Spray Booth Motors

I snagged a fan from ebay that is already "boom proof" whether it is needed or not.

It was an exhaust fan for a furnace, a replacement part, I think it was new, but I didn't care either way.

It does 300 cfm (cubic feet per minute) and I paid about $20-30 USD for it shipped.  I put it on a dimmer for variable control.  It's small too, about 7 inches around and 5-6 inches tall, with screw mounts too!

When I turn it on and shut the door, I can feel it sucking air under the door if I put my hand there...

My first booth had a table top fan motor from the early sixties and it worked ok. My second booth has a dayton blower with some ass kicken CFM which at the moment I cant recall. I use laquer thinner for cleanup and never had a problem. I think the amounts of thinner we are spraying through a airbrush are kinda small.

 

Bill

I use muffin fans, and have for years.  My current booth is my third, and is a keeper. I don't know if muffin fans are explosion-proof or not, but I have never had a problem in twenty years of using my homemade spray booths. I find muffin fans cheap and readily available for the amount of flow.  You need something at least in excess of 100 cfm (my current booth uses a 140 cfm fan).  I use furnace air filters as a furnace- available at my local hardware/building supply store for a few bucks each.

This last one I built has a slot in the top for a fluorescent cabinet light.  Having a light on the booth is sure a great addition. I cover the bottom of that slot with a sheet of clear plastic. I then stick on several layers of that clear packaging tape as "tear offs".  That is, when the bottom layer gets paint covered I tear it off and discard.  Eventually when the one remaining one gets dirty I have to put down half a dozen new strips, but being on the top they last a long time before I need to tear them off.

Those considering an explosion proof fan might want to look at this page.  Notice it says that there is no such thing.  There are spark and/or explosion resistant fans.  And, the thing that makes them this way is the use of non-ferrous materials, not motor type.  Most AC fan motors are brushless. Sparks from rubbing steel are the risk.

Then if you follow the link that says Paint Spray Booth Exhaust, you'll find that the most common fan used is axial flow, not centrifugal or squirrel cage blowers.

If you're going to worry about fan type, you also need to consider any sources of static discharge.  A spark is a spark.  You could set off an explosion with Scotch tape or a fuzzy sweater.

If you move enough air to keep the concentration of vapors below LEL (lower explosive limit), sparks don't matter.  This is something you should do for your own health anyway.

But make sure the air is moving before you begin to paint.  If you build up vapors and then throw an arc producing switch, you could get hurt.

Just some thoughts.

Don

A couple of years ago we purchased an inflatable water slide.  Suffice to say that after two years and a multitude of kids the slide is no longer.  The blower that came with it though now that is a different story.  I build my own Booth using that blower from the slide.  It works awesome.

Here is the blower... I connected it to the booth with a 4.5" air duct 

I'd hate to go through life with terrible scars from 3rd Deg. burns because I was careless in my booth setup.

Dave

QUOTE: http://modelpaint.tripod.com/booth2.htm styrene, have u seen this site? what do u think about his methods and approach to building a booth?

I think the link is a good one. Most of the tabular data comes from--or is repeated in-- the American Conference of Governmental Industrial Hygienists (ACGIH) ventilation handbook, and I pretty much agree with most of what the author has to say. Any disagreement I may have with his statements are picky and have no bearing on the general information he is trying to disseminate. I would recommend it to anyone wanting to build their own hobby spray booth.

Gip Winecoff

styrene, i agree with u 100%, and always try and be as safe aas possible. i should have made my self clearer tho... i should have said somethn along the lines of ,theres too much paranoia, coz in a booth thats deisgned properly, can handle the cfm required and is used properly, the chances of an explosin are very remote.....
i am building a booth for myself at the moment, and i have taken every precaution i can to make the booth as safe as possible, coz wots the point of building a half assed booth?? itll would be worse than no booth!

btw, if anyone need refrences for building a booth, check out this site http://modelpaint.tripod.com/booth2.htm
styrene, have u seen this site? what do u think about his methods and approach to building a booth?
thanks!

I propose we do a "mythbusters" and test this sucker of a theory out. Anyone volunteer to put life and limb on the line to once and for all bust this myth???....lol

While I agree with Gip in that you should be as safe as possible, I do agree that the likelyhood of vapors exploding in a spray booth, even with a motor with brushes, is next to nill unless it is in an airtight room. I am not advocating being dangerous either, I am mearly passing on what I know from automotive painters who have been airbrushing longer than I have been alive.

Mike

QUOTE: Just as an aside, who has had an explosion in their spray booth, and I don't mean third party hear say, I what to hear form the people that have accually had it happen.

There was one individual who did experience such an incident who was once a member of this forum. Perform a forum search; the topic should be there.

QUOTE: All this paranoia about the amout of vapor produced while doing hobby scale painting and the resulting explosion that will occur...

QUOTE: Too much paranoia about exploding fans!!

QUOTE: ...agree with the fact that theres too much paranoia about exploding fans,

You guys are funny. You sound like a bunch of conspiracy theorists.

The bottom line here is not paranoia, but how much risk are you willing to accept? Booths are designed for two specific reasons: (1) To prevent a fire, and (2) To eliminate or reduce the potential for inhalation exposures to the vapors and particulates produced during painting operations. I will be the first to admit that given the amount of paint that I put through an artists' airbrush during any given session, compared to the amount of air being moved through many home-made booths such as those mentioned on this forum, the resultant likelihood of fire or personal exposure is pretty much nil. However, once the spray cans of lacquer come out, or a Binks spray gun is used on that 1/8 or larger scale kit, the hazard potentials change dramatically.

The folks that developed the criteria for booth design and performance weren't paranoid psycho-schizophrenics. They were part of the painting and coatings industry--and a whole lot smarter than I am. They realized that there is great variability in painting functions, and sought to develop minimum standards that would provide adequate protection in the majority of painting and coating situations. Was some of it excessive? Possibly in some situations; but a lot of risk assessment went in to those developmental aspects. If you buy a spray booth off the shelf today from reputable dealers, you get the benefit of the work these folks accomplished.

Therefore, building a homemade booth should closely follow the standards set by the people who originally understood the chemistry and physics of what happens when controls are and are not adequate. By doing so, you are accepting a reasonable amount of risk. Obviously, no one is forcing you to follow anything. You have the freedom to do what you want, and make your own choices. But know this: At some point the statistical probabilities will catch up with you. If the risk you've chosen to accept is reasonable based on your applications, then you've nothing to worry about. If, on the other hand....

One final statement and I'll shut up. I agree with the statement that "anything worth doing is worth doing well". The statement takes on renewed meaning when the safety of myself, my family and where and how we live is at stake. When I offer advice on building spray booths, or anything dealing with exposures and prevention, I am putting almost 20 years of professional safety and industrial hygiene behind those recommendations. I cannot do less.

If you want to build a spray booth, then build one. If you want to build a toy, have at it.

Gip Winecoff

this is the fan that im going to use in my spray booth
http://www1.jaycar.com.au/productView.asp?ID=YX2520&CATID=&keywords=fan&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=
i think that this type of fan is less susecptible to sparking than other types.
i too agree with the fact that theres too much paranoia about exploding fans, like honestly, how much paint goes thru the fan anyway? not much at all... and im guessing that a proportion of it is dry by that tiome anyway....

I agree with Virago. Too much paranoia about exploding fans!! I have used a simlar setup with two 120mm computer fans and had no problem whatsoever...and i use all paint types and thinners. To me, there should only be a problem if you were to have your booth full of vapour ( not venting out anywhere) and then expose a "spark" via the fan (highly unlikely). If the booth is being continually vented by the fan and ducting, then there shouldn't be enough of a build up of vapours that should cause an "explosion"

Just as an aside, who has had an explosion in their spray booth, and I don't mean third party hear say, I what to hear form the people that have accually had it happen. All this paranoia about the amout of vapor produced while doing hobby scale painting and the resulting explosion that will occur, must make the manufactures of the "explosion proof" motors smile all the way to he bank.
I will make the assumption that most people need the spray booth to catch over spray while painting, thus keeping the work area clean. I have had no problem using an ordinary 24" square room fan with a quality furnace filter in front of it, mounted in a 3' wide x 2' deep x 2' high box with the fan/filter mounted in the back, to draw the air through the box. All that is needed is a cleaning every now and then to the fan and eveything works great. Any feed back is welcome

In priority order:
1. Try a squirrel cage fan/blower. They are available (at least here in the USA) from Grainger. The motor is mounted behind the fan. The air enters the fan parallel to the motor, but is exhausted at a right angle to the motor. Technically, the vapors should not impinge upon the fan motor.

2. In the absence of a squirrel cage fan/blower, you can use a shaded pole motor. These fans, as I understand them, have non-sparking armature assemblies, which make them MUCH more suitable than range hoods or bathroom exhaust fans (Bleccchhh!). I have heard these fan/motor combinations are available through local home improvement/hardware stores.

If, by chance, you are looking at explosion-proof motors, be prepared to pay the equivalent of Canada's national debt for one. They are quite expensive. In addition, these motors are usually not mounted in the air stream; they usually connect to the fan via a belt system (at least the ones I've seen).

Hope this helps a little.
Gip Winecoff