Incident Overview


A propane-powered box-type delivery truck has failed to negotiate a turn and has struck a utility pole. The engine compartment is on fire and the driver is unconscious and pinned inside the cab behind the steering wheel.

A propane-fed fire in the engine compartment has also ignited the left front tire of the vehicle. Fire from the burning tire is impinging on the truck's left side propane fuel tank.

The propane pressure relief device has not activated and there are visible signs that the tank has been stressed.

 

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Summary of Tank Construction Features


Propane motor fuel tanks may be installed in cars, vans, pick-up trucks, and buses. While propane-fueled vehicles have been around for decades, they are now entering the national fleet in significant numbers. They serve the same purpose as gasoline, diesel, or natural gas fueled vehicles, except the fuel is propane.

Many propane-powered motor vehicles are dual fueled and may also be equipped with gasoline tanks, which allow the operator to switch fuels based on availability and price.

Propane motor fuel tanks are manufactured in a variety of shapes to accommodate different vehicle designs. Their capacities range from 4 to 65 gallons, with most trucks and automobile tanks ranging from 35 to 65 gallons capacity. Many of these tanks are mounted in automobile trunks.

Motor fuel tanks have a maximum working pressure of 312.5 psig. NFPA 58-Liquefied Petroleum Gas Code requires that relief valves be vented to the outside of the vehicle. Discharge points on passenger cars are positioned 45 degrees from the vertical. Responders should locate the discharge points and avoid standing in this area. Relief vent piping on trucks often vents at the top of the truck.

Most valve fittings are threaded and are often limited to 1/4-inch, 3/4-inch, or 1 inch female normal pipe thread (NPT). Mobile tanks usually have a maximum of five threaded openings. Fittings must also be vented to the outside of the vehicle when the tank is installed in a confined area like a trunk or inside a camper shell. In some vans and cars, the tank installation may consist of two or three tanks manifolded together.

 

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Incident Action Plan


Tactical Objectives

  1. Protect and rescue the injured driver inside the truck cab by rapidly attacking and extinguishing the engine compartment and tire fires, which are exposing the propane motor fuel tank to flame impingement.

  2. Locate and manually close the fuel shutoff valve on the propane fuel tank.

  3. Continue to cool the propane tank while the driver is being extricated and receives emergency medical care.

Methods of Extinguishment

Fire water flows of 100 gallons per minute (gpm) are adequate for cooling motor fuel tanks of under 65 gallons capacity. Two 1-1/2 or 1-3/4 inch attack lines flowing 100 gpm or higher are recommended to cool the motor fuel tank, protect the occupant inside the vehicle, and attack and extinguish the engine compartment and tire fires.

Because the truck driver is pinned behind the steering wheel and will require extrication, an initial attack crew should place their line in service as soon as possible and rapidly attack and extinguish the tire fire on the left side of the vehicle, which is exposing the motor fuel tank to flame impingement.

Controlling the tire fire will also reduce the driver's exposure to toxic smoke generated from the burning rubber. Once the fire is brought under control, the attack crew should remain stationed on the left side of the truck and continue to cool the propane motor fuel tank.The crew should locate and close the fuel supply shut-off valve.

A second crew should attack and extinguish the engine compartment fire, then cover the rescue and emergency medical team while they rescue and treat the truck driver.

 

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Additional Factors


Additional Factors to Consider for this Operation Include:

  1. Rescue is always the highest priority and the decision to rescue and extricate an injured person from a burning vehicle is a judgment call. As a general rule, unless the patient is in immediate life-threatening danger from burning or smoke inhalation, it is usually better to attack and extinguish the fire which is threatening the driver's life, then provide life saving emergency care. You must weigh the risk of seriously injuring the driver by simply pulling him or her from the vehicle (e.g., spinal cord injury versus the risk of exposure to smoke and heat) while attempting to extinguish the fire. This decision has to be made on a case-by-case basis based on actual conditions.

  2. Tire fires on motor vehicles can present significant exposure problems. Remember that one tire contains about 15,000 BTU's per pound of energy (double the output of class-A combustibles) and can generate intense heat and toxic smoke. A combination hoseline and dry chemical extinguisher attack is an effective combination for quickly extinguishing tire fires.

  3. Propane fires in engine compartments can be controlled by stopping the engine and shutting off the supply valve on the fuel tank. Remember, even though the supply valve has been shut off, the fuel line still contains propane. It will take a very short period of time for the leak or fire to stop, depending on the size of the fuel line and leak.

  4. Motor fuel tank shut-off valves are right-to-tight, left-to-loosen. Make sure you are turning the valve off, not on.

  5. Continue to cool the tank until well after the fire has been extinguished. The metal surface should be cool enough to touch.

  6. Secondary hazards should be evaluated including energized power lines, traffic control, the integrity of the damaged utility pole, etc.

  7. Once the fire has been extinguished, the area around the tank should be monitored for flammable gas using a combustible gas indicator.

  8. Continue to cool the tank until well after the fire has been extinguished. The initial application of water to the super-heated steel will generate steam. When steam no longer appears it is an indication the situation is coming under control. The metal surface should be cool enough to touch.

  9. The area around the tank and inside the adjacent structure should be monitored for flammable gas using a combustible gas indicator (CGI).

  10. Contact the local propane marketer for technical assistance.

 

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 Incident Map


This is a top-perspective view of the incident area. Its purpose is only to get the general idea of the incident and surroundings.
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 Incident Video


In this section, we present an animated version of the incident.