i’m going to construct a charcoal filter system for glassing. my main concern is what will pull the air. i’m thinking about a box style fan, maybe a motor. any suggestions on what will be powerful enough to pull the air?
I don’t think a box style fan will pull the air effectively. The open area in the fan in the corners of the box frame will just let the air vortex around the blades and not get pulled/pushed into filter, and the fan motor is only strong enough to spin the blades and not strong enough for the high drag application you are talking about. A Wind Machine fan might work a little better with the circular housing and closer tolerance to the fan blades, but the motor is still weak like a box fan.
Try a “squirrel cage” type of fan. They move a sizeable volume of air and they have a seperate motor that can handle higher loads. You can even replace the motor with an air compressor type of motor if you need to.
Or what about a wet/dry-vac type of system with the charcoal filter in the dust canister? It may not move enough air though. Just a thought.
Unclear just what you intend to do. Most of us use portable single or dual cartridge respirators. It’s referred to as a negative pressure system because you suck the air in through the filter, and breathe out through a one-way flap valve. You strap 'em on your head, and away you go. When you start to smell stuff through the filter, you sh*tcan that filter cartridge and replace it with new.
A larger system such as used in spraying booths, called a “supplied air” system, uses a low pressure pump or fan to push clean air into a hood or full face unit over your head. This seems to be what you’re referring to, but it’s really not well adapted for glassing, at least because you have to drag/carry the air supply hose around with you. It’s also a lot of additional “stuff” to clutter your glassing bay.
Painter use them because the protection factor is much greater with a positive pressure hood and supplied air. The TDI, and so on, in most modern paints is so toxic that by the time you can smell/taste it through a respirator, you’re already cooked. Thus for really toxic stuff supplied air is the answer (no filter to periodically change out).
Honolulu…i am referring to the air in the room, not my face,sorry for the confusion. Ozzy got it right…
where might i find a squirrel box fan? Home Depot?
Hi Teddy,
Typically, the squirrel-cage fans are those kinda spiral looking deals as you will see in sizes from tiny ( hair dryers, car heaters, computer fans, etc)
to huge for pulling air out of stadiums. .
They all look pretty much like snail shells, ya know?
Home Depot probably won’t have 'em, though your friendly neighborhood junkyard almost certainly will - one from a forced hot air heater would probably work quite well. Or larger…
Now, having said that… what you might want to do instead is set up a reasonable sized dust collection system for the whole shop area and with a few blast gates, etc, run the air you pull out of your glassing room through an inline charcoal filter before it gets to the blower. Other bits of plumbing could deal with your shaping and sanding dusts, all led to the same central dust collection setup.
http://www.grizzly.com/products/G8027/ for instance, and lots of others out there…
hope that’s of use
doc…
i just ran to Home Depot to check out what they had. they had an 8" duct fan that was 500cfm. strong enough? only $38. …i am also debating wether to use a big 2 hp dust collector or a 5hp Craftsman shop vac for my foam dust collection. it will be rigged with the overhead hose connecting to the planer.
thanks doc…so what you’re saying is to use the dust collector as the exhaust power source with a charcoal filter in the line. how will the fumes escape outside? or will the charcoal take care of that…thanks guys for your input ,it’s much appreciated…
Teddy
Measure your room: Length x width x height = room’s volume (for CFM selection). Example - That 500cfm fan would roughly give (1) air change per minute in room that was 8x8x7.
Best,
Herb
Hi Teddy,
Well, lets put it this way, if the charcoal filter doesn’t take care of the fumes then there’s not much point in having it, y’know? And if so, a simple exhaust fan on your glassing and glossing rooms ( with filtered intakes, by the way) will take care of keeping fumes from invading the rest of your shop.
If you’re going with a sizable dust collector system, it’s best if it is located outside the main working areas anyhow, accessible and well ventilated and all so that in case of a blowout or the guy changing bags getting clumsy you don’t wind up with a layer of dust over everything, like glass jobs and gloss jobs. 4" PVC pipe is the way to go for your ducting ( cheap and easy to mount to ceilings) , mebbe a few copper grounds in there to deal with any buildup of static electricity.
hope that’s of use
doc…
i have been told that it is a good idea to keep your vents low on the wall. resin funes are heavier then air so they sink. pulling the funes down will also help keep them out of your face…
i have also been told that “code” for filtration systems says that the incoming air must be from an externial source, so you can’t pull the air from your office into your glassing room, or the air from you shaping room into your sanding room etc…
just some thoughts…
Quote:
Honolulu…i am referring to the air in the room, not my face,sorry for the confusion. Ozzy got it right…
where might i find a squirrel box fan? Home Depot?
I don’t think that “squirrel cage” is the technical name for them, that’s just what I and everyone I know have always called them.
This one is really close to what I’m talking about. But the older ones I remember had a belt drive and a seperate motor like an air compressor, but not so big as to handle stadium exaust. They were more of a component assembly, built to last, and made to be easily serviced by the farmer in the field.
I’ve seen them in shaping bays mounted on the floor for an exaust fan. A place like Granger would be a good start, but I didn’t see any on their site – that doesn’t mean they don’t have them of course. This one is a good candidate also http://www.grizzly.com/products/G8027/ but it’s made for dust collection (no filter air drag), and the main thing to remember is the charcoal filter needs to be looser packed (if that is possible) so that it will allow high volume air flow through it. Tighter packed filter equals lower air flow, and less effective for purging fumes from a room. Like someone said, you also need a place for the air to flow into the room. You don’t want that air to be contaminated with dust or anything, then you might be creating more problems for the quality of the lam/hotcoat/gloss. A window with a couple or three home a/c filters to help filter out any dust particles from the air flowing into the glassing room might be a good way to go. Like the intake window at one end of the room and the exaust fan at the other end of the room for a smooth effective air flow across the room. Try mounting the cage fan directly to the filter, either on the intake or exaust side of the filter canister. I’m guessing mounting the fan intake to the back side of the filter, that way if there is an air flow problem the fan can cavitate and not burn up the motor as quick.
–{ The wet/dry-vac thought I had before would be just way to low of an air volume flow, and not workable at all for a room size application. }–
Hope that helps, and isn’t too redundant from the other suggestions ppl posted.
No do not use a box-style fan. It will not work well unless you have a duct that is very large (basically the size of your fan housing). Go to an air-conditioning supply place and buy round galvanized ductwork. The pieces snap closed and can be held together with sheetmetal or lath screws. There are fans that are designed to blow into round or other ductwork, usually of the squirrel-cage variety, though not all. Grainger has some, but they’re really expensive. Try to find a used one on the net.
500 CFM is not nearly enough. Think 1000 or more, at least. I’ve just gone through something like this. The way my system is set up now, the people I share walls with can’t even smell resin when I’m in full polyester production, and my shop clears out fairly quickly. System still needs some tweaking, but it’s keeping me open for now.
Quote:
This one is really close to what I’m talking about. But the older ones I remember had a belt drive and a seperate motor like an air compressor, but not so big as to handle stadium exaust. They were more of a component assembly, built to last, and made to be easily serviced by the farmer in the field.
Right, like one of these I happend to bump into today, ex-restaurant exhaust fan
Note the belt drive, you can change the motor pulley to futz with the blower RPM, easier and cheaper to change the motor pulley than to try and find a big sucker to put on the fan shaft.
One of these will move a lot of air, although it won’t draw a lot of pressure. This one in particular would pull the doors open from the front of the house…
hope that’s of use
doc…
What about the noise, Doc? I’m planning to have this kind of stuff installed when I build my new shop and I don’t want to bother the neighborhood…
Uhmm- depending on installation, condition of bearings and choice of ducting materials, such systems usually are quieter by far than shop-vacs, most dust collectors ( like mine) or any power tool louder than, say, an orbital ( flat-pad ) sander. Usually a low-mid frequency sound too, not high pitched or one of those really low freq sounds that make you slowly crazy.
For an example, stand outside the back of a restaurant - this one came out of a restaurant exhaust hood setup, over the cooking line.
If you wanted to mount one of these inside, with maybe a few baffles in the exhaust vent, people would probably think you were running a clothes dryer.
hope that’s of use
doc…