Exhaust fans shuttered- for finish room exhaust

[Tom Bender]

One challenge when designing an automobile paint booth is airborne mist of sprayed finish settling on the fresh paint. Great effort and expense is lavished on this issue. Commonly the air is kept as still as possible and filtered air is pulled in thru the ceiling and contaminated air is pulled thru the floor.

In your case you will be pulling from a wall. Ideally you will make opposite walls out of filters for 72 square feet each. Beyond one wall will be a wall of fans, say 72 of them. They will pull air thru the intake filter wall, thru the booth at very low velocity and thru the exhaust filter wall.

Well obviously you will not build an ideal booth but it helps to understand the mist issue.

[Leo Graywacz]

I got my shutters from Grainger.com. I have a 36x36 shutter I believe. I have a 3HP 36" Tubeaxial fan for my exhaust. The shutter I picked has felt on the ends of each shutter so it closes softly and seals better than one without. But don't expect a tight seal. They operate by airflow and gravity. When the wind is whipping up you can hear them open and close because of the pressure differences created from inside and outside the booth For the most part they work well.

[Ole Anderson]

I just replaced a 16" kitchen exhaust fan at church with this shuttered fan from Northern Tool. Max 2300 cfm, Canarm brand, 3 speed, good shutters, reasonable price, not explosion proof.
https://www.northerntool.com/shop/to...1892_200631892

[Dan Coker]

I will add my .02 cents. I built a separate dedicated 8ft x 8ft x 10ft spray booth that I use to spray my finishes. I also have a 16ft x 20ft+ paint room that basically functions as a drying room to keep air born particulate and such from the main part of the shop from getting into the finish. This has worked very well for me. I use several 1,200cfm exhaust fans vented through the wall outside. I have never been too concerned with the make up air nor do I know how to optimally design the make up air system. My shop is huge and I never spray more than a couple hours at a time. I have never felt the effects of loosing my cooled or heated air. This setup has severed me well. My fans are explosion proof too. One day I will setup a real system done correctly.

If you are on a budget, Harbor Freight makes a common cloned model tube exhaust fan just like I use that is cheap as heck at like $75 and it moves over 1,000cfm.

[Alan Lightstone]

OH, ok, TY. You must have two windows in finish room then, one for exhaust, and one for intake? Or do you use a louvered exhaust fan for outside?

No, actually one window, and the 20'x20' hole we cut in the cinder block and installed the fan and louver assembly in. Had electric louvers, but they failed almost instantly, and took out the motor and let them open manually.

I've spent all weekend making a filter holder for the fan, and now will be making a overhead Plexiglas plate for over the spray table, and completing the booth.

Should be able to spray soon.

I also had to build a filter holder for the window for incoming air. So, all-in-all, a tremendous amount of work, but I should have a working finishing room, hopefully by the end of the week if I can source large enough plexi/lexan.

[William Hodge]

It's worth reading the code for spray booths to catch some other stuff, before you do it.

I built a spray booth for the shop I was working in. The lights needed to be explosion proof, so that you would,'t be in the dark of something popped. All the conduit in the spray area needed to be threaded and sealed. There was a bunch of other stuff, too. Most of it was common sense, but it doesn't hurt to be reminded.