Thread Tools
Nov 23, 2005, 11:44 AM
sensitive artsy type
Treetop's Avatar
Thread OP

building table top spray booth


I want to build a table top spray booth, sort of like the picture. The question, could I use computer fans, and since they are brushless (I assume) would they be safe for flammable fumes, ie. explosion proof.

These things cost over $200, wonder why, one of those I looked at looked to have computer type fans.

I also plan to duct the exhaust outside the workshop.

Thanks

tt
Sign up now
to remove ads between posts
Nov 23, 2005, 11:43 PM
Suspended Account
i don't see why you couldn't. you will still have to use some kind of filter. they would probably make less noise too.
Nov 24, 2005, 12:09 AM
sensitive artsy type
Treetop's Avatar
Thread OP
I just wonder if I am correct in assuming that the brushless motors have no open spark? I really don't know much about them.

I guess the safety thing could be achieved by only using the booth for acrylics, and just do the other stuff outside.

Yeah, filters are a must, some of the filter media used is available in large rolls, like the fiberglass that is white on one side and green on the other. The charcoal filters can be found as the replacment filters for room air cleaners. It is interesting that most of the small booths I see, don't mention replacement filters, like Testors, Badger, etc.
Nov 24, 2005, 12:39 AM
Suspended Account
talked to this guy at a model trade show. nice stuff but a little $$$. he does give dimensions for his booths so there's a start.

http://www.pacepaintbooths.com/pace/
Nov 24, 2005, 01:12 AM
B for Bruce
BMatthews's Avatar
Shaded pole AC fan motors do not use brushes either and have far more power than computer fans. You need to move a surprising amount of air to ensure you don't get blowback from a spray booth

If I was doing something like this I'd start by making the "booth" from something like corroplast or door skin plywood. It would be made collapsable and notch together for assembly using locking tabs and slots cut directly into the material. The rear portion would use a round coupler that hooks to a short section of 8 inch air conditioner flex ducting that would connect to a panel that fits into an open window. The window panel would have the fan in it with the connector cord. And of course the beauty of a tabA into slot B assembly is that it also disassembles for easier storage. With a bit of care you should be able to set up the hood within about 10 minutes of first laying your hands onto the bits in their home.

Just be sure to buy a fan that is intended for flammable dust and fumes. They are quite common and should not cost that much. Explosion proof is another thing though. But I'd be willing to trust a shaded pole fan and have done so since I made a temporary setup as above and still have the fan.
Nov 24, 2005, 03:20 AM
sensitive artsy type
Treetop's Avatar
Thread OP
Sgt.dirt, the pace page is interesting, love the way one of them is named the "peacekeeper". These use shaded pole motors and a pleated filter, likely from 3M. Seems like a good solution.

Bruce, lots of good ideas in that short post. Portability and storability are certainly good points. I searched for "shaded pole AC fan motors" and came up mostly with manufacturers sites. Seems they are used on stove hood exhaust fans, which could be oriented to make a booth. Do you have a suggestion as to where to get one of these motors retail on the internet?

Explosion proof seem to start at around $500 and up. I did find a site where a guy built a spray booth using a stove hood, and he bravely sprayed laquer into the thing while it was running and lived to report no explosion.

Most of the booths I have seen of the size I would like to build have about 320 CFM. A stove hood, from the scratch and dent section (we have a Sears outlet here that has this type of thing) would probably be pretty reasonable.

The other source for shaded pole may be bathroom vent motors, any thoughts?

Thanks for the replies, tt.
Last edited by Treetop; Nov 24, 2005 at 03:28 AM.
Nov 24, 2005, 07:23 AM
Will fly for food
Another source of sparkless fans is boating supply places. Look for fans used as bilge blowers. They are used to exhaust gasoline vapors from the engine compartment before you start the engines (and blow up the boat if you don't ventalate). Only thing is, they are mostly 12 volt, but very high CFM.
Nov 28, 2005, 02:25 AM
All posts Copyright '07
Quote:
Originally Posted by Treetop
I want to build a table top spray booth, sort of like the picture. The question, could I use computer fans, and since they are brushless (I assume) would they be safe for flammable fumes, ie. explosion proof.

These things cost over $200, wonder why, one of those I looked at looked to have computer type fans.

I also plan to duct the exhaust outside the workshop.

Thanks

tt

Browse to www.grainger.com and search for "shaded pole" motors.

I suggest you make a downdraft table. I am actually building a table now, and have done extensive research. A downdraft table requires less CFM, provides a better paint job, and is easier to store, as the motor is under the table. Flexible pipe increases required CFM dramatically - stick with rigid ductwork if possible. I plan to have only a short section of flexible pipe. Fans are rated at 0" static pressure. You will need to calculate your static pressure value and ensure you have a large enough fan.

My other materials are the 2 x 4' plastic pegboard (~$12) at Lowes, 2x4 plastic "egg crate" ceiling tile from lowes (little plastic squares), and 2x4 acrylic ceiling diffusers. My booth "upper" is is essentially a 2*4 frame, which will accept the flexible acrylic panels that will slide into routed slots. It is downdraft, and uses the plastic pegboard over a filter, and a small plenum. Discharges straight out the back. I draw air in from the top, and pull straight down across the work. A good filter sits on top to minimize dust, and a cheap fiberglass filter is used on the bottom. The sides are "hollow"; I plan to put lights in between, where they will be sealed from vapors.

The base is on casters. I can roll around if needed. The pegboard will be recessed; I can pull it out and stick a piece of MDF in its place and use as an extra work surface when not painting.

My goal is to keep my three kids safe while painting - so it might be overkill. I expect to spend ~$200 when complete - and it will be explosion proof and OSHA approved. If you are going to go the trouble of building a table, it should provide adequate safety; I don't think computer fans will move enough air; a good fan from grainger is ~$65.
Nov 28, 2005, 02:50 AM
sensitive artsy type
Treetop's Avatar
Thread OP
abqlloyd, sounds excellent. Lots of good info, I know about the flexible duct, from experience with our dryer vent. I didn't know about plastic pegboard.

A couple questions:

Is the plenum just an empty space below the pegboard and filter, made of sheet metal or something?

How many CFM are you thinking you need for this setup?

So that is a total of two filters, one on top, and one under the pegboard?

Thanks, tt.

PS, if you could post a picture or drawing, I am sure there are many who could benefit from this. Your description is quite good though.
Nov 28, 2005, 02:13 PM
All posts Copyright '07
Quote:
Originally Posted by Treetop
abqlloyd, sounds excellent. Lots of good info, I know about the flexible duct, from experience with our dryer vent. I didn't know about plastic pegboard.

A couple questions:

Is the plenum just an empty space below the pegboard and filter, made of sheet metal or something?

How many CFM are you thinking you need for this setup?

So that is a total of two filters, one on top, and one under the pegboard?

Thanks, tt.

PS, if you could post a picture or drawing, I am sure there are many who could benefit from this. Your description is quite good though.
The empty space is created by raising the pegboard from the base, which consists of plywood. It is 3.5" (a 2x4 on edge).

50 delivered CFM (adjusted for friction and volume) is required for downdraft, 100cfm actual for sidedraft, and 150 cfm for updraft. Downdraft is the most efficient, as you have gravity on your side.

Two filters. A HEPA furnace on top to minimize dust, and fiberglass below the pegboard to catch spray.

I will take pics and post when completed.
Nov 29, 2005, 03:05 AM
sensitive artsy type
Treetop's Avatar
Thread OP
Well, I ordered a Whirlpool model 2030XJQ 30 inch range hood from Lowes, (to be picked up at the store) for $51 plus tax. From what I understand these have shaded pole motors, and this model is one of the few cheap ones that have a blower, so that should also keep the motor out of the paint stream. It is rated at 220 CFM (from the Whirlpool website).

Since this is a blower style, it may be that I can mount it as a downdraft unit, when I get it and put a cord on it we will see if it likes running upside down, but it seems it shouldn't matter. I want the booth to be four feet wide, so only the area of the hood that has the filter, ie the part that does the suction will be exposed to the booth.

We will see how this works out. If it can only be used in it's intended position, hopefully the 220 CFM will be enough to use it that way. tt


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Making a building table? mudfarmer_mike Beginner Training Area (Aircraft-Electric) 12 Mar 23, 2002 07:03 AM
Grid table top JayParke Electric Plane Talk 4 Mar 11, 2002 02:09 PM
New building table??? Hammer Electric Plane Talk 1 Sep 09, 2001 06:35 PM