Clear Vue Cyclone...

[dan sherman]

By the way, I find it interesting that so many people intensely question the credibility of the Wood Magazine experts but nobody is questioning the credibility of Bill Pentz, who designed the Clearvue cyclones.

What makes them an expert, the fact that they work at wood magazine?

[Art Mann]

First of all, I agree that the write-up, and possibly the test procedure as well, leave something to be desired. For example, they did not repeat the test (as far as I can tell) to verify their results. I consider that essential. Secondly, there could have been quite a wide variation in the quantity and timing of dust generation, which was accomplished by sending MDF through a drum sander. On the other hand, at the expense of repeating what someone else has said, if it takes all that much trouble to seal a Clearvue cyclone so it won't leak fine dust, then maybe the product isn't a very good product in the first place. If the guys who did the testing couldn't find all the leaks even though they were looking for them, what is going to happen to some guy who buys one and doesn't have access to either a particle meter or an anemometer? I certainly don't blame the testers for giving up searching for leaks after a while since they didn't have to do that with any of the other units. To continue to work until the Clearvue performs like its competitors is unfair to the competitors.

I really doubt that the Wynn filter is the source of the problem. I have seen the performance of their standard filters measured and it was very good. I wish I could remember where.

I don't see why it is so hard to believe that Clearvue would perform in a mediocre fashion. Blower and cyclone design are complex and are important to the performance of a dust collector. Maybe the CV1800 is just not that good a design, but nobody has previously proved it by doing a comparison based on actual measurements.

I'm not willing to say Clearvue is as bad as the measurements suggest but I am not willing to declare the Wood Magazine consultants inept or incompetent simply because they didn't find Clearvue to be the best performer either.

That's easy. Because truly impartial experts would not have left it at "unit B passed 20x the fines of previously tested unit A," they would have explained WHY that was occurring.

There are really only two possible explanations that I can think of (anyone reading this is welcome to offer others): (1) Inadequate filters. (2) Leak.

So let's employ the process of elimination...

If you think the filters are inadequate, just say so and provide a little documentation (there are well-defined standards for filter media) and you're done.

Excluding the filters, it has to be a leak, right? Just fix the leak and retest. Smear every seam with a gobs of silicone if need be. Get another tube of caulk, if necessary, make it ugly. And you can mention this in the article ("man, that thing had a leak and it was a bear to find").

If you have smeared all the seams, and the problem continues, it has to be a hole somewhere in the filters, right? They could have swapped the filters between unit A and B. They could contact the manufacturer and request a 2nd set of filters.

Those are the steps I believe a true expert would have taken.

Leaving the reader with the impression that unit B passes 20x the fines, and that this is typical of all unit B's, not so much.

All just my personal opinions.

[Alan Schaffter]

I have no way of knowing if this often-overlooked characteristic of cyclones came into play during the testing, but I will mention it anyway in case others are making the same mistake.

The separation of dust in a cyclone is dependent on centrifugal force which is a function of the velocity and mass of the dust particles. As the air spins the particles are forced to the cyclone wall where they will hopefully decelerate because the air at boundary layer at the cyclone wall is much slower. Fine dust has low mass and that is why they are harder to separate cyclonically. Decreasing the radius (the cone) is an attempt to counteract the natural tendency for air to decelerate as it goes from a small duct to the large volume of the inside of the cyclone and to give the cyclone more opportunity to separate the fine dust. Unfortunately, with low mass, the fine dust won't want to fall out of the airstream easily either.

If you commence collecting dust before your blower is up to full RPM and the air is moving at maximum velocity or you turn the blower off and let it begin to decelerate before you have stopped generating dust, the velocity of the air within the cyclone will decrease as will the the separation effectiveness. The end result is that more dust than normal will continue on to the filters. This is something that is easy to forget or overlook.

[Paul Stoops]

One thing about the testing article that struck me as strange was the gross difference between their test results and Clear Vue's own published fan curve:

Clear Vue Fan Curves 1.jpg

The comparison would lead me to believe that there was something wrong with the equipment or testing or both.

Paul

[Ole Anderson]

Makes you wonder who is right. Many fan curves from the manufacturers don't agree, even roughly, with curves in the side by side magazine tests. At least the tests by the magazines, and there have been more than one, supposedly test all of the machines in the same manner, so there is a fair comparison between them. I would lean toward using curves from a side by side test rather than manufacturer's curves simply because you have no idea if the manufacturer's info is right compared to another manufacturer's data.

[Ole Anderson]

Finally, the fan table (they don't include an actual fan curve, at least I coluldn't find one) shows a CFM of over 500 CFM through 4" duct. At a typical(?) DC air velocity of 4000 fpm, 4" duct will only pass max of 349 CFM! Even at 6000 fpm (possible?) a 4" duct will only pass a max of 524 CFM. Add the pressure drop from a machine, pipe, fittings, filters, etc. and what are you left with?

Here is a pic of my 2 hp Oneida SDG sucking 570 cfm at the end of a flex hose fitting (4.12" diameter), velocity measured at 6,160 fpm. With the hose removed I measured 752 cfm at 11,250 fpm through the 3.5" diameter blast gate on a 4" snap lock vertical connected to a 5" horizontal run connecting to a 7" main.

[Phil Thien]

Here is a pic of my 2 hp Oneida SDG sucking 570 cfm at the end of a flex hose fitting (4.12" diameter), velocity measured at 6,160 fpm. With the hose removed I measured 752 cfm at 11,250 fpm through the 3.5" diameter blast gate on a 4" snap lock vertical connected to a 5" horizontal run connecting to a 7" main.

Not really. You have more math to perform, to compensate for the obstruction by the anemometer itself, and you have to compensate for the fact that the air is moving faster at the center than at the sided. In a nutshell, it is more complicated than that.

[Phil Thien]

If the guys who did the testing couldn't find all the leaks even though they were looking for them, what is going to happen to some guy who buys one and doesn't have access to either a particle meter or an anemometer?

Two points:

(1) I think I've made this one before, but people with particle counters and steel cyclones have found leaks as well. Leaks aren't limited to the Clearvue.

(2) If you can't find/fill every leak with a tube or two of caulk, then how much of an expert is one? Seriously, not asking anyone to split atoms here, we're plugging leaks with caulk. Non-experts have certainly accomplished this. It just doesn't make sense to me.

For the record, I'm not particularly a fan of either CV of BP. But fair is fair.

[dan sherman]

Makes you wonder who is right. Many fan curves from the manufacturers don't agree, even roughly, with curves in the side by side magazine tests. At least the tests by the magazines, and there have been more than one, supposedly test all of the machines in the same manner, so there is a fair comparison between them. I would lean toward using curves from a side by side test rather than manufacturer's curves simply because you have no idea if the manufacturer's info is right compared to another manufacturer's data.

Fan curves are usually just that, the fan only (impeller, hosing, & motor). It's like when a car manufacture quotes horsepower, it's the power at the flywheel, not what eventually get's to the wheels.

[Art Mann]

Here is a pic of my 2 hp Oneida SDG sucking 570 cfm at the end of a flex hose fitting (4.12" diameter), velocity measured at 6,160 fpm. With the hose removed I measured 752 cfm at 11,250 fpm through the 3.5" diameter blast gate on a 4" snap lock vertical connected to a 5" horizontal run connecting to a 7" main.

You really need to use a hot wire anemometer to measure the velocity in an area that small. The little fan will have more of an effect than you might think. Also, as Phil said, you need to have some way to compensate for the fact that air velocity is very far from uniform across the cross section. With a hot wire anemometer, you can measure velocity at many points at the inlet and then average them as a pretty good approximation of the effective air velocity. My observation of small diameter pipe has been that the average air flow is something like 0.6 to 0.7 of the maximum.

[Ruhi Arslan]

Wow... nothing steers it up as good as the sucking sound of air mixed with dust.

[Chris Parks]

Wow... nothing steers it up as good as the sucking sound of air mixed with dust.

That does seem to be the case. I have often wondered and have asked the question before, why does DE cause such a huge contrast in views, some quite strong. I wonder if a company ordering a DE system causes this same phenomenon of strongly divergent views between engineers etc. Even the manufacturers, particularly Oneida, take extremely strong positions. I think it must be because there is no single standard and quite a few are like smokers and refuse to see the health issues. No one it seems has a balanced view, it is one side of the fence or the other in any debate that happens.

[dan sherman]

That does seem to be the case. I have often wondered and have asked the question before, why does DE cause such a huge contrast in views, some quite strong.

I can think of a few reasons:
1. grumpy old man syndrome
2. ignorance
3. pride in what someone has already purchased. By that I mean people who get butt hurt when they find out what they purchased might not be the best and then will vehemently say that it is.
4. vendettas

I wonder if a company ordering a DE system causes this same phenomenon of strongly divergent views between engineers etc.

I'm going to go with no, because when they order a system it's a large custom job that sit's outside the work area, usually even outside the building. Take a look at the specs of a 20+ HP machine, the fillets are usually less efficient 99.9% not 99.9X% that he see on home shop or one man shop set-ups. basically they care a lot less about the air quality and a lot more about getting the dust away from the machines.

[Michael Mahan]

that and the large shops just want the chips/dust outta the room & away from the workers due to OSHA

Home shops are some people's last bastion of personal freedom IE; look at the SawStop threads , the same polarizing effect there too

as pointed out on a In-famous woodworker site it's the Dusties VS the Chippies as per Stumpy Nubs

[Chris Parks]

Mmmm, I am not sure. I suspect that in the commercial world there is a very large divergence of views but a contracting company never allows the debate and just signs the cheque. it would be interesting to take a few systems along with their designers and do some real research, not some half baked magazine article. No magazine has the time or the funds or the inclination to do it properly. this isn't a hand plane test this is something that has a lot of hidden and unseen problems and needs proper research, none of which has been done by anyone. BP as good as his intentions and information are is not the end all and be all of the problem.

Having said that I wonder why no one else has tried to extensively refute what he has done or produced a similar body of knowledge confirming what he has done. We see a lot of minor criticism of his work but those who criticise do not seem to want to PROVE in a similar volume of work that he is wrong. His work is always upheld as the bible for one reason only, there are no other similar sites at a comparable level and this p+++es people off as they get sick of it being rubbed in their face as "the bible or DE". Fair enough but if that is the case then why don't those same people gather their facts and start a site explaining what they think is happening.

We see it in this thread, some people questioning the efficiency of the CV. Why don't those same people prove their point not just spout criticism. I have never seen this volume of criticism leveled at other cyclones available on the market, Why is that? Any criticism of any DE system no matter who makes it needs to be substantiated in my view not just words in a post.