Anyone here built a spraybooth? I think I can make one for a lot less than the asking price. The one question I have is about the size of the exhaust fan. I want to use one that has an external motor so I can spray solvent based paints. I found an online source for reconditioned centrifugal blowers at a good price (http://www.blowerwheel.com/blowers-centrifugal-fans.htm). So now the question is how much air do you have to move? These come in sizes from 15 to 225 CFM. How much air do you need to move for an effective spraybooth?
George V.
Get the biggest one you can......225 CFM is not that big. That would be about a minimum I think.
Check out this link:
http://www.briansmodelcars.com/tutorials/tutorial.asp?TutorialID=23&CurPage=1
I think it would rather depend on the size of the booth.
Mine is 17" x 17" x 24" and has a 350CFM fan. It works great as I have no paint smell when I use it. A buddy of mine has one that's about the same size (the Paasche) with a 300CFM fan and I do smell paint when I use it...but that may be due to the kind of filter he uses.
IMHO, the bigger, the better. Whatever you pick, you shouldn't be smelling paint in the room when you use it.
Paul A. Cutler III************Weather Or No Go New Haven************
I believe that a duct fan listed on that sight of 250 + would be sufficient for this purpose. However if you are using a paint that can be considered explosive use a sealed fan unit.
I built my spray booth a long time ago. I made it from .040 aluminum that has a baked white enamel finish. I put car wax on the inside and don't buff it off. This makes it really easy to clean. My booth is a down draft. One reason being that the fan and motor are heavy and I didn't have to make any extra support for the booth. The other reason is that if I paint something that I need a perfect finish on I paint it upside down so any dust that gets pulled in will land on the bottom. It works quite well. I used an under cabinet light mounted to the outside with a piece of acrylic between the light and the booth. I would recomend puting in lights on the side. I designed mine to use a standard size furnice filter. Mine vents through a 4" dryer vent that I run out the window through a sliding screen thing that has louvers in it. I got my fan from Granger, its a 225. I moves a lot of air. I think the amount of air that is moved changes by the size of the vent on the other end too, which is something to consider.
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I built mine "in" so to speak, using scrap lumber attaching the Paintshop to an outside wall of the Trainroom.
Here is what I found as I was preparing for the project:
After some research, checking out the OSHA requirements and the local Motor Shop regarding blowers, I put on my engineering hat and got down to work. When using organic solvents, OSHA recommends an air flow of between 100 & 200 cfm (cubic feet per minute) at the point of spray, or in my case, at the level of the painting table. Two things determine that air flow; one being the size of the booth opening and the other being the capacity of the blower; the two go hand in hand. The formulas needed to size one to the other are really quite simple.
1) Size of the booth opening, height x width in sq. in. divided by 144 = sq.ft.
2) Blower rating in cfm divided by the booth opening in sq. ft. = the air flow.
In my case, using a base number determined by the two blowers that I had readily available, one being 525 cfm and the other 815 cfm and the area I had available to construct a spraybooth I worked out the numbers. With a 16" x 32" opening; 16 x 32 = 512 / 144 = 3.5 525 / 3.5 = 150 Armed with this information, I dove into the construction of the "Colvin Paintshop".
In addition here are a few safety tips:
1) Make sure the blower is correctly sized, installed outside of the air stream and/or has a brushless motor.
2) Be sure to seal all joints in both the wood and metal ductwork.
3) Always vent separately, with as short a run as possible. 4) Don't have exposed lights in the spray area.
5) Be sure to have a source of "make-up" air equal to you exhausted air.
6) Over size when in doubt. Elbows and extra length in a run will decrease the Air Flow. A good rule of thumb is to add 10%.
You might consider putting in a speed control for the fan motor--just in case it's too "brisk".
Ed
colvinbackshop,
Do you have a source for the brushless motor?
Thanks
Terry
TBat55:
Sorry...No, I don't. I may be able to find something out though.
Anyway add a bit of info: I didn't go the brushless route and mounted a blower with the motor outside of the air stream. The one I settled on is a Dayton Mod. # 4C445A. It's worked well and I haven't blown up yet (it's been in use for about four years now) so I think it must have been a good choice.
You got me to do some good hard thinking, regarding "brushless". As mentioned I hadn't given it much thought because I was mounting my blower outside of the air stream of the paint booth exhaust! But I was giving some thought....I have four Dayton blowers doing different things all about my house and Paintshop. I've never seen any place, to replace brushes on the motors of these blowers and soooo....
I went to my "go-to-guy" at the Motor Shop for an answer. All of the new AC motors (at least on Dayton blowers) are brushless! So there you have it. I learned something today!
Why do you need a spraybooth?
According to building codes, bathroom and range exhaust fans must be brushless or have external motors. I built my plywood booth (14x24) 17 years ago and used a cheap ($10 at the time) closeout bath room fan rated at 200cfm, (I believe bathroom fans have to be able to replace the air in a bathroom in 3 or 4 minutes). It has worked perfectly for all those 17 years.
Jay
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Thanks for all the info, guys, and the pictures of what you have done. I can get going on this project now.
To answer the question above about "why do you need a spraybooth?" - I am tired of having to lug all this crap out on the patio when I want to paint something! It takes more time to set up and break down than it does to do the work!
Plus, it appears I can generate a great sailing breeze on a perfectly calm day by setting up the airbrush. (I can also generate a calm day with the sailboat... Maybe I should paint in the boat!)
I've done some spraying in the workshop, shooting the paint into a cardboard box. It doesn't take long for the air to resemble the fog of London. You wonder how long that stuff lingers in the air..... And then you leave the workshop and wonder why everything is still foggy - and then you realize you have to clean your glasses! I've sprayed trees without a respirator also (once - hey it's acrylic!) and blew green goop out of my nose for a few days.
That's why I want a spraybooth!
colvinbackshop wrote:TBat55:You got me to do some good hard thinking, regarding "brushless". As mentioned I hadn't given it much thought because I was mounting my blower outside of the air stream of the paint booth exhaust! But I was giving some thought....I have four Dayton blowers doing different things all about my house and Paintshop. I've never seen any place, to replace brushes on the motors of these blowers and soooo....I went to my "go-to-guy" at the Motor Shop for an answer. All of the new AC motors (at least on Dayton blowers) are brushless! So there you have it. I learned something today!
Having worked in another lifetime at a company that made fans, blowers and air conditioners for process control equipment and other electronic stuff, I can put at least an early date of 1979 for brushless motors in blowers and fans. Some of the rack-mount pieces we'd get back from a customer for repair would be absolutely plastered with dust and who knows what else and there was never an explosion or fire of any kind. Rather, a usual failure of a blower motor would be galled bearings due to all the dust and detritus.
The type of blower with the motor outside the air flow is called, generically, a squirrel-cage blower because the blower wheel that actually moves the air resembles the exercise wheel in an animal's cage.
de N2MPU Jack
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