Paint booth pos or neg pressure?

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Nochain

Promoted Users
So, after reading many many posts, I have yet to found a definitive answer to what pressurization is best for a garage set up. I was planning on a negative pressure ie large exhaust fan and passive filters on the inlet. I am confident to be able to tune the system for correct airflow my main concern is fire/explosions. So is there a safety advantage of either positive or negative pressure enclosures?
Thanks
 
For a garage set up, I really think a negative pressure system is better. And there have been posters here who went from a pos pressure to negative pressure set up and had much better results. I think it's better because I think it's going to be more efficient at exhausting overspray/VOC because it's a direct exhaust without the turbulence like you have in a positive pressure booth, unless you have a fan forcing air in as well as a fan pulling air out. That seems like it might be the best route but I've never tried it. My home booth exhausts at the floor at the rear of the booth and the fresh air intake is in the ceiling and the front of the booth.
 
Nochain said:
So, after reading many many posts, I have yet to found a definitive answer to what pressurization is best for a garage set up. I was planning on a negative pressure ie large exhaust fan and passive filters on the inlet. I am confident to be able to tune the system for correct airflow my main concern is fire/explosions. So is there a safety advantage of either positive or negative pressure enclosures?
Thanks
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I've played with lots of setups and I'm sold on negative pressure, at least for a home shop setup. High volume, low velocity so lots of air moves but doesn't swirl or kick up any debris that is present.

Each person needs to do what makes them comfortable and feel safe.
I continually see guys posting that they use torpedo propane/kerosene heaters (open flame, like a jet in afterburner) in the booth, while spraying. Some woodstoves even.
I wouldn't do that, but I'm not worried about my standard fan causing an explosion.
 
Thanks for replying. Good to hear positive experiences on negative pressure. I was able to hook up with a 42 large 3 blade 1300 rpm (slow) drum fan that I intend to use. Like Dean stated above low velocity high volume is exactly what I was looking to accomplish. No matter how hard I clean the garage its never going to be good and blowing a small high velocity fan would be a nightmare IMO.
 

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I like mine at equal or slightly negative. Meaning both fans going and the roll up door cracked and sitting on my stool about a foot high .
 
RosharonRooster said:
I like mine at equal or slightly negative. Meaning both fans going and the roll up door cracked and sitting on my stool about a foot high .
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Are you saying you have fans both intake and exhaust and are close in cfm making just a small negative overall negative pressure? What type of fan are you using?
 
Nochain said:
Are you saying you have fans both intake and exhaust and are close in cfm making just a small negative overall negative pressure? What type of fan are you using?
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No. I have 2 fans from tractor supply mounted on a wall...on the opposite end of the room is a roll up door that I cracked open about a foot. I know it's slight negative pressure because the man door still sucks in shut....without the roll up door cracked, the walk in man door really slams shut
 
I tried the big exhaust fan out a window with the garage door closed - dirty ! The problem was it was too powerful and sucked dirt from everywhere . I don’t remember how big it was but my entry door would close when it was on . I tried cracking the main door a bit and that helped but still dirtier than I wanted- I settled on 2 Walmart box fans under the main garage door ( negative pressure)- 10 years of cleaner paint jobs and zero explosions. Maybe I’m lucky that there wasn’t any explosions ? I don’t know but it works
 
RosharonRooster said:
No. I have 2 fans from tractor supply mounted on a wall...on the opposite end of the room is a roll up door that I cracked open about a foot. I know it's slight negative pressure because the man door still sucks in shut....without the roll up door cracked, the walk in man door really slams shut
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In through the windows and out through the door? Wouldn’t that be positive pressure? OR are these two fans just blowing from the wall? I am confused.
 
My filtration is an explosion proof fan and a standard window that I put a furnace filter in. With the fan on low, it empties in just a few minutes. The filter has practically eliminated any dust.
 
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Nochain said:
In through the windows and out through the door? Wouldn’t that be positive pressure? OR are these two fans just blowing from the wall? I am confused.
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If I'm spraying primer I'll open the windows and use them as "intake" but I dont like doing that went painting because the lot next door is vacant and has lots of cotton wood floating around...in that case I don't open anything....and I get a pretty strong suction slamming the walk in door.....most of the time I just crack the roll up door (which is in the area I was standing in this picture). And use that as an intake. Total backyard hack job but, it works and I've gotten good and wet sanding and buffing lol....in hindsight, I wish I had put the fans on the floor that was the draft is kept down low and away from whatever I'm painting. I'm looking to expand this room to about 28ft long. Right now it's 20ft long, 15ft wide
 

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RosharonRooster said:
If I'm spraying primer I'll open the windows and use them as "intake" but I dont like doing that went painting because the lot next door is vacant and has lots of cotton wood floating around...in that case I don't open anything....and I get a pretty strong suction slamming the walk in door.....most of the time I just crack the roll up door (which is in the area I was standing in this picture). And use that as an intake. Total backyard hack job but, it works and I've gotten good and wet sanding and buffing lol....in hindsight, I wish I had put the fans on the floor that was the draft is kept down low and away from whatever I'm painting. I'm looking to expand this room to about 28ft long. Right now it's 20ft long, 15ft wide
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I'd suggest keeping the garage door closed and put a filter in the farthest window. I think you will see a big difference.
 
AAE said:
I'd suggest keeping the garage door closed and put a filter in the farthest window. I think you will see a big difference.
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I used to do that. Ac filter fits perfect in the window. Still get nibs and stuff.ive never tried the grounding with a chain thing though
 
I have a simple but clean negative pressure solution for a panel booth. I use a $175 plant grow tent from VivoSun Rigid frame that is strong enough to hang parts. I had to try a few different exhaust blowers (less is better) but the overspray clears quickly and I haven’t had trash issues (yet). Furnace filter for inbound air, small paint arrestor in box outbound.
 

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austincooper said:
I have a simple but clean negative pressure solution for a panel booth. I use a $175 plant grow tent from VivoSun Rigid frame that is strong enough to hang parts. I had to try a few different exhaust blowers (less is better) but the overspray clears quickly and I haven’t had trash issues (yet). Furnace filter for inbound air, small paint arrestor in box outbound.
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Tell us about the paint arrestor please.
 
Last time I sprayed clear I was using very low negative pressure. Almost no pressure. I was in a cloud doing a whole care. Never again. I need to see what I am doing and need better air with only a tyvek suit and half mak with goggles. I can dial back my 42 inch fan but I plan not to have a cloud. I am going to analyze and tune the ventilation using a cigar and glass of whiskey.
 
You guys painting with only a small amount of air moving through the booth I hope you have some kind of full face respirator. You don’t want ISO’s in your eyes.

Sorry if I am stating the obvious.

Don
 
dhutton01 said:
You guys painting with only a small amount of air moving through the booth I hope you have some kind of full face respirator. You don’t want ISO’s in your eyes.

Sorry if I am stating the obvious.

Don
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Yes agree completely. Fresh air hood always. Also there is no fog at all with this setup.
 
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