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"WOOD" Magazine - On Dust Collector Filters ???

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Forum topic by jimintx posted 05-05-2017 03:16 PM 2155 views 1 time favorited 41 replies Add to Favorites Watch
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jimintx

509 posts in 1419 days


05-05-2017 03:16 PM

Topic tags/keywords: dust collection reviews filters canister bag

I just got the July 2017 issue of WOOD. It has an interesting article comparing eight dust collectors. They are floor-standing models, ranging from $335 to $900 stated prices. They are typical single stage collectors from most of the major recognizable brands.

Here is the surprise, and the question:
The test results show that the six units with bag filters accomplish better filtration that do the two canister filter-equipped models. The two canister filter “losers” are from Jet and Powermatic.

I have always been under the impression that canister filters were definitely the way to go if one can afford that style. I am really surprised by this result from the magazine tests. What do you folks have to say about this outcome?

In case you’re interested, they label a Shop Fox and a Jet with bag filter as the best tools, and a Grizzly (1028Z2) as the best buy.
,

-- Jim, Houston, TX


41 replies so far

View Bill White's profile

Bill White

4802 posts in 3795 days


#1 posted 05-05-2017 03:29 PM

I have the felted bags (2) on my HF unit. They do all I’ve ever needed. So much for the canister idea.
Bill

-- bill@magraphics.us

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mrg

781 posts in 2834 days


#2 posted 05-05-2017 03:56 PM

The take away was that the cartridge filter when it had a cake on it was better at filtering but lost cfm. When you cleaned it it lost its ability to collect all the fines where the bag filters had the better filtering when cleaned. This leads me to believe that the cartridge material is not woven as tight so when clean it would not collect the smaller particles. But that would also means if it were tighter you would need to clean more often. That would lead me to believe that to use a cartridge filtered DC effectively you would need a system with a lot more cfm out of the gate to compensate for the drop. So the two that tied and the one that won best value had the best filtration and airflow for a hobby shop.

-- mrg

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bigblockyeti

4697 posts in 1555 days


#3 posted 05-05-2017 04:28 PM

Merv ratings aside, the primary advantage of a cartridge filter is greater filtering media surface area in a compact unit resulting typically in more time before the media is clogged and needs to be cleaned. It’s only good at filtering if the media is of the required rating for the task.

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jimintx

509 posts in 1419 days


#4 posted 05-07-2017 02:48 PM

Powermatic offers the same collector system with either a cloth bag or a canister. They state the bag is rated at 30 micron removal, while the canister removes down to 2 micron. Their canister has six-times greater filtering surface area than does their bag.

From the chart in the article: measured particle count^ emissions after sanding five MDF panels in the test:
~ the Jet with bag is emitting about 100
~ the PM with canister emits nearly 1,000
This data says the PM canister is 10 times worse for small particle emission.
[^for particle size of less than 0.5 micron]

I have a hard time squaring the specs on the filtration level of the bag vs the can, with the actual measured data in the WOOD test. It somewhat suggests that the manufacturers spec data on the canisters is either wrong, or misleading, or maybe both.

I am not trying to say their data or methods are flawed, but I am saying this article clearly indicates that paying extra for a canister filter to get down to the 2 micron level is not money well-spent, at all. And that is quite different from all I have read, or perceived, or thought, or observed, over my 30+ years of woodworking.
.

-- Jim, Houston, TX

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Rick_M

10610 posts in 2214 days


#5 posted 05-07-2017 04:50 PM

Marketing people exaggerating specs? I’m shocked. Next thing you know they’ll be trying to pass 3/4hp motors off as 1hp or trying to sell you a 3hp router.

-- http://thewoodknack.blogspot.com/

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AlaskaGuy

3642 posts in 2144 days


#6 posted 05-07-2017 05:56 PM



Marketing people exaggerating specs? I m shocked. Next thing you know they ll be trying to pass 3/4hp motors off as 1hp or trying to sell you a 3hp router.

- Rick M

+1

-- Alaskan's for Global warming!

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jimintx

509 posts in 1419 days


#7 posted 05-07-2017 07:53 PM

I appreciate you guys wanting to be wise-a$$ about marketers and marketing.
Turns out that I do understand the hazard of taking marketing claims as being totally correct.

My point – that I hoped to read some discussion about – is not about the specs being right or wrong. It is about a test outcome that indicates that if you want to filter out particles down to 0.5 microns, you are better off with a filter medium that will filter down to 30 microns versus one that will filter down to 2 microns. It is a paradox, a conundrum, maybe even a bit of irony.

-- Jim, Houston, TX

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Rick_M

10610 posts in 2214 days


#8 posted 05-07-2017 08:15 PM

In both your posts you express surprise and skepticism that the results do not match the marketing specs so I don’t think my comment is off the mark, though I will admit to being a smartass about it. But I’ve only glanced at the article, not actually read it so when I’ve done that I’ll try to contribute something more useful. In the meantime, I’m surprised they used 30 micron bags because I thought those had been supplanted by sub-5 micron bags.

-- http://thewoodknack.blogspot.com/

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jimintx

509 posts in 1419 days


#9 posted 05-07-2017 08:50 PM

Rick, you might be on to something.
Perhaps the bags in the test filter to lower particle size than the one that comes on the Powermatic system.

I guess I am still not saying this in a way that expresses what surprised me, so at the risk of being redundant, I will try one more time:

If my goal is to filter down as much as possible to 0.5 micron (and that is wha the test measured), then I would have predicted that a 2 micron filter would do better than a 5 micron, or a 30 micron, even though none of those claim to filter down to 0.5.
And the test results say my sense on that is wrong.
So that is what was surprising to me. Marketers overstating stuff and slanting the actual data – that doesn’t surprise me.

.

-- Jim, Houston, TX

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TravisH

551 posts in 1770 days


#10 posted 05-07-2017 10:33 PM

The test results may very well be flawed due to improper set up, other issues with the collector, and introduced bias into the testing. Tricky part of testing you need trained people to do it. Now the test may very well show that they need to make the system simpler so monkeys can set it up properly.

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Rick_M

10610 posts in 2214 days


#11 posted 05-07-2017 10:34 PM

I just finished reading it and the results are suggestive. They tested the Jet with both filter and bag and the bag was clearly a better filter, but the cartridge had better CFM. Not really my area of expertise but in a way it makes sense that if there is more air moving then more fines may be pushed through the filters. But then what is intuitive doesn’t always turn out to be true. Edit; actually they address it in the article that more cake will reduce air flow but increase filtration.

-- http://thewoodknack.blogspot.com/

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Rick_M

10610 posts in 2214 days


#12 posted 05-07-2017 10:42 PM



The test results may very well be flawed due to improper set up, other issues with the collector, and introduced bias into the testing. Tricky part of testing you need trained people to do it. Now the test may very well show that they need to make the system simpler so monkeys can set it up properly.

- TravisH

Actually I wouldn’t consider improper set up a testing flaw but an example of real world conditions. The guys doing the testing are representative of woodworkers in general so if they make an easy mistake then many of us will probably make the same mistake.

According to the article they actually went to great lengths to improve machine performance beyond how it was received, which to me is a testing flaw.

We also discovered that each machine
had small leaks where dust escaped, sometimes
particles so tiny we couldn’t see them,
but could feel the air movement. Before
beginning our “official” testing, we sealed
up leaks around metal seams and welds with
silicone sealant or duct tape, and used
adhesive-backed foam weather stripping to
improve the seal around bag rims.

-- http://thewoodknack.blogspot.com/

View ArtMann's profile

ArtMann

683 posts in 651 days


#13 posted 05-09-2017 03:09 AM

I have lived with a 1 micron felt filter bag on my Delta single stage dust collector (50-760 I think) for a long time. I haven’t decided whether to replace the bag with a canister style filter or just retire the machine and get a better collector. The point is I hate those filters and don’t ever want one again. If you use a filter bag machine a lot, you will find that the suction quickly goes away due to filter clogging. Cleaning a bag filter is one of the messiest things I have ever done and it is very, very dangerous to your lungs. When you start handling a clogged bag, ultra fine dust comes off the surface and causes a dense choking fog in the immediate vicinity. I always wear the best respirator I can find and still I sometimes feel the effects of dust inhalation. There is more to judging a filter apparatus than just measuring particle counts. Right now, if I went out to my shop and hit the filter bag with a fly swatter, a big puff of dust would come off into my face. I don’t think a cartridge would do that.

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TungOil

744 posts in 329 days


#14 posted 05-09-2017 03:34 AM

I’ve not read the article, so I’m speculating. It could be that they simply didn’t have enough ‘stick time’ on the cartridge filter to get to full filtration efficiency yet- not enough cake built up. I’ve used both style filters and based on my (admittedly small) sample size the cartridge filter is waaaaay better than the bag for filtering out the fines. Even with a new filter bag from American Filter my old DC would still leave a build up of very fine dust around the piping. I get significantly less with the cartridge filter. It took some time to get to that level of filtration however. When I first put my new DC into service I was disappointed that there was still a good bit of dust around the shop. It went away with time however.

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

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Rick_M

10610 posts in 2214 days


#15 posted 05-09-2017 04:11 AM


... it is very, very dangerous to your lungs.
- ArtMann

It’s wood dust, not uranium. Let’s keep things in perspective. Shaking out a dusty bag isn’t going to hurt you unless you do it all day, every day. Stand up wind, wear a respirator if you are sensitive. Long term exposure is what gets you. When I shake out my bag, I leave it on the dust collector and give a few good whacks with a dowel, that way the dust falls into the bottom bag.

-- http://thewoodknack.blogspot.com/

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