Air cleaner pics

[Tom Andersen]

Hi guys,

there have been some discussions on air cleaners lately. During the last days I have finished my air cleaner, so here are some pics and details.

I got a rather large squirrel-cage fan for some bottles of red wine. The toughest thing was to decide upon the filters and to choose their type and size. I ended up selecting

1) a low-grade electrostatic furnace pre-filter
2) a high-grade electrostatic furnace filter for fine dust
3) a final, high-grade glass-fiber bag filter.

The two first filters are washable and my hope is that the bag filter will last for a long time because it is rather expensive and not washable.

I made the air-cleaner of 1/2" MDF with some internal stiffeners for the ceiling fixation bolts. The sides transfer the weight to the end board that holds the motor.

The air cleaner is rather heavy (I can only barely lift it), so it's going to be a challenge to lift it up and fix it to the ceiling.

After having built the thing, I believe that I have these conclusions:

a) It would have been much easier and almost as cheap to buy a standard air cleaner (although mine has a high capacity)
b) I should have made the box out of 1/4" plywood on a frame to keep the mass down. That's really a killer.

Here are the photos: No 1 is the fan. No 2 shows the box before the side boards were installed. The third and fourth pics are with the side boards and no 5 is info on the high-grade furnace filter.

More pics in the next thread. I don't know how well the cleaner works, I have only tested it briefly on the table. If anybody is interested, I may report on the efficiency once I get it up under the ceiling.

Rgds
Tom

[Tom Andersen]

Here is the rest of the pics. No 6 shows the filters from the side, no 7 the inside with the fan, no 8 the exhaust end, and no 9 the box after fixing the remaining holes from the dowels before painting.

[Todd Hyman]

Tom,

I'm about ready to build the same thing. What size are the filters and where did you get them from. I am determing how I want to mount the fan horizontal or vertical as it is really heavy and the flange is only about 1/2" wide and has no holes. I like how you built the access doors to the filters. What size is that exhaust grill?

As you can tell I have a lor of questions. Let me know how efficient your is.

Todd

[Tom Andersen]

My workshop is in Sweden but we usually do not use airborne heating here and furnace filters are hard to find, so I bought the filter during a trip to the US. I found that Lowes is a good place to buy furnace filters, better than HD. You can see them all on the Web (http://www.lowes.com/). The bag filter I bought from Wynn (http://www.wynnenv.com/). My filters are 20x24". They are actually too big, but I couldn't get the dimensions right with smaller filters. The exhaust grill I bought at some hardware shop, it matches the opening in the squirrel cage fan. I may replace the exhaust grill with another type (grid) with less pressure drop.

I am holding my fan at the exhaust flange.

I attach a primitive drawing with dimensions in cm = 1/2.54 inches. When I made the box, I changed the design by taking away the triangular plate and adding the hinged door.

It took too much time to build the thing... and I still have to paint it, get it up under the ceiling, and fix the electricity. From my trial runs with the unit standing on the table, it seems to be doing a good job. It does make some noise but there is anyway so much noise in a woodshop, so it's not too critical.

[Jim Dunn]

Nicely done Tom.

[Julio Navarro]

Nice job Tom.

Thanks for the info on the filter bags.

[Bruce Wrenn]

I've had my homemade filter for about seven years now. I use one of the pleated air filters ahead of my bag filter. Pleated filter gets most of the dust, especially after loading up. Bag filter is still the original one. Bought two from Grainger as that is the way they were sold. Pleated filters come from Lowes. Both filters are 12"X24". After I have beat dust out of prefilter a couple of times, I replace it. I use the cheaper brand, a package of three is less than $8.00 Put one of those Christmas tree remotes on unit to control on/off function. Bag filter can be cleaned with shop vac. Take a piece of 1 1/2" PVC pipe about 12" long, and drill several 1/2" holes in it. Attach to shop vac hose and work inside filter to clean.

[Nick Clayton]

Tom can I ask what the specs on the motor are?

[Tom Andersen]

Tom can I ask what the specs on the motor are?

I won't be at my workshop for some days (:()but I believe that it pulls 1.6 Amp and with 230 V, cos phi, and some efficiency factor, it should then be around 1/3 HP.

[Joe Trotter]

Very nice!

[Todd Hyman]

My workshop is in Sweden but we usually do not use airborne heating here and furnace filters are hard to find, so I bought the filter during a trip to the US. I found that Lowes is a good place to buy furnace filters, better than HD. You can see them all on the Web (http://www.lowes.com/). The bag filter I bought from Wynn (http://www.wynnenv.com/). My filters are 20x24". They are actually too big, but I couldn't get the dimensions right with smaller filters. The exhaust grill I bought at some hardware shop, it matches the opening in the squirrel cage fan. I may replace the exhaust grill with another type (grid) with less pressure drop.

I am holding my fan at the exhaust flange.

I attach a primitive drawing with dimensions in cm = 1/2.54 inches. When I made the box, I changed the design by taking away the triangular plate and adding the hinged door.

It took too much time to build the thing... and I still have to paint it, get it up under the ceiling, and fix the electricity. From my trial runs with the unit standing on the table, it seems to be doing a good job. It does make some noise but there is anyway so much noise in a woodshop, so it's not too critical.

Tom,

Can you tell me what type of Wynn filter you bought as I am thinking about gettign one from them as well along with the cannister filter for my recently purchased HF dust collector.

Thanks, Todd

[Al Willits]

Thanks for posting, thinking of building one of them also.
I live in Minnesota and I think our temps are close to yours, so venting to the outside is to costly during the long heating season.

Just wondering, do you have your filters up or down stream from the blower?
I've seen some designs with the filters on both sides and wondering why.

I'm thinking a three speed 1/4hp furnace blower might make a smaller and lighter unit, we use enough of them here, so they'd be easier to find used.

Al

[Jim Fox]

I am a new face here. Hung out on Woodnet for years. But I thought I'd share my filter unit too, just incase people were looking for ideas.

It has 3 high volume (340cfm ea) fans from old computer hardware. Think they cost me $20 each. I got the shortest filters I could find, 10"x24" which is the only downfall (I have to order online). But it does it's job. I have it on a 60 min timer and can run 1, 2 or 3 fans. 99.9% of the time it's 3 fans running.

Only thing missing is on the exit side of the fans should be 2 dividers so when I run 1 or 2 fans, it partitions the space off and it wouldn't cause a back feed.

http://www.planesnsuch.com/Woodworking/shop/airfilter_1.jpg
http://www.planesnsuch.com/Woodworking/shop/airfilter_2.jpg
http://www.planesnsuch.com/Woodworking/shop/airfilter_3.jpg
http://www.planesnsuch.com/Woodworking/shop/airfilter_4.jpg
http://www.planesnsuch.com/Woodworking/shop/airfilter_5.jpg
http://www.planesnsuch.com/Woodworking/shop/airfilter_6.jpg

[Al Willits]

Jim, nice filter box, just wondering though, if these are comp blowers, can't you run a varible speed control and just run all at the same time with out the dividers?
Might be easier?

Al

[Jim Fox]

That probably is possible, never thought about that. LOL

Something to look into!

[Tom Andersen]

Todd:
The bag filter is of type 24X20X14 inch Vee Bags with loops, part Number 242014VBL, about 50$ ea, available only in two-packs.

Al:
My filters are upstream, i.e. on the suction side. I believe that is what everybody does, because it keeps the fan and the blades clean. I agree with you that a somewhat smaller fan than mine would have been better due to size and weight considerations.

Jim:
The quality of your box is really impressive! I believe that axial-flow fans are less capable of overcoming a pressure drop from filters, so you may have less flow than with a comparable radial-flow squirrel-cage fan. Anyway, your air cleaner is surely fine.

[Jim Fox]

Yeah Tom, the backflow of air is minimal, but I know it happens as I see the fans moving.......albiet not a lot.

[Tom Andersen]

Yeah Tom, the backflow of air is minimal, but I know it happens as I see the fans moving.......albiet not a lot.

My comment was mostly related to the characteristics of axial-flow fans vs radial-flow squirrel-cage fans. I believe that the squirrel-cage fans have a "stiffer" characteristic, so that they maintain higher air flow with a pressure drop.

[David Epperson]

Tom. Not to be nitpicky, but in the situations where I've seen "bag" filters like that (as pistured in #6) used they hang verticaly with airflow from below. As such yours looks to be sideways and reversed. But the applications I'm familiar with are industrial baghouse filtration and sandblast cabinet filtration, on those you can "bump" clean the bags. The big baghouse filtration units actually use a reverse blast of air (High intensity/short duration) to clean each bag one at a time during use, the smaller ones use a simple shaker bar to "disturb" the dust layer while the unit is shut down.

[Tom Andersen]

Tom. Not to be nitpicky, but in the situations where I've seen "bag" filters like that (as pistured in #6) used they hang verticaly with airflow from below. As such yours looks to be sideways and reversed. But the applications I'm familiar with are industrial baghouse filtration and sandblast cabinet filtration, on those you can "bump" clean the bags. The big baghouse filtration units actually use a reverse blast of air (High intensity/short duration) to clean each bag one at a time during use, the smaller ones use a simple shaker bar to "disturb" the dust layer while the unit is shut down.

Thanks for you comments. You are right, it would have been nice to use bag filters that can be cleaned. I couldn't find any that would fit into my small box and also clean the air to below 1 micron. If you or anybody else knows where to buy them, I would be very interested.

[Todd Hyman]

Tom. Not to be nitpicky, but in the situations where I've seen "bag" filters like that (as pistured in #6) used they hang verticaly with airflow from below. As such yours looks to be sideways and reversed. But the applications I'm familiar with are industrial baghouse filtration and sandblast cabinet filtration, on those you can "bump" clean the bags. The big baghouse filtration units actually use a reverse blast of air (High intensity/short duration) to clean each bag one at a time during use, the smaller ones use a simple shaker bar to "disturb" the dust layer while the unit is shut down.

David,

Can you tell us where you can get these at?

[David Epperson]

I'll look into it and see if I might be able to find out. I never had the responsibility of ordering them (the filters), just cleaning and maintaining the systems.

[David Epperson]

They looked very much like the filters you have pictured, a bit longer perhaps. But the key thing was that the bags were attached to the top of the frame and allowed to "hang" down. The "dirty" air was ducted in from the lower section of the frame through the filters and out the upper section. So gravity was used to "clean" the bags. Granted, these were also never removed for cleaning either, but the majority of the dust burden would fall off due to gravity(into an open area below the bags) when the system was shut down and the bags were shaken. This was done in most cases with a simple round bar arangement that went between the bags with a handle attached. Shake the handle to beat the bags. Collect the fines at the bottom and discard.

The industrial bag house filters were 6 to 8 foot long and 6" to 8" in diameter of an eggshell filter media cloth around a steel wire frame, on a 10" to 12" spacing - with around 120 bags per filter house. Each bag had a reverse flow blast nozzle (1-1/2" quick exhaust valve at 110psi) at the top which was "fired" periodically, one bag at a time, on a timer. to knock the gross buildup down. This way they were "cleaned" even during active service.
But these baghouse collectors also had 50 to 75hp blowers on them too.

[Benjimin Young]

Tom, re lifting the heavy assembly. Perhaps you can rent a drywall lifter used to hold drywall sheets on the ceiling while you screw them in place.

Ben

[Darrick Hartman]

That probably is possible, never thought about that. LOL

Something to look into!
Those look like 120V fans, not the 12V fans you'd find in a computer. More likely these were used in a big plotter. If they were 12V fans, you could easily put a resistor inline and slow them down. You might be able to put a variable speed fan control, as long as the amp draw doesn't exceed the switch...most of those are designed for small ceiling fans.

I am in the process of setting up my shop in our basement. We bought the house in June (06) and did alot of the brute construction type work over the summer and into the fall. I'm finally ready to get started on the drawers and doors for the bathroom vanity. Before I start doing woodworking here, I definitely want to set one of these up (the wood working room is in the basement).

The previous owner did alot of wood working in this house. NO dust collection at all! We are still wiping up dust any time we touch a piece of duct work, pipe etc in the ceiling.

I was having a hard time finding the compact fans (at a reasonable price), so I opted for duct fans from Menards. 250 cfm 6" fans were around $25. I hope to get something assembled in the next week or so.

Thanks for sharing the ideas.

Darrick