Fighting Truck Fires Demands Knowledge of Many Hazards
Truck fires provide an unusually broad challenge to the fire service in small towns as well as large cities. What the small town lacks in local hazardous material is trucked over its highways, and the lack of hydrant systems on limited access routes, some of which are elevated, is a problem that metropolitan fire fighters share with their rural brothers.
A small town may not have a propane bulk storage facility, but when a propane tanker overturns on one of its highways, it then has what amounts to a bulk storage incident. We had just such a situation when a loaded 2200-gallon propane tanker overturned near a shopping center.
We detected only a small amount of vapor around the meter, but we nevertheless cleared the area and set up a deluge set with a 750-gpm fog head. Then we kept the tanker drenched in water fog. When men arrived to right the truck, they asked us to shut off the water, but we told them: “Work in the water fog or don’t move the tanker.”
I have often watched fire fighters with dry lines standing by on jobs like this. If the tanker ever flashed, they wouldn’t have had a chance to open a nozzle.
Much has been said in the fire service about approaching any tanker from the sides because if a tank explodes, it is most likely that the explosion will occur at one of the ends, which are the weakest parts of a tank. However, little has been said about positioning apparatus to protect it against a flammable liquid spill.
Always position apparatus upgrade from a highway incident because you may not get a chance to move the equipment in time if a flammable liquid spills and flashes. Some tractors with saddle tanks can carry as much as 250 gallons of fuel and even if only 100 gallons spills but some of it flows under a piece of apparatus and flashes, you are in trouble.
You never know what may be involved in a truck fire. The placarding on trucks is not dependable and by the time you have read all the bills of lading, it may be too late. Furthermore, abbreviations used on some bills of lading make them difficult to understand, and the driver usually doesn’t know what is in his truck unless he is hauling a load of a single material or product. On the other hand, a driver may be hauling a mixed load that was perfectly safe when the truck left the terminal, but when the cartons, drums or other containers are ruptured in a crash or a fire, you may have real trouble on your hands.
When a trailer is afire, one of the basic things to do is to separate the tractor from the trailer if at all possible. When the trailer box shows signs of pressure and heat, ventilate it as you would a building. Vertical ventilation is often effective and is relatively easy to accomplish because the roof represents the lightest construction area of a trailer box. Roof ventilation is also desirable from the owner’s viewpoint because the roof is the easiest part of a trailer to repair and the patch is on the least noticeable part of the trailer.
One precaution should always be observed: Never stand in front of trailer doors while they are being opened. The result of opening doors can be explosive, and fire fighters have been killed while standing in front of doors as they were opened.
Just as in structural fire fighting, charged lines must be in position when a trailer box is vented. If there is delay in getting lines stretched, then ventilation work must be held up until charged lines are available.
Getting data on chemicals
Just because you are working in the open, don’t overlook the need to wear breathing apparatus at incidents involving chemical products that can cause lung or skin problems. NFPA No. 49, “Hazardous Chemicals Data,” and the “Chem-Card” manual published by the Manufacturing Chemists’ Association describe hazards to personnel exposed to various chemicals as well as the extinguishing agents to use. Both of these are small enough to be carried in the glove compartment in the cab of apparatus.
They also should be kept at the fire department’s base radio station. In response to a question over the air, the base radio station operator can look up the information about a chemical under good reading light conditions and free from the distractions of the initial fireground operations.
The vehicle itself makes a problem because the ideal of the truck industry is to make the lightest truck possible to carry the heaviest load for the maximum return in freight charges. State laws govern gross vehicle weight, so the lighter the truck, the greater the payload.
This is why many engine parts, as well as the frame and bumpers, of the big, expensive trucks are magnesium. We all know what this means when magnesium is involved in fire. Solid streams will create an explosive effect, so only water fog should be used on burning magnesium.
We all regard diesel engines as much safer than gasoline engines because of the higher flash point and ignition temperature of diesel fuel. This is very true, but there are other things to watch for when a diesel is involved in fire.
Sometimes an ether canister is carried in the cab for easier starting, and that is all you need to get things cooking. We were all set to use a gasoline power saw to cut a cab apart at a crash scene once. The large tractor was buried in a frozen embankment with the dead driver in the cab. Just as we were ready to go to work, we smelled ether. Immediately changing our plans, we pulled the cab apart and removed the driver’s body without any further trouble.
We once were called to extinguish a fire around the engine of a cab-over diesel truck. The driver stalled the engine in a forward gear without pulling the diesel stop. He got out, tilted the cab, partially smothered the fire with his jacket and covered the diesel air intake. When fire fighters hit the jacket with a booster line stream, the engine started by itself and the truck went 200 feet along the highway and smashed into a concrete abutment.
When you are working on a refrigerated trailer, beware of the small gasoline or propane tank under the trailer box that supplies fuel for the freezer unit.
Danger of air bags
Air-suspension tractor-trailers and buses cause a different problem when they are involved in fire. There is no warning when the air bags blow, letting the body drop suddenly. Always use an applicator on a hose line when attacking fire under a truck or move back on the hose line and slide the nozzle under the vehicle. Never let your arm or any part of your body get under the truck or bus body or between the wheel housing and a wheel. If an air bag blows, you’ll never get out of the way in time.
Axle bearing failures and poor tires cause more highway fires than anything else I know of. The friction from axle bearing failure causes heat that is transferred by conduction to the tires. The tube inside the tire starts to burn first because of its lower flash point, and this can result in delayed recognition of the fire.
The driver of an open trailer loaded with beer was driving through our area when he spotted a hot wheel with no visible fire. He parked the truck and walked down a highway exit ramp to get help. Some 15 minutes later, flames burst through the tire and spread to the trailer body. The fire did extensive damage to the trailer, and the portion of the load that was not lost in the fire was condemned by state consumer protection officials.
Recently our department was called for a grass fire on Interstate 91 around noontime. We found a large truck tire on a rim burning on the side of the highway. A man with a service truck was with the tire. He said he had changed tires on an oil tanker 2 miles down the road and had put the flat in the back of his pickup. The flat was hot but not smoking, he said, but as he drove toward his shop, the breeze fanned the tire and caused it to burst into flames.
You also have to keep an eye open for electrical hazards in highway incidents. Overhead wires may be knocked down or underground wires may be torn up when a light pole is knocked over. If the wire is on the far side of the truck as you approach the vehicle, you may not notice it. An overturned truck can conceal live wires rising from the base of a highway lighting pole, or the wreckage can be on top of a downed overhead wire. It pays to anticipate such situations and look around carefully.
It is difficult to make pre-fire plans for highway incidents because you never know what will be involved. However, there are some things you can do to make your work more effective.
When we started to replace apparatus in the Wethersfield Fire Department seven years ago, we increased the size of our booster tanks to 500 gallons and required a 300-gpm flow from tank to pump. We did this mostly because of the fire potential on our highways.
Our new Engine 1 has a 55-gallon bladder for 3 percent protein foam concentrate and an around-the-pump foam system. Engines 2 and 3 each carries a high expansion foam unit with all the associated equipment so that each pumper can work independently of the other.
These three engines and our large rescue truck respond to all parkway and expressway fires. On local streets, which are all served by our hydrant system, only two engines respond to vehicle fires.
Our operating procedures for fires on parkways and expressways, which like most such highways have no hydrants, require a 2 1/2-inch line to be dropped off at an overpass. We are then prepared to lay more than a mile of hose and use a relay pumping operation starting from a hydrant near the overpass.
In municipalities that have elevated highways, it is often standard procedure to have an aerial ladder or elevating platform company respond on a city street to the overpass nearest the incident. The aerial equipment can then be used to get water from the city street up to the elevated highway.
In our own case, we have made good use of a 4000-gallon tanker from the Rocky Hill Fire Department, which provides our mutual aid from the south.
The problems of highway fires are as varied as the loads involved, but by anticipating these difficulties and learning from the experience of others, we can keep our difficulties to a minimum.