Spray room set-up and operation

Hot to get lighting and exhaust details right, eliminating safety risks in spray-finishing operations. February 13, 2001

I'm setting up a spray room and doing it as safe as I know how, but I am not using an explosion proof fan.

The room is 10 x 12 with an 8' ceiling. The fan that I have ordered is a 14" or 16" axial fan with a TEFC motor (direct drive). The fan is rated at 2000 CFM and I will have a 48 x 24 filter panel for inlet air and I can add a further 24 x 24 panel if needed (into the room). I will fabricate a filter panel to catch overspray before it gets to the fan. The size and shape of the exhaust hood will be based on the size of the filter media (an air filter supplier is suggesting using roll material, cheap and easy to replace as it gets plugged).

I have two sets of basic fluorescent four-tube fixtures in the room, and the switch is outside.

I will be using a supplied fresh air system, which uses a helmet.

I will be spraying no more than 5 - 10 hours per week. I make home furniture and sometimes need to finish in lacquers. I also do some refinishing, and spraying is necessary to provide the quality of finish.

My questions are:
1) Are the fluorescent lights a risk in the spray booth?

2) Should the exhaust hood pick up fumes from floor height, bench height or higher up for the best and safest operation?

3) Can I shut the fan off and close the finishing room when I've finished spraying or do I need to exhaust fumes as the lacquers flash and set up?

Forum Responses
I have the same size spray room that you have. I bought a used small spray booth and mounted it in a hole I made in the end of the wall.

Your lights should be encased with a sealed frame with 1/4" wire glass over them.

The fan I have is in the duct itself. It has a belt drive to an explosion proof motor. The explosion proof motor is a must no matter how much you spray.

I have a 24" x 24" filter on the opposite wall and I can clear the air in 20-30 seconds. Lacquer will build near the floor more than up near the ceiling, so the lower the fan, the better. When I used to shoot lacquer, I would leave the fan on for five minutes after I finished and it always worked great. I have switched to waterborne lacquers now and have had great results with them.

You may want to check with your local fire department for their rules on having a booth.

Check with your insurance company, too. Should some bad accident occur, you may find that you are alone with no insurance to cover your damages. Plus, you could be liable for some negligence.

Think about a switch from solvent coatings. Then you can keep the fan that you have.

From the original questioner:
What brands of waterbornes are you using?

The coatings that I use are ML Campbell waterborne lacquer, Oxford conversion varnish and Aqua-coat. I use the Aqua-coat to finish the inside of my case work and the ML lacquer for my furniture and cabinets. The Oxford varnish works good if you are looking for that oil-base solvent amber finish. All of these are non-flammable and will clean up with water. They are harder to put on than some of the solvent-base coatings.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor A:
I think you are taking enormous risks with your setup, especially if you are spraying nitrocellullose lacquer. When you spray a solvent, you are creating an explosive atmosphere. Explosion proof lighting and motors are designed to both minimize sparking and thereby ignition, and to contain the force of an explosion, should one occur. The chance of explosion may be low but the risks are very high indeed.