NEW FIRE TACTICS FOR NEW-CAR FIRES

NEW FIRE TACTICS FOR NEW-CAR FIRES

BY BILL GUSTIN

Changes in the design and construction of automobiles demand a change in the way fire departments fight car fires. New car materials and components have resulted in improved performance, increased fuel economy, better crash resistance, and reduced exhaust emissions. Unfortunately, some of these same materials and components make fighting a fire in a modern automobile more difficult and dangerous than with older cars. Let`s examine how changes in automobiles over the past 20 years have necessitated a more cautious strategy, less-aggressive tactics, and a highrer level of personal protection.

HAZARDS/PROBLEMS

Plastic parts. Twenty years ago, firefighters routinely and very effectively extinguished significant auto fires with a booster line flowing no more than 30 gpm. Today, a significant fire in a car can require flows of as much as 60 to 100 gpm for a fast and safe knockdown. What has changed? To achieve better fuel economy, many components of late-model automobiles are made of hydrocarbon-based synthetic materials to reduce the vehicle`s weight. When plastics replace parts previously made of metal, they add significantly to the fuel available to burn and produce thick, toxic smoke.

Many fire departments have recognized that modern cars burn hotter and require their engine companies to stretch 112-inch or 134-inch hoselines on car fires of any significance. The larger line delivers a higher rate of flow, necessary for a quick knockdown, and provides more protection for personnel. Some firefighters, however, maintain that a booster line is adequate for well-involved car fires, conserves tank water, and is so much easier to pick up. Booster line advocates probably would be surprised to learn that they are using about the same amount of water, in total gallons flowed, as a 134-inch hoseline because they have to operate the booster two to three times as long to achieve knockdown and extinguishment.

Twenty years ago, we were just beginning to learn that the rate of cancer among firefighters was much greater than that of the general population. We now know that inhaling gases of combustion from burning synthetic materials is a major cause of cancer among firefighters. A burning car loaded with plastic components produces a witch`s brew of toxic gases. Keeping your face out of the smoke is not good enough; firefighters fighting an auto fire must protect their lungs and long-term health by wearing SCBA.

Explosion. On television and in the movies, burning cars always manage to blow up into a spectacular fireball when fire reaches the fuel tank. This is why civilians usually are afraid of an explosion when there is a car on fire. Many firefighters, however, believe that explosions at car fires occur “only in the movies” and will aggressively attack a fully involved automobile at close range. These firefighters are incorrect, but their belief is understandable–serious explosions at car fires are not that common. Firefighters can respond to hundreds of auto fires in their careers and never witness an explosion of any significance. However, do not be lulled into a false sense of security–burning cars can and occasionally do explode. You must be aware that there is a definite possibility of an explosion or a sudden increase in the size and intensity of a fire whenever a vehicle is involved in a significant amount of fire. The explosion may not be as impressive as one staged in Hollywood, but it still has the potential to maim and kill.

All automobiles have components that contain liquids or gas in a sealed container that can burst, rupture, or explode from excessive internal pressure when exposed to heat. For example, tires, batteries, hollow drive shafts, and parts of the air-conditioning system can explode under fire conditions.

The front and rear bumpers of most late-model cars are mounted on hydraulic cylinders designed to absorb the energy of a five-mph crash without damage. Energy-absorbing bumpers are vulnerable to flames licking from under the engine compartment or fuel tank. When heated, the hydraulic cylinders can explode and become projectiles, with sufficient impact to shatter the leg of a firefighter standing within range of the bumpers.

Gas-filled struts are rapidly replacing springs to assist in raising hoods, trunks, and hatchbacks. These devices are capable of exploding into two pieces, propelling the piston and cylinder assemblies in opposite directions.

Fuel injection and pollution controls subject the fuel systems of modern cars to greater pressures than those of older cars. Many new cars are equipped with plastic fuel lines that supply gasoline at pressures of 15 to 90 psi from an electric fuel pump inside the fuel tank to the fuel-injection valve body on the engine. A leak in a fuel line under pressure from fire or collision can produce a sudden, intense fire fed by a spray of atomized gasoline.

Those who pump their own gasoline are familiar with the “whoosh” sound of pressure escaping when the gas cap is unscrewed on a hot day. The fuel tank is under pressure because of environmental regulations that require auto manufacturers to configure the fuel systems of late-model cars into a closed circuit to prevent hydrocarbon vapors from escaping into the air. The fuel tanks of older cars vented directly to the atmosphere, usually through the gas cap. Fuel tanks of newer cars vent remotely into a charcoal canister in the engine compartment. The vent system is designed to regulate pressure under normal conditions, such as when fuel is withdrawn from the tank or during changes in temperature–not as a relief valve under fire conditions.

When the fuel tank is heated by flames, the gasoline begins to vaporize and increase the pressure within the tank and fuel lines. Excessive pressure can cause a sudden, catastrophic failure of the fuel tank, usually along a seam, spilling several gallons of gasoline at firefighters` feet. Whether a bursting fuel tank can technically be called an explosion is purely a theoretical discussion. As a practical matter, it can cause a sudden, rapid intensification of an auto fire and engulf firefighters in a pool of burning gasoline. Another problem that results from a pressurized fuel system occurs when gasoline liquid or vapor under pressure escapes from an opening in the tank or a fuel line connection and burns in a blowing, three-dimensional fire.

Many vehicles today are equipped with fuel tanks made of polyethylene or polypropylene plastic as original equipment or installed by the owner as an auxiliary fuel supply. Plastic fuel tanks are lighter and more durable than steel tanks but will melt after a few minutes of flame contact, spilling their contents and causing a sudden, dramatic increase in the fire`s size and intensity.

Firefighters must consider that the trunk of a burning automobile can contain just about any type of hazardous material. An LP gas cylinder carried in the trunk or installed there for a propane-powered car is a hidden hazard with great potential to injure unsuspecting firefighters. Personnel also are at great risk when they are unaware that the trunk contains gasoline cans or a plastic auxiliary fuel tank.

STRATEGY AND TACTICS

All fire operations, including automobile fires, should be preceded by a thorough, accurate size-up to determine appropriate strategy, tactics, and an acceptable level of risk to personnel. Life hazard is, of course, the primary consideration. Firefighters naturally will take risks at an auto fire involving trapped occupants that they otherwise would not take. There is, however, a certain amount of life hazard at every fire (the firefighters), whether or not it is readily apparent. When civilian lives are not threatened, the fire officer can direct most of his attention to the protection of personnel–and make sure they are not operating at an excessive level of risk.

A junk car burning in a scrapyard is a fairly routine call for most fire companies. When no exposures are immediately threatened, seasoned firefighters will go about the business of extinguishing the fire at a methodical pace. Their restraint is understandable and appropriate: Why take unnecessary risks by aggressively attacking a fire in a junk car with little or no value?

Firefighters can place themselves at unnecessary risk when they fail to realize that any automobile well involved in fire for a few minutes is not much different from the junk car burning in the scrapyard–its value has been diminished to the point that very little can be saved and, thus, the car is not worth the risk of an overly aggressive attack.

Protection of personnel usually begins with proper positioning of the apparatus. At fires along roadways, firefighters often are in more danger of being struck by a vehicle than of being injured by the fire. A 16-ton pumper is a substantial barrier between firefighters and oncoming traffic. Spot the apparatus diagonally, blocking the lane or shoulder where the firefighters are operating and the adjacent lane(s). The pump panel should face the scene to protect the pump operator from traffic and give him a view of the scene. Positioning the apparatus at an angle also facilitates advancing hose crosslayed in a transverse hosebed that otherwise would have to be pulled directly from the side and advanced to the front or rear of the apparatus.

Positioning the apparatus with regard to traffic can, unfortunately, directly conflict with positioning with regard to flammable liquids. Whenever possible, firefighters and apparatus should be positioned uphill of a vehicle fire in case the fuel tank suddenly fails and sends a torrent of flaming gasoline running downhill. Thus, where to spot apparatus at a car fire can be a complicated and difficult decision. Proper positioning requires thorough consideration of the following: traffic conditions, grade of roadway, smoke, fog, rain that can obscure vision, police assistance available, and the extent of fire. (For more on apparatus positioning, see “Safe Placement of Apparatus on Roadways at Nonstructural Fires” by Doug Leihbacher, Fire Engineering, April 1994, page 22.)

Since automobiles contain components, systems, and possibly contents that can explode, attacking a well-involved auto fire should begin with defensive tactics similar to those used to control a burning tank of flammable liquid or gas: Cool the car down from a distance, and avoid the ends. Wearing full protective clothing and SCBA, use the reach of a 112-inch to 134-inch line on a straight-stream pattern to keep a safe distance until the fire is reduced in size and intensity. Cool the fuel tank by sweeping burning fuel from underneath the vehicle and directing a stream into the rear fender wells. (See photos A and B.)

Once the fire subsides, it is time to cautiously move in. Avoid approaching directly in front of or in the rear of the auto until you have thoroughly cooled the cylinders for the energy-absorbing bumpers with the stream. As the attack team approaches the car, the nozzleman widens his pattern to a narrow fog. As the firefighters get closer to the car, they become more vulnerable in case the fuel tank ruptures. (See photos C and D.)

If possible, the company officer should not be on the hoseline at this stage of the operation so he can closely observe his crew and warn them of hazards they may not notice. For example, firefighters insulated in bunker pants and focusing on fire inside the car may not be immediately aware that they are standing in a pool of burning gasoline.

The company officer or his designee should stand by with a large dry chemical fire extinguisher at every significant vehicle fire. Application of dry chemical can rapidly extinguish a gasoline spill fire and the firefighters who are standing on it. Dry chemical is the only common extinguishing agent that can suppress a pressurized, three-dimensional fire burning at the fuel tank or in the engine compartment. Water, on the other hand, must be used judiciously on spill fires to avoid spreading burning gasoline toward and into sewers. Foam, when available, is an excellent agent to suppress flammable liquid fires and prevent reignition by blanketing a spill.

Once the accessible fire has been knocked down, it is time to move to the engine compartment–but do not be in a big hurry to open the hood. The combination of a hot engine compartment and the confinement of an intact hood is ideal for indirect extinguishment with water fog. Pry open the hood along one of its sides just enough to direct a short burst of fog into the engine compartment. The water will immediately flash to steam and, contained by the hood, will blanket the engine compartment and suppress fire remote from the point of application. (See photos E, F, and G.)

You will, of course, have to open the hood to complete extinguishment; however, the lever that operates the hood latch mechanism from the driver`s seat will have burned or melted away in the fire. Forget about prying the hood open; the hood latch is very strong, and there is nothing substantial to pry against. All you will manage to do is crush sheet metal in the hood and grille. Although the hood release lever is gone, the cable connecting the lever to the hood latch often remains intact and operable.

It often is possible to access the cable and pull it to open the hood–if you know where to look for it. The cable usually runs from the lower left corner of the dashboard and along the upper left side of the engine compartment. It bends to the right in the left front corner of the engine compartment and runs either behind or above the grille, where it connects to the hood latch. Begin at the dashboard. See if you can find the end of the cable and give it a pull with pliers.

If this is not successful, move on to the grille. On many automobiles, you can reach the latch mechanism by removing the plastic grille (if it has not been melted/burned away) and pulling the cable with a pliers. This procedure, of course, requires you to work directly in front of the car and should not be attempted until you have thoroughly cooled the front bumper cylinders and engine compartment. (See photos H and I.)

If you are not successful there, pry up the left front corner of the hood, reach in with a hook-shaped tool, and attempt to snag the cable. Usually, the plastic outer sheath of the cable burns away during the fire, which makes it easier to open the hood because you can pull anywhere along the length of the cable. (See photos J and K.)

If you are not successful at opening the hood with the hood latch, you will have to cut the hood. (Use the procedures detailed in “Car Engine Fires: Tactics for Quick Knockdowns” by Brian G. Anderson, Fire Engineering, February 1994, page 37.)

You usually can knock down serious fire in the trunk`s contents by directing a stream through the remains of the back seat and taillights. To overhaul the contents (usually a smoldering spare tire, if nothing else), you usually will have to open the trunk. Again, forget about prying. Thoroughly cool the rear bumper assembly and attempt to open the trunk with the “through-the-lock” method. Drive the adz of a halligan tool behind the decorative trim surrounding the lock cylinder, and pry the lock cylinder out of the trunk lid. (See photo L.) If this is not successful, place the point of the halligan directly on the keyhole and drive the cylinder into the trunk by striking the halligan with an axe. (See photo M.)

Once the lock cylinder is out of the way, you can release the lock mechanism by substituting a screwdriver for the turning action of the flat stem or tailpiece at the back of the lock cylinder. (See photo N.) Cars with long, sloping trunk lids usually have a latch mechanism recessed into the trunk, several inches from the lock cylinder, necessitating a very long, slender screwdriver to operate the latch. (See photo O.) This usually is not a problem, as the dipstick makes an excellent key tool in this situation. (See photo P.) n
















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