Spray Booth Fan

[hooterville75]

Which external motor fan would one recommend for a DIY Spray Booth ? I have a cabinet that my folks were going to throw away that is about four foot high, it sits on four legs, has about a foot compartment for storage and then another three foot opening that I would like to make into a spray booth.

I would like to have the fan mount to the bottom of the booth in the middle, which I'm assuming would take up one foot (give or take) then insert 1/4" rails around the booth for the filter to rest on. I would like the filter to be as big in size as I can get to match the depth of the booth which guessing would be about 24". I would then like to put a piece of pegboard on top of the filter. I'm assuming without doing any measuring I would then have approximately 2 foot to spray in.

Would anyone know how many CFM's I would need to sufficiently run this spray booth and which type of fan with an external motor I would need ? Any recommendations or suggestions would be greatly appreciated.

I would like to build this booth within the next week. Thanks in advance for any info you guys could give me.

[CadillacPat]

Okay, here we go----------------------------

Good Luck Hooterville,

This gets discussed quite often and there's a recent thread within the last page or two.

CadillacPat

[hooterville75]

Thanks for the info. Ill be sure to search for spray booth fan. Remember Im a newbie here so I was unaware of that. Thanks for bringing to my attention.

[hooterville75]

Just did a search for Spray Booth and Spray Booth Fan to find my only two posts. Guess Ill go back through the past ten pages or so in attempt to find what Im looking for.

[Aaronw]

The preferred fan is a shaded pole blower (aka squirrel cage). This style of fan has a paddle wheel looking fan in the air stream, and the motor is outside the air flow turning the fan through a shaft drive. You can get one of these blowers relatively cheap ($50-150 depending on size). The fan is the major expense in any spray booth, so in my opinion it is better not to get cheap here.

To figure out your CFM needs take the size of the opening and divide by the CFM, ideally you want to have 100 for a cross draft booth (air goes out the back) or 50 for a down draft (air goes out the floor of the booth). It is not the floor of the booth that matters, it is the opening into the booth. If you have a 2 foot x 2 foot opening (4 square feet) then you are looking for a 400 cfm fan for a cross draft or a 200 cfm fan for a down draft. You also need to factor in some extra based on your ducting, use a duct sized for the blower (don't put a 4" duct on a blower with a 6" outlet). Keep it short and straight and you don't have to worry to much about this, but using a smaller duct or having a bunch of turns will make the blower much less efficient.

These are ideal cfm specs, lots of people are happy with booths that rate 3/4 or even 1/2 the ideal amount, and many of the commercial booths rate less than the ideal. Still if you are building your own, might as well do the best you can.

Personally I find Grainger a good source for these fans. It is kind of a pain setting up an account, but they have a good selection, good prices and great service. I had my blower 24 hours after ordering. You also may need to buy a cord, most of these blowers do not include a power cord or on / off switch. The cord is around $8. I ran mine to an outlet with a light switch, but it is almost as easy just to unplug it when you don't need it on, or run it to a power strip with a switch.

http://www.grainger.com/Grainger/wwg/start.shtml

[Aaronw]

This is the blower I used in my booth.

http://www.grainger....TDR7?Pid=search

Mine is a cross draft booth a pinch larger than yours so overkill for your needs.

Something like this would probably serve you well, assuming a 2x2 foot opening down draft style booth and a fairly short run to the exhaust point.

http://www.grainger....FHX9?Pid=search

You will probably get lots of suggestions to use a bathroom or range exhaust fan, personally I think that is a bad idea whether or not there is a real safety issue (the oh no not this again pat aludes to). Shaded pole blowers are more expensive, but they are better fans and don't get exposed to the fumes of your paint booth, so should out last your booth.

Whatever you do, do not use a shop vac to vent your booth.

Edited September 29, 2012 by Aaronw

[hooterville75]

Thanks for the explanation AaronW, much appreciated and gives me a starting point to start looking. See Cadalliac Pat that wasnt so hard was it ? Just sayen!!!!! Thanks again Aaronw

[hooterville75]

Aaronw, when helping my father clean out his garages and basement the other day I was able to snatch this blower motor as he was going to throw it out. I have no clue how many cfm's it is all I know is that the exhaust runs down through the bottom of the blower motor and that the exhaust opening is 3 1/4" X 10" and they make a universal adapter that is 3 1/4" X 10" X 4" to get the 4" standard dryer duct. We just remodeled the laundry room moving it from the basement (Which is where my man cave now is), moving the washer and dryer upstairs so I have the old dryer vent to use as my exhaust for the spray booth. The dryer vent starts at the floor elbowing to straight pipe the entire way up to the ceiling into a crawl space outside (which is under a addition added to the house years ago). So what I figure I can do is cut the straight pipe to match the level of the spray booth. Run straight pipe to the booth, using a elbow to connect to the straight pipe going to the ceiling and outside. I will get exact measurements for all the vent pipe later this afternoon. Here is the blower motor I picked up from my father. I don't know anything about it other then its a blower motor and says Fasco on it. Ive researched it online and can find nothing about it. I will tell you that its OLD. But hey I plugged it in and it still works and blows a good amount of air. If its not broke, don't fix it right ha ha.

[mikemodeler]

While everyone likes a bargain, not knowing much about that motor may make it more expensive in the long run. The motor Aaron pointed out has been around for ages and is easy to get another should something go wrong with it, whereas the "freebie" is probably long out of production and once you design your booth around it, you would have to make changes if the motor doesn't last.

Bottom line- do what you can afford to do but if given the choice- I would go with the new motor and be done with it.

Oh yeah, welcome to the forum and show us your booth when you get it ready.

Edited September 29, 2012 by mikemodeler

[hooterville75]

I just went and measured the cabinet that I'm going to use as the spray booth. It measures a total of 35" tall. It has 4 3/4" legs, then a 9 1/2" storage compartment (which can be knocked out eliminating the tiny lil storage area at the bottom), then 20 3/4" working area. It is 24 1/2" wide and 19" deep.

I think I'm going to knock the plywood floor out of the bottom on top of the storage compartment and replace it with a piece of pegboard and mount the motor where the storage compartment is. That will give me a cross draft I believe (remember I'm new to all this lol). If I'm following this right I could vent it out the back going straight into the dryer duct (vent) already there for the previous dryer hooked up to it. The blower motor is 6" thick at the most. So Ill have plenty of clearance with the 9 1/2". It should make a pretty nice spray booth. Unless I'm missing something, if the motor should fail, the new motors are still the same principals and a few simple modifications and I'm back in business. If not Ill take everyone's suggestions and create something that will work. I have been watching a couple of fans from a couple websites that I am interested in if this motor definitely wont work. They are both 1550 CFM fans the first is $26.99 and the second is $27.99.

.

[CadillacPat]

See Cadalliac Pat that wasnt so hard was it ?

Hooter you're new so I can see why you did not get the gist of my reply,

I've answered your question online since 2004 on AirBrush sites, Customizing sites, DieCast sites and here.

I've not only detailed the methods I use to make my TableTop Paint Booths but also posted pics.

It always ends up the same way here about this subject,

Some Hobbyists take the info and use it,

Some, while having no experience in even trying to build these units, scream the Sky Is Falling and will recite horror stories of Homemade Paint booths exploding and consuming entire towns, mostly from 2nd and 3rd hand rumors.

Some copy and paste adages from Wikipedia or elsewhere that really impart nothing useful.

So Hooter I wan't making light of your request for info, I've answered the same question many times.

It's good that people actually want to improve their AirBrushing and their projects by adding tools like this to their shop.

I began showing my TableTop Paint Booths and CadillacPat Ovens at DieCast Conventions years ago and many serious DieCast Customizers have built their's from the specs I offer.

Look through some of my posts in Tutorials and I think you'll find some pics of my pieces.

Oh,

Discard the idea of laying pegboard over your fans.

If you have to put anything over the fan or fans, thinking you will trap overspray, just lay a piece of screen.

Pegboard will defeat the whole purpose of air flow.

Good luck,

CadillacPat

I just answered this question a few days ago so I thought I would sit back and let it ride for awhile.

[hooterville75]

I went through the past several pages of this and didnt see anything answering the questions I had so I asked. Perhaps a few hyperlinks to your information would have been more appropriate. Ill attempt again to find what your speaking of and try to build from that.

[CadillacPat]

And Good Luck again,

CadillacPat

[hooterville75]

What do you recommend that I put over the blower motor ? The only post I could find through your six pages history of posts in regards to what I'm looking for is this. http://www.modelcarsmag.com/forums/index.php?showtopic=56874&st=0 and it explains very little on how your booth is designed or what type of fan your using only that each are 80 CFM. You mention that you have baffles in your booth yet say or show nothing about how to insert them to the booth. I have a cabinet that I would like to make into a booth. It measures a total of 35" tall. It has 4 3/4" legs, then a 9 1/2" storage compartment (which can be knocked out eliminating the tiny lil storage area at the bottom), then 20 3/4" working area. It is 24 1/2" wide and 19" deep. Any and all info on how I can turn this into a airbrush spray booth would be greatly appreciated. Like you mentioned, I'm new to this hobby and want to have every the correct way as well as wanting to build it myself.

I wish I knew more about the blower motor I had but I know nothing more then its a Fasco and its a "older" model. Its sat in the garage unused since probably 1980. I'm not opposed to buying new fans I just need to know what I need to get. I'm not opposed to using your design for a spray booth, I just need to know how to build it lol. Perhaps why I'm asking questions in the first place. I'm not here to fight with anyone just looking for suggestions and knowledge which is again the reason for the original post.

[hooterville75]

I was going to put a filter over the blower motor, then put the peg board on top of the filter.

[CadillacPat]

I was going to put a filter over the blower motor, then put the peg board on top of the filter.

I don't use a filter and don't advise using one, as I have stated in many of those earlier mentioned discussions on Paint Booths..

Forget about the pegboard, it's mostly board and very little peg (holes).

CadillacPat

[hooterville75]

K Pat, thanks for your info you have given. I'm going to stop the discussion with you any further as I don't want to come off at you like SEVERAL other new members have in the past. Its apparent that your a genius and us newbies are all dummies. I have talked with many other "Experienced Veterans" of the hobby on this site and others, that LIKE to answer any questions a new person has instead of making them look like complete fools. So thanks to the "bits of information" you've given me to this point, Ill use this info to the best of my ability to try to achieve a spray booth you would deem appropriate. Remember you were once a new guy to this hobby as well. I sure hope no one else on any of the sites you visited when you started this hobby were as rude and obnoxious to new members as you are to newbies on this forum. Best wishes Sir!!!!!

[Aaronw]

Deron, there just happens to be a spray booth build post right now in the general section that might give you some ideas. If you search in General you will probably find a lot more posts like this one. For some reason they seem to turn up in General instead of the Q&A section or tips & tutorials. The search is kind of spotty though so good luck.

http://www.modelcars...showtopic=52266

The fans you posted for $26 and $27 are axial fans which puts the motor right in the air flow which is generally not considered a good idea.

As far as the salvaged motor, without any specs on it I have no idea if it is appropriate for a spray booth. However if it is free, and does not appear to have any safety concerns (like it smokes when you turn it on), it can't hurt to give it a whirl to see if it draws enough air to run your booth. The nice thing with a spray booth is you will know pretty quick if it is working, because if it is, you won't get much odor, and if it isn't you are going to be sucking on paint fumes.

As far as the downdraft, I think what Pat was getting at it the filter is the bottom of the booth, you don't need pegboard or anything else to work on. I couldn't figure that out when building mine so I went with a cross draft booth which seems to work fine, but requires a bigger motor since gravity isn't helping to draw the paint out.

This is my booth if it is any help in designing yours, I used a 6" metal duct (not shown) to exhaust outside.

This shows the plenum I made which is supposed to help spread the air flow more evenly across the booth (I read about that, I'm not smart enough to even spell plenum otherwise ). It is just a wall with lots of big holes about 3" infront of the back wall. If you just had an opening for the fan, then supposedly the airflow would be concentrated there, and the edges would have little airflow.

Edited September 30, 2012 by Aaronw

[hooterville75]

Aaronw, Thanks again. I have pretty much figured out what I'm going to do with my design of the spray booth. While its a great concern for many, I know of many people that have used a axial fan with great success. I don't feel I do enough painting to actually cause a threat of fire. Axial fans are about the safest of internal motor fans explosion wise. Its still something that I have to toss around. With the amount of CFM's Ill be having and the amount of painting I do at a time, I feel safe in using a axial fan IF the blower motor I have doesn't work. If and when the time comes I need to re modify my fan in the booth if the funds are available Ill resort to something like you have. Thanks again for the valuable information.

[michael1969]

Deron, I, too want to build a spraybooth. I think what the guys are saying is that safety is important. Your free fan, is the motor outside of the case? If not, you may have two problems. First, the issue of exposed arcs or sparks in the flammable fumes of the paint which may cause a fire. Second, if the motor is internal, the overspray being paint can build up on the exposed parts of the fan and motor causing them to go or burn out. As for the pegboard comment, It will restrict the airflow your are working so hard to acheive. Hope this helps. If it is any consolation, I still haven't got a good fan for my booth so I don't use it.

[CadillacPat]

Safety is important in everything.

But don't let speculation hold you back.

What is really important is that you press ahead and build your Paint Booth so you achieve better results AirBrushing.

CadillacPat

[hooterville75]

Ok so I'm ready to finish my airbrush spray booth. Everything is built other then positioning the Bilge blower motor I'm using for the exhaust. So to get a downdraft I would want to position the motor on the bottom of the booth ???? To get a cross draft I want to position the blower motor on the side of the booth ? Tis the only part I don't fully understand yet. Which is recommended ? The Bilge blower motor is 250 cfm's.

[Patrick H]

Ya with that fan you definetly want to use an explosion proof rated fan as any paint that could find a way to be exposed would be a fire source.  It often makes sense to buy a little bench top booth there pretty affordable and will meet all codes.  For an overview on paint booth fans and air flow this is a good article.  Best of luck.