Stay Grounded

by Janet L. Keyes

Which of these are in your shop: brake cleaner, gasoline, windshield washer fluid, motor oil, parts washer solvent?

Which of these can catch fire?

Which are classified as flammable liquids, with flash points under 200 degrees fahrenheit?

The answer to the first question: all, if you’re a mechanical shop. If you don’t do any mechanical work, you probably don’t have a parts washer or brake cleaner. But everyone has gasoline, washer fluid and motor oil.

The answer to the second: all of them can ignite. It takes the most energy to burn motor oil – that’s the least flammable of the bunch, followed by parts washer solvent.

The answer to the third: Most readers will readily answer brake cleaner and gasoline. The one that people often don’t guess is windshield washer fluid. But in northern climates like Minnesota, it contains enough methanol to make it very flammable. 

We classify flammable liquids based on their flash point, the temperature at which they give off enough vapors to ignite. If you bring gasoline down to a temperature below -45°F (that’s 45 degrees below 0°F), it won’t ignite. (Maybe you’ve heard of someone plunging a lit match into gasoline, to show that it won’t burn. It doesn’t – because it’s the vapors that burn, not the liquid. You need the oxygen in the air, mixed with the vapors, for ignition to occur.) According to OSHA, if it has a flash point below 73°F, it’s a Category 1 or 2 flammable liquid. Below 140°F, it’s a category 3 flammable. The Fire Code classification is slightly different: if the flash point is below 73°F, it’s a hazard class I-A or I-B flammable liquid. If below 100°F, it’s I-C, and below 140°, hazard class II.

Gasoline and brake cleaner are OSHA hazard category 2 flammable liquids and Fire Code I-B. Partswasher has a flash point just above 140°F. Motor oil’s is usually over 400°F. Ready to use all season washer fluid: usually between 80°F and 110°F. If it’s concentrated, meant to be diluted for use, the flash point will be 54°F, making it a hazard Category 2 or I-B flammable liquid.

Why does the classification make a difference? The more flammable the liquid is, the more fire precautions you need to take. 

You need to limit how much you have on hand. OSHA and the Fire Code limit you to 120 gallons of 1B or 1C flammables per fire control area – that’s an area separated by fire-rated construction from the rest of the building. If the area is sprinklered, the Minnesota Fire Code lets you double the amount. If you use flammable cabinets for storage, the Fire Code allows double the amount. Most collision repair shops have mixing rooms, designed as inside storage rooms for flammable liquids. If that room is sprinklered, with exhaust ventilation designed to capture vapors from a spill, a sill to contain any spill and fire-rated construction, you can legally exceed those limits. But if you have multiple drums or totes of washer fluid and brake cleaner sitting out on your shop floor, you’re probably over the limit.

Use the right containers. The original manufacturers’ containers are supposed to meet certain specifications. Don’t transfer flammable liquids to your empty plastic jugs. Containers for gasoline need to be self-closing, have flame arrestors and be vented – and you need to be able to ground or bond them.

Ground and bond your containers. When you pour a flammable liquid, the action of pouring creates static electricity. Combine static electricity with flammable vapors and you have the ingredients for a fire. Know the warnings about not filling gas cans in the back of your pickup truck? That’s prohibited because of static electricity. Whether you’re emptying a car’s gas tank prior to repairs or dispensing brake cleaner or thinner, you need to control that static. 

Grounding is done by connecting a grounding wire to a building ground. That can be a grounding rod sunk into the ground, metal water pipes or metal building components that are grounded. Bonding is connecting a metal wire between the original container and receiving container. Bonding equalizes the static charge between the two containers. Grounding gives the static charge somewhere safe to go.

Plastic containers cannot be grounded, but a dangerous static charge can still build up when you pour from or into them. Metal containers are a better choice. 

A lot of suppliers provide washer fluid in plastic drums or totes (IBCs). That doesn’t release you from the need to bond and ground, but it does make doing so a lot harder. You can put the drum on a steel plate that’s grounded. For dispensing, you can use a stainless-steel pump that extends to the bottom of the container. 

For effective bonding and grounding, you need to ensure that you have a solid connection between the container and the grounding or bonding wire. If the drum is painted, make sure you scrape off the paint or use a clip that can penetrate through the paint.

We have seen an increase in citations from OSHA for flammable material storage and lack of grounding and/or bonding.

We learn from others’ tragedies. Even a small container of a flammable liquid can start a fire. A repair shop in California learned this the hard way, when one of their mechanics poured gasoline from a bucket into a newly installed fuel tank. Gasoline spilled onto an incandescent work light. The resulting fire killed the mechanic. Treat flammable liquids with care.

For more information, contact Carol Keyes via email at or (651) 481-9787.

Want more? Check out the July 2024 issue of AASP-MN News!