# Another dust collection option... A pressurized box?



## oldoakwooddesign (Sep 25, 2016)

So, I'm still new to the Forum but have been reading lots of the different posts about dust collection. I'm currently running a 3hp 2800CFM DC w/ a cyclone. I currently have the 2 bag version and I'm wanting to upgrade to canisters. ...BUT… Given the price of canisters and where I live it would cost almost $400 for two Wynn environmental canisters. I've been considering other options. I know that Donaldson truck filters are an options but they are designed to go from outside the filter to the inside (please correct me if I'm wrong!) if i'm not mistaken… I like the cost of the filters but given their design was considering a pressurized box to put two filters inside of with ports that are open on either end of the filter (obviously an open/open canister). I was going to run a 8" flex hose from my DC exhaust to the box to pressurize the box, then the fine particles would enter the box and air would travel through the filters in their designed fashion.
Am I totally off my rocker or is this a decent idea? Also what are the Donaldson canisters that people have found to be most effective? Parts number?
I'm also completely redesigning my dust collection system so that the DC is in my Attic so that i have more space and less noise so the DC and box would be built and mounted into the attic. Hence the total re-design. Unfortunately I have neighbors close so venting directly outside is not an option:/.

Thanks for all the help,
Bart


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## JBrow (Nov 18, 2015)

oldoakwooddesign,

I am not familiar with Donaldson Truck filters but from what I gather in your post these filters sound as if they are similar to my shop vac canister filter. Air flows from outside the filter into the filter's center cylinder which is then exhausted back into the shop. Therefore, if the Donaldson filter is designed to filter air flowing from outside to inside, your idea should work.

Some considerations regarding your overall plan include ensuring there is sufficient air flow exiting the filter box, which is needed to keep air flowing at full capacity through the dust collector. If the inside diameter of the filter's cylinder is equal to or, better yet, greater than the diameter of the dust collector inlet and the filter box exhausts from each end I think you would probably have sufficient air flow. There should probably also be sufficient space between the walls of the filter housing and the filters although I am not sure how much distance is enough; at least 3 inches I would think.

Since the filters are going in the attic, sealing the filters in the housing would keep the fine dust out of the attic. Also, assuming conditioned air in the workshop, returning the clean filtered air to the workshop could prevent condensation in the attic and avoid the problem of finding make-up air to replace conditioned air in the workshop.

Another consideration is cleaning the filters. The manufacturer of my filters recommends backwashing the filters by blowing compressed air through the filter to dislodge dust. I could see how this method of backwashing could be a little tricky when trying to push backwashing air from inside the filter cylinder to the outside. Less frequent filter cleaning would be required if the overall filter area is large. The smallest total filter area I have seen with 3hp dust collectors is 95 square feet.

Lastly I know how heavy and cumbersome it is to empty the dust bin. Developing a system that would make the job easier should the dust bin also be located in the attic would probably be appreciated each time you have to empty the dust bin.

As to the part number or which Donaldson canisters would be best, I cannot say.


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## wapakfred (Jul 29, 2011)

Deleted by me, I found the answer in the other post.


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## oldoakwooddesign (Sep 25, 2016)

Fred, yeah its a 2 upper bag unit.
Jbrow, Thanks for the insite!
So the collection canister (55gal) is in my shop under the cyclone, so it is easy to empty. The ducting then goes up into the attic from my cyclone to the blower and fine dust collection bags/to be canisters. The truck filters i'm look at are 177+ square feet each giving me over pretty decent air flow. I think it will be enough, but if air flow seems restricted I could always modify the box to add another filter, given since i haven't built it yet. 
You brought up a good point with exhausting back into the garage. I'm in Idaho and given the climate here i'm not to worried about moisture in the attic but in the winter it will be pretty inefficient to exhaust warm air into the attic and make my heater work double time:/ I like the attic for noise control and for the space savings but might have to reconsider other options for piping warmed air back into the shop. Might have to build the box on the wall in my garage instead of having it up in the attic.
thanks guys! lots to think about.


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