Spray booth. Need opinions

I'm not an expert on spray booths, but I would seal around those two fans where they mount to the plywood with silicone caulking to provide a more effective throughput into the hoses.  As is, they'll pull more air around the gaps and into the fan, than pushed through the hose. (path of least resisitance, you'll be venting clean air through the hoses mixed with a little of what was in your spray booth)   Don't know if this was already in the plans, just the first thing I noticed..

Otherwise it is an interesting design and would like to know how it works out... I've been thinking about building my spray booth to custom fit my desk, and yours has interesting possibilities!

tho9900 wrote:

I'm not an expert on spray booths, but I would seal around those two fans where they mount to the plywood with silicone caulking to provide a more effective throughput into the hoses.  As is, they'll pull more air around the gaps and into the fan, than pushed through the hose. (path of least resisitance, you'll be venting clean air through the hoses mixed with a little of what was in your spray booth)   Don't know if this was already in the plans, just the first thing I noticed.. Otherwise it is an interesting design and would like to know how it works out... I've been thinking about building my spray booth to custom fit my desk, and yours has interesting possibilities!

I never considered caulking up the fan area.  Great input!

It is 11 inches high, and 20 inches long from corner to egde.  I drew a rough draft on a sheet of paper and measured the area on the left portion of my desk to get the final dimensions.  It will be a couple more weeks before I finally use it, I'll give you an update on how if fares.  The case fans, computer power supply and cable only ran me $19.00.  I aquired the wood from work and borrowed the tools from a buddy if mine.

Thanks again for the input.

It's diffrent to say the lest, and that's a GOOD thing :)   I am in the works on making a spray booth too. I saw some people on here that made there own and WOW some nice one's and your in the top 5, hehehe

Please update us on how you make out with it.

Good Luck to you

Bud

A couple of questions... are you sure the fans can move enough air out/away? I've had to take a peek inside my tower more than a few times, and I've never been impressed by how much dust is left behind. Cool? Sure, cool enough for the system to keep running, but in terms of moving a volume of air... not too impressed by them.

Second, I recall reading that certain types of paint and fan combinations can be a problem (vapors moving by the motors)... there are a few ways to take the issue to heart or not, but I was curious if you've come aross any info on that?

I hope the set-up works really well... need to do something for my own set-up here (lugging stuff up and downstairs to the garage... blurgh)

vfxart wrote:

A couple of questions... are you sure the fans can move enough air out/away? I've had to take a peek inside my tower more than a few times, and I've never been impressed by how much dust is left behind. Cool? Sure, cool enough for the system to keep running, but in terms of moving a volume of air... not too impressed by them. Second, I recall reading that certain types of paint and fan combinations can be a problem (vapors moving by the motors)... there are a few ways to take the issue to heart or not, but I was curious if you've come aross any info on that? I hope the set-up works really well... need to do something for my own set-up here (lugging stuff up and downstairs to the garage... blurgh)

I've thought about the air flow situation.  I really will not know until I can get it tested.  Worse case is I will have to cut out one or two more slots.  I was actually hoping someone would be able to tell me yah or nah on the air flow situation.  I use only two types of paints, Tamiya Acrylics and Alclad.  My old set up was a big box with a small circular bedroom fan in the back of it.  I would lug it in and out of the window.  The nice thing was I could use rattle cans indoors, as it was enough to suck it all out.  The bad part was it is heavy as hell and doesn't completely cover the whole window, so it would get hot as hell in the room (and humid). 

On the vent board I was going to use on the window I was thinking of attaching a fan to it as well however, I do not think that would help the paint left inside the booth.

Thank you for the compliments on the design!!

Wolfpack,

Read this thread. It should cover most of your questions on air flow.

Erik,

Your design is interesting, but unfortunately, not very functional.  Just a couple points:

1. For spray booths to function like, well, a spray booth, they need to look like a box.  As a basis for starting, the width and height should equal your required work size plus about 12".  The depth of the booth should be 3/4 the width or height, whichever is larger.  This allows for proper airflow distribution throughout the entire booth area.

2. Computer fans are, by design, supposed to draw cool air over electrical components.  They work pretty good at that function in small enclosures (hoods?) like CPUs, but in a larger spray booth they simply aren't efficient at extracting both the vapor fraction and the particulate matter generated during painting (Organic vapor and particulate capture requires the maintenance of certain velocities to ensure that capture happens.).  And as soon as you put ducting on them, you put a load on this type of fan that it wasn't designed for.  In addition, the electrical components of the fan are located directly within the air/vapor stream, which add to the potential for fire--one of the primary reasons for spray booths:  fire/explosion hazard elimination.  I guess one other concern would be solvents attacking the plastic fan blades...

(Take a look at the fan exhaust outlet in the electrical box next to your booth in the bottom picture; that's what those little axial fans are designed for.)

3.  Take a look at the link(s) that Ross provided; they're pretty helpful.  And come back here with your questions.  There are some knowledgeable folks here who can help you along the way.

Just my 2 pennies in the pot,

Gip Winecoff

About time you got to posting on here again brother!
We missed you!

The computer power supply doesn't have it's normal load from the motherboard and other peripheral devices which may be a potential hazard.  (Some PS's won't even turn on without a load.)  Whether this could cause overheating/melt-down or a shorter/longer life depends on the design and quality of the PS.  I would be tempted to ditch the computer PS and use AC fans or just use a simple AC/DC converter with the DC fans.

That said, there's a wide variety of computer case fans whose performance ranges from useless to sucks-like-a-black-hole.

I am just a computer geek, not an electrical engineer....

--David

the computor fan motors will not draw enough air throw the filter pads. To make it sucessful you need to use kitchen extractor fan like the ones used in cooker hoods.
Also the box needs to be more of a cube shape.
Try and visit a local furniture makers they normally use spray booths. which have the extractors in the top not the sides.
Hope this helps.

The computor fan motors will not draw enough air flow through the filter pads. To make it successful you need to use kitchen extractor fans like the ones used in cooker hoods.
Also the box needs to be more of a cube shape.
Try and visit a local furniture makers they normally use spray booths. which have the extractors in the top not the sides that would give you some ideas.
Hope this helps.

Erik;

 

I have a spray booth I built a few years ago while working in a furniture shop. I used 3/8" particle board and a bathroom exhaust fan, with a furnace filter. Even that wasn't enough to pull all the crud out of the air around the booth!

You want a high-volume fan with an external motor (one NOT in the airstream, for fire reasons!) that can grab the air inside the booth, suck it through your first-stage particulate filter (a good furnace filter WILL do the job), and slam it down the duct to your outdoor vent, whether it's a clothes-dryer type vent or a chunk of plywood caught in the window. I know this adds a LOT of cost to what you were hoping to make a relatively inexpensive project, but it depends on what your lungs are worth to you, and how much homeowner's or apartment renter's insurance you carry.

IF you are using all acrylic paints, it's not so critical; however, if I remember correctly, AlClad is NOT acrylic. If I'm right, back to the value issue we go.

It's up to you, guy. Me; I quit using enamels and mineral spirits and turpentine. I like to breathe, and I haven't gotten my new 'n' improved booth built yet - too darn many plastic models to build, no time for safety and health and longer life expectancy and easier breathing and cleaner walls and; and; and.

You know; all the really GREAT excuses for not doing it right the second time.

 

Good luck, and hope to see ya 'round the hobby shops!

 

Jim

The fans you propose using won't do the job. The fan motor should definitely be out of the airstream to avoid potential fire. I didn't look at the link mentioned, but am guessing the discussion involved how much air was needed to move the fumes even a short distance. Wearing a high quality respirator when spraying volatile paints is also a good idea, as you've only got one set of lungs - and that is with the booth functioning. When I built mine, I decided to add a bathroom fan for the room I spray in. It is "upstream" of the vent for the booth fan, so the possibility of fire is almost nil. My decision for this was based on the fact that the work room is in the basement, and after taking off the respirator, I could still smell the fumes from the spraying after I closed the door on the booth. The two fans move a LOT of air, but the fumes are almost undetectable. Be happy to send photos, if you wish. Good luck.

I'd like some photos. Thanks!

You folks are lucky!  When I was in a 2-bedroom, I used the bathroom, and bathroom vent. Covered all of the counters, facilities, & Tub rails, with huge beach towels. Now, in a 1-bedroom, I use the kitchen stove and vent! Covered with newspapers, and some taped to the walls, too!

What can make for a neat booth? Try a vent hood, for a kitchen stove. It has a light fixture, which you "can" use a 100w bulb, for drying heat,(Take the plastic shroud off, though.)  And use  the vent fan, for a vent.  I use one like that, in my storage unit!

Another idea, for painting, if you don't have an "elaborate" booth? And? It's almost, completely "dust-free"!   Prop ypour painting subject on a Rubermaid Lazy Susan. (Formally, your wife's or girl friend's spice rack.)  Have some kind of a vent, running. The Lazy Susan allows you to turn the subject, while painting, and without touching it.  After painting, cover the subject and the Lazy Susan, with a clear plastic "round" cake cover. (Like the ones that are put on store bought, cakes.) Put something between the cover and the Lazy Susan, for air to circulate, inside. (Clothes Pins, work good.)  Position a "Swing-arm" lamp above the plastic, close enough for the heat to penetrate the plasic, without melting it!  Leave it for a few days, to dry.  Works, very good!

Sometimes, you got to do, with what you got!

 

If you want to move a lot of air safely, (no explosions!) try using a bilge blower. These are twelve volt exhaust fans ment for boats. Due the posibility of gas in the bilges they're made explosion proof and move a lot of air quickly. Not too expensive either.

Well, for a first try it's pretty good. I like the open layout. Works for just about any size object. There are a couple of thing though . . .
1. This design can only work with HUGE amounts of air flowing through it. Those computer fans aren't even close. On my third try I finally hooked up one of those squirrel cage blowers and not a little bitty one.
2. Fumes, dust and paint particules getting to and through the fans. Those furnace filters just ain't gonna cut it. I used these as a first layer, followed by those high density filters. But this still won't keep the fumes (potentially explosive??) from getting to the fans & motor. Only a water trap filter will solve that (imagine the waterpipe principle or a big bong for those who would know about such things (not moi!))
3. The straight through airflow of this design has a problem. Dirt & dust coming into the booth with the room air. That's why the right angle design is preferred. Because it slows the air down enough to allow the contaminants to drop out before getting to your fresh paint surface. The best right angle designs pull through the floor of the booth.
But it's a really good booth for as fast as you made it up. And any booth is better than none at all.

If you bought the cheap filters they suck. Try one of the allogen types, I use one in my kitchen hood spray booth and it works great.

THERE IS A PULL-OUT SECTION ON SPRAY  BOOTHS IN FINESCALE ISSUE DECEMBER 2000.

IT GIVES ALL THE SPECS  ON HOW AND WHAT IS NEEDED.

READ IT AND SEE IF IT WHAT YOU NEED.

I BUILT ONE AND IT WORKS FINE

Not too long ago, someone built a pretty nice one and documented it here somewhere.  The thing I remember was that he got this honkin' big exhaust for it.  Moved something like 250 CFM (cubic feet per minute) for about $45, half the cost of the booth.

Did some searching and the best place I've found so far is from Grainger (http://www.grainger.com/Grainger/wwg/productIndex.shtml).  They've got two by Dayton at the top that move 148 CFM for $58.65 and 265 CFM for $68.40.  Put a filter in front of that, hook up your exhaust, and spray away.

Tripper wrote:

Not too long ago, someone built a pretty nice one and documented it here somewhere.  The thing I remember was that he got this honkin' big exhaust for it.  Moved something like 250 CFM (cubic feet per minute) for about $45, half the cost of the booth. Did some searching and the best place I've found so far is from Grainger (http://www.grainger.com/Grainger/wwg/productIndex.shtml).  They've got two by Dayton at the top that move 148 CFM for $58.65 and 265 CFM for $68.40.  Put a filter in front of that, hook up your exhaust, and spray away.

Need to remember that booth size determines fan cfm requirements.  For example, a 2' X 2' booth is going to need, at the very least, a fan rated at about 350 cfm.

Gip Winecoff

So far the info on the Grainger is correct, bought mine and have yet to put it together.  Another point that no one has mentioned is that you need a return source of air for any air that you are exhausting out of the room.  Had a good friend that didn't do that and was getting his return air thru the furnace flue, which filled his basement with carbon monoxide. He was found dead on a monday  when he didn't report for work.  Always consider where the air is coming from and going to.

 

Mike.

This is a very good point! I just had my house remodeled with new doors and windows and additional insulation in the roof, new furnace, and the installers had to put a vent in especially to return some fresh air into the house as it was now so airtight. They also installed carbon monoxide sensors on all the floors of the house.

My spray booth is movable, and I use it outside on the deck during the summer months so airflow is never a problem. When I move it indoors I open a window regardless of how cold it is outside. I like breathing! A lot!!

Erik,

Unless you are willing to risk turning your airbrush into a FLAMETHROWER !!!!!!!!! Then use Fans that are sealed!!!!

Buddy of mine used a Exhaust Fan from over the stove and Suffered burns and had his gloves melted to his hands......

The best fan I have found is one used to purge gasoline from boat bilges....mine was under $20.....

Just a word of Caution...This is a fun hobby - STAY SAFE AND HAVE FUN!!!!!!!!!!

 

SEMPER FI

PAUL

Back in the early 90s (1992 I believe), Model Railroader published a set of plans and instructions to build a metal spray booth.  (It was good enough that Northwest Short Lines produced a copy of it that sold for around $400).  Based upon their calculations, a fan/motor combination that deveoped a minimum of 350 cfm was required and it had to be explosion proof.  What they recommended was one of the Grainger units (which are UL rated as explosion proof).  The spray booth I ended up with was a used one and works great and I have no fears that the Grainger in it will cause an explosion.  My problem with either a computer fan or a bilge isn't really an explosion, rather the failure to remove the paint fumes fast enough and letting them back out and fill my modeling area.