Wood Magazine to Test Whole Shop Cyclones

[Michael W. Clark]

For those of us who can't seem to find a copy, what did they find?
Everyone is critical of what they didn't do, but what did they do?

Wade, take a look at my post #168. It doesn't entirely describe the article but provides a few comments on what they did/didn't do.

Mike

[Chris Padilla]

So who read the latest issue of WOOD? I just got mine. The article was okay...nothing ground-breaking but I'm not into all the measuring like some on this thread are.

[Paul Wunder]

I read it also, but my response is much different. They called the 3 hp Oneida their top tool because of its performance (CFM) and room air dust readings from a particle counter, but the only other cyclones they tested were 2.5 hp or less (they also tested a 2 hp Grizzley, and a 2.5 hp Penn State cyclone). Apples, pears and bannas!

The test parameters didn't strike me as a "real world" test. They ran MDF boards through a drum sander for a given number of passes and measured room air particles before and after the sanding. I would have preferred they use a table saw, jointer, planer, etc. similar to most shops. How many hobbyist shops have drum sanders and run MDF through it all day.

ClearVue was not included.

They also tested various 220V canister and bag single stage collectors and stated that the 2HP Powermatic was a good choice instead of the Oneida 3HP as its performance was similar when used in an average shop. No mention of the huge differences between single and two stage collectors and the strong possibility of having to replace the single stage filters more often than a cyclone.

To me, the test was not credible in the least. If anything , I think it would lead a dust collection novice in the wrong direction.

[Mark Burnette]

Any test should be reproducible and repeatable. Sanding a board x-number of strokes isn't very scientific. How about taking 1 pound of mdf dust and feed it into the duct in x-seconds time. That eliminates more variables. Then you measure the bag/drum and filter before & after to see how much of that 1 pound got into each. That's useful information & tells you how long your filter will last before needing to be emptied.

[Michael W. Clark]

Mark,
What you describe is precisely the way cyclone efficiency should be tested. If you know how much you are putting in, then you don't have to weigh the filter, only the drum. This gives you an overall collection efficiency on that particular dust, at that feed rate, CFM, temp, loading, etc. IF any of these variables change, then the efficiency will vary. Short runs give you results that are all over the place, the runs have to be long enough to produce reliable results.

The issue is that the different cyclones may be designed (I use the term loosely) for different volumes. So an Oneida cyclone may do very well at one flow, while the Grizzly is better at a different flow. Of course all of this depends on the pressure drop of each and the relative fan capability to maintain flow at that pressure drop. Maybe the performance difference across the different flows is negligible?

In my opinion, what really matters is how often you need to clean the filters, when you should clean them, how good did you clean them, and what is the filter rating. The only thing a cylone (or preseparator) does is reduce the loading on the filters allowing you to go longer between cleanings. Because of its arrangement, disposing of the bulk of the dust can be easier.

A highly efficient cyclone will only let the very small fines through. IF the filter velocity is too high, the fines embed too deeply in the media and cannot be cleaned. Over time, the clean pressure drop of the filter = the dirty pressure drop and the filter has to be changed. If it is not changed, you can loose flow at the hood and allow more dust to get airborne at the source.

A simple solution would be a gauge telling you the back pressure on the filter and the range where it should be. When you clean it and cannot get it back to an acceptable range, it is time for replacement. I don't understand why manufacturers don't do this as it would boost their filter sales and the cost to add this from an OEM standpoint would be minimal. How quickly this happens is directly related to the amount and size of dust being handled, filter velocity, and filter efficiency rating.

This is why I was disappointed that so little information was provided about the filters in the Wood review. They are the critical part that makes the system work so you can discharge inside.

Mike

[David Kumm]

Well said, Michael. Dust collection is complicated but not so far above our heads that we can't understand. I don't know if magazines assume we are too dumb or they are too stupid. The result generally serves little purpose. Dave

[Jim Neeley]

The result generally serves little purpose. Dave

I'd wager it meets its #1 purpose.. and that's to sell copies!

[Mark Burnette]

Mark,
What you describe is precisely the way cyclone efficiency should be tested. If you know how much you are putting in, then you don't have to weigh the filter, only the drum...

But it's good practice to so. If you suck up 1lb. of fine dust it will either go
In the drum or bag
In the filter
Settle in pipes, etc
Leak to atmosphere

The first 3 get the dust out of the air so are "good". If you input 1.000 lb. of dust but don't get 1.000 lb in the drum (you won't) where did the rest go? Measure everything and hopefully the numbers will add up & you'll have that warm-fuzzy feeling you've done it correctly.

[Alan Schaffter]

But it's good practice to so. If you suck up 1lb. of fine dust it will either go
In the drum or bag
In the filter
Settle in pipes, etc
Leak to atmosphere

The first 3 get the dust out of the air so are "good". If you input 1.000 lb. of dust but don't get 1.000 lb in the drum (you won't) where did the rest go? Measure everything and hopefully the numbers will add up & you'll have that warm-fuzzy feeling you've done it correctly.

The big problem is the wide variation between particle size and particle weight. The fine stuff is soooooo small and light. A couple of oz. of 50 micron or larger dust is not the same (volume and number of particles) as a couple of ounces of 5 micron dust. The little stuff gets nearly impossible to separate and weight in a shop environment. I can't say, but it probably takes some complex and expensive equipment beyond what Wood can afford to rent or buy. You would probably need to figure out a way to do this with a Dylos.

[Michael W. Clark]

Mark, one pound of dust will not tell you anything. If you are measuring cyclone efficiency, you don't care about the ductwork or filters, only what goes in the cyclone and what gets caught. The rest goes through the cyclone outlet by subtraction.

We have a pilot system at work and do this for industrial applications, plus our own R&D. You have to run it long enough so the ductwork gets coated and the cyclone does too if you want repeatable results. The testing is usually done to provide insight on full scale applications as necessary. It costs a lot of money to have the right equipment and the time to execute the testing.

I doubt Wood has these funds available since this is not their primary business.

Mike

[Mark Burnette]

Mike,
A manufacturer likely would require different measurements during DV & PV (design & product validation) than a user might find useful. I recently performed similar testing on my 3HP 2-stage Cincinnati DC. I bought the unit used and the PO had installed a large shroud around the fan intake. Not sure why--but the the result was it cut the capacity of my drum in half. I rarely need to empty my filter so the question for me was what effect would removing this shroud have on the amount of dust that gets into the filter? I dumped out the contents of my drum and sifted it through a 1/4" mesh to eliminate long or coarse shavings, then measured the weight of my empty filter & drum. I sucked up the pile of dust (about 15 pounds worth) and re-weighed the filter & drum. This told me what percentage of dust bypassed the drum & ended up in the filter. I did this 3X and the test was very repeatable.
I then removed the shroud and re-ran the series of tests. The outcome was I did end up with more fines in the filter--but it was a more than acceptable increase.

People DO care how much dust gets caught in the drum AND in the filter. If people didn't care we wouldn't have Dust Deputys, Thien Baffles & similar separators that attempt to extend the interval between filter cleanings & replacement.

[Phil Thien]

I doubt Wood has these funds available since this is not their primary business.

Mike

So are you guys volunteering to do a test of an Oneida vs. a Grizzly vs. a Clearvue?

Sounds like you're all setup for the testing.

[Michael W. Clark]

So are you guys volunteering to do a test of an Oneida vs. a Grizzly vs. a Clearvue?

Sounds like you're all setup for the testing.

Sure..get out the checkbook!

Seriously though, our target business is industrial, high efficiency, severe applications. I doubt we would have any interest unless the testing was profitable as compared to our equipment sales. It would be personnaly interesting for me though.

Mike

[Phil Thien]

Sure..get out the checkbook!

Seriously though, our target business is industrial, high efficiency, severe applications. I doubt we would have any interest unless the testing was profitable as compared to our equipment sales. It would be personnaly interesting for me though.

Mike

I think you guys should start an independent certification process.

You could certify units for separation, volume, and lift.

Then you could charge manufacturers to have their units certified, and consumers would benefit because they'd be able to make educated decisions.

To get the process started, you would have to purchase the first unit for testing purposes. But once you certify it, it will be the only one to be able to boast that is has certified results. The others would almost be forced to submit units for testing.

[Insert diabolical laughter here.]

[Michael W. Clark]

I think you guys should start an independent certification process.

You could certify units for separation, volume, and lift.

Then you could charge manufacturers to have their units certified, and consumers would benefit because they'd be able to make educated decisions.

To get the process started, you would have to purchase the first unit for testing purposes. But once you certify it, it will be the only one to be able to boast that is has certified results. The others would almost be forced to submit units for testing.

[Insert diabolical laughter here.]

Yes, and annual re-certification is only 50% of the innitial fee!