Explosion proof exhaust fans for paint booth

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Rktman

Rktman

Eric
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Can any of you more knowledgeable gents point me in the direction of explosion-proof exhaust fans for my homemade paint booth? Units that won't cost thousands to purchase? I've been using two bathroom exhaust fan units to duct rattle can paint particles outside, and although I use two stacked household HVAC filters, I'm nervous that at some point the perfect storm of conditions will result in an explosion.

My current fans are 8" X 8" (outside frame dimensions) so the holes cut into the plastic container paint booth are slightly smaller. Any help would be greatly appreciated.

Paint booth.JPG
 
My booth is 10'x13'. Fully enclosed, fresh air vents in wall, fan in ceiling. I forget the exact cfm volume of the fan, but is will evacuate the room in 30 seconds. Bought at HD, just look for explosion proof.
 
David Schwantz said:
My booth is 10'x13'. Fully enclosed, fresh air vents in wall, fan in ceiling. I forget the exact cfm volume of the fan, but is will evacuate the room in 30 seconds. Bought at HD, just look for explosion proof.
Click to expand...
Couldn't find this item at Home Depot. Any suggestions on search words to use?
 
I've used a marine bilge exhaust fan for my paint booth it worked well. I bought it like 15 years ago and it was very affordable...maybe $30? I think you should be able to get one for under $60 today.
 
I am no expert but here are a few ideas.
Look for a sealed motor (no vent holes in the motor housing).
Also, a fan motor that is not in the fan airflow.
This keeps the paint vapors from passing directly over the motor.
 
mh9162013 said:
I've used a marine bilge exhaust fan for my paint booth it worked well. I bought it like 15 years ago and it was very affordable...maybe $30? I think you should be able to get one for under $60 today.
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I think this is my solution! Relatively inexpensive, small(er), and since they're meant to exhaust fuel fumes from the engine compartment, I'm assuming they're explosion-proof. Thanks!!
 
mh9162013 said:
I've used a marine bilge exhaust fan for my paint booth it worked well. I bought it like 15 years ago and it was very affordable...maybe $30? I think you should be able to get one for under $60 today.
Click to expand...
BTW, I'm assuming these are corded units that can be plugged into my 120V outlet at home?
 
Rktman said:
BTW, I'm assuming these are corded units that can be plugged into my 120V outlet at home?
Click to expand...
The one I bought was DC, so I plugged it into a 12V power source (I bought a CPU power supply for this). If I recall correctly, most of the units I saw when I last shopped for one were 12V or 24V.

I don't think they make AC powered ones (or they're rare) because these are designed to tap into a boat's power supply/battery. I'm no boater, but I imagine bilge bays don't have readily available AC outlets.
 
1704978531175.png

Maybe something like this 12" ventilator (from Walmart), and mount an extra tube going to your paint booth. Of course, you would have to use some sort of paint filter panel in the back wall of the booth. I use the setup with a big carboard wardrobe box as booth, and when I set the ventilator on it sucks all the overspray to the filter. I just put the end of the tube outside the window, and all the fumes go outside. The key is to get something with a lot of velocity and suction to produce negative pressure in the paint booth.
They make these inline fans in all sizes and capacities, often as bathroom or greenhouse ventilators. Find one that fits a flexible hose made for a clothes dryer, and maybe a bigger plastic or cardboard box, that might be more the size you're looking for. I like cardboard boxes as booths, as I can fold them flat and store them when not in use.
 
ghostfather said:
Maybe something like this 12" ventilator (from Walmart)
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No offence to the poster but "explosion proof" implies the motor is outside the airflow.
I found a really nice one on Craigslist.
More air is better - don't skimp.
And don't forget you'll want filters in the path - intake and exhaust and those suck up fan power.
 
What about a squirrel-cage blower that has the motor mounted outside of the squirrel cage? (Smaller units often mount the motor inside the cage for cooling and compact-ness.) Have the output directed some distance from the motor, with appropriate ductwork.
 
A giant squirrel-cage is essentially what we bought.
Was "explosion rated" but not sure what other attributes make it that beyond the motor outside the airpath.
One must assume the exhaust is nasty.
Fans on the exhaust side is preferred as that tends to have less dust as you DRAW air through the input filters instead of RAMMING it though the filters. We have a literal wall of filters on input and output. The input are on one wall with the output on the opposite feeding a plenum to the fan above that exhausts outside. Input filters control the dust. Output filters capture the surprising amount of paint that's overspray.
 
My present inline ventilator is more or less waterproof. It was designed to exhaust a humid greenhouse. It may not be "explosion rated", which is fine for extensive use in a automotive painting business where it might be required by insurance or code, but I trust it enough to not be dangerous. It's like IP 5 moisture proof, while that might not be good for immersion, it can be operated out in a rain storm, so it's sealed enough not to be very dangerous.

But do your own risk analysis, and if having a explosion rating lets you sleep at night, fine. My ventilator cost me 50 euros, a professional rated ventilator is maybe 10x as much. I run through maybe 10 rattle cans of paint a year, and sometimes some 2K clear coat in a mini paint gun. I'm a hobby user. I also have a column drill machine, but it's a hobby grade, I'm not using it daily or professionally, and it's good enough for a hobby. I'm trying to put this in perspective.

In short, I question the need for a professional "explosion rated" ventilator for simple hobby use. A good sealed fan (without rating) is probably good enough.

Instead, concentrate on getting enough flow to exhaust the volume of your paint booth at 2-3 air changes per minute, use some good filters to catch most of the overspray, and exhaust it outside to remove most of the fumes. Looking at the OP's original post, he's not looking for a professional paint booth.
 
ghostfather said:
My present inline ventilator is more or less waterproof. It was designed to exhaust a humid greenhouse. It may not be "explosion rated", which is fine for extensive use in a automotive painting business where it might be required by insurance or code, but I trust it enough to not be dangerous. It's like IP 5 moisture proof, while that might not be good for immersion, it can be operated out in a rain storm, so it's sealed enough not to be very dangerous.

But do your own risk analysis, and if having a explosion rating lets you sleep at night, fine. My ventilator cost me 50 euros, a professional rated ventilator is maybe 10x as much. I run through maybe 10 rattle cans of paint a year, and sometimes some 2K clear coat in a mini paint gun. I'm a hobby user. I also have a column drill machine, but it's a hobby grade, I'm not using it daily or professionally, and it's good enough for a hobby. I'm trying to put this in perspective.

In short, I question the need for a professional "explosion rated" ventilator for simple hobby use. A good sealed fan (without rating) is probably good enough.

Instead, concentrate on getting enough flow to exhaust the volume of your paint booth at 2-3 air changes per minute, use some good filters to catch most of the overspray, and exhaust it outside to remove most of the fumes. Looking at the OP's original post, he's not looking for a professional paint booth.
Click to expand...
Thanks, appreciate the refocus Steve.
 
ghostfather said:
In short, I question the need for a professional "explosion rated" ventilator for simple hobby use.
Click to expand...
When the motor makes a spark and there's the right mix of fuel and air, the resulting explosion doesn't care whether you're a hobbyist or a professional.

It doesn't necessarily need to be certified or rated, but I think you do need to eliminate the possibility of a spark where there's flammable vapors. Putting the motor outside the spray booth/box and away from the airflow should suffice.
 
Azamiryou said:
When the motor makes a spark and there's the right mix of fuel and air, the resulting explosion doesn't care whether you're a hobbyist or a professional.

It doesn't necessarily need to be certified or rated, but I think you do need to eliminate the possibility of a spark where there's flammable vapors. Putting the motor outside the spray booth/box and away from the airflow should suffice.
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Exactly. After a year of use, my bathroom exhaust fan motor/blades already have a light coat of rattle can paint on them despite a 1/2" foam filter over a stack of two HVAC filters covering the fan inlets. It's not just the aerosol propellent that I'm concerned about, it's the finely divided paint particles. I'm sure you're all aware of explosions happening in even flour mills. The fine particles of milled flour become flammable in such fine form. I've had other hobbyists, even here, warn me of the very real possibility of explosions from using rattle can paint and unprotected fan units.
 
mh9162013 said:
The one I bought was DC, so I plugged it into a 12V power source (I bought a CPU power supply for this). If I recall correctly, most of the units I saw when I last shopped for one were 12V or 24V.

I don't think they make AC powered ones (or they're rare) because these are designed to tap into a boat's power supply/battery. I'm no boater, but I imagine bilge bays don't have readily available AC outlets.
Click to expand...
Can you give me info on your CPU power supply (what make, model, amperage, where bought from, etc.)? Did you need one for each fan? When it comes to electronics I'm pretty much illiterate. :rolleyes:

Thanks in advance,
Eric
 
The fan I bought mounts in the ceiling. This is a pic of it's grill on the bottom. It might be a bit large for your needs. And yes, mine is a separate room in my basement. Built just for this purpose. It has fresh air intake filters, completely sealed from rest of house. You can smell no vapors outside the door. Has air lined in from compressor in garage. Very nice water trap in line. And it has fresh air supply for me to breathe from its own little compressor. It is called Hobby Air. Comes with a very nice half mask, flexible hose, and of course the compressor.
And explosion proof refers to the motor and wiring. Not the fan. Motors rated as such are designed to be in the airflow, dust, gas area. I am in those areas almost daily for work. ie, grain elevators, food plants for both you and me and our pets. Every single exhaust fan in any of those areas are explosion proof. Granted for some of the hobby uses a huge fan may not be needed. But my booth is sealed and if I did not have a fan to evacuate it will fill with fumes and be deadly to breathe.
 
Rktman said:
Can you give me info on your CPU power supply (what make, model, amperage, where bought from, etc.)? Did you need one for each fan? When it comes to electronics I'm pretty much illiterate. :rolleyes:

Thanks in advance,
Eric
Click to expand...
Basically any desktop computer power supply will work. They will have various wires coming out of the power supply offering various voltages. The trick will be deciding which one is which, but a multi-meter should be able to make quick work of that. Something like this will work:

https://www.newegg.com/thermaltake-smart-series-ps-spd-0600npcwus-w-600w/p/N82E16817153232
You'll note that it outputs 12 volts at 45 amps...way more than enough for a properly working 12V bilge blower. I'm a bit surprised at the price, though. I bought mine from Newegg about 10 years ago and it was like...$25. I'm sure those prices will still exist if you shop around.

You don't have to use a computer power supply for the bilge blower fan as those motors are pretty forgiving when it comes to exact voltages (my power supply served double duty as the fan blower power source and a power source for my R/C battery charger).

If you got a 12V fan version, you'd probably be just fine pushing anything between 6 and 16 volts through it. Although, it'd probably be safer (and give longer life) if you undervolted it as opposed to overvolted it. Heck, a basic R/C car stick pack (3s lipo, for instance) should power the bilge fan blower for hours and hours and be able to serve as a plug-and-play option.
 
mh9162013 said:
Basically any desktop computer power supply will work. They will have various wires coming out of the power supply offering various voltages. The trick will be deciding which one is which, but a multi-meter should be able to make quick work of that. Something like this will work:

https://www.newegg.com/thermaltake-smart-series-ps-spd-0600npcwus-w-600w/p/N82E16817153232
You'll note that it outputs 12 volts at 45 amps...way more than enough for a properly working 12V bilge blower. I'm a bit surprised at the price, though. I bought mine from Newegg about 10 years ago and it was like...$25. I'm sure those prices will still exist if you shop around.

You don't have to use a computer power supply for the bilge blower fan as those motors are pretty forgiving when it comes to exact voltages (my power supply served double duty as the fan blower power source and a power source for my R/C battery charger).

If you got a 12V fan version, you'd probably be just fine pushing anything between 6 and 16 volts through it. Although, it'd probably be safer (and give longer life) if you undervolted it as opposed to overvolted it. Heck, a basic R/C car stick pack (3s lipo, for instance) should power the bilge fan blower for hours and hours and be able to serve as a plug-and-play option.
Click to expand...
Much thanks for the info!
 

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