By Janet L. Keyes, CIH and Carol A. Keyes, CSP
Mouse nests burn easily. That isn’t something you want to discover when you’re doing hot work on a mouse-infested car. Mouse nests are only one of many ways to start fires in auto repair shops. Collision repair shops are at higher risk of burning down than mechanical shops, but we can find lots of ways to start fires in either shop.
To start a fire, you need heat, fuel, and air (more precisely, an electron donor such as oxygen). Add the right chemical reaction and you have a fire. That’s the fire triangle. Remove any of those and you remove the risk of fire. Increase heat, increase the amount of electron donors, or increase the ignitability of fuels and the risks of fire go up.
What fire hazards are in your shop?
Flammable and oxidizing gases. That cylinder of acetylene used with a torch and the tank of propane for your forklift or grill burn ever so easily. To add to the fun, acetylene wants to explosively decompose. It’s dissolved in acetone and put into a cylinder filled with a porous material to prevent that reaction in storage. In use, keep it below 15 psi.
Oxygen used for torch work does not burn. But if you want to encourage a fire, add oxygen.
Hot work. Oxygen and acetylene are used to create a hot flame that can easily ignite clothes or cars. Welding or grinding? Hot work, too. Sparks from those tasks can fly quite a distance, as some techs have discovered when their work ignited car interiors.
Flammable liquids. Nearly all the cars in your shop have tanks full of gasoline. That’s more flammable than lacquer thinner. Brake cleaner, parts washer, lacquer thinner, solvent-based paints and primers, wax and grease removers, and even hand sanitizer give you even more fuel for fires. Pouring them? That generates static electricity, leaving you with all the parts of the fire triangle, fuel, heat and air, in one place.
Aerosol cans. Know what keeps most aerosol cans under pressure? Propane and isobutane – essentially, natural gas. And we all know how readily natural gas burns.
Electrical problems. Damaged equipment can spark or arc. Overloaded circuits or cords overheat. Do you have any toaster or microwave ovens? Heat guns? The power demand of those can overload and burn up power strips. Undersized cords can do the same.
Flammable metals. A door frame made from magnesium or a panel made of aluminum won’t burn easily. But the dust from grinding or drilling on those readily ignites. Put water on that fire and it will burn more intensely.
Body shops are high hazard occupancies because they have so many fire hazards. Mechanical repair shops aren’t considered as dangerous, but if they don’t have exhaust ventilation near the floor, the area within 18” of the floor is considered a potentially hazardous location. To protect your investment, control those fire hazards.
- Keep oxygen away from things that burn – oils, flammable liquids or gases. Don’t even store it with acetylene. The only time you want oxygen near acetylene or other fuel gases is when it is set up for torch use, on a cart with gauges attached.
- Use flashback arrestors on oxyfuel torches, to keep sparks from traveling up the hoses and back into the cylinder.
- Remind anyone who welds, uses a torch, or grinds to look around first. There’s no reason for a spark to ignite a rag because rags are easily moved. Move anything else that catches fire easily – that spray can or the bottle of lacquer thinner doesn’t need to be nearby. You can’t remove all the combustible parts of a car, but you can cover those with welding blankets.
- When the hot work is done, keep an eye on the area to make sure there are no smoldering sparks.
- Store flammable liquids and aerosol cans in safe areas, such as a flammables cabinet or a mixing room designed for that purpose. Keep the amount left out to a minimum. And keep the containers closed.
- Bond and ground flammable liquids when you transfer them to another container. Bonding means you have an electrically conductive connection between the two containers; grounding gives you an electrically conductive connection back to ground. Doing both reduces the buildup of static electricity.
- Keep electrical equipment in good shape. Take damaged cords or equipment out of service. Use extension cords only when you need them, check their condition, and unplug them when done. Don’t wrap them around building components or run them through walls or over rafters.
- Use electrical cords sized for the load. Use power strips only for low amp loads, not for heating equipment.
- If you’re grinding on flammable metals, use nonsparking equipment. Clean up the dust promptly and get it outdoors, in a closed dumpster. Have a Class D fire extinguisher at hand.
A fire can put you out of business. Keep a clean and tidy shop. Train your employees on what they need to do to control fire hazards. Keep your fire extinguishers and emergency exit doors and sprinklers (at least in paint booths) ready for use, but we hope you never need to use them.
This article first appeared in AASP News (September 2021).