Wood Magazine to Test Whole Shop Cyclones

[Lou Stags]

Don't think it's possible to knock Bill P - he did the work, established a design which many many users (myself included) have found works extremely well for them, and stuck his neck out big time to get get it established - and money clearly was not the motivation. His pages remain far and away the most usable, comprehensive and readily accessible source of dust system data around.

The issue of lack of hard data on dust system components and on the health implications of dust that we have discussed is a more general one - it extends right across the board in the case of especially DIY and hobby dust systems. Bill himself made efforts to get testing done, but in the end it's an expensive undertaking and there's limits to what a single man can achieve.

I'd really love to see the means emerge for the creation of the dust collection manual we've been discussing. The suggestion of taking up a collection here is a decent start, but my personal sense is that it needs some professional involvement too to make it happen...

ian

Help me understand the following quote from his site: " Independent medical school testing shows my innovative cyclone provides five times better airborne dust separation than its nearest competitor."

ClearVue makes reference to this fact on their website as well.

Where can I read about that test? Who conducted that test? How was it conducted? What were the actual results? Who was the nearest competitor? ... etc... etc...

For a design that is all about the science behind it all, I am very curious why the details of an INDEPENDENT test that demonstrated such amazing results is not plastered up and down the Pentz website as well as the ClearVue website?

[David Kumm]

One thing no one has brought up how JDS manages (or at least claims) to achieve high volumes at high static pressures, despite (or because of) having a really short 3hp cyclone. I find it fascinating that they come up with some magic no one else can do.

• New and Improved "Turbo Fan" impeller is larger, resulting in more Power!
• 2300 Max CFM!!!

They don't give the fan curve anymore, but it is astonishing.

Maybe a little magic but not a lot. They are running 15.8" impeller on an 18 amp motor. If the motor is fairly efficient it is closer to 5 hp. The short cyclone will have less pressure drop. The impeller is likely a little more efficient than most but a 16" 5 hp system gets close to those numbers. The curve of the blades can impact that cfm at pressure but the risk is overheating the motor at low pressure. Dave

[Alan Melbourne]

i think the problem is that there is no clear guidlines that all these systems must adhere. or even a set group of spec criteria that must be documented
be it cfm(true independant figures) ,fan curves, filter resistance ,seperation efficiency. etc etc

until those numbers are documented (and are independantly verified) you cannot truly compare each system to each other



i agree with lou to a point.
a test like that is irelivent if it isnt shown and documented properly and can be scrutanised and your own opinions gathered.
why isnt it shown
if a billl pentz fan. he is the main go to guy on dc on the internet. when ever anyone starts a thread on dc two names come up, bill pentz and phil thien.
i started building a pentz cyclone but hadnt the metal tools to finish it. now im hooked on the thien baffel.
not sure if it is as efficient as bills cyclone but it is easily effient enough for my needs

[ian maybury]

Hi Lou. I think you'd have to take up with Bill and/or Clear Vue the question of where that information comes from. The major thrust right through this thread (and in others) though has been the question of the low availability of hard test data for DIY and hobby dust system components - filters, fans, cyclones and the like.

What i did try to say was that while the available test data is limited that there seem to have been many examples of Bill's system tested in terms of the room air quality delivered (both using the Dylos meter and similar, and by subjective experience), and that it clearly seems (as a total system) to do a very good job. He's still very clear though that additional precautions are necessary, especially if you are sensitive to wood dust.

I'd love to see more comprehensive data available on these and the related topic of actual risk vs dust exposure levels (Bill briefly addresses this briefly in section E, 'Probability of Harm' in the intro to his pages), but the point made was that this scenario applies right across the industry...

ian

[Michael W. Clark]

Seems like I remember reading an article on the Clear Vue site about how they did their testing. The article I read described alot about how they generated the particles. They were very concerned about generating all the particles to be the same size which I really didn't follow. Why would they be concerned about all particles being the same size?

Cyclones have an efficiency curve, more efficieny at larger particles and less efficient on smaller particles. In addition, its not as much about the physical size of the particle as it is about the particle's aerodynamic properties. For this reason, cyclone efficiency is best described in terms of aerodynamic particle size. For example, two 10 micron particles, one is spherical, the other is flat. The flat one is going to be much more difficult to push to the outside wall where it can be collected, therefore it would have a much smaller aerodynamic size even though the physical size is the same.

There are a lot of myths, heresay, etc with regards to cyclone efficiency. Even with industrial cyclones, manufacturers will claim efficiencies that are not possible with their offering. The customer has to be educated as to what to look for in that particular application so they can properly evaluate the options proposed.

Mike

[Lou Stags]

The major thrust right through this thread (and in others) though has been the question of the low availability of hard test data for DIY and hobby dust system components - filters, fans, cyclones and the like.

What i did try to say was that while the available test data is limited...

But according to Bill and ClearVue, there IS some very hard test data available. Look at Bill's quote. Look at the reference to that quote on ClearVue's site. According to them both, there is some very hard data out there that supposedly demonstrates how well Bill's design works.

You mentioned that a big problem in the industry is "low availability of hard test data". Another poster mentioned that anytime the topic of dust collection comes up (here or elsewhere), that inevitably Bill's name is right at the top. If the "hobbyist woodworker dust collection guru" has some hard data from an independent medical school, why wouldn't he reference it? Why wouldn't ClearVue?

It really makes no sense to me, especially when Bill goes on and on about how other vendors are not truthful with their claims. Yet, Bill makes several claims on his site about his design that are backed by nothing other than the words on that web page. In my opinion, he has done the same thing that he complains about other vendors doing.

[ian maybury]

There's a lot of happy punters out there Lou, so clearly he's done something right - and there seemingly has been a lot of testing of shop air quality done as referenced above. As before though i can't answer as to the basis of any claim about his testing of actual cyclone performance. The five times comment is pretty highly generalised - it's not even clear exactly what aspect of performance he might have been referring to - but they do often talk about just how little dust is carried over into the tray after the filters and it may relate to that.

My personal suspicion on all of this is that single stage cyclones like those we're talking about operate very close to their limits in terms of capability on the finer dust we produce. It's hard to know even what to make of that. Michael's points about particle size and aerodynamic properties make sense, and the chances are that the density matters too.

It's actually quite likely that there are very big differences in performance between cyclones down in this territory - likely even between cyclones of the same design fed at differing airflow rates, with dust of differing particle size and shape distributions, and with differences in the installations. (e.g. longer or shorter straight runs into the inlets)

This might point to a scenario where (while there seem likely to be good and not so good designs) it's very hard to test a given cyclone and achieve repeatable results - and that even if the test is controlled tightly enough to be repeatable that it's not necessarily going to predict real world performance all that well. Hence hard to reliably and unconditionally say that a given cyclone will deliver xyz performance. The DIY and hobby field is often not generally very good at publishing the data, but it is available elsewhere for mainstream stuff like fans and even filters.

From the bits i've read it seems like maybe even high end industrial suppliers of cyclones tend not to advertise their cyclones as being capable of xyz. That they instead seem to prefer to test the client's dust samples on their equipment, and to only then (based on pretty comprehensive categorisation of the dust) to undertake a given level of performance....

ian

[Lou Stags]

There's a lot of happy punters out there Lou, so clearly he's done something right - and there seemingly has been a lot of testing of shop air quality done as referenced above. As before though i can't answer as to the basis of any claim about his testing of actual cyclone performance. The five times comment is pretty highly generalised - it's not even clear exactly what aspect of performance he might have been referring to - but they do often talk about just how little dust is carried over into the tray after the filters and it may relate to that.

My personal suspicion on all of this is that single stage cyclones like those we're talking about operate very close to their limits in terms of capability on the finer dust we produce. It's hard to know even what to make of that. Michael's points about particle size and aerodynamic properties make sense, and the chances are that the density matters too.

It's actually quite likely that there are very big differences in performance between cyclones down in this territory - likely even between cyclones of the same design fed at differing airflow rates, with dust of differing particle size and shape distributions, and with differences in the installations. (e.g. longer or shorter straight runs into the inlets)

This might point to a scenario where it's very hard to test cyclones and achieve repeatable results - and that even if the test is controlled tightly enough to be repeatable that it's not going to be very realistic. Hence hard to reliably and unconditionally say that a given cyclone will deliver xyz performance. The DIY and hobby field is often not generally very good at publishing the data, but it is available elsewhere for mainstream stuff like fans and even filters.

From the bits i've read it seems like maybe even industrial suppliers of cyclones tend not to advertise their cyclones as being capable of xyz. That they instead tend to prefer to test the client's dust samples on their equipment, and to only then (based on pretty comprehensive categorisation of the dust) to undertake a given level of performance....

ian

My point has nothing to do with people being happy with their purchase. Nothing at all to do with that. It has everything to do with what is in my opinion, very blatant hypocrisy combined with sensationalist claims and statements based on nothing.

The funny thing is I believe that a Pentz designed cyclone is probably very effective, maybe even more effective than other approaches.

In my efforts to research dust collection as much as possible, this summary is kinda how it always goes.

Newbie: I am new to woodworking and need a DC
BP supporter: Go read the Pentz website then buy or build a cyclone. That is only way you can do it right.
Thien supporter: Hey wait a minute. I built a Thien baffle with my single-stage DC, combined that with an air scrubber, and my Dylos meter shows I have amazing air quality - often times better than the fresh air outside.
BP supporter: You are not serious about DC unless you have a cyclone. Just go read what Bill Pentz wrote. And the Pentz design performs the best.

[Chris Parks]

Lou, send him an email with all your questions and you will get answers as he always replies. You can then come back here and let us know what transpired.

[Michael W. Clark]

Ian,
You are absolutely correct. The dust density makes a big difference (think lead dust vs. styrofoam dust) as well as the other items you mentioned and even more that have not been mentioned. Industrial cyclones are designed for an application. The design conditions are known, the dust distribution is known (from testing), the required efficiency is stated, then a cyclone is designed around this and performance guarantee is made. If the cyclone does not meet the required efficiency, the vendor has to fix it at their expense.

For "off-the-shelf" cyclone systems, the operating conditions vary from system to system, and they are often not known. How many people know the aerodynamic distribution of their dust, dust loading, the CFM, and static pressure capability of their fan? Many of the other variables would be common among home shops or could be designed for worst case. You might even say this for dust loading and dust distribution, pick a worst case. However, the CFM greatly affects the cyclone performance. But, the CFM is completely dependant on the fan's performance and how it matches with the system resistance. The vendor has no control over the system resistance, and most hobbiests would not have a way of telling the vendor what the CFM and SP requirements of their system needs to be.

In addition to this, there is a space (height) limit and budget is a major concern. As the height/size (and therefore cost) of the cyclone increases, so does the efficiency. Also, there is an imposed HP limit to keep circuits at or below the 20-30A range (3-5HP motor). So, the two things that affect cyclone efficiency the most, pressure drop and residence time (size), are limited. However, if you have a low efficient cyclone, it doesn't mean that all is lost. It primarily means that you will need to clean the filters more often and keep closer tabs on the filter pressure drop to avoid a reduced flow situation at the hood that allows more dust to escape the DC system.

Mike

[David Kumm]

So we should be talking about filters in terms of their ease of cleaning and durability as well as pressure drop and filtration ratings when new. I still would like to see mix and match components that an expert could advise us to use. This discussion has been interesting. One or two sizes do not fit all. Dave

[Michael W. Clark]

I think there are definitely multiple ways to get acceptable results. Air quality measurements are probably the most useful way of determining effectiveness. To Phil's point, if you could design the hooding appropriately, who is to say that a shop-vac could not work on some tools. Take the close capture DC hood on most new cabinet saws, that has to reduce the CFM required and should give better capture. It does come at the cost of static pressure, though. (4000 FPM through a smaller hose will have more loss)

Let's say a machine needs X CFM. If you had a DC system (cyclone, fan, filters) with a DP gauge reading the difference between the cyclone inlet SP and the fan outlet SP, then a curve/table from the manufacturer listing flows at various pressures, you would know the CFM you are pulling on your system by looking up your DP reading in the manufacturer's table. As the filters get dirtier, this DP would rise, and mean a lower flow. Once that flow dropped below X CFM, time to clean the filters. Obviously, you would determine filter cleaning time based on the most challenging branch (may not be the one with the machine requiring the most flow).

If this were the case with all the systems, then you could evaluate cyclone performance/filter offering vs. price based on reviews of how long it takes the DP to rise to an unacceptable level and frequency of filter cleanings. Obviously, filter efficiency is also a factor, but not sure HEPA is a must. I think your particle count will stay in an acceptable level with a media delivering 99.5% at 0.5-2.0 micron and maintaining the required flow at the machine. A HEPA filter doesn't help much if it blinds and reduces your flow so the dust never makes it to the filter.

This would remove a lot of the technical guesswork, but I don't think you can completely get away from the technicalities. The user would need to know how to determine when filter maintenance is required.

Mike

[ian maybury]

That's a thought of mine as well Michael - that it may be possible to do a good dust collection job with close hooding and lower CFM. The downside of it though (and seemingly the reason why Bill settled on a high CFM solution) is that (a) the reduction in volume of the low pressure bubble around the point of work means that any dust thrown out becomes less likely to be captured/ even more of a problem, and (b) the air cleaning effect is reduced proportionally as well. Neither is great news given the pretty much certainty that as a result of necessary compromises in e.g. saw guard design that dust inevitably will escape in certain cuts.

It indeed seems likely that short cyclones basically exist to save materials, shipping cost and head height - probably as you say at the expense of more dust in your filters.

We're pretty much stuck i think David. As before it'd help a lot if individual dust system components were properly tested to some agreed framework and characterised so that we could mix and match - or at least draw from enough information on the table to enable data based design of a complete system and choice of hardware. There's inevitably however going to be gaps until such time as the money, time and expertise can be brought to bear to get this job done, and the results published.

There's nobody that I've seen around here Lou indiscriminately knocking dust collection solutions - or for that matter hyping others. Most of the comment is based on practical user experience. That doesn't mean that there aren't differing takes on the issues - and I for one want to hear about it if somebody is running a solution and has a fact based view to offer on it - positive or negative. There's inevitably not going to be hard data available most of the time - but you're not i presume arguing that until 'proof' exists that nobody should report anything. Most of the claims made anyway have a basis in room air quality measurements - if not by the poster then at least by the originator and some users of the basic approach.

It'd be nice to think that completion of the above testing would settle these debates for one and all, but even if the work is done that's never going to happen. With the result that the answers are never going to be handed to the potential buyer of a system on a plate - the entry price to getting into a position where it becomes possible to specify a high performing system is either (a) do enough homework on how the damn things work, or (b) pay somebody who knows to do it for you...

It's real life again. There's ways we might like it to be - but in the end you pays your money and you takes your pick, but never have full information or the resources to do exactly what you might think you would like....

ian

[Lou Stags]

Just finished reading the article and I was less than impressed. If you spend 10 minutes on just about any forum and can find multiple threads about DC where people recommend adding a Thien Baffle to a single stage collector. Many have posted Dylos readings using that type of setup that demonstrate excellent air quality (especially when used in conjunction with an air filtration system). By not including this type of a setup in their testing, I think Wood's article missed the mark.

Overall, I give Wood's article a D+.

[Chris Parks]

Just finished reading the article and I was less than impressed. If you spend 10 minutes on just about any forum and can find multiple threads about DC where people recommend adding a Thien Baffle to a single stage collector. Many have posted Dylos readings using that type of setup that demonstrate excellent air quality (especially when used in conjunction with an air filtration system). By not including this type of a setup in their testing, I think Wood's article missed the mark.

Overall, I give Wood's article a D+.

Before you start thinking that a collector is god's answer to a single stage DE read the folllowing link and all the pages as it gets into exactly what you propose

woodworkforums/f200/want-your-dc-checked-invisible-dust-158263/

You may have to register to view the graphs but it will be worth it as the tests were done by someone who has at least a bit of an idea of what is needed to protect us from fine dust.