Re: Spraybooth Queston on fan placement?

I've designed and build a 1.5 by 2.0 sqft opening downdraft booth. I have a

>centrifugal shaded pole fan unit (plenty of CFM) to vent the booth. I've added >a 2.5 inch plenum to the bottom of the booth based on advice by others, >but........... > > Does it matter where the opening for the fan is? Should it be centered on >the bottom of the booth? Can it be off to one side without messing up the flow >(ex. more draw on the right vs. middle and left, if the fan is placed on the >lower right corner). Any help would be greatly appreciated. >

Haven't made one with a bottom placed fan yet. On theorethical considerations if you are right handed place the opening on the rear left hand corner. That's where most of the overspray goes. Don't place it in the center because that's where your workpiece will be and will cover the outlet.

I like this bottom fan idea. Its a good way to mount the fan, filters, compressor, store paint supplies, etc. The fan equipment can be mounted permanently under the tabletop. I make my spray booth from cardboard cartons that I dump once it becomes too messy. With a bottom fan set up all I will need to do is to cut a hole in the cardboard to match the tabletop fan. My present top fan set up requires that I get reasonably strong cardboard boxes and even then I have to add wood strip reinforcement to mount the fan, filter and switch. With the bottom fan set up I can use any flimsy cardboard box and dump them as often as I like.

Reply to
klmok
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I built a spray booth using a wood frame covered with a foam board exterior. The fan is side mounted and to the left rear. Since I'm right handed this is where the overspray goes when I aim at something placed in the middle of the booth.

Val Kraut

Reply to
Val Kraut

Baffle it or make a plenium(?). On mine its a 3 inch or so space at the back of the box with a furnance filter across the front and the fan mounted on the back board.

Tom

Reply to
Tom Hiett

Most commercial automotive spraybooths use a positive pressure system where air is drawn in from outside, heated, dried and forced through filters through the top of the booth exiting again through filters and passing into the open air... obviously this is impractical for an open booth but it's done for a reason, the exiting fumes contain atomised thinners, solvents and paint particles and when mixed with an electric motor of a fan nasty things can happen... my recommendation here would be to extract from both top and bottom using some kind of ducting (with filters) and keep the fan as far as possible from the booth. on my own airbrushing booth I have the fan mounted at the end of a 2m long length of flexible ducting which is filtered using a recirculating water filter. Just my two cents worth :-)

Reply to
Umineko

Or, you could use a centrifugal fan which avoids the issue entirely because its motor isn't in the airflow.

Could you tell a bit more about the water filter? How does it work? I saw a spray booth once that used one, but that was just a bucket with water, with the ventilation hose stuck into the lid of the bucket. I don't see how this would do any good.

Reply to
Harro de Jong

My cardbox booth is usually at least 3 ft wide by 2 ft high by 2 ft deep. I usually hold the model when I spray paint. I haven't experienced any problems with overspray settling back on the model. On overspray my greater concern is that atomized paint shouldn't drift out of the spray booth to settle on the furniture or floor.

Reply to
klmok

"Harro de Jong" wrote

a good suggestion but not an easy animal to find with mains volatge supply.

actually if the hose was partially submerged into the water it would work fine, the air would be drawn through the water which would trap the paint particles and airborne solvents... of course you need to change the water frequently... and you certainly shouldn't pour it down the drain... My filter uses a similar system as a final filter but also has screens over which a constant flow of water is fed, this traps most of the paint particles leaving the final filter to take care of the aerosol solvents, of course you could also use activated charcoal filters for this but they are less effective.

Reply to
Umineko

Are you married? Too?

Reply to
Charles Fox

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