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explosion proof fans
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=14354		 Page 1 of 1
Author:  DannyV [ Sat Nov 03, 2007 4:29 am ]
Post subject: 
I'm in the midst of building a new shop (I'll build some acoustic guitars in
it. Hopefully that being said this stays in the Main Discussion ).Having
access to the large Worldwide audience here, has anyone ever blown
themselves up or known anyone who has blown themselves up by not
using
an explosion proof fan? Even a little explosion? Small fire maybe? I know
it's the best fan to buy but you pay 3 times as much. If no one pipes up
with
a scary story here I'll just have to take my chances with being the first to
send myself to the Moon.

BTW Good on ya Lance for dealing with the petty bickering etc. Always
seemed like a lot of wasted effort people put into that stuff. More guitar
talk!!!!

Dan Vincent
Powell River
Author:  MikeP [ Sat Nov 03, 2007 4:54 am ]
Post subject: 
when I made my first spray booth in my garage to shoot automotive lacquer on an 11lf mahogany wet bar I was very concerned about this subject also...I ended up deciding to do a little test of it all...I constructed my temporary booth using heavy duty 10' wide plastic sheeting stapled to the ceiling and weighed it down by stapling it to 2x4's...I then made a frame for the box fan I bought (less than $20) and made a little chute out of some more plastic to direct all fumes/overspray/etc completely out of my garage (I had to have the door slightly open for various reasons, which meant my fan ended up about 3' from the front edge of my garage)...OK, info that is not really needed complete...I tested this by spraying lacquer thinner directly into the fan (yes, I had an extinguisher right next to me)...then sprayed properly mixed lacquer right into it....then stood back and tried to create more of a fumes situation...still, no explosion...considering I wasn't even supposed to be doing the finish work on this behemoth of a project, I didn't have the budget to set up a real spray environment so I ended up just going with what I've described above....

on the flip side of the economic equation is the fact I've gone through 3 of these fans over time after they became clogged up with overspray and eventually I guess choked to death (I bet a filter system of some sort would have solved this)...

the above is just my experience, and from everything I've read here and there I was flirting with disaster...i.e. 'don't do this at home'...what I've been assuming is such blowups and such occur from improper ventilation and HEAVY fumes from huge spraying operations and improper safety precautions (don't light a cigarette in your spray booth)
Author:  David Collins [ Sat Nov 03, 2007 5:22 am ]
Post subject: 
I've watched an old furniture repair man spraying lacquer in a poorly
ventilated barn, with a cigarette hanging out of his mouth. Did this for
fifty years and was fine. I also know of a fellow up around Alpena who
was spraying lacquer in a more well ventilated barn with a conventional
exhaust fan. About seven years ago something sparked, the place went
up, and he was killed, and not quick and painless end either.

A few hundred bucks savings is not worth the risk of killing yourself. Get
a tubeaxial fan with a spark resistant aluminum blade, or an explosion
proof motor with said blade. If your electrical is not hazardous location
approved, at very least make sure all lighting and electrical boxes are
entirely sealed off from the spray area. Either that or just spray outside
when the weather is good.

Yes, the risks are relatively low, but the wager is extremely high.
Author:  Shawn [ Sat Nov 03, 2007 5:55 am ]
Post subject: 

For over 15 years I sold German woodworking machinery (mostly panel processing and Weinig moulders) and was at a cabinet shop in rural Virginia when they had an explosion and fire in their finishing room.  Not only did it combust in an instant and with great force but in the explosion and resulting fire one of the owners family was killed as he was spraying lacquer.


What killed him was not the fire but in the explosion all of the oxygen in the area was consumed at once and he asphxiated before he was found.  In the confusion everyone ran and thought that they had seen him come out but he had not.


When the fire inspection was done to determine the cause it turned out the exhaust fan used for the finishing room was an off the shelf exhaust fan but not one that was explosion proof.  For the amount the proper fan would have cost, the person would have been alive.  It was also determined that the existing fan was also undersized for the space and the volume of air needed to exhaust the room so the amount of fumes in the air contributed to the conditions that created the tragedy.


Because I have chosen to only build classical guitars, I do french polish only and if needed outsource any spraying if lacquer needs to be done. 
Author:  DannyV [ Sat Nov 03, 2007 6:08 am ]
Post subject: 
David, Sealed lighting is something that never occurred to me but makes
perfect since. This will be a 10x16' booth and want good lighting. I was
planning on just using 8' florescent units. Do you know if you can buy
enclosures for them? I appreciate any input .......and thanks for the scary
story I was looking for.
Thanks, Danny       
Author:  DannyV [ Sat Nov 03, 2007 6:11 am ]
Post subject: 
And thanks for another scary one Shawn! OK, my mind is made up.

Thanks
Author:  Hesh [ Sat Nov 03, 2007 6:26 am ]
Post subject: 
The problem is Danny that some individuals who may have a story to tell as to the danger to themselves, their families, neighbors, pets, property etc. may in fact be dead........  So....... it's difficult to ask for a show of hands of folks who jumped off the Golden Gate Bridge and lived (even though a few have) the vast majority are now pushing up bridge pins AND probably rather infamous if their actions resulted in the death(s) of anyone else.......

Why take any chance like this what so ever.
Author:  BOBP [ Sat Nov 03, 2007 6:30 am ]
Post subject: 
Years ago I lived in Lexington,Ky. and there was a unfinished furniture shop there that had an extremly large fire with a very large blast from nitro cause?
you guest it, after losing a great shop full of tools and some pretty bad burns they installed a spray both
Yes its expensive but it money well spend in the long run imo
Author:  David Collins [ Sat Nov 03, 2007 6:31 am ]
Post subject: 
You can buy hazardous location lighting, but it is extremely expensive. A
more common solution is to build a room with glass or thick plexiglass
windows built in to the walls and sealed. Glass is often preferred, because
it it can be scraped with a razor to clean off overspray. Then mount your
lights just outside the glass, but far enough back to allow adequate
ventilation and cooling for the bulbs and ballasts. There should also be
no outlets, conduit, any electrical, etc., inside the spray room.

Now for the disclaimer. Neither I nor the forum are making any claims as
to safety, codes, any kind of formal endorsement, recommendations,
guarantees, yadda, yadda. I'll just say I've seen this method used in lieu of
the proper approved hazardous location electrical and lighting. It may or
may not pass code in some areas, but it makes sense to me.'

Then again, I can imagine last words being "Sure, seems perfectly safe to
me. Can't imagine what could go wrong". It seems adequate to me, but
other input or criticism is welcome.
Author:  Hesh [ Sat Nov 03, 2007 7:15 am ]
Post subject: 
I just searched the archives because I remembered a thread from a couple of years ago that resulted in my stopping to spray nitro in my condo.......

This is great reading and some very knowledgable OLFers participated.

Whoops the software won't let me post a link probably because of my new user name.

But here it is:   http://www.luthiersforum.com/forum/forum_posts.asp?TID=2976& amp;KW=nitro#forumTop

There was another thread after this one that I can't find in which someone posted that they had very nearly been killed from nitro use but I can't find that one.  Anyone else remember the thread that I am speaking of?  This thread also talked about how the white powder that gets everywhere when spraying nitro was essentially the same stuff that was used by the US battleships to propel 2000 - 3000 pound shells up to 32 miles......
Author:  Chas Freeborn [ Sat Nov 03, 2007 7:44 am ]
Post subject: 
"an ounce of prevention..."
Yes, they're more money, but the alternative isn't pretty.
I found a re-built EP motor for $90 at my local motor shop. Sparkproof fan
blade from Graingers, sheetmetal housing from a local shop for $300 or so,
and I can sleep at night.(So can my wife).
Grizzly has a nifty little self contained unit for about a grand, if you've got
more $ than time.
-C
Author:  Rod True [ Sat Nov 03, 2007 8:05 am ]
Post subject: 
Danny, I'd hate to hear of a house and shop fire in Powell River come on the news bud.

The other option is to get a good size aluminum fan from Princess Auto (the chicken barn ones), you know the ones which are belt driven and than mount the motor outside of the booth and all the fumes (seal the motor and electrical from any possible spray, fumes etc.). This is a perfectly safe way to go about creating your spray booth if you don't want the expense of the explosion proof fan.

Mind you there is another thought I've had with the explosion proof spray booths.

The cost to set up a spray booth using non explosion proof components can be nearly as high or as high as the cost to just buy the explosion proof components.

If you think about the lighting and doing what David mentioned (enclosing the non-explosion proof lights) the cost for the glass, you time to make the enclosures etc... would be close to the same cost of having the explosion proof lighting anyway.

Same thing with the fan.

Do it right and no one will ever have to be saddened from an accident that might happen. Sure there are lots of stories like David's first one (smoking nitro sprayer) but it's not worth it to save a couple hundred bucks.
Author:  David Collins [ Sat Nov 03, 2007 8:20 am ]
Post subject: 
I agree with you about the motor Rod, but maybe I'm looking in the
wrong places for lighting. About the cheapest I've found for a single
florescent fixture (two 32 watt bulbs) start at around $700 each. Even to
light an 8'x8' room that could get pretty expensive. The incandescent
fixtures seem to start in the $300-$400 range, plus you've got all the
electrical fittings and boxes to go along with. At that rate it would be easy
to drive up a few thousand dollars just to put three or four light fixtures
in.

It's also quite possible that I am looking at fixtures that are way overkill
for our applications, and there are less expensive suitable ones that I
haven't seen. I did see a powder coating booth in an OSHA inspected
factory recently that had the lighting arrangement I was referring to, and
it appeared to be factory original from the booth maker. That's powder
coating though, and I'm not sure if there are different standards for
lacquers.
Author:  DannyV [ Sat Nov 03, 2007 8:36 am ]
Post subject: 
Thank you all. You have more than made the point I pretty much wanted
to hear. David, I'm a commercial fisherman here in BC for a couple months
of the year and one of my favourite (tongue in cheek) sayings is "what could
possibly go wrong?" And thanks for the advice on electrical! I would have
put outlets in there without a thought but makes good sense.    
Thanks for the link Hesh! Reading all that was enough to put a person off
nitro altogether. I'll certainly invest in a fresh air supply.
Thanks Again,
Danny
Author:  David Collins [ Sat Nov 03, 2007 8:41 am ]
Post subject: 
Okay, a quick few searches confirms that I probably was going overkill with
the hazardous location lighting fixtures. Perhaps the more affordable
category of "vapor proof" would be suitable, in which case Todd, you're
probably right about the cost.
Author:  Rod True [ Sat Nov 03, 2007 9:00 am ]
Post subject: 
Wow for the $700 per unit your definatly right David.

I was basing my comment on what I saw on ebay recently. Check these out on ebay they would be about $300 (CAN) each with shipping
Author:  MikeP [ Sat Nov 03, 2007 10:12 am ]
Post subject: 
I've been using 500W halogen units from HomeDepot (aka HellDepot) that are sealed with an O-ring around the lens...the majority of them end up being outside of my 'spray booth' but I have taken one light stand in as needed...not sure as to how dangerous the amount of heat they generate is, but I can tell you it was a godsend in the winter when temperatures in my garage were way too low to spray without the heat generated by having a total of 5,000W of lighting going on!...these units are real cheap and I also use them when things get dark on my jobsites


Author:  grumpy [ Sat Nov 03, 2007 11:30 am ]
Post subject: 
Those halogen units are likely the most dangerous ones to have nearby when spraying. Accidentally knock one over and break the bulb, and you have one wicked ignition source.
Author:  MikeP [ Sat Nov 03, 2007 2:08 pm ]
Post subject: 
I've broken many a light bulb in my day...but have never broken the sealed lens/cover...i.e. the bulb breaks but it is still sealed within the enclosure...in general they are hung from the walls and ceiling outside of the enclosed area shining through the plastic..as noted, I have brought a stand (I have 2, the rest are single units without a stand) before when I was having trouble getting light to a specific area...

if a person has the funds to afford a totally ignition proof setup, then by all means go for it...I don't and after plenty of research and experimentation with a fire extinguisher handy I work under the above conditions...of course I am not a professional wood finisher, rather a carpenter who at times has the need to finish some furniture or whatnot I've made...I don't spray numerous items for hours on end, rather at most spend 1/2 hour at a time with the fan sucking out overspray as it develops....
Author:  davidmor [ Sun Nov 04, 2007 5:21 am ]
Post subject: 
Being an electrician who has wired his fair share of explosion proof environments, threads like this really bother me.  There is a clear misunderstanding about the purpose of explosion proof equipment as was demonstrated by the comments about halogen lights and the bulb being sealed in a fixture with a gasket. 

The purpose of explosion proof equipment is to keep the flammable vapor out of the equipment, not to keep the spark in.  It makes no difference if the spark is held behind a gasketed glass fixture if the vapors are able to flow inside the mounting system, or the wiring channels into the sealed fixture.  Once the vapors ignite, the flame will follow the vapor back out of the fixture and then BOOM!  This is why explosion proof fixtures are so expensive.  They go to great effort to eliminate any risk of the vapors getting in to the space where a spark can originate.  When we wire explosion proof spaces, depending on it's classification we put sealoffs in the conduits to keep vapors from traveling inside the conduit to the possible ignition source.  Next time you are at a gas station, take a look at the conduits going down into the ground anywhere around the gas pumps, and if you can find them, where they emerge at the building.  You will find a fitting with a cap on it.  That is a sealoff which is filled with a compound to seal the conduit from vapor travel.  It is the same thing in a spray booth.  Most commercial spray booths are built in a way that the lighting is outside the booth.  This is an inexpensive way to provide good illumination without buying pricey fixtures.  It is the same principal, keep the vapors out of the fixtures.

You may get away with using non-explosion proof equipment to light and ventilate your spray booths, but all it takes is one malfunction and you will wish you spent the money to do it right.  Believe me, the big spray operations don't spend all that money on proper equipment out of the kindness of their hearts, they do it because they understand the risk of doing it wrong.
Author:  grumpy [ Sun Nov 04, 2007 5:34 am ]
Post subject: 
What he says....

My comment on the halogens was mostly based on how hot they run. break the bulb or the lens, and she may be hot enough to ignite. And after reading the above, i suppose it's possible that vapors could sneak into the housing and ignite simply from the heat generated by the halogen light. Those suckers run hot!
Author:  davidmor [ Sun Nov 04, 2007 5:41 am ]
Post subject: 
Yep, they run very hot.  So hot that the oils from your skin will burn and ruin the bulb.  That is why you can't touch them with your bare fingers when you replace the bulb.  
Author:  DannyV [ Sun Nov 04, 2007 1:09 pm ]
Post subject: 
Thanks Guys,

All good food for thought. What do you think about using incandescent
lights? You can pick up sealed pots for pretty cheep. I find for spraying,
unlike the workshop environment, the type of lighting is not that important
rather having enough light hitting your work at the right angle. I'd be happy
to hear your thoughts on that?
Thanks For Your Help
Cheers,
Danny
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