Vehicle Fires: Plastic Fuel Tanks

Milford firefighters at vehicle fire with foam on the ground

By Adam J. Hansen

There are a vast variety of calls that firefighters respond to every day. When we arrive at the firehouse for a tour, the tones drop, setting in motion our familiar 911 response, but the various emergencies we might face runs the gamut from structure fires, medical emergencies, gas calls, motor vehicle accidents, and on and on. Among these frequent calls are vehicle fires. Depending on where we work, vehicle fires are sometimes the most common type of fires to which we respond. I’m not downplaying or discarding the endless list of hazards that come along with them, but often, we consider these vehicle fires as relatively “routine.” We arrive, position a block to provide for a safe working area, stretch a Mattydale, break it at 100 feet, extinguish the fire, conduct some overhaul, and try and get the VIN/license plate numbers. Sometimes there is more to it, but in a nutshell, that’s your basic vehicle fire, barring extenuating circumstances like explosions, below-grade parking garages, exposures, etc. At the same time, one factor which fire crews seem to encounter more often of late is the presence of gasoline on the ground that has ignited and is on fire.

Plastic fuel tank

(1) Plastic high-density polyethylene (HDPE) fuel tank from a Dodge Ram.

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Not long ago, fuel tanks on vehicles were designed and made exclusively using metal. These metals were mostly constructed out of steel or aluminum. This made for an extremely fortified tank and was less subject to failure from excessive heat during a well-involved fire. Fast-forward to the present day and we find metal fuel tanks are the exception, not the rule. In this highly competitive day and age, companies are constantly pursuing new ways of making things more cost effective, and this certainly holds true in the automotive industry. Given this impetus, the concept of plastic fuel tanks was devised, designed, manufactured, and such tanks are now found on countless cars on our highways and roads every day. The tanks are made using high-density polyethylene (HDPE). Although steel tanks are slightly cheaper to construct, other advantages of plastic fuel tanks make them much more appealing to manufactures attempting to maximize profits and make stakeholders happy. The benefits of plastic tanks come not from the direct costs but from the presence of lighter materials and greater freedom in design/placement, hence optimizing space. Without the presence of weld seams, plastic tanks are also less likely to rupture when they strike objects such as a curb. Although able to withstand elevated temperatures from everyday events, this is not true when considering the high temperatures involved in a vehicle fire. As compared to metal fuel tanks, all plastic fuel tanks will eventually melt and fail when exposed to fire. Metal fuel tanks can be exposed to and resist the high temperatures brought on by fires for much greater times. When fires occur, metal tanks are far less likely to break down when compared to the newer style plastic tanks. When I first began my firefighting career, it seemed as though most of the vehicle fires to which we responded simply involved vehicle components. Fast forward 15-plus years, and it’s not uncommon to roll up to a car fire with a stream of gasoline on fire and flowing down a graded slope on Interstate 95.

Metal fuel tank

(2) Classic metal style fuel tank from a 1980s-style Oldsmobile station wagon.

Most modern fire apparatus have some type of “on board” foam delivery system. Whether direct injection systems, around the pump proportioners, or balanced pressure proportioners, most pumpers have some form of an apparatus-mounted foam delivery system. At times, firefighters may experience delays in getting foam out of these delivery systems. Most but not all fires we respond to simply need water to confine and extinguish, and many fire departments may not be using foam on a regular basis. This sets us up for possible issues when a foam operation is needed, whether because of lack of use of the onboard delivery system, lack of knowledge with the system, or 30 gallons of foam simply sitting idle for long periods of time.

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Five-gallon bucket

(3) A five-gallon bucket provides another means of foam delivery for vehicle fires where the plastic fuel tank has failed.

As firefighters, I think we can all agree one of the worst things we can experience is to have active fire and not be able to extinguish it in a timely fashion. Fire service members justifiably have backup plans for most situations, creating redundant systems to ensure tasks are completed in a safe and professional manner. For example, when referring to options for water delivery we have hydrants, drafting, onboard water tanks, 2 1/2-gallon water cans, etc.

Foam should be no different. Having several options available is crucial to being an effective engine company. With the advent of greater involvement of gasoline when operating at car fires, it’s imperative to have a “Plan B.” An accessible and cost-effective backup plan for foam delivery is to simply carry a spare five-gallon bucket of foam on the apparatus. Instead of introducing foam from the on-board foam tank, directly add the foam from the bucket. This allows for the chauffeur to place the eductor/pickup tube directly into the bucket. If there is an issue with creating a Venturi effect and introducing foam, the operator can easily manipulate the tube and see where the problem is. If your company decides to explore such a backup plan, be sure to have all necessary tools/equipment needed for a foam operation, including a foam container wrench, be readily accessible. This will ensure access to the foam bucket in a prompt manner.

Foam container wrench

(4) A typical foam container wrench, which is needed to gain access to the bucket.

Technology keeps changing and advancing, but new approaches bring with them unintended consequences. The fire service is by no means immune to this hard truth. The advent of plastic gasoline tanks brings with it new challenges. Instead of arriving to simply find a fully involved vehicle fire, we now arrive to find other hazards not nearly as common compared to previous days. With proper knowledge, skills, abilities, and equipment on hand, we can minimize these new risks.

Adam J. Hansen

ADAM J. HANSEN is a lieutenant assigned to Engine 7 in the Milford (CT) Fire Department, where he has worked since 2006. He began his career as a volunteer in Branford, Connecticut, in 1999. Hansen has a bachelor’s degree in fire science (fire administration) and a minor in criminal justice from the University of New Haven. He is a nationally registered paramedic and is a state-certified fire service instructor 2, fire officer 2, incident safety officer, pump operator, and aerial operator. He is certified in rescue operations: trench.

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