WHEN THE ROUTINE BECOMES IRREGULAR

WHEN THE ROUTINE BECOMES IRREGULAR

BY CRAIG A. HAIGH

Some of my most enjoyable memories in-clude the times I sat around the fire station table drinking coffee and listening to the “old guys” tell their stories. These were also some of my best learning experiences. One bit of advice often given by the old guys was “Watch out for the routine.” They pointed out that when we become complacent, we walk into situations without thinking and without proper size-up. If the routine becomes irregular, we then lose or injure brothers and sisters.

This advice was vividly brought to mind on the evening of November 25, 1997 (two days before Thanksgiving) when at 1824 hours, Stokes County (NC) Communications dispatched an EMS call for a burned civilian. Squad 30 and Stokes County Unit 4 responded and were told en route that the subject had been burned by a “ball of fire” coming from a propane-fed gas range. Dispatch reported that there appeared to be no fire. Nevertheless, based on the information given, Engine Company 130 self-dispatched.

FIRST RESPONSE

On arrival, the engine crew found a 49-year-old female with second-degree burns to her face and legs and first-degree burns to her arms. The patient`s family said she was attempting to light the oven when a fireball blew out from under the stove and burned her.

As the patient was being treated and packaged, firefighters began to check the structure for fire extension and carbon monoxide (CO). A slight odor of propane was noted, but there was no evidence of fire or CO.

The victim`s family explained that the propane tank at the rear of the mobile home had been filled earlier in the day and that it had not been used for approximately four years. They said the victim had never used the range but wanted to cook Thanksgiving dinner this year. Armed with this information, a firefighter was sent to locate and shut down the propane tank.

ODOR OF SMOKE

As the patient was transferred to the ambulance for transporting, firefighters began to clean up the debris remaining from the EMS function and to obtain information for their reports. At this time, they noticed a slight odor of smoke. As the firefighters proceeded back to the kitchen area, the odor grew stronger, and a slight haze of smoke was evident. Fearing that they had missed something, they began to again feel the walls, looking for extension. A full-alarm assignment was requested for a possible mobile home fire. The crews continued to search the structure while awaiting the additional resources.

A hot wall was found in an area approximately six feet away from the range. This wall separated the kitchen from a utility room containing the hot water heater. A 134-inch line was stretched while the wall was being opened. The interior crews fully expected to extinguish the small fire with the pump can without need of the line.

Much to their surprise, however, a large fireball exploded from the wall as it was opened and enveloped the crew in flames. The crew instinctually dove to a prone position on the floor, and the roaring fireball vented out the open back door. The crew began to apply water from the pump can while waiting for the line.

The interior engine crew reported that the application of water was having no effect on the fire; no progress was being made toward extinguishment. Every time water was applied, the flames darkened and then immediately returned. Smoke continued to fill the structure, and the heat level was increasing.

The crews searched for the seat of the fire. Engine 230 was assigned to check the crawl space beneath the trailer. The firefighters entered the area in full turnout gear and SCBA and reported that a small fire was burning at floor level just below the interior crew`s location. On further inspection, they saw what appeared to be fire dropping down from the area under the hot water heater.

The officer radioed that when exposed to air, the fire looked more like a combustible gas igniting and extinguishing than a hidden fire. Interior crews now reported fire was breaking through the floor and walls and that they were having trouble extinguishing the fire.

Still unclear about the situation at hand, the incident commander ordered the opening of the roof directly above the fire area in an effort to control spread in the concealed attic space. Horizontal ventilation was also employed to relieve the heat on the interior crews. These actions enabled the crews to ultimately extinguish the fire.

INVESTIGATION FINDINGS

The victim`s family said they had been smelling propane all day but were unconcerned about it since they believed it was a normal occurrence after filling a tank. They explained that before the victim was burned by the fireball from the range, she had been experiencing difficulty in lighting the oven using its built-in igniter–a problem that apparently had existed over the years. The victim then began “poking” the igniter with a broom handle while the propane continued to flow. Then the fireball emanated from the range.

The investigation revealed that two alligator clips connecting the power to the electric igniter had been pushed together and were touching. A small burn or scorch mark was also found on the rear wall of the range next to the clips. Investigators concluded that the alligator clips were driven together when the owner poked the igniter, causing an electrical spark that ignited the propane-rich environment. This caused the first fire–the one in which the occupant was burned.

A Second Fire

Investigators believe that a second fire occurred, probably while fire personnel were on the scene, from a second ignition source and a propane leak.

Considering the area of origin, investigators were able to pinpoint a low burn pattern coming from the hot water heater thermostat. A V-pattern extended up and outward from this area, where the engine crew initially found the fire. As the hot water heater was removed, the chipboard flooring was found to have extensive water damage and holes for the passage of electrical wiring and the heater overflow. Still, the question remained: If we truly had a propane-fed fire, where did the leak occur, and how did a gas heavier than air vent itself up through the floor of the trailer?

A Propane Leak

Investigators began tracing the propane line from the tank to the range. They located a fitting just inside the underpinning of the trailer, and it was confirmed that a substantial leak was present. On inspection, the underpinning was found to be tightly weather-sealed around the frame of the mobile home as well as at ground level. All air-circulating vents located in the brick wall, including the entrance door to the crawl space, were closed. It is believed that the propane had been leaking out of this fitting since the time the tank was filled and had collected in the brick-lined crawl space. The underpinning acted like a pressure vessel; the pressure increased as the propane leaked. With this elevated pressure, the propane vented through the path of least resistance, exiting through the holes in the floor around the hot water heater. At that point, the thermostat acted as an ignition source, igniting the gas.

Investigators believe that the concentration of propane in the crawl space was above its upper explosive limit and ignited only when it fell within its flammable range. This explains the difficulty in extinguishing the fire and the drop-down flames witnessed by the crew in the crawl space. The only phenomenon still unexplained was that the gas in this area did not ignite as it vented and fell within its combustible range. Our only explanation is, “God was watching our backs.”

LESSONS LEARNED

This incident vividly taught us several lessons.

First and foremost, we were reminded that no call is routine.

We also learned that you can do everything right and still endanger your life. We feel fortunate that when the thermostat on the hot water heater kicked in, the spark did not ignite the propane trapped in the crawl space, blowing the trailer from its foundation and killing personnel, the burn victim, and her family.

There is no substitute for experience. Therefore, all of us involved will never look at a similar call in the same way. We have become very conscious of the fact that there is always the potential for leaks when propane tanks are involved. We frequently check low areas for an accumulation of the gas. Also, when interior crews report that a fire does not darken down in spite of extinguishing efforts, we immediately begin looking for something unnatural.

We were reminded also to pass our experiences on and to take the time to listen to the stories around the fire station table. They may save our lives. n




The mobile home after the fire. The brick underpinning acted as a pressure vessel. (Photos by author.)










(Top) The pressure in the brick underpinning in-creased as the propane leaked from the propane tank coupling. (Middle) The water-damaged floor under the hot water heater. The propane vented through the path of least resistance–the holes in the floor around the hot water heater. (Bottom) The thermostat acted as an ignition source for the propane.

n CRAIG A. HAIGH is chief of the King (NC) Fire Department. He previously served as chief of department for Hampton (IL) Fire Rescue and as a career member of the City of Rockland (IL) Fire Department. He is a paramedic with extensive EMS management/training experience and a field staff instructor at the University of Illinois Fire Service Institute.

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