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Thread: Paint booth fan?

  1. #16
    Quote Originally Posted by Leigh Betsch View Post
    Thanks for the 100 f/min number. It will help a bunch helping to pic a fan. I'd rather not over due it and create a noise monster. If I can't find something reasonably cheap ($150) I'll likely build something. The ebay axial fans I've been looking at are over 2675 cubic meters per hour, and 71db. Compared to the 100 cfm number they are way oversize.
    The 100 ft/min refers to velocity. If your booth is 5' x 6' (30 sq. ft.) you would need to move 3000cfm through it to meet that goal. Any ducting or filters will increase resistance and require a bigger fan. I assume flow #s quoted are for free air/no resistance.

  2. #17
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    Thanks I missed that the 100 wasn't cubic. My booth is actually 56"x56" and 36" deep. I took a gamble and ordered a cheap eBay fan. It's new and coming from China. It is advertised as explosion proof and 3530 M3/hr. This back calculates to 95 ft/min velocity. A bit short of the 100 but I think it will be ok. I hope it is explosion proof but I don't know if I will be able to tell. $165 plus shipping.
    The Plane Anarchist

  3. #18
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    Would a fan blade mounted on a 3phase induction motor qualify as explosion proof? Or even better, a would TEFC (Totally Enclosed Fan Cooled) 3ph induction motor be explosion proof? Assuming that the motor contactor is no where near the volatile fumes. ...Just thinking out loud more than anything.

  4. #19
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    Quote Originally Posted by Michael Schuch View Post
    Would a fan blade mounted on a 3phase induction motor qualify as explosion proof? Or even better, a would TEFC (Totally Enclosed Fan Cooled) 3ph induction motor be explosion proof? Assuming that the motor contactor is no where near the volatile fumes. ...Just thinking out loud more than anything.
    AFAIK, no. With the motor in the air stream...it doesn't matter what kind of motor it is as there can still be "sparking".
    --

    The most expensive tool is the one you buy "cheaply" and often...

  5. #20
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    Hereís a pic of the fan I have on order. Iím hoping it is actually explosion proof as advertised.
    Attached Images Attached Images
    The Plane Anarchist

  6. #21
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    Quote Originally Posted by Michael Schuch View Post
    Would a fan blade mounted on a 3phase induction motor qualify as explosion proof? Or even better, a would TEFC (Totally Enclosed Fan Cooled) 3ph induction motor be explosion proof? Assuming that the motor contactor is no where near the volatile fumes. ...Just thinking out loud more than anything.
    Nope, not at all.

  7. #22
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    Quote Originally Posted by Leigh Betsch View Post
    Here’s a pic of the fan I have on order. I’m hoping it is actually explosion proof as advertised.
    That's a great price. They are cheap enough that you could add a second if it doesn't provide enough airflow.

  8. #23
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    I also made the front curtain short enough so I can reach under it while standing outside the booth. Kinda like a bio glove box. I don’t know how much I’ll actually close the front curtain, but it’s an option.
    The Plane Anarchist

  9. #24
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    Doesn't have to be expensive to be explosion proof. Just Google explosion proof fans, lots of choices under $200. Reminds me that BigAss fans sells a 6 foot diameter shop floor air mover (not explosion proof) for $7k. There is a price point for most any market. https://www.amgair.com/big-ass-fans-...table-fan.html
    NOW you tell me...

  10. #25
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    BigAss Fans are awesome. We have 3 of them in our store that run at low speed 24/7. They've been running continuously for 7 years now and none have had an issues whatsoever. They are expensive, but I think they are worth every penny.

  11. #26
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    I'm seeing a great deal of ignorance on what "explosion proof" really means. The reality is it can mean a number of things depending on the risk level. It means different things depending on whether you're dealing with liquids, gasses, or dust. The NFPA is a great source of information on the subject. If you want to go whole hog, design to Class 1, Division 1. Everything sealed, no possibility of sparks, no possibility of static discharge, etc.. Note that this is crazy expensive and nothing you need unless you're processing fuel or running a munitions depot.

    To the OP: Please do some research. The fan you depict isn't explosion proof. If it was the impeller would be bronze and the motor would be both TEFC and out of the airstream. That said, I think you'll find that your proposed solution will be just fine given your stated scenario. Make sure you move plenty of air so the concentration of any fumes doesn't reach an explosive level.
    Sharp solves all manner of problems.

  12. #27
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    Quote Originally Posted by Rob Luter View Post
    I'm seeing a great deal of ignorance on what "explosion proof" really means. The reality is it can mean a number of things depending on the risk level. It means different things depending on whether you're dealing with liquids, gasses, or dust. The NFPA is a great source of information on the subject. If you want to go whole hog, design to Class 1, Division 1. Everything sealed, no possibility of sparks, no possibility of static discharge, etc.. Note that this is crazy expensive and nothing you need unless you're processing fuel or running a munitions depot.

    To the OP: Please do some research. The fan you depict isn't explosion proof. If it was the impeller would be bronze and the motor would be both TEFC and out of the airstream. That said, I think you'll find that your proposed solution will be just fine given your stated scenario. Make sure you move plenty of air so the concentration of any fumes doesn't reach an explosive level.
    Good catch on the fan Rob. I thought it seemed too cheap. Now that I think about it, just the termination cost to an explosion proof motor could easily more than double the price of that fan. That would include labor because that is not a DIY thing.

    The inside of the spray booth is Class I, Div I. Explosive concentrations of vapors will routinely happen there. Hence my strong suggestion (if I could insist then I would) that the LED lights be moved outside the booth.

  13. #28
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    Quote Originally Posted by Rob Luter View Post
    I'm seeing a great deal of ignorance on what "explosion proof" really means. The reality is it can mean a number of things depending on the risk level. It means different things depending on whether you're dealing with liquids, gasses, or dust. The NFPA is a great source of information on the subject. If you want to go whole hog, design to Class 1, Division 1. Everything sealed, no possibility of sparks, no possibility of static discharge, etc.. Note that this is crazy expensive and nothing you need unless you're processing fuel or running a munitions depot.

    To the OP: Please do some research. The fan you depict isn't explosion proof. If it was the impeller would be bronze and the motor would be both TEFC and out of the airstream. That said, I think you'll find that your proposed solution will be just fine given your stated scenario. Make sure you move plenty of air so the concentration of any fumes doesn't reach an explosive level.
    Why bronze impellers vs steel? I've seen aluminum suggested as well. Because they won't spark vs steel??
    Last edited by Alan Lightstone; 04-26-2022 at 9:36 AM.
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  14. #29
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    I found this link which seems to go into detail regarding the NFPA 33 Spray Booth Regulations. Interesting, but TL;DR parts of it.

    https://www.spraysystems.com/nfpa-33/
    - ďItís not that Iím so smart, itís just that I stay with problems longer.Ē Ė Albert Einstein
    - Welcome to Florida. Where the old folks visit their parents

  15. #30
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    Iíve pretty much concluded that Iíll stick to water base finished with an occasional rattle can of something. The fan is supposed to flow 2077 cfm which will give me 33 air exchanges per minute. Iím pretty sure this will be more than adequate for any rattle can work Iíll do.
    The Plane Anarchist

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