Paint exhaust fan

Discussion in 'Body Restoration' started by hig, Apr 26, 2010.

  1. hig

    hig Veteran Member Lifetime Gold Member

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    Feb 11, 2009
    Central NY
    I really need some advice on what to use for and exhaust fan in my garage. I will be painting my Camaro in my garage that is in the basement of my house. The walls are concrete block with 2 overhead doors and 1 entry door to the outside and 1 door that goes to the rest of the basement. I'd like to go with a shuttered fan mounted in the one exterior door.

    I'm thinking something like this:

    http://www.grainger.com/Grainger/items/4C361?cm_mmc=Google Base-_-HVACR-_-Exhaust Fans-_-4C361

    I'm concerned about it not being explosion proof, I see this motor is enclosed but not rated as explosion proof.

    Can I get some suggestions? I don't want to blow myself or my house up!!!!!!!!

    I see in a post that Wookie uses a large fan with a pad over it, what is everyone else using and how concerned do I need to be. I will be spraying catalized urethane products.

    Thanks
     
  2. BondoSpecial

    BondoSpecial Veteran Member Lifetime Gold Member

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    Sep 20, 2004
    Southern Maryland
    fans rated to be explosion proof are not only concerned about the motor, they also use non sparking bearings, non sparking blades.... so even a sealed motor regular fan will not really be "explosion proof". I bought a 15,000 cfm, 48" externally belt driven axial fan that I am going to use for a paint booth at some point. It won't be truly explosion proof either but it will have the motor completely out of the air stream which I figure is safer.

    I doubt you are going to blow up with any fan, I have seen people using all kinds of $15 box fans with exposed motors and they figure just because they are brushless that means explosion proof (it doesn't) but I have never heard of anyone blowing up using a $15 fan either


    Also, that fan is way small, 12"? I hope you were not planning on using just one of those. Usually when people use box fans they use a bunch of them, when I painted a car using box fans for exhaust I used 3 of the full size box fans under the door, and usually the plastic box fans do move a decent amount of air.
     
    Last edited: Apr 26, 2010
  3. BusDriver

    BusDriver Veteran Member

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    Apr 28, 2004
    Charlotte, NC
    Using something like the 3 fans above, there is never even close to enough fumes in the air stream at once to ignite. youd have to build up a big cloud, then turn them on to even have a chance at blowing up.

    Another option is to use fans for air input (filtered of course) and let the pressure push fumes out. The fans will be blowing clean air and nothing that could ignite.
     
  4. hig

    hig Veteran Member Lifetime Gold Member

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    Feb 11, 2009
    Central NY
    I don't think this is an option for me with the garage attached, I want to make sure I vent the fumes to the outside and try to keep them out of the house.
     
  5. Cityguy

    Cityguy New Member

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    May 23, 2009
    cleveland, ohio
    You also need to remember to have a source of incoming fresh air as well. You need to replace the air that is being exhausted. Be careful about dust and dirt.

    You do not need to extra expense of an x-proof motor. The paint fumes would need to be in a very high concentration to even have the possibility of igniting.

    Also you would need something to ignite the fumes. This would require the fan motor to have a high surface temperature or some type of failure in the motor that would cause a spark. Both of these are unlikely in your case.

    One last note. As far as I know there is not such thing as non-sparking bearings.

    Rick
     
  6. BondoSpecial

    BondoSpecial Veteran Member Lifetime Gold Member

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    Sep 20, 2004
    Southern Maryland
    no steel on steel is what I think would be considered non sparking. Steel roller balls on a steel shaft, in some far-out failure situation that someone could conceive, could probably spark. Bronze is non sparking. I know it sounds rediculous but the certified explosion proof fans cost a fortune and they probably had engineers sit down and go nuts designing it so they don't get sued if they sell it as explosion proof.
     
  7. hig

    hig Veteran Member Lifetime Gold Member

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    Feb 11, 2009
    Central NY
    My garage in the basement is 26' x 32', I plan on partioning it off with plasic down the center of it so I'd end up with 26' x 16'. I'd put intake filters in the plastic wall drawing air from the unused side.

    How any CFM's should I be shooting for?

    If you use box fans in the bottom of the overhead door how do you seal the top of it from air coming in.

    Thanks for the replies!!
     
  8. BondoSpecial

    BondoSpecial Veteran Member Lifetime Gold Member

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    Sep 20, 2004
    Southern Maryland
    Last edited: Apr 26, 2010
  9. pulpcowboy

    pulpcowboy Guest

    Is a typical screened window ok for the inflow from the outside? Would smaller bugs or gnat flies get in or is something else needed? Thanks!
     
  10. BondoSpecial

    BondoSpecial Veteran Member Lifetime Gold Member

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    Sep 20, 2004
    Southern Maryland
    You're gonna need a lot more than that. Like very fine micron filters. Paint booth inlet filters are fibrous and also usually treated w/ sticky stuff to grab and hold even more contaminants. Also square footage of filter media has to be considered because if you pull too many cfms through a small filter the velocity is going to be high enough that the dirt will pull through the filter and render it pretty useless. Which is why you see booths have not only high air flow but also lots and lots of filter surface area. Don't try to pull 8k cfms through a 20"X20" single filter, not gonna work

    Guys will use furnace filters for home built stuff which are fiberglass but a real paint booth fiberglass inlet filter is going to be much thicker and denser (and treated most likely)
     

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