Model Railroading > paint booth exhaust fan question

I just finised building a paint booth. It is 2' x 1 1/2' x 1 1/2'. I am having trouble finding a explosion proof fan in the 400 to 500 CFM range. I have tried Grainger and on their web site all I found was bathroom fans. Any and all help is really appreciated. I have not cut a hole in the back yet for mounting it so I am open to all ideas.

Scott O'Dell

Most bathroom fans use induction motors that have no brushes, so they are effectively explosion-proof. There's no need to buy a fan that's specifically "explosion proof" because it'd likely be horribly costly.

No doubt you'll hear from people telling you that's horribly wrong and it won't work.

I've been using an old bathroom fan, with a standard induction motor, as a paint booth fan for years and have bumped (so to speak) large volumes of solvent-based paint fumes through it with no ill effects. Most of my painting is small model-size material using acrylic paint, but I also do some light manufacturing that involves volumes of rattle-can paint like Rustoleum. Due to the nature of the induction motor (no brushes, no sparks, no explosions) and the relatively small concentration of fumes, the setup works fine.

Jeff Johnston
SPLCo/MWRy circa 1927

I've also seen where people have bought cheaper range hoods and mounted them on top of their paint booth. I believe a while back someone had a link to plans for this as well. A bathroom fan of course is going to be cheaper as you can get them for $20-25. I think the cheapest range hood I've run across was just under $100.

BNSFCSX

Range hoods are nice if you do a lot of other stuff. The bathroom fan should work fine. One fellow used 2 high capacity sealed computer fans into a shroud he made. Works well for him too.

Whatever type of fan you use, it will move a lot more air if you have a good incoming source for outside air. I added a fresh air intake duct right into my booth and it made a world of difference. An open window near the booth will also work well.

Dennis

I use a large capacity(CFM) Muffin type fan that can be purchased at most surplus electronic stores or through their catalogs. You can get them in AC or DC versions at various voltages. They are relativly quiet and take up little depth.

George

I use a fan from a range hood. I've used it for 30 years and it does just fine.

My bathroom needs an explosion proof fan.

KG

Whoeeeeeee, you let that many go?

I looked up explosion proof fans and yes they were extremely expensive. If you paint extensively, and especially on a commercial basis they are definitely a prudent measure, and I expect needed to meet code. I think, however I found a possible substitution, marine bilge clearing fans, used in small craft to exhaust possibly explosive vapors from the enclosed bilge spaces before the engines are started. I am particularly almost completely certain that those are explosion-proof, after all they are designed to move explosive or toxic vapors and must meet USCG specs.

Do you need explosion proof fans? finding out the hard way means survivors digging out from the remains of your garage or at least your paint booth. Not a bad idea. Then again some guys get away with storing gasoline in their garages, some don't.

If you don't want to protect yourself from the hazardous vapors, it's still a good idea to exhaust the toxic vapors.

Yeah, that methane could produce a blue flame! <G>


kgmontreal Wrote:
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> My bathroom needs an explosion proof fan.
>
> KG

We brought this up for discussion in the past and the consensus was that modern 'bathroom style' fans don't have brushes or commutators, ergo no sparks and no concern about igniting the residual vapors. Something of a surprise to me as it has/had been a big deal at work. This info lets the price of a decent paint booth drop into the affordable zone and encourages a better organized operation and moving those vapors out of the building.

Attached is an idea I plan on using based on the way we pull selvage from a trimmer. This isolates the blower completely from the air flow. The idea is to employ PVC schedule 40 pipe with a sanitary wye using an old high capacity leaf blower. I plan to put the blower in the attach eave next to the gable vent...

Hank in AL

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They get excited at work because they have codes to comply with requiring certified "explosion-proof" fans and need to get positive ventilation because of toxic fumes.

Georgiaroad illustrates an eductor type system. If I was to do something like that or any other solution not using a certified "explosion-proof" motor, I'd make it a "temporary" installation, that way you would avoid possible entanglements with code requirements you might run into with "permanent" installations. Like my "temporary" flag pole which has been in for almost 20 years now. It doesn't quite meet code for set-back and height, but folks generally don't get upset about flagpoles.

If you're not using it all the time, you probably can get away with draping a drop cloth around and not sweating over spray. But let's be realistic a little effort to prevent exposure to toxic fumes and eliminate hazardous fumes is worth taking.

I was in high school when I saw some kids set their house on fire and lose about half of it cleaning things in the garage using flammable solvents which were ignited by the water heater. We had one of the more "professional" model custom painters in Long Beach, CA die from liver damage from paint fumes. His demise was written up in MR.

A little forethought is cheap compared to the possible negative outcomes.