Conference 7.286::home_work

    One thing that might help; have the fan blowing IN, so the fume-
    laden air is not going through the fan.  (This assumes you have
    another window open someplace else for exhaust.)
    
    Steve

If the fumes are "dilute enough" you shouldn't have problems;
however, you probably don't want to have fumes, sawdust, lint,
etc. running over your motor.  If you use a pully/fanbelt (funny
how fan belts can be used for fans) arrangement neither
explosions nor fouled engine will be a problem.

R.

  The painting room in my high school shop had "sparkless" switches
  as well as brushless fans.

  JP

re: fan motors

	Just a thought, but aren't capacitor start motors the ones 
without a centrifugally operated switch to cut out the starter winding? 
I believe that induction motors are inherently brushless (vs 'universal' 
type in your electric drill), but the starter winding can be energized 
by either a switch or a phase shifting capacitor.
	So, if you're going to set up a shop for use with volatile 
fluids evaporating, ALL your switches should be rated to be installed in 
flammable environments...another thought too...for all you 
woodworkers...you should think seriously about a similar problem with 
sanding dust...many a pattern shop in a foundry has 'blown up' because 
of dust.

    It's not only the motor that you must worry about (although it should
    be an explosion proof motor) but you also should worry about the fan 
    construction. Spark resistant blowers are normally used to avoid
    explosions caused by the fan blade touching the blower frame for
    some reason. Usually this is caused by accumulated dirt on the blades
    or worn out bearings which causes the blade to run out of round.
    These blowers are made with aluminum frames or blades and explosion
    proof motors to avoid sparks. A 12" fan with these qualities will cost
    about $175.
    
    You might also want to put disposable filters over the input openings
    to the room so that only clean air enters the room to keep your
    finish peices from being ruined.

    Nick

    I used to work in a laquer-spraying room.  While the sprayers were
    directly right into the exhaust chute, we still had sparkless switches,
    as previously mentioned, and sealed lights.  We had to wear
    rubber-soled shoes, too.
    
    I would suggest that you try your local fire department for info.
    
    Better safe than ....
    
    Lee

    explosion proof switches and motors are ver expensive to have a
    complete system you must have everything in the shop vapor proof
    as the trade refers. This includes motors on all tools as well
    as the power connects. I once did a bid for a small refinishing
    shop that totaled >2000.00 not cheap.
    The best route is to provide plenty of air exchange with the air
    being replaced once every five min would cover you just fine.
    The other improvement would be to have vents at floor level
    with your vent fans forcing air into the shop -vs- pulling out
    as most solvents are heavyer than air and tend to collect at
    floor level.
    If you like i can copy and send you the NFPA regulations,ect
    on this subject along with flashpoint info on common solvents
    and the air/solvent ratios that produce explosive conditions.
    VERY interesting reading if you do much refinishing.
    
    -j
    

    
        I am looking for information regarding "Explosion-Proof" fans,
     (ie, cost, sources, etc)
    
        I have set up a spray paint booth in my home workshop, and it has
     been highly recommended ( ie; its against the law if you don't) to
     install an explosion proof fan for removing the paint vapors. I
     understand these units can be quite expensive, but when you weigh
     it against a trip to the hospital, they become much moe reasonable :)
    
                                   Any help would be appreciated.

    I bought a spray booth with fan included from Paasche (sp?) for about
    $200.00.  Badger sells a smaller one (very small, alas) for less --
    I've seen it advertised for about $140.00
    
    The bigger the booth, the more air you have to move, and the more
    expensive the fan gets.  The basic requirement for the fan is that no
    electrical components are in the air stream where they might provide a
    spark or heat to ignite flammable vapors.

    Is there any chance of setting up a totally enclosed spray booth
    so the fan can blow into the booth and force air out an opening
    on the opposite side, so the air from the booth doesn't go over
    the fan?  I don't think you'd need an explosion-proof fan for
    that kind of setup.

    It probably would work, but you'd need a way to reach into the sealed
    box (rubber gloves sealed to plexiglas, perhaps?), and an air filter,
    unless you like lots of dust on your paint job.  I don't think  you'd
    save any money in th end.

    
    
       For what its worth, I have built a 8 by 6 by 7 foot spray booth. The
   purpose is to spray paint RC aircraft.
    
       I have done some additional research into this area since posting the
    original note,including talking to a couple of folks who do bodywork
    and have spraybooths.
     
       I have been able to determine that "explosion-proof" fans cost
    between $300 and $600 (depending on capacity needed).
    
       An alternative suggested by one person was to look into
    "whole-house" fans. Some of these are designed with belt drives which
     isolate the motor from the airflow. Even though this is not s "true"
     "explosion-proof" fan, it goes a long way toward additional safety by
     taking the motor's sparks and heat out of the vapor-flow. They also
     cost significantly less than the "Explosion-proof" fans
     
        At this point, I will probably check into the "whole-house" fans
     based on the type of painting I am doing, however, if I come across a
     cheap "esplosion-proof" fan, I will still go that route.
    
       Thanks for the help, and I will moniter this note for any
    additional updates.
    
      
    
                 

    My Granger catalog show several explosion proof motors in
    the $180-$300 price range.

    Also, if you have a reasonable sized air compressor for
    painting, you could use an air motor to drive the fan.

    	- Lee

    
    Is is just the motor for $180 - $300, or the entire fan unit?
    

     re: .5
    
    	Oh sure. But first you have to be able to get your hands on 
    	one of those (much coveted) Grainger catalogs. ;-)
    
    					I drool at the very thought.
    
    								- Mac

        Not tough  -  I  just  walked into Grainger's in Manchester and
        asked for one...
        
        Andy
        

    
    This is for the large (2-3" thick) catalog???
    
    Humpf. I called their main number a month or two ago and they told
    me they don't send catalogs OR sell directly to the public. They said
    I needed a contractor's number (or something like that).
    
    Where is Grainger's in Manchester???
    
    								- Mac 

I was able to purchase parts from Grainger as a Digital Employee (i.e., since
Digital has an account w/Grainger).  This was last May in Framingham, MA.

								-- Chuck Newman

        Grainger's in  Manchester  is on Industrial Drive - Candia Rd /
        Hanover St.  ramp off Rt 93 N (exit 6?), right at the light and
        right again at the next light.  Grainger's is about 1/2 mile on
        the right.
        
        Andy