Indeed Michael, dont get me wrong - I am learning a lot about DC and the technical curiosity of the SMC community is one of the things I like the most about it!
I am always impressed and humbled by the knowledge here.
Contributor
Indeed Michael, dont get me wrong - I am learning a lot about DC and the technical curiosity of the SMC community is one of the things I like the most about it!
I am always impressed and humbled by the knowledge here.
Member
Me too Carl. I do this in my day job and realize that each industry/application has very specific design challenges. I am starting to form the opinion that home/hobby use has its own design challenges. There are some similarities to commercial/industrial woodshop dust collection, but because of the intermittent use and different machining situations (planing/sawing/sanding) there are some differences. For example, my post about the HEPA filters after the cyclone. I would shy away from it in an industrial application, but it may give acceptable results in home use.Originally Posted by Carl Beckett
Indeed Michael, dont get me wrong - I am learning a lot about DC and the technical curiosity of the SMC community is one of the things I like the most about it!
I am always impressed and humbled by the knowledge here.
Nothing beats real world experience and actual hands-on experience.
I think Ian has said this before, but I find these threads kind of addictive.
Mike
Last edited by Michael W. Clark; 03-21-2012 at 5:38 PM.
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When you think of the choices, fan design and how it affects flow at different pressures, cyclone design and how it is affected at different velocities, how the cyclone intake works with the "neutral vane" and how the helical fins affect the separation, how fan housing minimizes the turbulence to increase flow, how filter media and area affect the flow and how much is enough. Even knowing the actual resistence of the cyclone and filters, clean and dirty would make me feel like I had some handle on what works and what doesn't. Maybe more than I need to know but I like it when the info is available for me to NOT understand. Dave
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If I'm to be blunt my sense as an engineer with a background in R&D and manufacturing is that the hobby/DIY dust system field is a mess. There's lots of variables in the applications, but boy would it help if the makers would get their act together and produce test figures that (a) haven't been massaged to make them look good, and (b) use consistent test methodologies so that apples are being compared with apples...
ian
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I agree Ian - and obviously its needed or else there wouldnt be so many threads about it. (and sites like Bill Pentz! He had to do all that work himself!)
But that was what I was inferring - I dont believe a lot of design went into these systems. From a marketing point of view, a company might shoot their foot off if they did publish the technical specs. The manufacturers want to put a product out to maximize sales and minimize invested development cost. These companies arent set up to do eloquent design/development (it aint rocket science, just weld something together!). So you get the systems they make available, and you might be surprised (and disappointed even) at just how little design work went into them. (the Oneida system was clearly engineered - that surprised me!)
Clearvue has made a business by catering, to some degree, to this market. But at the end of the day just how many highly engineered hobby dust collectors can be sold each year?? (complicated by the fact that each individual install becomes a custom engineering effort - the business model doesnt scale past.... 1 )
(ok ok .... sorry to get off topic on yet another DC thread !!) Todd! Todd! This is your thread - let us know how we can be helpful.....
Last edited by Carl Beckett; 03-22-2012 at 7:30 AM.
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Don't read this as lobbing anything in your direction Carl, but TBH it's for me a matter of basic morality and integrity. There's a lot more engineering than one might think that goes into hobby/DIY dust systems - how else do they consistently manage to end up specified so that specific performance parameters that 'big up' the kit in question often end up dropping where it suits the maker?
The problem to me is mostly just that the objective of this engineering endeavour is often not what the buyer might hope it to be. That there are many prepared to sell stuff that does little or nothing to protect the health of the user. We of course often collude in this via our frequent unwillingness to face certain realities in this regard......
ian
Contributor
I'm not sure we should blame the companies when we as consumers don't ask enough questions to force the manufacturers to comply. I think hobby DC is like the US auto industry in the 1960s. It took competition to raise the bar and in the process the consumer got educated by the choices. We are spoiled to think someone should educate us rather than taking the responsibilty to do so on our own. This thread has provided all with a good list of questions for Oneida, clearvue, and others. My own belief is the clearvue is very well designed within the narrow parameter it markets to- the 6" main size. Oneida covers all sizes but gives no details regarding separation efficiency at any level. If we held their feet to the fire I think we would all benefit with some product improvements at a reasonable cost. Dave
Member
At a minimum, seems like a manufaturer could provide an intended operating window for their equipment. In other words, for a model "X", recommend an operating window of 1400 CFM at 5"wg inlet SP down to 1000 CFM at 8"wg inlet SP. If you know your machines, and number of users, you can come up with the CFM required. A little work by the manufacturer's could be done to guide you on approximate SP requirement depending on shop size and location of DC. In actuality, we don't care if the unit is running at 1150 CFM, but was advertised at 1200 CFM (probably couldn't measure it repeatably anyway). However, we do care if we are buying a unit advertised at 1200 CFM and it can only develop 750 CFM on our system.
You would have a cap on the max CFM related to the fan's performance and a minimum CFM due to the low efficiency of the cyclone and carryover to the filter.
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Mike, I think just knowing the SP the manufacturer uses to calculate the cyclone and filter losses would tell us a lot and allow us to compare given an inlet size. I may not believe the curves but solid numbers about the cyclone at 4000 fpm and how much and what type of filter is used and the difference between new and seasoned would allow for comparisons. The amp draw at your 5" and 8" example would tell us a lot as well about the fan efficiency. CFM can be juiced if the amp draw is more than the motor can sustain over extended periods. Airflow is still only part of the battle as separation efficiency- which is harder to measure- needs to be standardized. Right now we have no clue whether 99% is based on weight , volume, or smoke and mirrors. Dave
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Ok, here is a thought.
This group has the knowledge, equipment, and instrumentation- collectively- to generate the desired data. The manufacturers aren't motivated to do it, but it's perfectly acceptable for users to map performance and publish on a personal website ( like pentz site did ). Pick the top 5 most interesting systems and create our own database?
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This type of information for the hobby manufacturer's would be a big step in the right direction, in my opinion.
http://www2.donaldson.com/torit/corp...lone_08.11.pdf
[OP]
Member
I'm still here.
I've spent many hours modeling my dust collection system in Sketchup. I've been moving various dust collectors around trying to find nirvana. My latest plan is to put the Oneida Pro 2000 dust collector in the far corner of the garage, so instead of 12-13' run to the shop it would be ~24' run. The DC would be less intrusive in that corner of the garage. The longer distance has me leaning toward the Pro 2000 5HP, so I can run the larger ducts across the garage (as Oneida recommended).
By the way, If anyone wants Sketchup models of 6" PVC fittings, just PM me. I also have the Clear Vue CV1800, 2HP Super Dust Gorilla and my best guess at the Oneida Pro 2000 modeled.
Contributor
Mike that is my cyclone and although Pentz tells me it isn't as efficient as the Clearvue I've had what at least seems like very good separation when using my Performax 37x2. Filters seem to stay good for a long time although I'm a hobby guy so it might be different full time. The helical baffle looks like the clearvue and if you look hard you can see the round inlet converts from 8" on the 20" cyclone to a rectangle 13x5 and then narrows to 13x4" right at the side of the cyclone as it enters into the chamber. I have no proof but believe that is what helps to direct the air around the baffle and minimize turbulence to aid in separation. If you need 8" mains as I do the Torit is in my non scientific opinion the pick of the litter. If you look at Dust Vent, Sternvent, or other industrial units you see similarities in size, cone length and diameter. Either they are all right or all wrong. I'm sure it costs more to manufacture but it does seem to make sense. Dave
Member
The Donaldson looks like a good cyclone. They seem to be a good company, I know a few people that work there. They would probably build a unit (if they haven't already) with a cartridge filter on the outlet. They are very well known in idustry for their cartridge dust collectors.
The rectangular inlet is easier to fabricate. I'm not sure about the Donaldson from the pictures, but a lot of industrial cyclones have the inlet located on the outside of the body. It wraps around the cyclone on the outside and tapers into the body. This would be very difficult to fabricate round. They also probably change the area of the inlet to get the DP and performance they want. Inlet air speed directly affects efficiency and DP.
Member
I've not seen cyclone separation capability data like that published before Michael - although that doesn't mean much as I'm not in the way of it. Those cyclones are quite Pentz/Clear Vue like.
It's encouraging that they permit a pretty wide range of (highish) inlet air speeds (3,500 to 5,000ft/min in the sort of sizes we are interested in), but these as discussed before are higher airspeeds than many of lower HP dust systems will achieve. The diameter is not too far off that of the Pentz at 20in.
What's not so encouraging (if I'm reading it correctly) is that they only claim 40% retention/separation or less below 1 micron for the cyclone on its own - but maybe that's taking account of the wide range of permitted air speeds and their quoted 'actual efficiency may vary depending on the application. Dust concentration, airflow, particle shape, and density affect filtration efficiency. '
It could well suggest that the sort of very high levels of separation we see claimed/hope to achieve on fine dust are (if at all) only available over a fairly narrow range of airspeeds and dust types. It could be for example that unless we design dust systems to target optimium inlet air speeds that we may be risking a dis-improvement in cyclone performance.
Unbiased testing would be great Carl. Two issues though: (1) it could result in individuals being leaned on by 'concerned' interests who it seems like to play hardball, and (2) it's pretty labour intensive.
David said it before, but maybe testing by an independent authority would be an alternative. It would avoid these issues, and by reducing the problem to being one requiring only funds to get it moving might make it easier to arrange for many more people to contribute.
The question is where should one stop. Testing of available units is one option, but it'd also be highly useful to end up with a model predicting performance for given dust type and airflow conditions - perhaps predicting the effect of changing dimensions too.
Such models probably/may well already exist, and there is very possibly relevant test data already out there. Perhaps we could establish a fund to enable a committee to interface with one or more chosen groups working in the field of modeling cyclone performance? To access and make available this data?
ian
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