garage ventilation

[bosshoss61]

I didn't have a whole lot of things going on today. Wanted to work in the garage, but don't feel to well. I have painted quite a number of vehicles in my lifetime and enjoy it immensly. I've painted vintage motorcycles, older cars, bicycles, motorcycle helmets, even some skateboards and enjoyed every minute of it.
My garage is a 24' by 30' with a 36" wide service door. I paint in there at least once a week. But the weather does not cooperate sometimes.. high humidity and cold temps hinder things. The larger projects are done in acceptable weather conditions with proper garage ventilation and the right mask. Changing the air in the garage about 6 times an hour accomplishes what I need to help protect me from explosions, fire, lung problems...things I do not want. For those of you that paint, then feel like you can't breath very well when you get done....read on.

This is the fan set up I use. OOPS wait a minute, that's not it.

This is The fan itself sits outside. And one garage door closes down on top of the duct. When your standing in the garage, all you see are two- 20" by 20" filters taped over two- 18" by 18" holes cut in the 24" high duct. The fan does not blow directly into the holes, but rather centered in the duct between the holes. The duct piece is 24"by 8" by 5 feet long. Pretty standard size at the wholesale house. I blow air into the garage under one door with my furnace fan/ductwork arraingment and out the other door, which is raised up 4" off the floor. The holes in the end of the duct are holes I have put there to slow the velocity down through the garage. I could have slowed the velocity down by raising the door higher, but dust can come in to easy. So 4" works for me.

One thing I have that you may not is a velocity meter. And with that meter the formula "Q=V times A" comes easy. All it means is your CFM or Cubic feet per minute equals the velocity times the area. I took six averaged readings under the door that was up 4". So I know the area under the door and I know the velocity. Now I can calculate my cfm's. Easy stuff------but, after 42 years in the HVAC business one would think so right?If all I've done by this article is save your lungs, your life, I would be so happy....good luck and god bless

Rick

[Colgate Studebaker]

Rick, that looks to be the way I would like to build an air handler for my garage. We have just moved to Florida from Wisconsin, and I have the blower fan assembly from our old furnace we replaced 2 years ago. My thought was to design and build a unit to pull air through the garage from 2 windows (one on each end of the garage), and out under the overhead door. I don't know how to figure how much air will be moving, but that is one project I will be working on. Thanks for the info, and yes, your help is definitely appreciated. Bill Van Alstyne

[Welcome]

I have an explosion proof type exhaust fan in my painting area.

Otherwise, you can never be sure when just the right mixture of vapors/fumes could be present and then ...KABOOM!!!

[55 56 PREZ 4D]

bosshoss61 is PUSHING fresh air through the garage, no real need for an explosionproof motor there. Although it wouldn't hurt to have one.
bill van alstyne is talking about PULLING air through his area. A very real possibility of explosion there as the vapors/fumes pass by the electric motor.
The fan setup he talks about WILL NOT be safe for his application.
A belt driven fan with the motor outside and away from the exhaust airflow would work.
No electrical should be within the paint area, no motors, no light fixtures, no receptacles, no j-boxes, no electrical panels.
No air compressors, washers, dryers, forced air units, water heaters, dehumidifiers, humidifiers, a/c units, etc, etc, etc.
At least unplug, disconnect the appliances. Turn off gas.

[Colgate Studebaker]

Thanks for the warning, so if I were to build a "booth" inside the garage and use the blower to push air through it to the exterior of the garage, via ducting of some type, will I be safer? I could build it to be non electrical inside the booth, but the garage itself will have all the above mentioned hazards. I would make sure to duct the exhaust out beyond the parameters of the garage. Thanks for your input, B.V.

[bosshoss61]

I would never recommend anyone to remove the fumes from their garage by pulling air from the garage. What I do is to slightly pressurize the garage with fresh air, and allow the pressurized air to exit itself out an opening. As far away from the fan as I can. An over concentration of any explosive vapor can expload in the garage from any spark of any kind. And you would be surprised by how somee sparks are created. Even shoes scuffling across a garage floor can do that. There is a lot more to what I did with the fan than I could or should explain in a thread. The motor I used was 1/3 HP, PSC on low speed. It had enough HP to push roughly 1200 CFM. And there was very little friction at all.

I do painting like this in my garage and believe it works for my way only. I would never recommend or help anyone in any way set up such a system in their garage. Too many variables.

I am pretty good with Natural gas. (CH4) Natural gas has an LEL or Lower explosive limit of only 5% and an upper explosive limit (UEL) of about 15%. That is not much at all. Some labels and MSD sheets may give you their LEL if it's in parts per million or PPM.....divide the PPM by 10,000 and you can have a percentage. Or just reverse the math and multiply if you have a percentage.

Such as carbon Monoxide--you know ASHRAE and OSHA set a limit of only 50 PPM. That means the percentage is only .005 %.

.005 % Carbon Monoxide (CO) can really make a person sick over an 8 Hour time period.
Please be carefull.

[DEEPNHOCK]

I've told this story before...but...
I remember a guy in Streamwood, IL named Bill 'Commander' Hoppy (sp?).
He used to paint letters for those business sign trailers.
Dayglow yellow, blue, green, orange, black.
He had a big blower moving all the air out of his 2&1/2 car paint booth.
It always cracked me up to see that flat overspray on all the trees around his place.
Blue and orange tree's just look weird

[garyash]

I won't ever paint in my garage, but I use enough solvents for cleaning, etc. that didn't want things to go BOOM. The propane heater I installed is a Modine "Hot Dawg" that has the burner section sealed up. It draws air from outside the garage through a sealed fan for combustion and vents the burned gases back outside through another pipe.

With the toxicity of most paints these days, a "supplied air" face mask/hood is probably a necessity if you are going to paint.

[jclary]

In one of my many careers(too many)...I sold finishing equipment and spray booths for over 16 years. There are volumes of engineering data and regulations pertaining to air flow and safety requirements for spray booths. Since I have been out of the business for a few years, I hesitate to offer my opinions as fact. However, an old rule of thumb was that the spray area needs to have a complete cycle of four volumes of air exchange per minute. Also the air flow should be evenly distributed in the work area at an airflow velocity of 100 linear feet per minute.

While all this sounds pretty basic and elementary...it really gets pretty complicated. Air moves best at a linear flow. Just like water...if you introduce turns (like drawing air around a corner) or place obstacles in a manner that introduces turbulence, (like rocks in rapids) you are likely to pick up debris and imbed it into your otherwise neat smooth paint job. I have seen spray booths with such poor construction as to have little tornado's swirling air and creating all sorts of havoc in the spray area. I have walked into buildings pulsating because the exhaust was overcoming the ability of the make-up air to supply sufficient air flow.

I have seen homemade booths with air flow, but absolute dead air spaces inside the spray area because of insufficient fan size and placement of intake air openings. I have seen some great work performed in poorly constructed booths with good tight filtration material. On the other hand, I have seen horrible work done in excellent top brand booths with cheap insufficient filter materials.

Don't even get me started on safety and respiration. Modern isocyanate (sp) laden paints aren't even supposed to contact your skin. I have seen the remnants of serious and some fatal accidents due to volatile materials igniting. Just as sad...are the slow illness and deaths I witnessed because of simply refusing to follow safety rules. And...don't think that switching to waterborne paints gets you off the hook. One of the worst plant fires I ever witnessed was a dumpster manufacturer who managed to ignite several inches of dried up waterborne over-spray with weld spatter.

I don't mean to be sounding like I'm preaching here, 'cause I have violated some of the rules myself. But, it never hurts to review the rules and take precautions.

[SN-60]

"Supplied Air" respirator systems are the ONLY safe way to use paints containing isocyanates......or really any other paint for that matter. But with isos's, any that gets into Your lungs will always remain and
possibly fester....NOT GOOD!!!! (Sneaky stuff,..it can't be seen and has no real smell....silent but deadly)

[Colgate Studebaker]

Seeing as my purpose for painting is going to be mainly prep work, I have no intentions of trying to do a finish job (I'm just not a good painter). My use of a "booth' type apparatus would be mainly to control overspray(which I know is impossible), but I would still like to have an airflow. Actually I mainly paint brackets, engine parts, suspension parts, etc. If I were to attempt bodywork, I'm one of the guys that could be in the fanciest "booth" and have a terrible outcome. Any help I can get for a safe way to reduce mess at what I'm doing is appreciated. Maybe I'll just say to hell with it, and paint out back of the garage in the open air. Thanks all you guys, your experience is invaluable. B.V.