas , Ontario ENGINE Type 4.6-litre V-8 Configuration Iron block and aluminium heads Valvetrain SOHC, 2 valves per cylinder Bore x stroke 3.55 x 3.54 in. / 90.2 x 89.9 mm Displacement 281 cu. in. / 4,606 cc Compression ratio 9.38:1 Horsepower Single Exhaust: 224 @ 4,800 rpm Dual Exhaust: 239 @ 4,900 rpm Horsepower per litre Single Exhaust: 48.7 Dual Exhaust: 52.0 Torque Single Exhaust: 272 lbs.-ft. @ 4,000 rpm Dual Exhaust: 287 lbs.-ft @ 4,100 rpm Recommended fuel 87 octane unleaded Fuel capacity 19 gallons Fuel Injection Sequential multi-port electronic Oil Capacity 6 quarts with filter Coolant Capacity 13.6 quarts DRIVETRAIN Layout Rear-wheel drive TRANSMISSION Standard 4-speed automatic overdrive Gear Ratios 1st 2.84:1 2nd 1.55:1 3rd 1.00:1 4th 0.70:1 Rear axle ratio Standard: 2.73:1   Optional: 3.27:1 SUSPENSION Front Independent short- and long-arms ( SLA) architecture with coil springs, monotube shocks and stabilizer bar Rear 4-bar link solid axle, Watts link, coil springs, monotube shocks, optional load-leveling air springs and stabilizer bar STEERING Type Power rack and pinion Ratio 16.4:1 Turning circle curb-to-curb 40.3 ft BRAKES Type Four wheel power disc brakes with standard 4-sensor, 4-channel anti lock braking system (ABS) Front 12-in ventilated Rear 11.5-in ventilated Power assist Vacuum, ABS WHEELS AND TIRES Base 16-in steel, P225/60R16 Largest 17-in aluminium, P235/55R17 DIMENSIONS (inches unless otherwise noted) EXTERIOR Wheelbase 114.6 Overall length 212.0 Overall width 78.3 Overall height 58.3 Track width, front/rear 62.8 / 65.6 WEIGHTS AND CAPACITIES (pounds unless otherwise noted) SAE passenger volume 106.4 cu. ft. Cargo Volume 20.6 cu. ft. Maximum towing capacity (properly equipped) 1,500 Base curb weight 4,129 Fuel Economy 17 city / 25 HWY