# DC filter surface area - how much do I need?



## gtbuzz (Sep 19, 2011)

I've started work on my new dust collector (3hp motor, eBay cyclone separator and Wynn Nano filter(s)?) and I've got a question about how much surface area I need for the filters.

I previously used my Wynn C-1425 filter with a Jet 1.5HP dust collector and it was a good combination. Since I'm moving to a 3hp motor, I've been looking at other cyclones in this class to determine what's a good number for filter area and the numbers seem to be all over the board. For example, the Penn State 2.5hp cyclone has 450sqft, while the 3.5hp cyclone has 700sqft (2 cartridges each). The Clearvue with the nano filter upgrade has about 600sqft. On the other hand, the Oneida V-3000 and Grizzly G0441 have "only" about 100sqft, comparatively.

I'm not sure of the filter area on the C-1425 but I think it's around 275 or so (I asked Dick @ Wynn about this and he said this particular manufacturer doesn't like their square footage disclosed but he told me it was about the same as the 35A series nano filters).

I'm gonna guess that my system will run fine with just the single filter, but the question is will I see that much of an upgrade going from 275ish sqft to about 550?


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## wapakfred (Jul 29, 2011)

I was also confused by the wide variation of what the commercial units have. I looked into it recently when I had to replace the OEM filter on my Oneida. I wound up buying a 350 square foot filter from Penn State (it was more or less plug and play on my DC), which gave me about 3.5 X the filter area I had. But the PSI guy still recommended 2 slightly smaller units that would have give me about 500 square foot total! Speculation on my part, but I think the units with excessively large filters are meant to go longer before they need cleaning, a lot og uys don't clean them so they will just run fine for a very long time. I know this, my unit had 2" of backpressure (I have a gauge on it) with my old filter, and it's now 0" (zero") of backpressure….more filter area would not lower that number, so I'm moving max air. Still, I'd like to know what the manufacturers are thinking with all that filter area. Especially since that does add something to the cost of the unit. Back to your question: you will be (my guess) just fine with one filter. Besides, buy one, and if you don't like the performance you can add a second. BTW, consider the PSI CYFN36 filter with your choices. It's USA made, Merv 15, 350 Sq. ft. and only $160 if it's dimensionally close to what you need (14" d x 36" long). I put that one on my Oneida.


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## gtbuzz (Sep 19, 2011)

That's kind of what I figured. I was leaning towards running the DC with just the single filter to start off with and just seeing how I liked it.

Out of curiosity, how do you measure the back pressure on your system?


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## crank49 (Apr 7, 2010)

The old rule of thumb for bag type filters used to be any thing over 10:1, air to cloth would probably plug up.
by that rule, 1000 cfm needs at least 100 sq ft of filter bag surface area.

Cartridge filters entered the market and because of their pleated form they increase the filter surface area within a given size package by about 7 times. But, also because of their pleated form they are easier to plug up. Also, the cartridges tend to have much smaller porosity which catches smaller particles but also tends to be easier to plug.

My gut feeling, based on my experience with dust control in a foundry environment, is that the cartridges are about 3 times better than bags instead of 7 times better.


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## wapakfred (Jul 29, 2011)

I put a Magnehelic gauge on it. The gauge cost about $25 shipped (flea-bay), amnd had the fittings needed to put it on my DC…it was a piece of cake. I put it on because the DC was blowing ALL the fines into the filter, this give me info on when I needed to clean it, and also told me when I couldn't get it clean anymore. Oneida suggests cleaning it at 3", I would clean at 2" and see the pressure drop various amounts, but it always dropped. I replaced the filter when I could no longer see the pressure drop after I cleaned it. Here's a pic:


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## StumpyNubs (Sep 25, 2010)

I would definitely shoot an email over to the guys at Wynn. They are super nice people to talk to since they're a small company. They will give you loads of free advice and then you can decide what to buy and where to buy it.

All of our shop filters are from them. They have the best quality, service and often the best price too.


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