Time to build a new spray booth

[sportandmiah]

I've been using a small home made paint booth for a few months now. It used a $25 bathroom fan and vented outside. I've been searching for a squirrel cage motor, and 2 landed in my hands for free a few weeks ago. The first motor was pulled from an old furnace. I tested on my small booth and it works good. Later that day a friend gave me a brand new Dayton motor.

The current booth is too small, so its time to make a bigger one. I am thinking of using both fans: the higher rpm new Dayton motor for a down draft fan, and the older fan for rear draft. Think its overkill? Im trying to avoid fumes in the house at all cost.

The basis for the size of the booth will be the standard 10x20x1 common air filter. I've read over Klaus 's article, but it is waaay over my head as far as calculations.

Any input encouraged. Here's some pics of.the motors:

[RodneyBad]

Oil every 6 Months.

Aint seen that warning label before, Guess I better check my fan.

I think with 2 fans, the paint won't make it to the model.

IDK, I bought a Pace booth.

[Dr. Cranky]

What is your set up going to look like?

[moparmagiclives]

How far are you venting this thing to the outside? maybe the smaller one pulling from the rear at all times to keep air moving, and the heavy one pulling from top or bottom just then your spraying?

[gasser59]

I've been wanting to build a small paint booth my self so I'll defiantely be dollowing along on this one.

[Mike Kucaba]

You can probably look up how much CFM those fans move at Graingers website. The smaller one looks like what's in my booth and it really pulls the air.It vents to the back and to cut down on the pull,I had to double up on the filters.The run for my booth was very short, just about six feet. The other on labled Fasco appears to be more of a blower if you specking this for some project. Good luck on this project.

[sportandmiah]

The picture.here shows my old spray booth. My new booth will be.similar in.design. Its currently resting on a mock up made out of.cardboard. The cardboard mock up is.going to house the down draft fan.The actual booth housing will look similar to the old one on top, but a little bigger.

[scalenut]

nice score on the Dayton motor and blower !..

the magic range seems to be 200- 300 cfm for cross draft , closer to 200 cfm for downdraft.

not sure if that's free air or under load

adding reducers,90's, type of vent pipe,size of booth opening ,and filter type has a big effect on the actual outcome of course.

I read that adding a simple 1" reduction in the vent pipe can reduce the cfm by 30%.

looking good so far!

[Dr. Cranky]

Looks good, but you are obviously going to run the line to the outside for exhaust, right?

[sportandmiah]

Yup...vented out the basement window with 4 inch round duct.

[moparmagiclives]

Where did your old one come from? What's your plans?

[greymack]

Hey guys if your looking for a cheap spray booth use a rubbermaid tub and a bathroom fan . I have a setup like this and it works great.

[sportandmiah]

Bathroom fan has been debated here and every other forum for safety reasons.

The old motor was from an old furnace.

More cardboard mock up. The cars and paint are for you to see size reference. The filter will simply drop in a recessed panel.

[Aaronw]

You might consider locating both fans below the booth side by side then boxing in the two exhausts to run into one duct. I think that would work better than a cross/downdraft set up which might confuse the air.

As long as the two fans are similar in flow I don't think having them side by side would cause any issues.

The calculation for recommended airflow is actually pretty simple, just take the square footage of the opening and divide by the CFM of the blower. Ideally this will result in a value of 100 for a cross draft or 50 for a down draft booth, but many commercial booths fall well below this figure.

So if the opening of your booth was 12" tall and 24" wide (1x2) it would be 2 square feet in area. If your blower was a 100 cfm unit then 2/100 would give you 50 meaning the blower was well suited to a downdraft booth of that size.

The actual size of the booth is largely unimportant, it is the size of the opening that matters.

[sportandmiah]

I will probably just do the bottom draft, like you mentioned the cross fan idea might be too much. Few.more updates of the mock up....height subtracted by inch and a quarter.

[Nick Notarangelo]

Hey if you got the space find a old armoie and modifiy that,say one with a big open top and you can use the drawers on the bottom for storage.

[sportandmiah]

And here's the motor specs

http://m.grainger.com/mobile/details/?R=4C442

[Mr. Moparman]

I like the way you are doing this.

[sportandmiah]

Thxmopor.

I tested it today. Not too bad, but I might use both fans as down draft. Under the filter is a 3/8 inch gap with a board that has many 1' dia holes, to help dissipate the air.being.sucked.in. I will make the final version of this open space 1/2".

[Art Anderson]

Methinks a lot of over-engineering is going on here! Almost any squirrel cage blower is more than enough! My Pace Peacemaker is not that huge, and yet, it's blower pulls every last bit of paint fumes out of the apartment, to the outdoors (through a very fine air filter, I might add!). In the bargain, it's more than whisper quiet, so much so that the old lady who lives downstairs doesn't even know I build models right above her bedroom!

Art

[sportandmiah]

I agree Art. Looking at pictures of the Peacekeeper gives me a general idea of its design, but the overall design and dimensions of the core are not easily attainable. I suppose.that when I build this correct out of wood that there will be.less open seams for air to leak in and out of.

[scalenut]

nothing wrong with building and testing a prototype from cardboard beforehand , I think it's a great idea

now's the time to make changes and improvements.

Edited December 18, 2011 by scalenut

[Amp3r3z]

great thread. thanks for the inspiration

[sportandmiah]

Although the down draft mock up works ok, Im going to build a back draft version instead. The natural flow.of.paint when spraying is towArds the back. I was having too much paint coming back out with the current setup. Pics soon to follow.

[crazyjim]

If you're going to build a booth with wood, caulk all the seams - but DO NOT use silicone caulk. It will probably leave fisheyes in your paint.