Unsafe paint booth fans - "prove it"

[Der Bugmeister]

I've been reading a lot of threads here and elsewhere discussing homemade spray booth solutions. A common comment in the vast majority of these threads is the warning that using the wrong kind of fan is dangerous due to explosive hazard.

Ok, I get that there IS a hazard. But then, there's hazard in most everything we do.

So my question is, has anybody personally experienced an explosion/flashback scenario while using something like a bathroom fan in a home made spray booth? Or is there reliable documentary evidence of this happening?

By the way, it's not my intentional to be confrontational in asking this question. I have seen the risk expressed many times, but I don't recall anyone relating personal anecdotes substantiating the concerns so I start wondering if it is a myth repeated so often as to be assumed true or is based on substantive personal experience.

Thanks

[Ace-Garageguy]

Here's a link to a thread on this very forum...http://www.modelcarsmag.com/forums/index.php?showtopic=28124

[martinfan5]

Clay, its pretty simple really, combustible fumes and sparks dont mix, do the math, and the only way to prove it to you would to video it happening, and I am not sure anyone is willing to put their life on the line, just to "prove it to you"

This is a case of what you are reading on different forums is true, and you should believe it

Edited September 8, 2013 by martinfan5

[Art Anderson]

I've been reading a lot of threads here and elsewhere discussing homemade spray booth solutions. A common comment in the vast majority of these threads is the warning that using the wrong kind of fan is dangerous due to explosive hazard.

Ok, I get that there IS a hazard. But then, there's hazard in most everything we do.

So my question is, has anybody personally experienced an explosion/flashback scenario while using something like a bathroom fan in a home made spray booth? Or is there reliable documentary evidence of this happening?

By the way, it's not my intentional to be confrontational in asking this question. I have seen the risk expressed many times, but I don't recall anyone relating personal anecdotes substantiating the concerns so I start wondering if it is a myth repeated so often as to be assumed true or is based on substantive personal experience.

Thanks

First of all, no I have never experienced a fire nor an explosion from using spray paint in any form, from rattle cans to airbrushes to a production spray gun (when I restored a couple of Model A Fords 40+ years ago), but I easily could have, even in my younger days of using rattle cans in the basement of my parent's house with an old-fashioned coal furnace about 15 feet away (such were the safety precautions in the 1960's!).

Assuming you have some sort of gas or oil heat for winter, ask yourself why the blower on a gas or oil furnace is a "squirrel cage" type, with a sealed induction motor (these have no brushes or commutator) positioned outside the air flowing through the blower. Also, have you looked at the labels on aerosol (spray cans) in recent years? All manner of aerosols including spray paints, use one kind or another liquified petroleum gas--generally either propane or butane (the Freon propellants of years ago were banned in nearly all countries for environmental reasons). In addition, even water-borne enamel paints have alcohols in them, so they can burn if conditions are right. Most certainly, any ordinary enamels, and of course lacquers are very flammable indieed, certainly in their liquid state.

Most modelers who install any kind of spray booth are looking to exhaust the paint fumes (vapors from the thinner and other solvents in the paint) out of their house, which of course means some sort of fan or turbine. While nearly every electric fan being sold today uses in induction motor of some design or another, most of those motors are "open", meaning that the armature and coil windings are exposed to air (and whatever is suspended in that air, BTW), and almost none of these are grounded against static electricity in any fashion whatsoever. Such open-frame motors, even if they don't rely on commutators and brushes for controlling the electicity going through the armature windings, and certainly don't produce the almost constant arcing and sparking that say, your electric drill, saw, sander do, they can still generate an electric spark from the buildup of static electricity. And, should the flammable vapors, even the finely divided (and flammable) particles of partially dried paint that is the overspray from rattle can or airbrush be in the right mix in the air--one spark, and WHOOM! You've got an explosion, and almost certainly a fire to contend with.

Enter the squirrel cage blower and it's sealed induction motor positioned outside of the air stream the blower is moving. Those sealed motors almost always will have a 3-prong plug, and assuming the electrical outlets in your house are 3-prong AND grounded, very little chance of any sort of spark or arc to set off an explosion and/or fire. My spray booth (a Pace Peacemaker), in addition, is constructed of galvanized 12-gauge sheet steel, to which the squirrel cage blower (also steel) and its sealed motor are bolted with steel bolts, is also thus grounded--the chances of any explosion or fire are extremely miniscule.

So, for "peace in the house" (exhausting those offensive (to many others) paint vapors, as well as trapping virtually all overspray "dust" in a filter, a properly built spray booth with a 4" dryer exhaust duct and outside vent will not only keep wives, significant others, even apartment mates happy, and at the same time effectlvely remove a potential fire hazard and safely so.

To sum up--yes there is a very potential fire hazard, and there are also health hazards from breathing sufficient quantities of paint solvent fumes and paint overspray particles.

Art

[epi4561]

Wow... I never even thought of the possibility of this happening. I just thought an exhaust fan was an exhaust fan. I have an extra range hood exhaust fan that I was gonna make a spray booth with, but I may reconsider now. Thanks, you guys may have just saved me and my family's lives. It's like those little adverts we used to see on NBC "The More You Know..."

[my80malibu]

I've been reading a lot of threads here and elsewhere discussing homemade spray booth solutions. A common comment in the vast majority of these threads is the warning that using the wrong kind of fan is dangerous due to explosive hazard.

Ok, I get that there IS a hazard. But then, there's hazard in most everything we do.

So my question is, has anybody personally experienced an explosion/flashback scenario while using something like a bathroom fan in a home made spray booth? Or is there reliable documentary evidence of this happening?

By the way, it's not my intentional to be confrontational in asking this question. I have seen the risk expressed many times, but I don't recall anyone relating personal anecdotes substantiating the concerns so I start wondering if it is a myth repeated so often as to be assumed true or is based on substantive personal experience.

Thanks

Clay, you could contact the Individual who originally posted the story, from the link Bill has posted. On the behalf of Anthony Oteri, and get the story firsthand from him. That may convince you that the hazards are real, or myth.

Edited September 8, 2013 by my80malibu

[martinfan5]

I've been reading a lot of threads here and elsewhere discussing homemade spray booth solutions. A common comment in the vast majority of these threads is the warning that using the wrong kind of fan is dangerous due to explosive hazard.

Ok, I get that there IS a hazard. But then, there's hazard in most everything we do.

So my question is, has anybody personally experienced an explosion/flashback scenario while using something like a bathroom fan in a home made spray booth? Or is there reliable documentary evidence of this happening?

By the way, it's not my intentional to be confrontational in asking this question. I have seen the risk expressed many times, but I don't recall anyone relating personal anecdotes substantiating the concerns so I start wondering if it is a myth repeated so often as to be assumed true or is based on substantive personal experience.

Thanks

Clay, you could contact the Individual who originally posted the story, from the link Bill has posted. On the behalf of Anthony Oteri, and get the story firsthand from him. That may convince you that the hazards are real, or myth.

Or he could wire up a fan with an unshielded motor, turn it on, & spray paint directly at it.

Which of course, is not a good idea

Edited September 8, 2013 by martinfan5

[PappyD340]

Well this may or may not satisfy your quest for enlightenment, but I finished furniture for 36 yrs before back sugery took my out of the job, but I will tell you that there is a real and present danger when dealing with conbustible materials!! there are very strengent safety codes in place for these types of operations from insurance companies, local fire dept, OSHA, and as Jonathan said chemicals and sparks do not go together,even the tools that we used on the equipment had to be made of brass because brass will not spark. Our spray booths, lacquer pumps and drums all had to be grounded due to static electricity, we used mainly nitro cellulous lacquers and lacquer based paints some of which have a flashpoint that is 6x greater than gasoline, so the mixture of chemicals and electricity is not something to take lightly. I personaly have not been involved in an explosion but I have witnessed spontanious combustion on 2 different occasions one of which completely destroyed the company I worked for, burned it to the ground in a matter of about 20 minutes. I also have a very good friend who works for Valspar here in High Point, NC and about 12 yrs ago was working on a tanker trailer used for transporting nitro cellulous, he was doing routine cleaning between loads and had followed all procedure protocal and static electircity ignighted fumes and he sufffered 3rd degree burns over 60% of his body and was in the hospital for 8 months at one point they did not think he would survive but he did and still works for Valspar as the safety director. So PLEASE PLEASE PLEASE do not take this subject lightly and do not think for one second that it a myth because my friend it is NOT. Take the proper precautions when using these products, because you and your family's life and health depend on it!!!!!

[64SS350]

Wow Larry, sorry about your friend, glad to see he's continuing on in a positive way!

My thought and observation over the years as many products come out with all these crazy warnings on them of what not to do, is that somebody somewhere has tried these things with disasterous results.

We are given one life,appreciate it!

Happy modeling

[raildogg]

Would an industrial accident be O.K. I made the mistake of going in a paint booth with a cup full of nitro-cellulose for a guitar body. Started up the fans began spraying and, BAM, BAM, WHOOSH. The whole thing lit up like a 4th of July display. I was thankfully blown right out into the next room slightly singed and woozy. So believe it when they say it, It's true Bro!!

[ScaleDale]

Every gas station I pull into has a No Smoking Turn Off Your Engine sign. I've never seen either of these activities blow up a gas station outside of the movies but I have no interest in pressing the issue. It's common sense.

Dale

[Rob Hall]

You'd have to be pretty stupid not to see the danger in such a setup (exhaust fan spray booth)...

Edited September 8, 2013 by Rob Hall

[Casey]

I think this question has been answered sufficiently. Expecting someone to "prove it" by taking it all the way to failure is never a good idea when peoples' health and lives are involved.