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Dreamcoat 12-01-2013 06:55 PM

How much cfm/fans to ventilate Painting Room?
Hey There, I'm spray painting with cans of paint in a 12' by 20' one car garage with a 7.5' high ceiling. The fumes are quite toxic and need to be removed!
I've read that you take your all 3 measurements and multiple them together to get your cfm for the room. Then buy a fan according to the cfm of your room so it has enough power to exhaust your room. I live in British Columbia so its very cold here in the winter to open the garage door to paint because the paint doesnt dry when it is cold.
I have one 2.5' by 2.5' to vent out and 8" opening in the wall opposite to the window that i could put a intake fan. I have a polyed off 20" box fan in the window right now but its not moving that much air through the room. Some say box fans push around 2500cfm and other says they push around 250cfm. But this obviously isnt working well enough because its only strongly pulling air/smoke about 2' away from the fan.
So my question is what would be the most efficient way to properly vent my garage
- Without spending a excessive amount of money?
- How much cfm do i really need?
- Possibly 2 fans for exhaust and 1 for intake?
Here is a few options ive been considering:
First 2 links i was thinking buying 2 or each and 3 link i was just going to purchase the one because its more expensive.

Please let me know what you think and suggestions

Thank you

ToolSeeker 12-02-2013 05:50 AM

Since your painting with rattle cans I assume the projects are rather small. Move your work area nearer to the fan, turn the fan to exhaust. Maybe use a sheet of plastic and fashion a paint booth around the fan area.

kkeith 12-02-2013 09:51 AM

You should get a respirator with carbon filters, not just a particle mask, that will filter the air for breathability, if health issues are your concern. The ventilation will clear the air afterwards, and should not be relied on for your primary air quality protection. Also keep in mind that if there is a gas water heater or other pilot light in the garage there is the explosion danger. The ventilation will help with that, but work far away from those flame exposures.

Dreamcoat 12-02-2013 04:19 PM

Thank you for the replies

Its just a space heater with oil inside of it. I dont believe it has a flame of any sort. I Do wear a full mask respirator with organic vapour cartridges to protect my lungs. I could build a spray booth with plastic or just simply move the my table right under the window for better suction from the exhaust fan.
I would like to keep where iam now to the right of window because there is much more room and my light is well placed here.
My only concern with a spray booth is it would block / interfere with my painting light.
Plus if the light was sealed into the booth it would be completely covered in painting in a couple weeks from the over spray alone.
That is why i was thinking venting out more then less my entire room would be pratical

ToolSeeker 12-02-2013 04:40 PM

If price is not a factor because I think to have a exhaust system for a room that size would be pretty expensive. Maybe someone else will have a better idea.

Dreamcoat 12-02-2013 04:48 PM

Money isnt a huge worry but the cheaper the better of course. But i am willing and expecting to spend around 300 to 500 but i believe you could pump the air out efficiently for the amount of power/fans i can install

But you are right for a full complete explosive proof motor you would need to spend around 1000 to 1500 for a legit complete setup. But i believe this is very unnecessary for the amount of paint that will in the air at one time.

firehawkmph 12-02-2013 09:09 PM

boxfans are not a good idea for ventilating a spraybooth area like you are talking about. Depending on what you are spraying, some solvents don't take much to ignite at all. I spent 25 years as a firefighter and put out a number of fires caused by painters. The worst was from spraying lacquer with a box fan in the window. Lit the whole room up and the room above it. Did a lot of damage to the freshly remodeled stately home. Burned a couple of the painters too. Keep in mind, the more air you pull out of the garage has to be replaced by make up air (cold probably), so the net effect might be the same as cracking your garage door a few inches.
Mike Hawkins:)

Gymschu 12-02-2013 09:53 PM

I might also add that, depending on what you are painting, there are many other alternatives to rattle can spray paint that will do just as good a job without the noxious fumes.

Dreamcoat 12-02-2013 10:48 PM

Thanks for the reply FireHawkmph but what is "spraying lacquer" what is lacquer? Just curious, because ive been researching how to ventilate and hear horrors stories such as the one you were describing. But last year i was painting lots every day and smoking so i had lit flame inside the room and i believe i at one time i used a spray can as a flame thrower to dry a painting quickly and never had any explosives/fires. I know it is dumb to have open flame and especially a flame thrower but i dont see the hazard of a fire because it wasnt a issue last year.

I understand that i could have just gotten lucky but nothing happened last year with a regular oscillating fan. So is rattle cans spraying lacquer?

The concentration has to be just right for the spray/fumes to ignite.

But are you saying that the direct concentration going through the fan and the fan motor it self could cause a fire?

My intake air is coming from the house, right now it is a 8" hole in the whole where air is being pulled through just from the air pressure change of the box fan in the window. Soon i will put a fan there blowing in air. The intake is from my house so it is warm air.

Dreamcoat 12-02-2013 11:00 PM

1 Attachment(s)
I'm using 1 can of paint at a time, no longer then 20 mins at time. Max 2 spray cans at once but not very often. Then i let the room ventilate before i continue to paint. To ensure that i am bringing in enough clean air
The intake fan i have is coming from the warm house and not the cold outside. So the the new air coming in is warming my room while the room in ventilating.
As you can see in the picture i have the painting table (the one with the computer on it) in front of the garage door to the right of the window.
So if your saying i were to put my painting table right under the wall closet to the fan it should be powerful enough to pump out the amount of paint im spraying?

ToolSeeker 12-03-2013 06:24 AM

I am also curious as to why the rattle cans there are alternatives that give a better finish, with no fumes, and no flammable propellant, and would be a lot cheaper.

Gymschu 12-03-2013 07:10 AM

Lacquer is a quick-drying clear coat finish usually used to coat wood.

firehawkmph 12-03-2013 07:18 AM

Lacquer is a type of paint and also a clear finish. It is available in spray can form and bulk form. It is highly flammable, a lot more so than enamel in a spray can. It is very fast drying. You are correct in saying the fumes have to be at the right concentration to ignite. Problem is, you have no way of knowing until it happens. You would probably be better off to put a blower in the house to pump the warm air into your garage along with cracking a window for the air in the garage to exit. When we needed to clear a building of smoke we would place a very powerful fan outside the house pointed at an open door from about eight feet away. Then we would open one window at a time and the house would clear out in a matter of minutes. The fan would induce a positive pressure inside the house. The smoke would just pour out of the window opening. If done right, we would clear out multi story apartment building using the same process.
Mike Hawkins:)

Dreamcoat 12-03-2013 08:58 PM

ToolSeeker i was wondering what kind of alterantive medium of paint could i use other then a acrylic air spray gun? These are quite expensive but i hear the replace paint is cheaper.

That would be very cool to see pumping the air out of the house that fast! I dont need quite a fan that powerful, but i understand how that works. The window is open and pushing out air and the intake from the house is warm air.

It cold here is Canada so i cant open the garage door my only option is the 1 window.

ToolSeeker 12-03-2013 09:44 PM

Lowes sells a graco hvlp set-up for $150 it's very good for smaller jobs and no overspray and easy to clean. Wagner makes a couple sprayers that would work for around a hundred bucks. The hvlp is a paint station 3900 even gives you a fine finish nozzle and is adjustable from 1/2" spray fan to 8".

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