Design questions on DIY air cleaner

[Eric Schubert]

I'm working on a design for a DIY air cleaner, and would love some additional feedback or suggestions, if you have them.

I have a used furnace blower that I want to use. A nice, big 3/4HP blower. And I'm debating between two different designs, both of which would double as a rolling cart/table for my shop. The first design would be a square-ish cart with filters on the sides of the blower, since that's where the blower pulls in air into the squirrel cage. (Maybe a third filter on the back, for filtration all around the cart.) The second design would be linear (and longer), putting a single filter stack directly behind the squirrel cage, moving air more in a line.

Pros for the double filter: larger filtration area, less air resistance, slower movement of air into the filter for better efficiency.
Cons for the double filter: more filters, would need to use disposable furnace filters

Pros for the linear, single filter: won't simply pull air from the front back in the sides again for better circulation, fewer filters to change/clean/replace, could make the cart longer to utilize washable pocket filters for better filtration of very small particles. (I'm considering the Grizzly washable pocket filters, which filter down to 1 micron for their air cleaner. I'd also use a pre-filter for larger particles.)
Cons for the linear, single filter: smaller filtration opening (may be less effective?), washable pocket filters for cost-savings (which also create more filtration surface area to counter the smaller opening..?)

Maybe it doesn't matter that much, but the engineer in me just can't decide between the two... Any thoughts on one design vs the other? Perhaps even a third design option?

[Brice Rogers]

Eric, thanks for posting this. I will be following to pick up ideas.

Right now I am using a 20 x 20" window fan with a pair of furnace filters. I have it set so it blows clean air at me when I'm at my lathe. If helps but plugs fairly fast. But that means it's doing its job. When airflow drops to an unacceptable level, I take it outside and use an airhose to blow out the dust. Seems to work.

I'm in the same boat as you are and thinking of making a square box with a squirrel cage fan to hang from the ceiling. I'll probably use 20 x 20 furnace filters on three or four sides. There are some that you can wash out.

There are Youtube videos from a guy by the name of Matthias Wandel who has made some air cleaners. Worth looking at for ideas.

[Jerome Stanek]

When you blow it out do you wear a mask

[glenn bradley]

One design parameter I will suggest you consider. If this is to be a roll-around cabinet I would have the air exit out the bottom. This way there is no "bad" orientation of the cabinet. You would want at least 3" casters to assure minimal resistance to the exiting air.

[Brice Rogers]

Yes, absolutely. Plus we typically have a breeze and I position myself up-wind.

[Eric Schubert]

Eric, thanks for posting this. I will be following to pick up ideas.

Right now I am using a 20 x 20" window fan with a pair of furnace filters. I have it set so it blows clean air at me when I'm at my lathe. If helps but plugs fairly fast. But that means it's doing its job. When airflow drops to an unacceptable level, I take it outside and use an airhose to blow out the dust. Seems to work.

I'm in the same boat as you are and thinking of making a square box with a squirrel cage fan to hang from the ceiling. I'll probably use 20 x 20 furnace filters on three or four sides. There are some that you can wash out.

There are Youtube videos from a guy by the name of Matthias Wandel who has made some air cleaners. Worth looking at for ideas.

I've seen a handful of decent videos and plans for air cleaners using furnace blowers. Some are more linear, while others have filters on 2-3 sides. It just has me wondering which one is best. I do have the option of mounting it along the floor joists above me, since I'm in an unfinished basement. I just don't know that having it up high will be as effective.

One design parameter I will suggest you consider. If this is to be a roll-around cabinet I would have the air exit out the bottom. This way there is no "bad" orientation of the cabinet. You would want at least 3" casters to assure minimal resistance to the exiting air.

Glenn, thanks for the suggestion. I had been considering whether or not to position the outlet of the fan along the bottom or top of the cart. Bottom seems to make more sense, as it won't blow papers off my bench and such. But are there other reasons you're thinking that along the floor is a better option?

[Brian Deakin]

I spent a considerable amount of time looking at this issue and the best solution I saw was

http://billpentz.com/woodworking/cyc...ir_cleaner.cfm

regards Brian

[Eric Schubert]

Thanks, Brian. But the point isn't to replace dust collection, it's to augment it. I also do neander woodworking, so I don't generate as much dust as someone with power equipment.

In any case, I'm just looking to help prevent the migration of dust around my shop and my home as much as I can. I figure an air cleaner will help with that goal.

[Brian Deakin]

Hi Eric
Thank you for your reply I decided to take the Bill Pentz root for the following reasons

(Please note I live in the United Kingdom)

(1) I was given a Vent Axia SDX 315 fan which had been used in the air conditioning system a Rolls Royce aerospace the retail price of the fan would have been $600

http://www.vent-axia.com/files/pdf-downloads/SDX.pdfhttp://www.vent-axia.com/files/pdf-downloads/SDX.pdf

(please note It may be possible to obtain a fan on ebay for a fraction of its price )

(2) I purchased the filter off ebay for $30

http://www.multifilter.ru/pdf/donald...n%20004249.pdf

I accept the system is overkill as it is used in a one car garage but for a total cost of $30 it does the job

[Eric Schubert]

Brian, that would be a great solution. I didn't read through all of the page, my apologies. I've been to Bill's site before to look over his DC systems, so I had just assumed that was what you were referring to. I'll investigate those filters a bit more to see if I could use them somehow. Thank you for providing more details!