I’ve had several spray set-ups over the years, ranging from extremely primitive to professional. I’d say first of all that while the 3′ recommendation you mention would be nice, you can definitely get good results with less. I had a spray room that worked quite effectively with 10 sq. ft of filter area and just 15″ of space behind. Another thought – if it’s still possible, maybe you can change the entire concept of the room, and instead of drawing air out with a suction, force the air out by creating pressure inside. This system has several advantages –
1. It’s ideal for keeping dust out of the room because any leak or door opening has a flow of air outwards instead of drawing into the room.
2. The outlet flows smoothly and uniformly, and not through any impeller which can get junk build-up. No fire hazard from sparking and inflammable solvents.
3. It’s quite simple to engineer the desired airflow in the room. The air being forced into the room (thru filters) usually would come from the ceiling or the wall opposite your out-take, creating a smooth stream that will carry away overspray efficiently.
David Ring
Replies
That certainly is a unique idea....
What happens when you open the door to exit the booth?
Bring new product in or out?
Cheers, Don
It's not my idea. My shop currently has a large spray room (you could drive a car into it) made in Italy which works like this. The entire ceiling is a filter through which the air is forced into the room. It exits simply thru a baffle at one end. When you open a door to go in or out there's a gust of wind leaving the room, effectively preventing dust from entering. The electronics industry uses the same principle for clean rooms. By pressurizing the room (with filtered air of course) any breach of the seal is rendered unimportant by the outward airflow.David Ring
http://www.touchwood.co.il/?lang=e&id=1
Okay, I understand that.
What I can't get my mind around is the "gust of air" contains whatever you were spraying and is now in the rest of the shop... I imagine it will soon be blown back into the booth :)
Cheers, Don Don Kondra - Furniture Designer/Maker
Not at all. The overspray in our set-up goes out the exhaust so fast you can't even get a whiff of it. By the time you can set the gun down and open the door there's nothing but clean air in the room.The intake of the fans that send air into the room has large pre-filters that need to be cleaned weekly, but it's not a big deal. The final filters in the ceiling haven't been cleaned in 2 years.David Ring
http://www.touchwood.co.il/?lang=e&id=1
Swell hijackin' you guys have going here!
You're welcome.That's a really intriguing name you've got...David Ring
http://www.touchwood.co.il/?lang=e&id=1
Post #6 was directed at you :)
Cheers, Don Don Kondra - Furniture Designer/Maker
Swell hijackin' you guys have going here!
If you are that concerned about your precious thread being "hijacked" then I would suggest taking your questions over to Sawmill Creek, where such "hijacking" is frowned upon.
Personally, I felt the conversation was relevant to your question.
Lee
Please correct me if I'm wrong but it sounds like you are talking about filtering the air going into the booth?
In a basement? In a one man shop?
If this is correct it is my experience you are simply wasting your time. I went through the same worries about filtering the intake air, installed a series of furnace filters and eventually ended up spraying with the door open :)
But, I am reasonably careful to collect as much dust as possible during normal woodworking processes.
If necessary, I will run the spray booth fan (2500 cfm) and use compressed air to "clean" the immediate area around my mixing station, etc. prior to finishing.
My thinking is anything large enough to contaminate a finish will either fall to the floor or be drawn out with the exhaust within minutes of starting the fan.
If you don't stir up any dust in the area the make up air is coming from, filtering is not necessary.
Cheers, Don
Don, please allow me to clear up the misunderstanding. I merely want to suck 850 cfm's (from a 6" round duct) through a 2' X 3' paint arresting filter and have the air movement (with paint overspray droplets) spread equally across all points of the filter. My goal is simply to have the filter work as designed, rather than loading just one point of the filter due to excessive cfm's and velocity. Common sense suggests an intermediate baffle, same size as the filter, located between the filter and the 6" duct, with appropriately sized holes on perhaps 2"centers that would force air to be drawn across entire filter area. Trouble is, I'm not sure just what sized holes to bore in the baffle (on perhaps 2" centers) that would force equal suction distribution, and at the same time not overload the blower (sucker) with unnecessary static pressure due to the holes being too small. Any help?
Hmmm, okay, my first thought is a baffle is unnecessary, depending on the mesh of the filters, the air will pass through fairly evenly.
I would be more concerned about the filters themselves restricting the air flow but six square feet of filter shouldn't pose a problem.
I would suggest moving forward without a baffle, if it is indeed necessary it will be visually apparant very quickly and you could design it in such a way that the baffle could be added later.
Cheers, Don
Don Kondra - Furniture Designer/Maker
Didn't think to ask... what kind of filter are you using?
And is there a code you have to adhere to or you just don't want to be blowing dust on your neighbors? :)
I used to spray in town for a local shop, the filters were paper and could be "cleaned" quite a few times before I changed them...
Cheers, Don Don Kondra - Furniture Designer/Maker
This probably isn't relevant but I do custom spray finishing from my shop on an acreage.
My van is parked fairly close to the exhaust fan and I've never noticed anything more than a light dusting :)
Of course by then nothing is going to stick..
Cheers, Don
Edit - my exhaust is not filtered
Don Kondra - Furniture Designer/Maker
Edited 7/27/2009 7:33 am by donkondra1
At the risk of asking a silly question, what do you expect the filter to do? The baffle alone will catch the paint droplets without any significant blockage to airflow. The filter will not stop airborne solvents anyway. Why do you want it there?David Ring
http://www.touchwood.co.il/?lang=e&id=1
This forum post is now archived. Commenting has been disabled