Incident Overview


A forklift operator driving a propane powered forklift was stacking wooden pallets in the rear of a warehouse loading dock when she smelled smoke. Upon investigation, she discovered that two battery cables on the forklift had come loose and contacted the engine’s manifold starting a fire. The operator immediately shut down the forklift, turned off the battery switch, and told her co-worker to call the fire department.

The forklift operator ran to the loading dock and grabbed a dry chemical fire extinguisher. Meanwhile, a third employee ran to the forklift and attempted to remove the motor fuel cylinder from the rear of the forklift by using the quick disconnect on the fuel line connected to the service valve. The fuel line was disconnected, and propane flowed freely out of the service valve. It was immediately ignited by the engine fire, and the fire flashed back to the cylinder burning the employee.

After observing what had just occurred, the forklift operator ran back to the forklift and discharged the fire extinguisher onto the burning engine compartment. Realizing that the fire was not extinguished, she pulled the injured employee clear of the fire area and waited for the arrival of the fire department.

Fire Department Size-Up

Upon arrival at the warehouse, the first arriving engine company officer observes a bright orange and yellow fire burning horizontally from the rear of the forklift. The Pressure Relief Valve (PRV) on the propane cylinder is not functioning. Heavy black smoke is seen coming from the engine compartment.

The company officer also observes a stack of wooden pallets about 50 feet east of the burning forklift next to a brick building used as a maintenance shop. A steel frame loading dock is located approximately 50 feet north of the fire. The loading dock is attached to a metal deck on steel warehouse.

The warehouse manager advises the company officer that one of his employees is lying on the west end of the loading dock and has been badly burned and in is need of medical attention. He also advises that the warehouse stores auto parts and is not sprinklered.

 

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Summary of Cylinder Construction Features


Motor Fuel Service Cylinders

Motor fuel service cylinders are used as portable fuel tanks for fork lifts and farm tractors. They are also used to power heavy-duty building maintenance equipment such as floor polishers and aisle sweepers.

Motor fuel cylinders are usually configured to supply liquid propane to the engine rather than vapor. They can have as many as five openings in the service end of the cylinder.

Fittings may be threaded or flanged. Each service valve opening is marked for either vapor or liquid service. The service valves are connected to a dip tube which runs into the liquid or vapor space of the cylinder. Motor fuel service cylinders are equipped with a Pressure Relief Valve (PRV) which is set to function at 375 psi.

 

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Incident Action Plan


Tactical Objectives

  1. Evacuate employees from the warehouse and the loading dock.

  2. Rescue the injured employee from the loading dock and provide emergency medical treatment in a safe area.

  3. Control the fire on the forklift and prevent the fire from spreading to the wooden pallets and the warehouse.

Methods of Control

Two 1-1/2 inch or 1-3/4 inch hoselines should be placed in service as soon as possible. The first hoseline should be directed onto the motor fuel cylinder’s outer shell to maintain its integrity while the propane is allowed to burn off under controlled conditions.

The second hoseline should be used to extinguish the engine compartment fire, then be redirected to cool hot metal surfaces on the forklift. Hoselines should remain in position until the propane burns off and there is no evidence of steam.

 

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Additional Factors


Additional Factors to Consider for this Operation Include:

  1. This scenario describes special life safety circumstances that may justify offensive tactics. These include:

    1. An injured employee requires rescue and emergency medical treatment
    2. Employees need to be evacuated to a safer area
    3. Fire is threatening to extend to a non-sprinklered warehouse

    The Incident Commander must weigh the risk of intervention using offensive tactics against non-intervention; e.g., evacuate the area and let the forklift burn. For example, if there are no life safety issues involved and no exposures, why should firefighters assume a risk for a forklift that is basically a total loss when the fire department arrives?

  2. Motor fuel cylinders can rupture under fire conditions even if the Pressure Relief Valve (PRV) is not functioning. The fact that the cylinder is attached to the forklift with a mounting strap is not a guarantee that a ruptured cylinder will remain attached if the cylinder fails. Not every motor fuel cylinder fire results in a tank rupture. Sometimes the cylinder simply burns off.

  3. In this scenario, the liquid service valve is in the open position. Liquid propane is burning from the open service valve. Consequently the fire will be more intense than a vapor fire. Care should be used in applying cooling water to the service end of the cylinder’s head so that the fire is not extinguished. If the fire is extinguished before all the fuel is consumed, liquid propane will leak from the cylinder and may reignite and flash back to the cylinder. The expansion ratio of propane is 1 to 270.

  4. If the fire is accidentally extinguished by hoselines, streams should switch to the power cone water fog pattern and be used to dissipate propane vapor. A Combustible Gas Indicator (CGI) should be used to check the area to determine if the atmosphere is flammable.

  5. Use maximum hose stream reach to place as much distance as possible between firefighters and the burning cylinder.

  6. Special attention should be given to rubber tire fires on the forklift. Tires contain lots of energy and can burn intensely. Note that the rear tires on the forklift are directly underneath the motor fuel cylinder. Dry chemical extinguishers used in combination of water fog from hoselines can be effective in extinguishing tire fires.

  7. Disconnecting a motor fuel cylinder from a burning vehicle is a dangerous practice even if the service valve is closed. Residual propane will remain trapped between the closed service valve and the fuel line and can ignite.

  8. Contact the local propane marketer for technical assistance in removing and disposing of the cylinder.

 

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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.