DIY vs. Commercial Spray Booth?

I am a proponent of the DIY approach, mainly so as to not be constrained by whatever size booth the manufacturers decide upon. The main expense is the blower, and yes, that is going to set you back a couple of hundred for a new unit (that is looking only at McMaster-Carr's prices), but if you are resourceful, you ought to be able to salvage a blower from some other application. As long as the motor is not physically in the airstream, there is little need for the hazardous location motors, so the squirrel-cage fans are the ideal option, but belt driven fans can be adapted. The commercially available booths are pretty pricey themselves, so the cost starts to come pretty close!

Right now, I am planning to build a positive-pressure booth, essentially a closet where the blower pushes outside air in, and the fumes exhaust out, thereby allowing the use of a much more inexpensive fan, but not everybody has the space to do that.

Don't believe that computer cooling fans will move the volume of air we require, unless you have a bank of 64 of them!

Thanks, Ashley.  In terms of the salvage route, what types of equipment are you thinking of? 

Yours is an interesting solution - I hope you'll post pictures and commentary once you get into the build of it.

Cheers, Rick

I've had both and I guess it depends on you abilities and resources you have...time included. All of my homemade booths have done what they needed to do. However, I don't seem to have the time nor many of the resources I once had...sold off my table saw and other woodworking equipment long ago...no time to use them.

My current booth is adequate but barely for my expanding needs. So to make life easier I will include the purchase of a Pace Peacekeeper as part of my workshop makeover...whenever I find time and and can get the materials on hand for that project.  There is a certain appeal for a plug and play apparatus this time around.

I have a huge commercial ventilation fan that was used at a lab to ventilate a large material handling workstation. It cost me nothing but the cost of materials and my time to build something to incorporate it into my workshop is probably more than the Pace. Easier is better I think this time around.

Hi, Rick.

First, a spray booth is not a necessity.  They are, however, nice to have and do offer a degree of protection that you wouldn't have otherwise.  In a well-ventilated area as you describe, a spray booth would probably not be needed.  Having a well-ventilated room including a partially open window, a room fan at your back, and possibly a respirator, would supply sufficient ventilation to minimize potential exposures.  I've done some exposure calculations based on worst-case scenarios, and if you're interested in discussing any of that and what it means, I can help.

After having said all that, I tend to like a DIY approach since I believe that many current booths aren't  designed to make efficient use of the indadequate fans they do have.  And many booths are simply poorly designed and equipped with less than adequate equipment--fans specifically. 

A good centrifugal fan is going to cost good money, partially because those items fall into what I believe is a niche market.  (Check out Grainger, or google Dayton blowers.)   I would be wary buying a used fan without seeing it first.  It doesn' t take a lot of negligent maintenance, or running without a filter to degrade the aerodynamic properties, and consequent efficiency, of a fan blade.  I see this quite often in laboratory settings. 

Stay away from computer fans.  There's nothing wrong with an axial fan for booth exhaust, PROVIDED the fan is designed for that application.  Computer fans are not.

Please don't hesitate to PM me with any questions.

Gip Winecoff

Rick, I just went and looked at the Paasche HSSB-22-16 Spraybooth over at the Paasche web site (see the thread regarding this booth), and if you're looking for a "plug and play" booth, this is one I would recommend.  Good design and a fan that actually pulls 100fpm or better at the face, for about 3 Ben Franklins.

Gip

The nice thing about having a paint booth is being able to paint whenever you want. And, if you're able to have it in the house, being in a controlled environment. Being able to shoot at about the same temperature and controlled humidity year round takes away some of the variables.

I bought a Dayton blower at Grainger about 7 years ago. Hadn't looked at them in a long time so out of curiousity I dug around to find how much the price has gone up. The one I bought, 4C447, for about $68 has been replaced with a 1TDR3 for about $92. It's top CFM rating is 273. There's a couple others with a top rating of almost 500cfm for $112-125. If you work for a company that can purchase through Grainger or have a friend that can that's not a bad price.

My booth is 18W x 18T x 15D. It's fine for cars but is a little small for 1/48 jets or larger. My fan has a top rating of 265cfm and it works great. I can keep it in front of a window so I only have about an 18 inch run of aluminum flex pipe. Smooth ductwork would be better but for that short a distance this works. The booth itself is made from scrap lumber and chipboard with a plexiglass top. I drew it up and a friend cut up the pieces for me. I bought some 12 inch flourescent light fixtures at WalMart that you can daisy chain and mounted one on each side and top just inside the door. Put a little trap door in the top rear to drop in a furnace filter. Basically built the whole thing for the price of the blower, lights and a dryer vent kit. It's been very handy.

I've seen several people at different sites invest in the Pace booths and they've all been very happy with them. I've also seen several people that have bought different types of pre-fab cabinets and installed blowers to use for a booth. Think WalMart or similar. If I still worked in a sheet metal shop I would have built one with aluminum sheet but wood works fine. If you don't have access to woodworking tools Lowes will cut up a sheet of plywood for you. Just figure out the sizes and lay it out. I put a heavy coat of white laytex house paint on mine and think I recoated the interior once.  So if you were inclined to build your own you could still come in under $200. Possibly well under. But whichever way you go a paint booth is very handy. Don't know what I'd do without one. Guess I'm spoiled.

Here's a link to some blowers: Grainger

Tony

Thanks to everyone for the excellent and complete replies - it gives me a lot to think about over. I struggle with the advantages of DIY and getting exactly what you want versus using my time and energy in other places.  This week I would have definitely been with Gerald on this one.

A follow-up for Tony:  in mentioning Grainger (and many thanks for the link), I take it you're saying that one needs to be a commercial entity to be able to order from them ("... If you work for a company that can purchase through Grainger or have a friend that can that's not a bad price...")?  Will they sell to the public or individuals?

Thanks again, Rick

RTrimmer I use Testors enamel spray cans and various full sized ones when no model specific ones are available. Look for plastic compadability.

Booth? Ventallation fans? Great outdoors seems to work. (spray up wind, find shelter in bad weather or delay untill favorable conditions)

According to Klaus Raddatz's article on building spray booths computer fans may not be specifically built to handle solvent's, but he feels they are safe (emphasis mine):

There are booths available that use computer type axial fans. These have induction motors located in the air stream, and while they’re not explosion proof, their design makes them a better choice than bathroom or kitchen fans. I’ve taken a few of these fans apart and found the stator windings embedded in epoxy. Since epoxy typically has a high resistance to solvents, I feel comfortable that the solvents won’t migrate into the stator windings and deteriorate the insulation.

He also mentions the Dayton fans from Grainger (emphasis mine):

Another alternative would be a fan with an externally mounted motor, such as the Dayton shaded pole blowers, available at Grainger.com (see table below). These blowers have been used successfully in spray booths, but please remember, they are not explosion-proof.

Considering that computer fans draw a tiny amount of power and amperage, I would hazard to say they are at least as safe as any other fan on the market, other than a bilge blower fan for a boat.

Interestingly enough, Paasche cautions against using their spray booths in explosive atmospheres. I haven't been able to find exactly what fan they are using, but I'm willing to bet they are axial fans like are used in computers.

Caution is always one's best bet, but the research I have done in the past keeps bringing me to the conclusion that the tiny amount of painting the typical modeler does, most fans will suffice, and we should be concentrating on having the correct CFM and proper venting.

200mm computer fans are capable of pulling 110CFM, and are quite thin and small compared to squirrel cage fans. For the booth I have, and the length of venting (those 90 degree turns eat up a lot of air) four of them would be ample.

Bgrigg

Considering that computer fans draw a tiny amount of power and amperage, I would hazard to say they are at least as safe as any other fan on the market, other than a bilge blower fan for a boat.

I would agree but the point I think Gip was making was their limited ability to move much air. Unless they are huge they move very little CFM of air and most of the larger ones are only in the 100-125 CFM range as you stated.

Interestingly enough, Paasche cautions against using their spray booths in explosive atmospheres. I haven't been able to find exactly what fan they are using, but I'm willing to bet they are axial fans like are used in computers.

None of the booths sold for modeling are explosion proof as the cost would be far more than we care to spend.

Caution is always one's best bet, but the research I have done in the past keeps bringing me to the conclusion that the tiny amount of painting the typical modeler does, most fans will suffice, and we should be concentrating on having the correct CFM and proper venting.

I agree and as I have said many times before it is more difficult to get a fire started from a modeling paint booth than most people realize. My friend Scooter airbrushed and painted autos and motorcycle for close to 40 years and only had one incident happen in all those years and it was nothing serious, just a flash and it was out. Mind you he was not using explosion proof fans or even fans outside the airflow and he was using solvent paints such as lacquers and urethanes. There is nothing wrong with being cautious but we don't need to be overly paranoid because getting something to ignite in a paint booth requires some stupidity for the most part, such as no airflow which is the recipe for disaster. There has to be a lot more PPM in the airflow than we are putting in there with an airbrush to cause an explosion.

This kind of reminds me of when you are near a diesel generator that is outside and it says, "Caution, no smoking within 25 feet" as if a cigarette is going to detonate diesel fuel. Good luck on that one!

But that is why I said I would need four of them! I would much rather put 2" thick fan pucks under my booth, than a squirrel cage fan that extends 6-8".

Lit cigarettes dropped into diesel or even regular fuel, will not ignite, but the fumes can and will. The fumes are what you will encounter up to 25' away.

I once watched a guy check his fuel level on his rig. The pickup in the tank had died, and he had to physically check by peering into the filler spout. He was smoking at the time and the jet of flame that shot out was impressive. He burned off his eyebrows, eye lashes and a good portion of his hair, and was very lucky not to have burned his eyes. Liquid fuel is hard to burn, but fumes are most definitely not! He used a stick after that, and made sure he didn't have a smoke hanging off his lip!

Last year after researching the various booths out there I decided to build my own. I got a much larger booth for $200 than I could have buying someone elses booth, and it has a higher air flow than most of the ones you can buy, most of the cost was the fan.

I bought the fan from Grainger, I'm not a commercial user and I had no problem, I just listed my name where it said company. Awesome service too, I had my fan within 24 hours of ordering it. If you do get a fan from Grainger make sure you also get a cord, the blowers assume they are going into a furnace or other built in set up. An 8 foot cord is only $6 or so and is pretty simple to wire in.

If you have the skills (did you pass 9th grade wood shop?) and the time I would suggest building your own. It will save you a lot of money and you can tweek it to your own preferances. For example I set mine up with a more open top than most, because I'm using spray cans and prefer to paint downward. I've got it set up where I can close down the top if I don't need so much room which will also increase the airflow at the face since the opening will be smaller.

This is what I built, 24" wide, 20" deep, 20" tall with a 485 CFM squirrel cage providing more than the 100 fpm at the face most sources recommend. Big enough to handle a 1/72 B-17 or 1/25 semi truck. It does a nice job sucking the paint fumes outside. It is sitting on a table now, because a stupid bear broke into the garage and busted up the stand it was sitting on. It took me about 2 days of work and just under $200, the fan was $144..

There is no need for an "explosion proof" fan, those are intended for moving serious flammable vapors like a full size automotive spray booth or evacuating vapors from a fuel trailer before working inside. Even a small explosion proof fan would cost you around $1000. I'm not in favor of the cheap booths made with a box fan or stove hood because of the potential hazard (Smokey Bear is a close personal friend and he would beat me senseless if I said go for it ) but would agree with Mike that the chance of a fire is very small. 

I have seen some cheapo booth designs using a shop vac and that is bad news. While the box fans and stove hoods have an ignition source (a sparking motor), there should never be a high enough concentration of vapors to actually burn. With a shop vac the cannister will collect fumes which will build up and can have explosive results if ignited.

Mike a cigarette can ignite diesel fuel, but you would have to get it pretty hot first so it makes enough vapor to burn.

The flash point (hot enough to burn) of #2 diesel is around 125 degrees F, the flash point of gasoline is -45 F degrees. So you might get some diesel to burn with a cigarette if it was spilled on the pavement on a really hot day, but gas will burn in Alaska in the middle of december. The signage regulations don't take this into account and pretty much treat diesel as gasoline.

Aaronw

Mike a cigarette can ignite diesel fuel, but you would have to get it pretty hot first so it makes enough vapor to burn.

The flash point (hot enough to burn) of #2 diesel is around 125 degrees F, the flash point of gasoline is -45 F degrees. So you might get some diesel to burn with a cigarette if it was spilled on the pavement on a really hot day, but gas will burn in Alaska in the middle of december. The signage regulations don't take this into account and pretty much treat diesel as gasoline.

True but coming from a line of heavy equipment mechanics I have seen it all.

My dad used to show people how he could put out a cigarette in a can of gas. Not recommended if you don't know what you are doing though.

My dad smoked a pipe all the time and even at times when he worked on equipment. He was not stupid though and knew the limitations.

As Bill said, the fumes are what is dangerous but when you are outside where there is a lot of air it is basically impossible to ignite the fumes of diesel that way. I think even gasoline would be hard to ignite in the air outdoors as the fumes have no place to accumulate which is what is needed for a detonation.

MikeV

Aaronw:

Mike a cigarette can ignite diesel fuel, but you would have to get it pretty hot first so it makes enough vapor to burn.

The flash point (hot enough to burn) of #2 diesel is around 125 degrees F, the flash point of gasoline is -45 F degrees. So you might get some diesel to burn with a cigarette if it was spilled on the pavement on a really hot day, but gas will burn in Alaska in the middle of december. The signage regulations don't take this into account and pretty much treat diesel as gasoline.

 

True but coming from a line of heavy equipment mechanics I have seen it all.

My dad used to show people how he could put out a cigarette in a can of gas. Not recommended if you don't know what you are doing though.

My dad smoked a pipe all the time and even at times when he worked on equipment. He was not stupid though and knew the limitations.

As Bill said, the fumes are what is dangerous but when you are outside where there is a lot of air it is basically impossible to ignite the fumes of diesel that way. I think even gasoline would be hard to ignite in the air outdoors as the fumes have no place to accumulate which is what is needed for a detonation.

That all makes sense until you remember OSHA has to consider the darwin award winners in their standards. If someone can blow themself up, they must assume someone will.

OSHA trying to provide common sense to the common sense deprived since 1970. 

When I made my booth a couple of months back. I bought the blower at Keenzo.com. It,s a Dayton 265 CFM #4C447 and it cost $81.97. They also have the 4" adapter for mounting to the booth, and the Vent tube. The booth itself was 30"x24"x14"deep and was FREE from "Freecycle". All together the booth cost me about $160. It works great and hasn't given me a bit of trouble . As was said above, I just put my name in where it said company and no questions were asked.

Jim

Rick, I guess it depends on the store and employee. I don't know. A couple of times I walked in the local store and they didn't want to sell to me unless I had an account with them or worked for a company that had an account. That's all I know. So when I bought this blower I asked my employer if I could order through them and he said ok. That was 7 years ago, maybe things have changed. Wouldn't hurt to try...

Tony

Wingman_kz

Rick, I guess it depends on the store and employee. I don't know. A couple of times I walked in the local store and they didn't want to sell to me unless I had an account with them or worked for a company that had an account. That's all I know. So when I bought this blower I asked my employer if I could order through them and he said ok. That was 7 years ago, maybe things have changed. Wouldn't hurt to try...

Tony

I ordered mine online, so maybe that makes a difference. I did have to set up a profile first so maybe that was enough of an account? Hey I'm a buisness I make spray booths, I just went out of buisness after building one.

Hehe, whatever works. Honestly I didn't even try when I bought the blower, just ordered through my employer. I hated to even buy from them but couldn't find anyone else around here to buy from. Not certain what I tried to buy before, maybe some gloves or something, but when I didn't have an account or employer with one they went so far as to tell me I had to leave. Right after that happened I changed jobs and my new employer sent me there to pick something up. That was fun. Would you believe that they even went so far as to call that employer to see if I actually worked for them? For a cash transaction at that. I just stood there smiling and the jerk that was *waiting* on me was about to blow a fuse. That was a few years ago, guess it just stuck with me.

Sorry for getting off topic Rick. And if you do decide to build one yourself don't hesitate to give it a try.

Tony

I built my own. I considered it part of my modeling after being away from the hobby for thirty + years.

I don't have any pics but if anyone is interested I could post some.

It is 30 x 30 x 27 (only reason for the 27 is I couldn't get it through the door - stupid me didn't measure the door first) and to me the most important fact is that it is a downdraft design. I have yet to have a single issue with fumes, overspray or anything else. Took most of a weekend to build.

Jeff

Hi Jeff,

Pictures would be great.  What type of fan did you use?

Thanks, Rick

Tony and Aaronw - thanks for your comments on your experience with Grainger. 

Cheers, Rick

RTimmer

Hi Jeff,

Pictures would be great.  What type of fan did you use?

Thanks, Rick

I'll try to take some pics tonight and then I'll have to find a host for them so I can post.

The fan is what I think they call a sealed pole fan. Paid about $80 cdn for it.

Jeff

I have a DIY booth that I intentionally built large enough to accomodate a 1/48 B-1B. I used dual 4" bilge blowers ducted out a window with a dryer vent in it and it works really well. I have noticed that if I use rattle cans I have to spray in bursts, spraying for a few seconds then waiting a few seconds to make sure the amount of area in the booth can be evacuated. Otherwise I have a fog of paint in the booth.
With all airbrushing activities the blowers keep up fine.

Hey Rick;

Here are some pics as requested. I just snapped them quick but you should get the idea of what I have done. If you have any questions just fire away.

So you could get an idea of the size the plane is a 1/48 Spitfire. 

Jeff

Interesting, Jeff.
A down draft hobby booth. Gives me ideas for my own and I may have to reconfigure it.

hkshooter

Interesting, Jeff.
A down draft hobby booth. Gives me ideas for my own and I may have to reconfigure it.

Downdraft booths are the most efficient style from what I have read.

On another note I think Jeff needs to change that exhaust hose on his booth as it is too long, has a big kink in it and those corrugations disrupt airflow badly.

Yes I do need to shorten and thus straighten the hose. It will help increase the airflow. The best scenario would be metal vent pipe.

Jeff

I'm a new member of this forum and just came across this thread.  Can you tell me how you mounted this blower to your spray booth?  I'm considering buying a Dayton 273 CFM blower for a 30 x 30 x 30 spray booth I want to make ( to accomodate my Guillows balsa/tissue paper P-51 that measures about 24 x 27 x 12.  Thanks!

I'm a new member of this forum and just came across this thread.  Can you tell me how you mounted this blower to your spray booth?  I'm considering buying a Dayton 273 CFM blower for a 30 x 30 x 30 spray booth I want to make ( to accomodate my Guillows balsa/tissue paper P-51 that measures about 24 x 27 x 12.  Thanks!