The Stovebolt Site Forums The Shop Area Paint and Body Shop Any suggestions for exhausting the spray booth?

In a prior life, in another house, with neighbors from Heaven I might add, I painted a lot of cars, motorcycles, airplanes, trailers, etc., in the garage. I used a two-foot high 2x2 frame under the door with a house fan in the center. Not very efficient or effective but it helped clear the air some.
I now live in a residential area and have been cursed with the neighbor from Hell living on one side and one going to Hell on the other side.
Anyway, I have a 45 x 45 ft. out building in back facing an open field that I can work in and would like to partition off one corner as a paint booth. This time I will need and want, to pay a little more attention to exhausting the booth and filtering the particulates.
I don’t do a lot of spraying, maybe in a years time a couple of vehicles a dozen or so pieces of furniture or machines.
Short of a professional spray booth and filter set up, I’d like to hear your solutions or suggestions for a home made fan and filter set up.
Denny Graham
Sandwich, IL

As far as a fan is concerned, you might try a fan from an evaporative cooler (swamp cooler). They seem to blow alot of air. If you mount it in the booth correctly, you might be able to use the filters for the evaporative cooler as well.

The fan should be explosion proof, that being said my painter buddy uses the standard cheap 20" box fans, one going in & one exhausting, they are disposable of course-he gets about a year out of them before they gum up enough to quit. He uses cheap furnace filters, doubling them etc. if needed.

I believe a professional spray booth clears the air at a rate of around 3 to 4 times per minute if I am reading the info I have seen right. An article in the December 2006 issue of Auto Restorer recommended that for a hobbyist/homeowner once a minute was sufficient. What you'll need to do is calculate cfm you'll need in relation to the size of your paintbooth.

The formula appears to be:

W x L x H x 0.8 = CFM

So for example for a 15' x 20' x 8' booth you would need a fan capable of 1920 CFM. An attic fan should be capable of this as should a decent sized box fan.

I would think about any squirrel cage fan would move enough air and would be relatively explosion resistant if the particulate & fumes are filtered well enough. As noted above I've seen a lot of "professional" body shops use HVAC home filters without blowing themselves up. If you want good filters try here.

just have an opening at both ends and make them adjustable it will draw just like a chimminey

I have been using a barn ventilation fan for over 15 years in my shop and I paint on ave 10 vehicles a year. Put the fan close to the floor on the wall away from the door and put enough furnace filters in the door to allow cross flow of air. I've got 4 16"x24" cheap filters. Make a frame so they can be easily removed and replaced. You want to filter the air coming into your booth to help prevent dirt. If your concern is the exhaust particulate then put a down turned duct to a couple inches above a tub of water. The paint will collect on top of the water for clean up and disposal. Just remember to keep water in the tub.

ha! I have the neighbour from hell. She is environmentally sensitive - as well as light and sound sensitive. I was out knocking rivets out of a frame one day she came out and told me to stop it was causing her to have an attack.

She has taken pictures of me working on cars to send to the city to prove I work on cars (its a hobby). She has even requested atht I not brush on paint as she is fume sensitive. Her husband was a mechanic - he had to give it up as he brought home smells on his clothes.

Meanwhile he was working on other folks cars in the neighbourhood for extra cash..hmm not sure how legal or hypocritical that was LOL.

I built a nine foot fence. It really helped. Out of sight out of mind.

carguy, I like your suggestions, makes a lot of sense, especially the water bit, thanks.

Wish they would let me put up a nine foot fence, my six footer just taint high enough!

Yep static is up there as one of my worries, I’m gonne stay away from a belt drive for that reason, and stick with a direct drive fan. Also I’ll drive a ground rod and pay special attention to grounding straps.
I’ve not seen any approved/professional booths that use Squirrel cage fans, they all seem to use a propeller blade. Also they are usually in a shroud or housing I would imagine to keep the tip losses down.
House fans really aren’t very efficient and they don’t move very much air.
My old garage would get fogged up pretty quick and I would have to wait for it to clear out using a house fan. I think I want something bigger and more powerful this time but that usually translates into bigger spending.
I really like that idea of bouncing the exhaust out over a water tub, I think that might work real good.
Thanks guys,
Denny Graham
Sandwich, IL

talk about worrying we used to paint in a big shop with a big barrel stove we had that fire just cranking to get it warm inuff to paint as it died down we would spray the car the paint was always smooth on the woodstove side but a little orange peeled on the cold side i was always nervise about the stove but the old guy said hed done it that way for years and vents we didnt have any guess the overspray just stayed in the shop