Replies

1. 
   northhouguy | Oct 13, 2009 05:18am | #1

   Be careful here.  If you are spraying liquids that are flammable or that could release flammable vapors you are dealing with a "Classified Location".  That means that you have to use equipment that is "listed" for the hazardous location.

   In the case of a spray booth or finishing room explosion proof electrical equipment may well be required.  It would be best to check with a qualified electrical contractor to make sure you are protected from fire and/or explosion.

   (National Electric Code, Article 500.5-B-1, Classifications of Locations, Class I Locations, Class I, Division 1 FPN 1 Section 2.)

   An alternative would be to duct clean air from outside the classified area through the hazardous area, thus avoiding an issue with the fan motor.  However, lighting, switches and receptacles inside the room would still have to comply.

2. 
   ring | Oct 13, 2009 08:33am | #2

   This is not based on any calculations, just a bit of experience. a room that size will need a fan of about 24" diameter.

   That said, I've several times in the past posted about the advantages of forcing air INTO the spray room, instead of exhausting it OUT. Given the choice I wouldn't build any other way.

   David Ring

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

1. 
   Dave45 | Oct 13, 2009 04:34pm | #3

   The only problem with forcing air into a spray room is that you're pressurizing the room and hazardous "stuff" will leak out where ever it can instead of where you want it to go.

1. 
   ring | Oct 13, 2009 05:04pm | #4

   In actual practice, it doesn't. While you're spraying all the airflow naturally goes out at the place of least resistance, which is thru the baffle and to the outside vent, taking all the overspray with it. Assuming of course the the room is sealed, it doesn't try to force its way out when it has this easy path to follow. When you stop spraying, by the time you can walk to the door all the overspray has exited the room. When you open the door you get a blast of air that goes with you (preventing any dust from entering the room), but that air is perfectly clean. My shop installed a spray room that works on this principle about 3 years ago, and it gets used almost every day. We never have any trace of odor that escapes the room where it shouldn't. Neither do we get any dust entering from the outside.David Ring

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