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DHR - SAFETY ALERT MEMO 02-02
DATE: September 17, 2002
INCIDENT TYPE: Fire at Caltrans Maintenance Yard
TYPE OF WORK ACTIVITY: Rag Disposal
THE ACCIDENT: The following is a newspaper story from a local newspaper:
Fire investigators have determined that a fire Saturday morning inside the Caltrans maintenance building was accidental, caused by fuel and chemicals on shop rags igniting. The local Fire Department was called to the fire at 8:45 a.m., and arrived to find flames coming from the windows on the north side of the building.
Several firefighters were away at the a fireman's muster, but adequate personnel remained to bring the fire down in less than an hour. Additional Fire Department personnel were summoned for backup, arriving about 15 minutes later.
According to the Fire Chief, the fire gutted the interior of the garage, destroying a Caltrans truck and damaging an office in the building. Pacific Gas and Electric personnel arrived shortly after the fire department to cut power to the buildings. Fire personnel remained at the location until about 3 p.m. to ensure that the fire was completely out, checking between walls and roofing for remaining hot spots. Caltrans officials said it was too early to assess the damage and are doing their own investigation into the cause of the fire. A Caltrans spokesperson said that the fire would have been a lot worse, had it not been for a Caltrans worker who happened to be in the area and called the fire department shortly after the fire began.
CONCLUSIONS: An investigation is continuing but it appears that fuel soaked rags were being improperly stored or discarded. These rags apparently spontaneously combusted, starting the fire. Spontaneous combustion occurs when oxygen from the air slowly unites with the flammable material in the rags. At first, there will be no fire, but as oxidation gradually takes place, enough heat accumulates to set the rags on fire. Spontaneous combustion of rags can be prevented by restricting the amount of oxygen reaching the rags (placing them in a sealed metal container) or by providing sufficient ventilation (hanging them on a clothesline) to quickly dissipate the heat. Materials such as rags or papers that are soaked with animal fats, vegetable fats, paints, motor oils, or solvents are particularly subject to spontaneous combustion.
RECOMMENDATIONS: Any paper or rags that have been soaked with a flammable liquid should be disposed of in an approved sealed metal container to prevent spontaneous combustion. By disposing of spontaneously combustible material in this manner, you are eliminating the oxygen supply; one of the three conditions (fuel, oxygen, heat source) needed to create a fire. Protect containers against physical damage. Outside or detached storage is preferred. Separate from oxidizing materials. Store in cool, well-ventilated area of non-combustible construction away from possible sources of ignition.
HEADQUARTERS OFFICE OF HEALTH AND SAFETY SERVICES (916) 227-2640