Replies

1. 
   BradG | Dec 09, 2007 07:12pm | #1

   bump to the top ... I'd like to hear about this, too!

2. 
   saschafer | Dec 09, 2007 07:41pm | #2

   Just some generic information: The term "explosion-proof" is frequently bandied about, without understanding what it really means. It doesn't mean that an explosion will not occur. What it means is that if explosive vapors manage to leak into the casing surrounding the electrical parts, the explosion that does occur--if it does--will not propagate beyond the limit of that casing. In other words, an explosion inside the device will not lead to a larger scale explosion outside the device. "Explosion-proof" is more about withstanding an internal explosion than preventing one. Of course, being explosion-proof doen't meant that a device will survive an external explosion caused by something else.

   First, you should look into the requirements mandated by your local jurisdiction, some of which may be absurdly strict.

   Now, regarding spraying flammable/explosive finishes: Different materials fall into different hazard classifications. For example, acetylene gas (used in welding) is in a more hazardous group than mineral spirits (paint thinner). Underwriter's Laboratories and the National Fire Protection Association publish tables listing the various materials and their hazard classification. I think you can find the tables at their web sites, but you might have to pay some fee.

   Once you've figured out the "worst case" hazard classification of the materials you're going to be using, you can look for a fan that is rated for use with those materials. For example, I just went to the McMaster-Carr site and found a fan rated for use in UL Class I, Group D and Class II, Groups F and G environments (I don't recall off the top of my head what all of those classes/groups represent, but I think Class I, Group D covers most solvents used in finishing--don't take my word for it, though).

   Finally, be forewarned that hazardous location fans are very expensive (typically $500 and up). Explosion-proof fans are even more expensive.

   -Steve

    

   
   

   ---

   Edited 12/9/2007 11:55 am ET by saschafer

3. 
   ring | Dec 09, 2007 08:51pm | #3

   Justin,

   Based on the use you describe, you can probably get by with an ordinary fan motor. (Don't sue me afterwards...)

   If you're really worried about the fan's motor starting a fire, there's an alternative set-up that will skirt the problem: You can install a fan on the AIR INTAKE side of the room, effectively pushing air into the room and letting the pressure inside create the exhaust. It requires a slightly larger capacity motor, but it works just as well as having the fan draw the air on the exhaust side. (PS - the pressure inside the room will always try to open the door - you need to have a door that swings inwards)

   Either way you need to filter the intake, and baffle to outtake.

   David Ring

   http://www.touchwood.co.il/?id=1&lang=e

1. 
   JMadson | Dec 10, 2007 07:46am | #4

   You could also house the motor in a box outside the path of the air and connect to the fan with a pully. 

1. 
   ring | Dec 10, 2007 07:02pm | #5

   Yes that's also a possibility, but I understand that it's hardly done because the solvents that are typically in the exhaust air shorten the drive belt's life considerably.

    David Ring

   http://www.touchwood.co.il/?id=1&lang=e

1. 
   JMadson | Dec 10, 2007 07:25pm | #6

   Yes, but you can buy a lot of belts for the difference in price between a regular motor and a explosion proof.  

2. 
   oldusty | Dec 10, 2007 07:46pm | #8

     J ,

         That's how my old fan was set up , it was like 24" or wider and like 20" deep it came out of an old body shop , probably weighed 60 or 70 lbs without the motor . I had an under powered motor out side for 6 or 7 years in the weather and it worked good .

      The fan was designed with the motor mount and pulleys's out side , changing the belt was an experience if I remember .The motor sat under the fan and was protected from weather somewhat .

       I used that fan for about 9 years then sold it to a body shop for $250

                   dusty

1. 
   sapwood | Dec 10, 2007 08:31pm | #9

   This type of fan is typically referred to as a tubeaxial fan. They can be purchased new or used and are evidently highly thought of considering their price.

4. 
   oldusty | Dec 10, 2007 07:34pm | #7

   Justin ,      Go to the Grainger catalog , they have small and large fans and they are made exactly for what you need .

      You either do as most of us do , the best we can with what we have , or do it right , if paying for explosion proof fan why not the same for all the lights in the room and any other areas that would need similar .

         Just for a good exhaust fan you can use the condenser fan from a heat pump unit , they can be bought for little more then scrap price from the dealer with a bone yard of old units . It's not rated as explosion proof .

                   good luck          dusty