Want to design a safe spray booth

[Wrecked944]

I need some advice about constructing a spray booth. I want to paint individual parts like rims and fenders. Nothing too big. I don't need to paint the whole car. I also want use this space to lay up carbon fiber and spray gelcoats. Again, just one part at a time. Small scale. So I am hoping to construct something small - maybe 30 square feet - just enough for a workbench. I have an excellent space available that is separated from the rest of my house by concrete with a window close by for venting - just about the size of a walk in closet. So I am hoping I can build a booth with plastic sheeting (sort of a closet within the closet), hook up an exhaust blower, and vent it out the window. I have seen specialty blowers for less than $200 that are designed for noxious and combustible fumes and move 300cfm. So I figure I can ventilate this little space pretty thoroughly. Filtered masks, gloves, and coveralls are readily available. Aside from those very basic parameters, what should I be thinking about? I really want to put safety first and avoid breathing noxious fumes and/or exploding. Does spray painting require any specific sort of air flow? Vent hoods? Filters? Should I build a downdraft workbench for the carbon fiber layup? Am I worrying too much?

[Joe Bob]

The best thing is good ventilation....the draw should be AWAY from the object that you are spraying. Then a good filter to keep not yet dry particles from going out and landing on hot car hoods and ruining the paint jobs.....

THEN consider a HEAVY duty filter mask or if you can afford it, remotely filtered supplied air. The newer paints have isocyanates that are REALLY nasty.

Also be advised that any source of ignition should be avoided.... hot water heater pilots can ignite a cloud of paint vapor very easily.

[Hugh R]

The American Conference of Governmental Industrial Hygienists (ACGIH) and the American Industrial Hygiene Association recommend a minimum face velocity of 100 feet per minute. That means air should be moving past you, from back to front, at 100 feet per minute. With a 30 square feet spray booth that means you should be moving 30 x100 or 3,000 cubic feet per minute as an absolute minimum. What Mike Z said, if your using enamels, or lacquers, you want a 1/2 face respirator with volatile organic compound (VOC) and particulate filters, or if your using isocyanates (meaning cyanide), you should be on supplied air (NOT FROM YOUR GARAGE COMPRESSOR). Explosion proof exhaust is a must, the lower explosive limit of lacquers is around 1-2% solvent in air. I'm traveling and don't have any data with me. PM me if you want additional info.

Edited and disclaimed for content due to being at a Health and Safety Conference in Atlanta during which I drank (a little) at dinner.

Regards,

Hugh
Certified Industrial Hygienist

[Westy]

Everything above is MORE than correct. Even though you're doing small tasks, please don't overlook the MANDATORY NEED for fresh air through an approved filter and breathing aparatus. If the job is small, put clean water in a small pump sprayer and spray the bench, the floor, and the plastic. This compensates for what the exhaust fan doesn't take care of. And by all means, the fan MUST be approved to not emit sparks. Can you say 4th of July in May????

[Wrecked944]

Wow, I knew I was going to the right source. Thanks !!

So I am thinking maybe a box framed with 2x4's with clear plastic sheeting for walls, floor and ceiling. If I understand correctly, a non-sparking blower behind me to provide fresh air and another non-sparking blower on the opposite side of the workpiece for exhaust. Both intake and exhaust filtered. Plus protective coverals, gloves, and maybe a full face mask with external fresh air supply? I'm game. I've seen this stuff for sale in the Eastwood catalog.

Does it matter where, exactly the exhaust is located aside from pulling air away from the workpiece? Like should I fabricate a hood for venting? I wonder if exhaust fan placement can impact the effectiveness of spray painting. And for carbon fiber layups, I have a friend who does photography who says it is a good idea to build a workbench that sucks air downward so the fumes get sucked away before they can reach your face. It seems like a cool idea but I'm not sure how to build one or if it is overkill.

Anyway, thanks again for the advice and please keep it coming. I am extremely averse to experiencing any form of poisoning and/or explosive events !!

[Westy]

Downdraft is the way to go, but not too many people want to cut up their floor, especially for such a small project. I've seen exceptional results out of garage jobs, but understand, there will always be that indescriminate piece of dust that lands where everyone sees it. Something about Murphy's Law I think!!

[no substitute]

HVLP?

[Jim Sims]

Explosion proof lighting/switches are also required if within the fume "bag". Jim

[Wrecked944]

Okay, this is great !! Where else can I get this kind of expertise?

So downdraft it is. I believe my buddy is planning to purchase some sort of downdraft "table" as a workbench. I assume it has a screened surface sitting atop an upside down vent hood connected to a hose going to a remotely located exhaust fan. Presumably, photo guys know where to buy these things.

As for HVLP, that was also recommended by a friend who does auto body work professionally. He said all the pros use HVLP guns because they spray the paint very efficiently - sending less paint out the exhaust. I'm there. Sounds good to me.

And Jim, thanks for the tip on lighting. I had not given it much thought. I'd hate to do all this work and then have the whole house explode when I flip on the light. Bummer. I'm guessing flourescents are required inside the spray booth and the switches should all be kept outside?

[jpachard]

Janus, Please check with the local laws too. MA is very strict when it comes to this stuff and will have no problem fining an individual. I looked into it for about 5 sec. and decided no due to regulations and safety. I don't mean to put a damper on your fun, I just don't want to see anyone get creamed with fines.

Cheers, James

[Hugh R]

Down draft is fine, or at the back of the spray booth as an exhaust so that your pulling the solvents away from you, as opposed to trying to push them away. A typical spray booth has doors, behind you with air intake filters, and the exhaust, with filters also, in front of where your spraying. If using isocyanates, fresh air from a hose supplied from outside the doors is good. Again, all compressors, light switches, blowers, etc. outside of the "bag" as someone said. I had a neighbor who blew up his garage, and him, by spray painting in his garage, the water heater pilot light got him.

[widebody911]

When it comes to ventilation, what you want to do is evacuate any paint that didn't land on the car; otherwise it creates a 'fog' and kills your gloss. Before I paint my next car (probably my '61 double cab) I'll be installing a slightly modified 1600 CFM gable vent fan.

[Jim Sims]

A gable fan is not explosion proof; the explosion can and will blow back into the spraybooth. Good explosion proof fans can be had for a few hundred dollars. One also needs the proper intake filters and spray accumulation/absorption filters (to avoid covering the fan with too much paint); these filters can be obtained at professional paint supply vendors or via mail order.

[thrown_hammer]

Try this thread.
http://hotrodders.com/showthread.php?s=&threadid=26965&highlight=paint+booth

[Randy Webb]

Two points:

1. You are in Mass. What permit are they going to require? Better check that out - needs to meet air regs.... ie safe for others not just you.

2. Price a pro booth -- they are not cheap -- the metal walls might not be needed, but how much of the cost is in the rest of it? That's another approach to figuring this out.

[Lukesportsman]

It never stops amazing me that no matter what the question seems to be, we can find someone on here that is an expert in the area. Just amazes me on the diversity of people we have on this board.

[Wrecked944]

Luke S., you are definitely correct. Ask any question from carb jetting to brain surgery and you get great responses. Amazing.

As for living in Mass, yes, I am concerned about staying within the law. I did a google search on regulations and only found references to storing small quantities of flammable liquids (i.e. you are only allowed to keep like a quart or less in or near your house which is more than enough for me).

So if anyone knows of a better place to look, please let me know. I have no interest in violating the law. jpachard, where you did you find the regulations when you were doing your research?

Jim Sims, I am very concerned about sparks. So far I figure I can get a safe exhaust fan either from Eastwood or, if I want to go hard core, Grizzly. But if you know of another source, I'm game to do some comparison shopping.

And Shawn, I have been following your painting efforts for some time. Very impressive. Your threads were the initial inspiration for my project.

[Hugh R]

Check out this link. It appears to apply to commercial operations, but you could be exempt under subsection (f)... which I posted below. I used to be an air quality engineer in Los Angeles, not Mass. but good luck. Call the Mass Department of Environmental Protection and ask for their Small Business assistance, I'm sure they have one.

(f) Exemption for Coatings Used in Small Amounts. For any person who owns, leases, operates or controls a facility with coating line(s) subject to 310 CMR 7.18, the emissions of VOC from any coatings used in small amounts at that facility are exempt from the emission limitations of the particular section, provided the person satisfies the following conditions:

1. the total amount of all coatings exempted does not exceed 55 gallons on a rolling 12 month period at the facility; and,
2. the person notifies the Department that this exemption is being used 30 days prior to its first use; and,
3. the person identifies the coatings which will be covered by this exemption; and,
4. the person complies with the recordkeeping and testing requirements of the particular section.