Safety in the spray booth is extremely important. You’ve got your safety glasses, steel toed boots, spray suits, and explosion proof lights. You quit smoking in the booth in the 80’s. So you’re safe, right? Hmmm… What about those grounding straps? They are there, but when you don’t hook them up, nothing happens. Usually…. So why use them at all? And are they working?
First, let’s discuss flash point. The flash point of a coating or solvent is the temperature at which there is sufficient flammable vapor on the surface of the liquid to support combustion. The lower the flash point, the more flammable the coating is. Let’s consider a coating that has a flash point of 32 degrees. It’s 70 degrees in the booth. Do you think there are flammable vapors on the surface of the coating? Oh, yes, there are. And these vapors need to be respected.
Now that you have flammable vapors, you’re just one spark from a fire. Sparks can come when anything with an electrical charge gets close to anything that is grounded. When the electrical charge jumps towards the ground, a spark occurs in the gap between the two items.
Here are some helpful tips to prevent sparks.
1) Always use properly installed and tested grounding straps. Be sure to hook up the ground strap to sprayers, paint pots, and containers of solvents or coatings.
2) Always use metal pails for flammable liquids. Since plastic is not an effective conductor of electricity, electrical charges can build up in plastic pails or drums.
3) If you are relying on the pail or drum sitting on a concrete floor to be an effective ground without a grounding strap, it isn’t. Paint buildup on the booth floor also acts as an insulator.
You MUST use ground straps to a proven earth ground if you want to be sure that your pails are effectively grounded.
4) Beware of paint buildup on metal pails or on alligator clips. The paint acts as an insulator that prevents effective grounding.
5) Only use intrinsically safe items in the booth or paint kitchen. Electric drills, paint sprayers, paint shakers, forklifts, and cell phones can all trigger a fire when flammable vapors are present. Air powered tools are preferable.
As an additional reminder, you should eliminate or minimize the amount of flammable liquids in spray booths or paint kitchens. Open drums or pails of flammable liquids are especially dangerous. Think of flammable liquids as fuel for your next fire. If you wouldn’t fill your spray booth with firewood doused with gasoline, you shouldn’t fill it with flammable liquids.
Please, be safe.