By W. Nim Kidd
With the increase in over-the-road commercial truck traffic, more accidents involve large commercial vehicles with large-capacity diesel fuel tanks. A minor vehicle accident can turn into a major response due to a fuel leak on a major thoroughfare or fuel impacting environmentally sensitive areas. Many times, the spill volume can be reduced if the first arriving fire company attempts to shut off the crossover lines that run between diesel fuel tanks in multiple-tank configurations. These tanks vary in size from 40 gallons up to 400 gallons.
If the truck has two or more fuel tanks, there usually is a crossover line that allows the two tanks to be used at the same time and equalize into each other. Some tank valves can be opened and closed from inside the cab by the driver. Controlling the flow leaking from these tanks will lessen environmental damage and the smaller fuel release will result in a shorter clean-up time.
Since most of these accidents occur on highways, shortening the recovery and clean-up time will result in less traffic congestion. It has been proven that traffic congestion due to an accident will increase the likelihood of an additional accident in the same location adding to responders’ risks.
Fuel Tank Shut Off Type
Most dual-tank configurations will have some sort of valve just off of the tank itself located at the bottom of the tank. However, some newer trucks will not have valves. Instead, they’ll have a fuel siphon line that picks up the fuel from the top of the tank and sends it to the engine block to be preheated to maximize fuel economy. Leaks from this type of setup can be very hard to control. Establish a series of dikes/dams to confine and control the run-off. If possible use a plug or patch to slow or stop the leak.
Stop the flow of fuel from a tank that has not been breached as soon as possible to prevent it from equalizing into the damaged tank.
Some trucks with a single fuel tank and those with two or more fuel tanks will not have a shutoff valve. In these cases, crimp the fuel line or restrict the flow as much as possible to minimize environmental impact. One way to pinch the fuel line is to use a pair of pliers to crimp the fuel line.
Some fuel tanks provide a garden-hose-type valve or wheel valve. During an accident, the valve can break off or crack, the line between the two fuel tanks might be cut or damaged, and/or one of the two tanks may rupture. In any of the above cases, all valves should be closed. Two or more fuel tank assemblies may or may not have a valve on each tank.
Another type of valve is the quarter turn type. This is the simplest type and can be found with a variety of handle types. Turn the handle so it is not in line with the hose or the valve body to close the valve.
Some trucks will have a small door under the driver’s side door that allows access to remote closures. These will look like small metal handles. There are usually two and will close the shutoff valve when you pull them away from the truck. Firefighters may also see cables in this door that release the air from the air brake tanks. This can be useful to set the brakes on the truck.
Any time a fuel leak occurs or the possibility exists for one, such as a rollover or a truck on its side, the fuel line should be shut off. If a truck is on its side, closing the crossover line as soon as possible will prevent the tank on top from filling the tank on the bottom and spilling out of the fill cap. The vehicle should be completely stabilized before you attempt any work under or around it. Disconnect batteries and electrical systems, if accessible, to avoid a fire from sparks combined with the combustible liquid spill. Remember the haz mat priority order: life safety, environment, and then property. Any actions that aid in controlling the spill or lessen the impact on traffic and the environment will benefit all parties involved.
W. Nim Kidd is the District Fire Chief, Emergency Management Coordinator for the City of San Antonio, TX.
