slickum paint booth

Bill,

I have brought services to a couple booths ... my HVAC backround tells me maybe the booth should have fans to pull the air out ... in a neg pressure which will pull outside air in .... down draft of course so the dust goes down to the ground ???? Pressurization will stur up dust ???

What is the volume, pressure and horsepower of the supply fan(12"dia.)? How thick and what is the ASHRAE rating, if any,of the filters in the room inlet filters?

Where does the 24" hole in the floor get ducted to?

How high a positive pressure were you looking for?

If you like, you can contact me at adi@pobox.com

John

I'll add a few more pics in a bit. The filters are just home A/C filters from the hardware store. The fan is mounted above the booth and is at least 4000 cfm, squerrel cage. When I tested the fan on the floor it blew itself over! I have the intake choked way back and is adjustable with the gate valve from closed for warming to full open for max flow. There is a 2 foot by 4 pit in the floor connected to a 24 inxh pipe out the rear of the foundation. I have a gable vent with some plastic flaps to keep cold air from blowing back in. Ron, My figuring is if the booth is sealed the air has no choice but to escape through the pit in the floor as that is the path of least resistance. I don't think turbulance is a problem, the floor and walls are wet when painting. I have seen new booths with ceiling fans to ciculate air. My last booth pulled out and sucked fresh in. This one cannot suck in trash or dust, so far it has preformed well.

Yes, you are right, the air is going to find the low pressure area which should be the pit in the floor. It's the air's path and the velocity getting there that is giving you the problems.

You said that the fan is handling approx. 4000 cfm. If that close to true, your 12" inlet's velocity is over 5100 feet per min. That is very high. By the time it gets to the room because of system losses it will be considerably lower. It also takes a lot of horsepower to do this.

If your object is to put the booth under a positive pressure that doesn't take a lot of air, it takes pressure. I doubt if you would need to go over .5" water column (1psi= 27.68" water col.)

Have you looked at the outlet to see what level of air volume you have there?

If the object is to ventilate the booth, I don't think you are going to like to go the positive route.

Bill,

Your design is backwards.

Downdraft, crossdraft and side draft all use a Tubular Axial EXHAUST fans. You DO NOT want to pressurize a paint booth. That causes turbulance. You want to exhaust the air out and bring clean filtered air in.

The theory is to filter and some times heat Makeup Air and then pull it down or across the booth with an Exhaust fan.

The way to measure the density or how dirty your filters are is with a magnahelic guage with 2 ports or tubes one on each side of the filter plenum.

Either way your sealing the booth is correct.

The problem is and why you see white paint trying to escape is your forcing 4000cfm thru a 24" pipe which is too small to maintain a negitive pressure ... your want the air pulled down and out.

The only change I would make is remove the intake fan and put it on the exhaust.

Good points Ron, but remember that I am chocking back the intake with the slide valve. So not really the full 4000 cfm. If I pull air out...(my original plan) I would have to use a tubeaxle type fan. The way I do it now, my fan stays in clean air. I had at the begining a sheet of plywood over most of the hole on the floor too keep out the cold, and that did create too much pressure. Now I have the plastic loovers st the outlet instead. They flip open easily and I do'nt belive I'm really creating a lot of pressure. Really all I would have to do is install the tube axle fan outside and not run the overhead squiell cage. I even have one under my other booth at home. Then I would need a larger intake area too. So far this has been my cleanest booth ever. What I really need is even heat, Like another gas burner near the entrance door. Yeah, thats right, I paint with an open flame burning, been doing it for 14 years. I can't wait for spring!

Bill,

The existing fan can stay, duct can stay, install a manual damper on the intake and you can open and close it as necessary and maybe just add a heat coil to it and waaalllaaa you have what we call a make up air unit.

Gas burner while painting .. i did it all my life ..too. ... I say add a coil to the the make up air fan and your done or just move the fan to the exhaust side and add the coil on the intake.

my 2 cents.

By the way really nice job on the shop ... best of luck...

Ron

I added a suction fan to the outlet. If I turn it on first it sucks the door in, when I turn on the fan that blows in, I can pretty much move the door freely. It sucks out a bit more than blows in. Now I have a balance, and a lot of air moving. Thanks Ron, I knew I needed it.

Bill I like your shop! Looks like the paint booth is a huge improvement over anything I've ever used. My first paint booth was in my garage with water on the floor to keep the dust down and I had to staple plastic sheeting to the ceiling 2x4's to stop the termite droppings from falling in the paint! Thank god for color sanding and buffers...it hides a lot of inexperience! Ah the good old days when you would try anything and not over think everything...we just did it. Good luck with you booth.

quote:

The dirty air is pushed out through the 24 inch hole in the floor.

Bill,

Is it actually legal for you to discharge your paint process overspray out to the atmosphere?

I just had my wheels re-polished and the polishing shop owner told me how they just received a $36K fine, lowered to $12K, for dumping their shop trash in their regular city container. They had done it that way for years, but once the city noticed, all hell broke loose.

Now they have it separated and it goes into a different disposal stream.

Almost put them out of business. And they are the last metal polishing shop left in town.

Larry

California vs South Carolina?

Always improving Bill ... looks good.

-G

That's alright Bill, wish I could spray paint but I'd be afraid of the environment Nazi's. Us folk in the Metropolitan areas won't be happy till we have catalytic converters hooked up to our ass's in case we fart (':'). Keep up the good work brother, I enjoy your progress.

Mark

I've been using the new fan setup for a couple of weeks now and I love it. Check out this link.. http://www.slickpaint.com/inde...p?p=1_11_Latest-News I'm doing a 4 day job.. Live March 20-21-22.. You ask about the paint mist. In SC we have DEHC They control the ENVIROMENT. If I filter the mist in the building, they don't come inside. I took old sheetrock to the landfill. They said they don't take sheetrock. I asked them what to do with it? They said put it in a black plastic bag and bring it back so they can't see whats inside. I kid you not!