How big a fan do I need for a spray booth?

Here's a great tutorial on how to design and build spray booths along with a chart on selecting the proper fan:

http://www.briansmodelcars.com/tutorials/tutorial.asp?TutorialID=23&CurPage=1 

Brian's models is a great source for all sorts of tips. Most are auto related, but can easily be used for other genres.

Hey Karl,

Before people start throwing ideas your way about stealing the exhaust fan from your stove/range hood or your bathroom exhaust, I thought you might be interested in calculating the proper fan for your situation.

Check this tutorial at BMC - Spray Booth Design And Fan Selection

Good luck

Guy's thanks for the link.

That's given me a few things to think about, not least finding a suitable type of fan, as I had been thinking of using a bathroom fan, as I only spray with acrylics.

Thanks

Karl 

I actually use a kitchen fan, though I do only spray acrylics through it. I also have a very short travel length to the outside air, the whole thing is under 3 feet. I wouldn't attempt to use lacquer or enamel based paints though, the risk of explosion is too much. I was more concerned about the light source being dangerous and put in fluourescent lights.

Here's a pic, I've boxed in the fan area to concentrate the flow and prevent leakage:

I have acrylic doors to prevent dust, works pretty good! 

Bgrigg, nice looking set up.

Looks like you've got a 10 inch fan unit similar to the ones I've been looking at.

Like you I've only a short distance to cover to vent externally, 6 foot tops.

How long have you been using that set up?

Karl 

Karl,

It's actually a kitchen hood and I boxed in the fan area and used a bathroom fan vent to make it look nicer. I built that the summer before last, so almost a year and a half.

Here's an external view:

What a messy room! 

The power bar on the right leg controls power to the lights, fan and compressor, the existing switches on the hood also controls the fan (2 speeds) and the light, while the switch covers on the front panel cover a switch for the compressor and another outlet.

I built the cabinet using scrap wood (skid tops for the sides and bottom), and I was only out of pocket for the doors, hood, lights and miscellaneous electrical bits & pieces, so not counting my labor it was under $100. If I had to buy the wood it would have cost another $40 or so. It was designed to be used outside on my covered deck before I managed to snag the space in the basement. You can't see the hose very well, but it vents to the top, has one right angle bend and out the wall through a laundry flap vent. I just measured it and it's only 27" long.

Bgrigg, it looks very good, especially for under a $100!

I'm currently using an old kitchen cabinet shell, with lights attached!

Unfortunately mine has to be mobile, as I spray in the kitchen, obviously when it's not in use. I spray next to the back, door, but even in England it gets a bit cold airbrushing with the door open in January!  

Karl 

One good source for a fan is a store for boat parts, the fan that is used to vent the engine compartment has the motor out of the air flow.

I just found one for 19,90e and it runs on 12 volts, have to start building the booth soon.

Michael

Karl,

To answer your question:  If the face size of your booth is 18" X 18", then you'll need a fan that will provide about 225 cfm.  If the face size is 18" X 24", then approximately 300cfm is what you'll need.  Those are fans that will provide a face velocity of 100fpm, which will ensure good vapor capture.  Depending on the length and diameter of your duct work, you might consider increasing your cfm ratings by about 25%.  These are figures for a back drafted booth.

If you are in the mood for a downdraft booth (a much more efficient setup, IMHO), you can cut your velocity requirements in half. 

If you're looking for a commercial booth (ie, one you don't have to build yourself), trawl a bit farther and look at both the Artograph downdraft, or the one sold by Micromark. Paasche has a good selection of back drafted booths, as well.

Stay away from kitchen and range hood fans.  They're the wrong fan, period.  While they may work, you do NOT want to introduce any new potential hazards into your modeling setup.

Lastly, research this forum.  This question has been addressed previously in numerous postings.

Hope this helps.

Gip Winecoff

Guy's thanks for all the feedback.

From what I've read, it looks like I need a relatively large fan, and preferably one without an exposed motor, though seeing as I only use acrylics, that is probably less of an issue.

Karl