# Spray paint booth questions



## JivRey (Jul 2, 2016)

Hi guys, I have a few questions. I want to build a little spray paint booth and I want to ask if any of you have advices for me.

My main question is if my intake/exhaust placement makes sense. Right now it is designed to have the air intake at the top and air exhaust at the bottom, opposite sides. Should they both be at the rear of the spray paint booth?

The booth size will be 5' x 5' x 7"6", it will be covered with polythene plastic, have 4x 48" neon (Outside the booth of course). I have a a belt-driven fan I plan to run over a ~10 meters 6-8" flexible duct outside. And I will use 12" dust free filters for incoming and outgoing air.

I came up with this design reading about dozens of posts, but as you know, there's nothing like personal experience (Which I don't have yet!)

Thanks for any advice that can help me start this project on the right foot!


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## ZeroGravity (Mar 25, 2016)

No real experience, but I assume that commercial booths are usually down draft for a reason. I guess this helps gravity in pulling the vapours, solids, dust etc that are falling down faster.


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## vadsy (Dec 2, 2010)

Make the exhaust portion of the wall bigger, maybe the intake as well. Air in needs to equal air out, its like water at that point. Also, I've used filters for this sort of application that are sticky and they help keep the dust and paint particles down when the system is up and running. I purchased those filter from Acklands Grainger but I'm sure you could track them down at similar places.


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## mhammer (Nov 30, 2007)

I would think it is safer and healthier to have the clean air intake closer to the human intake valve (i.e., your mouth).


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## vadsy (Dec 2, 2010)

mhammer said:


> I would think it is safer and healthier to have the clean air intake closer to the human intake valve (i.e., your mouth).


It wasn't mentioned but I would suggest a mask as well.


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## mhammer (Nov 30, 2007)

My dad once brought me a chunk chiseled off from the wall of an industrial spray booth.  It was about and inch and a half thick, and was the most glorious multi-layered thing I've ever seen. I mean, we are talking literally _thousands_ of alternating layers of different colours of paint that had dried over the years.

Does yur out-take provide any means for concentrating the airborne particles so that they aren't simply dumped outside? I.e., is there a means to concentrate them for later proper disposal?


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## vadsy (Dec 2, 2010)

If you use a proper paint booth filter on the exhaust side it should have an open weave design with tacky skin on the opposite side, this helps trap the paint. I worked in a place where a lot of painting in a booth was going on, when the filters were replaced as necessary the back side of the chamber was clean and free of paint. A layer of those will help collect any overspray.


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## Lincoln (Jun 2, 2008)

I've built a few temporary spray booths over the years. Even used a large cardboard box mounted on a table. What I find works best is the air intake in the top of the enclosure, slightly behind where you will be standing to spray. Normally I use furnace filters and make the intake about twice the size of the exhaust. The exhaust I put at floor level behind where you will be spraying, using the special paint filters Vadsy mentioned, or multi-layers of furnace filters. And again as Vadsy said, ALWAYS wear a mask.


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## mhammer (Nov 30, 2007)

Forty years ago, I was working in a neuroscience lab, and one study we were conducting involved studying light-dark cycle effects on hamsters. The hamsters were housed in cabinets - essentially free-standing metal lockers - that had been specially modified to keep light out but permit air flow in/out. I guess there must have been about 6 shelves, with 2 or 3 cages on each, and about 180 hamsters in each cabinet. Mini-fluorescent lighting inside the cabinet was set by a timer, so that one cabinet got more "daylight" than the other.

The air intake was on the bottom, and outtake was at the top. A slot had been cut in each shelf, alternating left and right, such that the flow direction zig-zagged its way from the bottom to the top. Unfortunately, that resulted in whatever pathogens the hamsters carried accumulating as the air worked its way from bottom to top. If there wwere any germs in the cabinet, the guys at the top got 'em all. Regularly, we'd find dead animals on the top shelf, near the outflow. Their cage-mates would have started eating the corpses, face-first.

An unpleasant tale, and seemingly unrelated to this thread. I just wanted to make it clear that there are all sorts of tragedies to be avoided by _strategic planning_ of air flow. Not just health-related ones (which are top-priority), but also matters related to consistent coverage of whatever one is spraying.


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## Scotty (Jan 30, 2013)

Couple of important things here;

Your fan has to be explosionproof. That includes the fan and the motor if the motor is in the airstream. Metal squirrel cage blower's are not intended for this use. Any spark and it could be ugly. You should be using an aluminum prop.

Secondly, you want to situate your exhaust situated behind where you're spraying.
Create a plenum that goes right to the floor. Vapours are heavier than air.

If you don't paint in front of moving air system your overspray may not clear and circle back around. You want to draw that overspray into the filter rack.

Thirdly if you're mixing solvent based paints with metal cans, make sure they are grounded. You may have recall hearing that radio commercial many years ago about an 18-year-old kid that burned to death on his first day at work. It was a solvent fire if I'm not mistaken. Static charge created the fire because the canisters weren't grounded.

As for the booth itself, I would make it longer than it is wide to induce airflow. Saying this because I assume your fan it's not a large industrial unit. (??)
The wider your plenum, the more you're going to need from your exhaust fan. This also gives you a bit of space behind the subject for the overspray to go between it and the filter rack.

And definitely, absolute minimum is to wear a properly fitting respirator not just a mask. Make sure you're using organic charcoal filters, prefilters help keep them from getting plugged up if you're doing a lot of painting. Disposable masks are total junk


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## mr trick (Sep 21, 2013)

the filters for the intake could be mounted in the door, and some misting of the floor with water will help keep the dust down. we always kept a vacuum handy for the floor in our shop


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## dradlin (Feb 27, 2010)

Contact your local fire department, building department, and insurance company to get their input into your plan.


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