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Maker of Fine Sawdust
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Discussion Starter #1
Hi All,
This is not quite a HVAC question, but I figure you guys might be able to answer a static pressure question. I am building a spray room to do finishes for cabinets. I am planning on using a tubeaxial type fan, 36" diameter 6 blade fan powered by a 3HP 3 phase electric motor. The room is 18' x 9' (x 24') in cross section and the code is for 100 feet per minute. The door opening is 5' x 7' and will have filter material on it. The fan output will be through the wall into an auto-shuttered vent with filter material before the fan. I need to maintain 16,200 CFM to stay with the 100 FPM code. The fan has these ratings for static pressures.

[email protected] In. 17570/98
[email protected] In. 16890/98
[email protected] In. 16135/97
[email protected] In. 14450/98
[email protected] In. 12345/100

I think that the SP will increase as the filters clog, I know that the load will, which is why I picked a fan with greater capacity. Eventually I will need to place an output shroud/filter unit on the exhaust of the fan also, but that will come later when the budget permits it.

What I would like to know I guess, is this fan going to cut it? And what are the slashed numbers after the CFM rating (17570/98). How would I be able to calculate various SPs, or do you need a tool to do some measurements? Any other SP information you could give to me would be appreciated. Thanks

Leo
 

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DGR,IABD
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9,683 Posts
Related to your question...
Sorry to threadjack right off the bat, but I see a potential big safety issue here. Is the fan you selected rated as explosion proof? Spray booth fans aren't something generic and off the shelf. If you use an otherwise normal exhaust fan, you stand a really good chance of blowing yourself and your shop to kingdom come. Such an exhaust fan must be rated "explosion proof" right on the dataplate. If you already knew this or you're only using water based finishes, disregard what I've said and call me a crackpot.
 

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Administrator
Maker of Fine Sawdust
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Discussion Starter #3
mdshunk said:
Related to your question...
Sorry to threadjack right off the bat, but I see a potential big safety issue here. Is the fan you selected rated as explosion proof? Spray booth fans aren't something generic and off the shelf. If you use an otherwise normal exhaust fan, you stand a really good chance of blowing yourself and your shop to kingdom come. Such an exhaust fan must be rated "explosion proof" right on the dataplate. If you already knew this or you're only using water based finishes, disregard what I've said and call me a crackpot.


Yes, explosion proof :rolleyes: blah blah blah yada yada yada. I have'nt witten a question about spraybooths without being reprimanded by 4 or 5 people. I never seem to get my questions answered though. Everybody is so worried about being safe. Mind you, it is imperative to be safety minded. But do you really know how hard it is to cause an explosion in a booth. To get the perfect concentration of air and fumes you would need to be unconscious on the floor. You have to watch out for fire more than you have to watch for explosions. Thanks for your concerns. But anybody have the static pressure answers?
 

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DGR,IABD
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9,683 Posts
Most spray booths have a Magnahelic gauge mounted on them to let you know the static pressure in the booth and at what point to attend to the filters. Magnehelic gauges are a couple hundred bucks, but an oil filled manometer will give you the same measurements for less than 50 bucks. You'd have to have really, really super clogged filters to get greater than -.25 inches of static pressure in the booth, which seems to be your performance cutoff point for maintaining your air exchange requirement.
 
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