I need a portable spray booth

Box Fans

Mark Mandell - Gone Round In New Jersey

Are brushless induction motors so no sparks in the air stream other than maybe one from the switch. That can actually be moved out of the fan case if you're concerned; just need the appropriate wire if you want to keep the 3 speeds. I have a K-D booth made from 2x firing strips, a roll of Vizqueen (sp), and a 20" box fan. Does fine, but mind the amount of solvent you're putting into your shop air.

Re: I need a portable spray booth

Dick Coers

I designed explosion proof electrical systems for gas turbine natural gas compressors at Caterpillar early in my career. The first thing I learned was that the system was not designed to prevent explosions, but to contain them and prevent it from propagating outward. That said, the possibility of meeting the perfect air/fuel mixture from a spray gun into a moving stream of air is highly unlikely. Even in the paint booth in the Caterpillar model shop, the most important safety feature was having the light switch a minimum of 4' from the booth door. The fans used on it were belt driven so the motor would not be in the air stream. In my most shade tree spraying days, I put a box fan right on the spray table and let the spray dust pull through it. Moving that much air again made an explosion highly unlikely. Now a room full of vapors just sitting there is a much different problem.

Re: Box Fans

john lucas

Mark I toyed with just cutting out the back of a box and mounting the fan there with a filter in front. probably run it at low speed all the time and could just plug and unplug it to eliminate any switch sparks.

Works

Mark Mandell - Gone Round In New Jersey

for small stuff.

Re: I need a portable spray booth

Barry Irby

I was using a box fan with a filter on the inlet side, but my son absconded with the fan so he could put an epoxy flake in his garage. I also run both of my ambient air cleaners, one a Jet and the other a homemade one with a furnace blower in it. And I run my DC with several gates open, one to the hose that hangs right behind where I am spraying. Since the motor is not in the air stream I think that's pretty safe. Been doing these things for years and had no problems.

My friend has a shop with a spray room, complete with explosion proof fan. There is a 400,000 BTU gas furnace located outside the spray room in the shop that blows heat into the spray room and out through the fan. No re-circulation. One day the furnace failed to fire and my friend realized something was wrong and opened the door from the spray room just as the propane reached the pilot on the other furnace. Fortunately, he had made huge windows for the shop and they were only tacked in place. The explosion blew them all out into the yard but only broke one or two panes. He picked them up and tacked them back in place after he changed his pants.

That furnace had a few issues

Dick Coers

Allowing gas to flow with no ignition is always going to be trouble!

thanks Mark

What Dick said.....

Tim Greif - West of Chicago

It's highly unlikely that any hobby spray operation is going to generate enough flammable vapor to reach the lower explosive limit (LEL) for combustion in normal ambient room conditions where there is air movement. In a small spray booth - yes. But unlikely in a garage shop open to the outdoors. Use a small fan to move air gently through the booth and don't worry about the buildup of explosives. You need to be much more concerned about wearing the proper air respirator. If you're painting something as involved as a car, you need a supplied air respirator. If a small project in a booth, an OV (organic vapor) cartridge respirator will work nicely.

Re: I need a portable spray booth

Don Stephan

Many years ago I made a portable spray booth using three 2" x 4' x 8' sheets of high density styrofoam. Laugh away, but I literally joined them with three inexpensive door hinges with removable pins. A cabinet on caster wheels supported a used furnace fan, and hole in the middle styrofoam sheet allowed the fan to draw air from the spray booth. I was only spraying water borne finishes, so I did not worry about explosions. My spray table was a pair of circles perhaps 24" diameteer, each a double layer of 3/4" plywood. The support column was 4" schedule 40 PVC, two different lengths. A 4" PVC flange was mounted to one side of each plywood circle. A large heavy duty lazy susan (Lee Valley?) was placed on the top of the spraying stand when needed. A furnace filter was on the spray booth side of the furnace fan.

Re: I need a portable spray booth

Jerry Gibbs

I made a portable booth out of 2” foam sheets from Jeff Jewitt’s book. I was spraying latex and using a furnace fan. By accident I placed a gallon container in back of the fan creating back pressure I guess. This increased the suction in front of the fan. I’m no engineer, all I know is that I increased the efficiency of the fan.