Dust Collector too small (HP) and locating in garage create dust on cars? [Archive]

Todd Brewer

03-16-2012, 9:49 PM

I bought a 2HP Super Dust Gorilla in December of 2008. My new shop with attached garage is now complete. I mounted the dust collector but have not installed pipe. Still playing with pipe design in Sketchup.

After some time using Sketchup I decided it would make more sense to put the dust collector on the garage side, you know, the side that is supposedly for cars and meant to remain somewhat clean. :)

I am the only user so only one machine operating at a time.

All piping is to be 6" S&D from DC to each tool.

Distance from DC to SCMS would be about 31' 270 degrees of turns.
Distance to TS would be about 40' and 360 degrees of turns.
Most other machines are further,maybe 45'. Jointer, router table, band saw, drill press.

So my questions are:

1. Is my DC underpowered? The more I read the more I see people using 5 HP DCs (mostly clear vue folks). I emailed Oneida mid-day today (Friday) to see if I can get a more powerful motor for my DC. Haven't heard back yet.
2. Locating the DC in the garage has benefits, lower noise, DC is not taking up shop space. But will I regret it if it creates dust on the garage side? Has anyone had the canister connection fail and end up with a giant dust cloud? (Hopefully this is very rare.)

The Super Dust Gorilla is very heavy! I want to relocate it this weekend but won't bother if the consensus is to sell it and get something bigger. Weight is not an issue once mounted, but moving it, oh boy!

The Super Dust Gorilla is a very nice looking machine with it's bright yellow paint job. The clear Vue is highly regarded, just doesn't look as nice. :)

Keep it?
Upgrade it to a bigger motor (is this possible?)
Put it on Craig's List and get a more powerful machine?

Thanks for any and all advice/opinions.

glenn bradley

03-16-2012, 10:04 PM

I run a 2HP and have much shorter runs than you. Longest is maybe 25 feet. I sometimes wish for more power but, couldn't physically fit a larger unit. Maybe others with long runs could chime in.

Ron Natalie

03-16-2012, 10:17 PM

ian maybury

03-16-2012, 10:20 PM

It's bed time over here Todd, but some basic points:

1. It depends on what CFM you are shooting for. Around 400CFM is the recommended min for chip collection on most (smaller) floor machines, but up to and above 1,000CFM on especially larger machines if you buy the Pentz doctrine (which practice shows time and again checks out) on creating a large enough low pressure volume around the cutting process to capture the fine dust. You then need HEPA cartridge filters from a reliable source to catch that fine dust, and a cyclone to stop them blinding too quickly.

2. To get up towards the higher numbers requires around 3HP minimum, and that's with short hose runs as found on say a mobile unit. Longer runs and more bends will drop you back towards the lower CFM numbers.

3. Longer runs like what you seem to have require more like 5HP - that's maybe something over 4HP running steady state.

4. There's no point fitting a larger motor on a fan - it won't move any more air. For a given RPM the CFM at a given pressure is determined by the size of the fan impeller. It takes a 15in or better still 16in like the ClearVue to properly load a 5HP 3,450 RPM motor. The other advantage of a larger impeller is that it delivers much better performance at higher pressures, and so is less disturbed by the likes of a slightly restrictive hood or an extra bend or two.

Bill P's tables in sections 1 and especially 5 here provide a pretty good summary: http://billpentz.com/woodworking/cyclone/DCBasics.cfm

ian

Todd Brewer

03-16-2012, 11:13 PM

It's bed time over here Todd, but some basic points:

1. It depends on what CFM you are shooting for. Around 400CFM is the recommended min for chip collection on most (smaller) floor machines, but up to and above 1,000CFM on especially larger machines if you buy the Pentz doctrine (which practice shows time and again checks out) on creating a large enough low pressure volume around the cutting process to capture the fine dust. You then need HEPA cartridge filters from a reliable source to catch that fine dust, and a cyclone to stop them blinding too quickly.

4. There's no point fitting a larger motor on a fan - it won't move any more air. For a given RPM the CFM at a given pressure is determined by the size of the fan impeller. It takes a 15in or better still 16in like the ClearVue to properly load a 5HP 3,450 RPM motor. The other advantage of a larger impeller is that it delivers much better performance at higher pressures, and so is less disturbed by the likes of a slightly restrictive hood or an extra bend or two.

Bill P's tables in sections 1 and especially 5 here provide a pretty good summary: http://billpentz.com/woodworking/cyclone/DCBasics.cfm

ian

1. The whole CFM calculations thing make my head hurt. :)

4. That makes sense. I wonder if I can get a bigger fan and motor for my system.

Todd Brewer

03-16-2012, 11:24 PM

Those who slavishly follow Bill Pentz as the authority will tell you that nothing short of 5HP with one of his designs with the appropriate ramped vanes, yada ydada will suffice.

I've got a 2HP griz which has a 7" input wye-d down two 2 6" trunks around my shop. Works fine. The cyclone itself sits outside the shop in the adjacent aircraft hangar. Believe me, sawdust in the air out there would have my wife going crazy. Don't get obsessed over your configuration unless you realize and actual problem.

Thanks Glenn. I think part of my problem is reading on line and thinking my setup is insufficient, maybe it is, I just don't know. I'm hoping people like you will chime in and tell me if their system is acceptable. I have never run a DC. My shop has wood chips and saw dust all over the place. I'm not looking for "white glove" clean, but I do want to capture most of the dust. If the 2 HP is sufficient then that's great!

Glad to hear dust in your hanger, DID HE SAY HANGER? LOL is not a problem.

David Kumm

03-16-2012, 11:59 PM

Runs 40-45' ft long with lots of ells will not work effectively with a 2 hp 12" or so impeller system. Too much resistence in the pipes and not enough cfm will be moved to make your investment in time and money make sense. Six inch pipe over long runs simply needs more fan capacity. I have runs that long with a 5 hp 15+" impeller and actually run it at 63.5 hz to achieve fully loaded amps. You may find that with your machines a 3 hp 14" impeller might be adequate but that will be as low as you can go and not waste your money. I'm not a Pentz follower but have done enough actual testing of velocity and cfm over pipe sizes and distances to know the numbers. Dave

Paul Wunder

03-17-2012, 8:42 AM

Todd,
We can all offer opinions, but as they say, "your results may vary". Have you tried using Bill Pentz's Excel based worksheet (staticcalc) to calculate your needs? You will need the fan curve for your machine and your ductwork info (sizes, lengths, bends, etc) what machines you are using and where they are placed. Once you plug all of this into
his spreadsheet out will pop the answer based upon your situation. As I recall in using his tool I had to decide what level of collection I was after: chip collection, most fines, medical level.

billpentz.com/woodworking/cyclone/staticcalc.xls

Carl Beckett

03-17-2012, 9:07 AM

Hi Todd,

If you do any searching at all you will find nothing that generates so many threads (and some of them somewhat heated), as dust collection. There are some philosophical aspects, some specific aspects of your exact layout, and some technical aspects (with little common generalized understandings).

The Bill Pentz site does try to help guide you through these various aspects, while at the same time providing his own views/opinions on the subject.

So good luck on your decision - here is my experience (so far):

I had a 2hp bag system that filled my shop with fine dust every time I used it (I limited use to planing and my drum sander). I knew I was inhaling bad dust, so finally decided that yes I should make my health more of a priority and suck it up and do the dust collection. So I thought I could use some of the existing parts and add a cyclone, and do a permanent install and vent to the outside (thinking that I didnt care if it didnt separate great, because in my area I CAN vent to the outside so this is the best way and just let all the little stuff get blown out).

It just didnt work. Low suction at the tools. I thought about messing around with the ducts and tweaking and trying to get it to work on the ones that put out the most dust, but slowly had to acknowledge that it wasnt going to be adequate. Recommendations of air speed monitors, dust particle counters, pressure gauges, etc to take quantitative data to validate against design calculations had my head (and wallet) spinning (and Im an engineer!!! (or used to be) I have a day job, dont want to spend my hobby doing this crap). So in the end I am going to just add a super giant monster motor/blower to the cyclone and swap some pipes to 6 inch and be done. Then I dont have to worry about upgrading in the future (to add more equipment, or the DC itself). I can know its about as good as it gets in terms of keeping the dust down (and lungs clean - just the other day I cut some MDF on the table saw and can say I was wanting for better DC then).

For reference, I do subscribe to the philosophy that its the little stuff that is the worst health problem. So that really fine stuff floating around in the air (like every time you shut your car door - if its settling on the cars - isnt good for you. When I was younger I paid no attention to this stuff. Now I do. (age has a way of curbing immortality)

Another poster recently stated the two things they used most, was their table saw and their dust collector.

Ole Anderson

03-17-2012, 9:12 AM

If you kick up your main horiontal run from 6" to 7" you will reduce your pipe losses, but with PVC you would need to go to 8" which is likely too large for a 2 hp. I have the 2 hp Super Dust Gorilla, my main run is about 30 feet of 7" steel and works fine with my planer at the far end.

If you put the DC in the garage, will you leave the door open to allow that 1000 cfm back into your shop? Lots of issues with remotely located DC, particularly if you have a furnace.

If your '08 unit has the HEPA filter, dust in the garage won't be an issue.

ian maybury

03-17-2012, 10:25 AM

The more marginal the fan HP vs the size of the system, the more dependent it all becomes on getting the details exactly right if it's to work - and even then you'll be pulling the devil by the tail.

This has all been covered lots of times before, but the key choice is what minimum airspeed you decide to design your system to deliver. There's absolutely no argument about that in industry where dust systems are regulated - it's around 4,000ft/min. Which delivers 785CFM in a 6in duct.

Bill P sets out the background to these numbers (which he didn't invent) in the page I linked in the post above. The calculator that Carl linked will be based on the same. Cincinatti Fan in their Engineering Data manual (a .pdf download on their site) list 3,700ft/min for 'light shavings', 3,700ft/min for 'sawdust', and 4,500ft/min for 'heavy woodchips'. They don't even list data for transportation of any material for airspeeds below 2,600ft/min.

One problem with dropping below these numbers is that it leads to an increasing risk of dust accumulating in the ducts leading to fire and other risks.

It's hard to predict exactly because such small differences in pressure drop make such a big difference to CFM with a small fan like a 2HP when it's heavily loaded like this. Your ducting runs are very long for a system of this size. It's safe to say though that this discussion wouldn't be happening in the context of an industrial system - as a solution it'd be rejected instantly as hopelessly underpowered.

Depending on how the cards fall in your case you'll probably end up somewhere around 350CFM plus or very likely significantly minus which is very marginal (about 1,900ft/min in a 6in duct - see above on speeds) - depending on how finely tuned the set up and what equipment you are using it may or may not reliably do the basic job of picking up chips. It's certainly not going to be able to reliably handle say a 12in planer in a heavy cut, or do much to help capture fine dust/clean the shop air. Even a slight increase in restriction due to a dirty filter is likely to have very noticeable effects.

I took a look at the maker's data for the unit you have. They publish a curve, but don't list the impeller size. What I can say though is that I'd need some help to understand how they get a (presumably sustained - nothing else has any useful meaning) 1,349 CFM at 2.3inWG out of a 2HP fan using a BC radial impeller.

The highest that Cincinatti Fan claim from any low pressure (SPB) impeller and fan combo at 2HP is 1,108CFM, and that's at 1in WG - so low a pressure as to be useless for the sort of dust system we are talking about.

You're the customer Todd - and it's you that gets to pay your money and make your choice. You're going to have to do the work if you want to make an informed decision on this. There's as Carl suggests though one hell of a pleasure in having a system that does a really good job, protects your health, and does this regardless of the phases of the moon or the wind direction...

ian

Todd Brewer

03-17-2012, 11:31 AM

Paul, I didn't see the calculator on Bill Pentz' web site I'll check that out. Thanks!
Sounds like the 2 HP is too small. I have no problem selling it and getting a bigger unit. I'll invest in a 5HP unit. Health matters! :)
I could increase my main duct to 7" but then I have to deal with transitions back to 6" PVC. Maybe it's not that big of a deal.
Yes I will have a means for air to return to the shop, open door or other opening of some kind. My shop is not heated or cooled.

I appreciate you taking the time to help a fellow wood worker. Lot's of valuable information in all of your posts.

Thanks to all for your help!

Paul Wunder

03-17-2012, 12:44 PM

Todd,

I didn't want to color my original response to your question, but I also wound up with a 5hp unit (ClearVue). I use a 6" PVC duct system all the way (the CV main inlet is 6" and I have an around the room duct with the run approaching 50'. I'm in a basement with the cyclone in a separate room from my shop. Tremendous pull from the cyclone and very quiet since there is a room separating me from the cyclone. I have severe lung issues so I wanted the best collection I could. I am very pleased.

Paul

David Kumm

03-17-2012, 1:42 PM

Todd, as Paul said, with a 5 hp motor and 6" mains you will still have approx 1000 cfm. You will only be using about 4 of your 5 available hp but unless you have a machine that needs more cfm- 24" planer, edge sander, shaper- you will be fine. When you get to the 3 hp level you need to be careful to maintain enough filter area and limit the bends to keep the cfm up and minimize the resistence. The benefit of the larger motor is you avoid the real testing and run the motor a little under capacity. When you get to the 1200-1500 cfm level you need to watch the components of the 5 hp system to max it out. Dave

Ole Anderson

03-17-2012, 1:58 PM

Depending on how the cards fall in your case you'll probably end up somewhere around 350CFM plus or very likely significantly minus which is very marginal (about 1,900ft/min in a 6in duct - see above on speeds) - depending on how finely tuned the set up and what equipment you are using it may or may not reliably do the basic job of picking up chips. It's certainly not going to be able to reliably handle say a 12in planer in a heavy cut, or do much to help capture fine dust/clean the shop air. Even a slight increase in restriction due to a dirty filter is likely to have very noticeable effects.

I took a look at the maker's data for the unit you have. They publish a curve, but don't list the impeller size. What I can say though is that I'd need some help to understand how they get a (presumably sustained - nothing else has any useful meaning) 1,349 CFM at 2.3inWG out of a 2HP fan using a BC radial impeller.
ian

Ian, I am not going to take time to run his system through a pipe analysis, but 350 cfm in a 6" duct with that cyclone, just doesn't seem correct, nor do your conclusions based on that assumption. Oneida's curve shows 8" of suction at 785 cfm with a clean filter in place. http://www.oneida-air.com/Images/Static/2hp-super-fan-curve.jpg

An independent test of that Cyclone by American Woodworker in 2006 was in the same ballpark. http://www.oneida-air.com/PDF/AWW article jan 2006.pdf in fact their test shows the Oneida 3 hp at around 11 inches of suction (static pressure). I was not quickly able to pull up the CV fan curve, if someone would post a reference I would appreciate it.

At 350 cfm, most cyclones max out their static pressure at 10-15 inches, so at those low flows, you aren't going to see much practical difference between manufacturers, or in fact between models within one manufacturer, it is at the higher flows that the differences become more apparent to the woodworker.

To look at static pressure at very high flows does not make sense for the typical woodworker with only one large (6") blast gate open, it would make much more sense to compare the static suction numbers from the fan curve at 4000 fpm in a 6" (common size) duct as you have, 785. The result would be a comparison of cyclones at the normal required system flow of 785 cfm. 785 cfm would adequately serve a TS with a 5" bottom and 3" top connection.

David Kumm

03-17-2012, 2:31 PM

Ole, you are correct with your system numbers but the problem is that at over 8" SP the flow drops like a rock. Given the resistence of the cyclone, the filters as they fill given the surface area, the long runs with 270 to 360 degrees of bend, the flex at the end, you might be lucky to to stay at 8". If the real world ends up with SP of 10 or 11 you are dead in the water and have no plan B other than sell a used unit. Given that Todd has taken some hit already he might want to hook it up and measure the cfm but if it turns out all he can get is 500-750 he will have spent a lot for pretty crappy results. My experience with the cfm requiements of most machines is that they are low as well. almost all will benefit from 5000-6000 fpm. Dave

ian maybury

03-17-2012, 6:11 PM

I had a look at O's curve that you linked too Ole, and not being an expert perhaps am missing something - but as earlier don't understand how it's possible to get 785CFM at 8in WG with 2HP. Or the 1,349CFM at 2.3in WG the same curve mentions. Especially when that's presumably for the as delivered 2HP system - the fan, cyclone and filter combined and tested as a unit.

I'm more used to working with Cincinatti Fan's model SPB fan series data as representative of typical dust system fan performance - which so far as I know is for the fan on it's own in a stock test set up.

As before the highest CFM they list at 2HP for any sort of 6in inlet fan is 1,108CFM at 1in WG - this is for a 12x2 7/8 in impeller. That's such a low pressure as to be almost useless for our purposes (i.e. upping the pressure drop to a useful number will drop the CFM so much that it's an irrelevant number), and despite a lower CFM than the above being claimed does not include the additional pressure drop of a cyclone and filters.

It's not clear exactly what size of impeller O use, but it's a fairly conventional BC radial judging by the picture. It's just possible that there is something different about it, but all being equal Cincinatti don't seem to list any impeller size that does better than the 1,108CFM at 1in WG and 2HP mentioned before.

You're right that the pressure drops for everything will fall away rapidly as the CFM drops.

The 5in WG/100ft of duct run Cincinatti list for 6in steel ducting at 4,000CFM for example (but you have to extrapolate from published data to get to this because it's outside of any normal operating range) drops away to perhaps 1.5 to 2in WG at 350CFM.

The pressure drops created by the cyclone and filter will presumably drop accordingly (I've seen no published data), with the result that by the time the whole lot is totalled and something is allowed for entry and exhaust losses you might hope to get away with something like 5 or 6in WG - even with the sort of pretty long runs Todd's number suggest.

There's several major problems at that though as already pointed out. First as David fingered straight away the seemingly respectable approaching 400CFM this gives at 8in WG (which number gives some cushion) has (according to Cincinatti) dropped to a pretty useless less than 200CFM by 9in WG.

Secondly this 380CFM amounts to only 1,900ft/min in a 6in duct which seems unlikely to give reliable transportation of anything except very fine and light dust in small quantities. The duct diameter is in essence too large for a 2HP fan to drive it properly over the sort of distance Todd mentioned.

Finally there's at best only a minimal cushion in there for duct leakage/misalignments, unexpectedly high duct losses due to factors like machine hoods/extra bends, and most importantly of all filter blinding. (HEPA flters may increase their pressure drop by up to x4 over their life) If it works it'll just about manage basic chip collection, and a minor step up in pressure drop may kill even that.

The bottom line if all of this is true is that a 2HP ducted cyclone system is at best going to be unreliable and pretty unpredictable (at the level of accuracy of this discussion) in its performance on long ducting runs like this - although the situation would improve significantly if the ducts were kept short and the pressure drop very low.

Anyway... that's just one view. We each decide what we do.

ian

Ole Anderson

03-17-2012, 10:26 PM

My concern here is that you are using incorrect assumptions to in effect say that a 2 hp cyclone just won't work and that is simply not true. Ask most anyone with a 2 hp cyclone from most any manufacturer if they are generally satisfied with the performance and you will get a resounding yes, with maybe a few wishing for more horsepower simply because that is what guys do. But in these days of energy conservation, saying that you must have a 5 hp DC or you are wasting your time is not the kind of direction we should be going.

You seem to ignore specific fan curves based on empirical data in favor of looking at curves from Cincinnati Fan. I can't explain the difference, but to dismiss the data provided by the manufacturers and independent test groups is almost suggesting a conspiracy.

By the way, my 2 hp cyclone, the yellow one, will move offcuts nearly 7 feet vertically up a 6" duct after negotiating two 90 degree bends and 8 feet of 6" horizontal duct then though a wye and a double bend in a 7" aluminum flex pipe before being deposited in the dust bin. So I am thinking the cyclone is pulling at least 4000 fpm and 800 cfm. Surprise: when I ran that particular run thru Bill's calculator I got 6.95" of loss at 785 cfm, which puts it almost exactly on the fan curve for my yellow 2 hp DC.

You quote 5" of loss per 100 feet of 6" duct per Cincinnati Fan. Using Bill's calculator with just 100 feet of 6" duct and 4000 fpm velocity gives 4.28" of loss per 100 feet so those numbers are reasonable. However if you input 350 cfm in 100 feet of 6" duct in Bill's calculator you will get 0.92" of loss per 100 feet of 6" duct, almost negligible.

I am only responding because I really hate to see this misinformation and resulting conclusions floating about the Internet, which then to someone looking for their first cyclone becomes gospel because they didn't do their homework. As a result they buy the big hulking 5 hp DC because they are convinced that anything else just won't work. Now if they are running a 26" drum or belt sander, by all means go big or go home.

george wilson

03-17-2012, 10:57 PM

I have a 2 H.P Dust Gorilla(refused to mount the silly decal!!) with 6" spiral main pipe in my woodworking machine room. It works quite well for my 10" table saw,8" jointer,16" planer and 18" Delta thickness sander. The farthest thing from it is my 14" Delta bandsaw,which I reach with a 4" drop. About 24 feet away.

The unit works fine,BUT,you might want to consider the NOISE that even a 2 hp unit puts out. It is rated at 74 decibels,but that is nonsense. It could be the 8' ceiling,and 16'x22' original single car garage I have the "mess makers"in,but the unit is quite loud. I have a radio that has a decibel reading on its dial,and 74 db on the radio is child's play compared to the dust collector.

I think 5 hp would be entirely too loud to put up with without wearing hearing protection.

My main room is 30'x40',but I have my metal working machine shop in there,and try to keep it clean of dust. My dust collector is at the rear wall of the small garage which I added the big building on to. Right beside the dust filter,I had a 18" shuttered 3 speed fan mounted into the wall. Got it from Enco,and I don't see why they cost like they do,as it's motor is Chinese. It WILL move about 5200 FPM of air on full,though. I only turn it on low,though,and it makes a mild breeze going towards the rear of the room,away from the big room. Any fly stuff is floated in that direction,as well as anything that might get through the filter. It works pretty well to have that extra fan.

David Kumm

03-17-2012, 11:18 PM

It is always tough to determine what works for the other guy. The only way to really know what you have is to measure the flow and get the actual cfm. I have every Onieda system curve and am surprised at the difference among the 2,2.5, and 3hp gorilla systems. The 2.5 and 3 seem to have much more capacity at higher SP which is what scares me about the 2 hp unit. The problem I have with calculating pressure loss vs using measurements- and i'm a bean counter in real life- is that I don't know the actual pressure loss of each cyclone or the filters and the additional loss as the filters clog. The more efficient the cyclone at separating dust the higher the pressure drop. Cyclone efficiency can range from 2" to 10+" of drop so in effect the better the cyclone the larger the blower needed to operate it. The longer cone fine dust cyclones keep the filters cleaner but at a pressure drop cost. It is pretty easy to calculate the pipe and fitting loss, less easy to figure out the machine hood efficiency, and mainly a guess as to the cyclone loss. If you assume 2-3" filter loss and 2-4" cyclone loss those guesses can really screw you up if wrong. Ole, sounds like yours works for your machines although a Dylos type monitor would tell if the air gets worse when the machines are running or better. I agree that the 5 hp is likely overkill in Todds application but with a fan curve that provides 750+ cfm at 8" and about 200 cfm at 9" there isn't much room for error. Dave

Ole Anderson

03-17-2012, 11:50 PM

The unit works fine,BUT,you might want to consider the NOISE that even a 2 hp unit puts out. It is rated at 74 decibels,but that is nonsense. It could be the 8' ceiling,and 16'x22' original single car garage I have the "mess makers"in,but the unit is quite loud. I have a radio that has a decibel reading on its dial,and 74 db on the radio is child's play compared to the dust collector.

George, The dB rating numbers on the radio are at best useful only for relative volume changes and will not relate at all to actual absolute sound levels. Yes the DC's can be loud, but they can also be quieted enough to make a huge difference by enclosing them in a silenced closet. http://www.youtube.com/watch?v=8X8qwMqm3Ek

ian maybury

03-18-2012, 12:36 AM

I've no experience Ole of your system, and have not used the calculator you mention. It was however Bill that tipped me off to the accuracy of the Cincinatti data - it corresponds very closely with the numbers i linked in the 'basics' page that he himself published.

That said nobody has said that 2HP doesn't work, the caution was that with the sort of long ducting runs Todd mentioned with multiple bends, the possibility of unforeseen further restrictions and the fact that filters quickly add resistance as they get dirty there is a significant risk that he could on occasion have ended up at pressures very close to the 8 or 9in at which a 12in impeller drops from maybe 350CFM to much less.

You on the other hand are running what sounds like short ducting runs with few bends, with part in 7in dia. If as is possible with clean filters your total pressure drop is the 4in or so region the Cincinatti tables have a 12x2 7/8 impeller doing 930CFM which is a very respectable number - with enough cushion to tolerate some extra restriction as the filters blind up. Add 4in of pressure drop to that though and you would probably be back down to the previously mentioned 370CFM, add another inch and you would be below 200CFM.

It's consequently all in the pressure drop, and the unfortunate fact about that is that the estimation of it is a fairly approximate affair. Which necessitates building in factor of safety at the design stage.

It's possible that my guesstimated numbers are overly cautious, but knowing that even an inch or two change in pressure drop (the difference between dirty and clean HEPA filters is it seems alone potentially 4in WG) could potentially have such a marked effect on CFM in the region he was likely to be operating in there were not going to be too many takers to guarantee he would experience no problems at 2HP.

It's normal engineering practice in these situations to build in some cushion to guard against such possibilities. Adding impeller size (and hence the HP to drive it) rapidly lifts one clear of potential problems. Step up to 14in dia and you're knocking on the door of 1,000CFM at 8inWG at 2.3HP - so a 3HP motor would do a better job and leave some protection against the risk of problems.

Against that 1,000CFM would shove the pressure drop well over the 5.13in WG/100ft, meaning that the total pressure drop could exceed 8inWG so that 3HP might actually deliver something more like 6 or 700CFM over Todd's runs - reducing as the filters blind up.

That's in turn going to be marginal if you're running a big old planer like what David does, or are keen to maximise the air cleaning/fine dust capture effect - so there's reasons to go higher at times too.

ian

ian maybury

03-18-2012, 9:08 AM

:) David as ever says with more impact in a few words what I'm busily trying to explain and then justify with some numbers.

Noise can be a bit of an issue all right George. That said bigger systems don't necessarily sound significantly noisier to my ear than smaller ones, just a bit deeper in tone. How it measures might be a different matter - we don't always perceive sound levels in the same way as the dB scales read them.

I suspect that much like predicting pressure drop and CFM it's subject to variables that are hard to precisely tie down. Balance and vibration of parts, and transmission of that vibration into the system and building structures is probably a significant part of it - the plastic Clear Vue cyclone could possibly do better in that regard than a metal one. Some build sound proofed enclosures.

As before I took care to isolate my '5HP' blower and cyclone from the inlet and exhaust ducting using flexible hose, and got a very nice reduction in noise and softening of the tone by double soft mounting my fan and cyclone assembly. The Clear view set up hangs it on rubber bungs on threaded rods screwed into the mounting bracket. I added polyethylene pads under the feet of my non standard floor mounted ply mounting bracket.

The double sprung mount principle is well proven and used on spin dryers and lots of machines, although getting it optimised requires calculating the optimum spring stiffnesses and suspended weights. I just took a shot at it to see what would happen....

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george wilson

03-18-2012, 3:27 PM

I am not a dust collector expert,only ever having the one of my own. I'm concerned about heat buildup by putting my 2 hp unit enclosed.

I think my unit has always had a bad control in it since new,because I cannot start it more than about 3 times an hour,or the motor cuts off. I need to call the makers about this.

Rod Sheridan

03-18-2012, 6:06 PM

Hi Todd, I have a few comments;

1) ignore HP ratings for fans, they are of no use except for the fan engineer. You could put a 5,000HP synchronous motor on my cyclone and it wouldn't move any more than the 1.5HP motor that's on it.

2) Your cyclone is capable of 1,000 CFM at 6" water column. In a hobby shop, 1,000 CFM will support your machines unless you buy large industrial stuff.

3) write down what you need for your machines,

-500CFM for a table saw cabinet, 200 to 300 CFM for the over blade collection

- 500 to 700 CFM for a good size stationary planer

- 500 to 700 CFM for a shaper

- 500 to 800 CFM for a sander.

See a pattern emerging? You need somewhere around 800 CFM maximum.

Plugging 1,000 CFM into the calculator with 7" pipe and the following'

- 1 hood

- 4 right angle elbows

- 3 Wye fittings

- 50 feet of pipe

It yields 3.71" water column, yet your cyclone is capable of that air flow at 6" water column.

You have a bigger machine than you need, if you use larger than 6 inch pipe................Regards, Rod.

David Kumm

03-18-2012, 6:24 PM

Carl Beckett

03-18-2012, 6:44 PM

Hi Todd,

Welcome to the world of Dust collection threads.

I hope you are finding some useful information.

An update on my system: I redid some piping and sealed all the connections to reduce restrictions and losses, and this did significantly improve performance. I vent to the outside though so if going through filters I would still deem it inadequate. I havent determined yet if the current performance is acceptable for me (need more use).

You can always just use yours and see how it goes. Since its a used unit already, you wont lose much resale value if you decide to upgrade later.

Rod Sheridan

03-18-2012, 8:00 PM

Rod, you are ignoring the cyclone which adds 3+ and the filters which will add 2-4 depending on area and how clean they are. The 3.71 may well be 8.71 or higher which why Ian and I have been saying it is on the marginal side. That doesn't even account for losses or flex that will add more resistence. Dave

Hi David, of course I'm ignoring the cyclone and filter, the Oneida curves are for the complete cyclone with filter, no need to account for them............Rod.

David Kumm

03-18-2012, 9:03 PM

Hi David, of course I'm ignoring the cyclone and filter, the Oneida curves are for the complete cyclone with filter, no need to account for them............Rod.

Rod, I see what you are saying. The Oneida system curves are supposed to have taken the cyclone and filters into account so when they show 730 cfm at about 7+" they are only speaking of the duct and flex loss. My mistake. I do have some suspicion however about those system curves as they have always seemed in line with the Cincinnatti fan curve data which led me to believe - evidently in error- that you had to add the cyclone and filter pressure to the totals. I went on the CF direct drive backward inclined fan table and could find a bunch of 12" diameter fans that provided 800 cfm at 7" at 2hp but could find none that came even close at 10-11". The ratings at 2" on the CF table seemed similar to the Oneida system ratings at 2.3" which to be comparable should be about 5" on the fan rating chart.

Rod, I'm agreeing that you were using the Oneida tables correctly but I'm going to look more at the numbers. Pentz always argued that the DC companies juiced their ratings by running the motors over amperage and using larger particle filters. I always discounted that analysis but there is something that needs more explination. Dave

Todd Brewer

03-18-2012, 9:04 PM

I sold the 2 HP SDG today. I made no misrepresentations to the buyer. He wanted it for a very short run setup and understood that when he puts his final shop together he will most likely need a more powerful DC.

Now which DC to buy?

I like the professional looks of the Oneida but the Clear Vue is a heavy favorite. It is less expensive but as I understand it, requires other items to be purchased, and requires some fussing around to set it up. I would definitely paint the wood pieces to give it a more professional appearance. Lots of pictures in Clear Vue gallery. I totally understand wiring, so that is not a problem at all. I wired to code (and was inspected) my entire house and new garage shop.

Oneida has two 5HP units. The 5 HP SDG has an 8" input port, if I connect my 6" system what happens to performance? Oneida also has the new Smart Pro. Very nice comes with almost everything, remote starter (not sure I care once I get my dust gate triggers operational, but in the mean time will be nice), infrared dust sensor. It has a 7" input port (maybe better when connecting 6"?) but is very pricey. I have no idea what the infinitely variable fan curve means. Is it worth the splurge?

The beauty of the clear Vue is that it is sized for 6" duct, and PVC at that!. Seems like a lot of people have this setup so I would be in good company. :) I have to buy more and fuss more but will cost less than the Smart Pro, not sure it will cost less than the 5 HP SDG..

David Kumm

03-18-2012, 9:28 PM

Todd, how could you do that. We were still arguing about whether it would work. The Oneida smart has a vfd with software that adjusts the airflow to compensate so in effect it speeds up the motor if needed. You can get that by buying a three phase motor and running it a vfd. A change of 3hz increases or decreases my airflow by about 13%. It isn't a bad option if you find a good used Torit, Dustvent, or Sternvent 3-5 hp system which tend to be three phase. For your application the Oneida hi vac 5 hp is overkill and the regular 5 might be as well. On the other hand the 5 hp motor will run on less amps if the ducting restricts it so you aren't wasting all that much energy. I like the steel in the Oneida but the clearvue cyclone design is more efficient at fine dust separation. In fact that cyclone was developed primarily for the fine dust so it excells at that. If I were buying the clearvue I would buy the Max cyclone for $200 more to get the 8" inlet and then reduce to what made sense. If you decide to add a drum sander or bigger shaper down the road you will only need to swap out the main line. Having said all of that I have a Torit 20-5 cyclone with an Oneida stand alone blower-5hp three phase and run it off a vfd. That is more than you need but I have less $ in it than what a new Oneida 2000 would cost, and I still have the original Torit blower and motor as a backup. Dave

ray hampton

03-18-2012, 9:33 PM

I do not wish to HiJack this post but how can we compare the furnace with its 12x6 duct work to this business of dust collector ? if the dust collector duct work were 12x6 " how big motor will you need

ian maybury

03-19-2012, 8:38 AM

Far be it from me to question makers curves either Rod :) (says he), and it's clear from what you and others have said that the unit works well over shorter ducting runs. But as I posted before I'd love to hear why it is that the curve seems to say it manages to move more air on 2HP through a filter and a cyclone than probably similar stand alone fans from another respected manufacturer.

My guess as before Todd is that hooking smaller ducting to a somewhat larger cyclone inlet won't have any significant downside in terms of system performance, and may actually help the cyclone (if it's a shortish one) by reducing the inlet velocity a little. i.e. the ducting will determine most of the pressure drop. Going the other direction the opposite would likely be true though.

The good news about these big units is that by and large they are much more tolerant of small increases in pressure drop.

A VFD can be a very real advantage if it's set up the right way - it costs a bit, but it offers the possibility of controlling the start up current, less wear and tear on frequently started motors, easy remote control using low cost commercially available key fob operated radio switches with low power relays - and of course speed control to adjust CFM and pressure output. It probably depends to a degree on the installation, but upping the fan RPM to get more pressure (for restrictive tools) is only an option up to a point due to mechanical limitations and increased noise. Dropping a little can make a big difference to noise with no obvious effect on dust collection.

How useful the extra pressure the higher RPM gives might be (bear in mind that a 15 or 16in impeller is still already moving decent quantities of air to 15in WG or a bit more) depends on how high the fan goes vs likely needs - it's unlikely to get even close to vacuum levels. I'd want to check if buying a commercially supplied unit with a built in VFD that it didn't have built in limitations to what you can do with it - it's not as an alternative very hard to buy a freely re-programmable and full feature VFD yourself and fit it to whatever system you want.

The big difference between ventilation and dust collection Ray (which I guess you know) is that in dust collection we need to maintain a high enough air speed in the duct to give reliable transportation - around 4,000ft/min. This will sharply drop the CFM available from most low pressure fans. It's as before possible to persuade a smaller fan to punch above it's weight by running larger ducting, but then it becomes a question of how far can you safely shade it in dropping below the recommended 4,000ft/min number. Most smaller dust systems end up running at lower air speeds than is ideal...

The other factor I'd want to look at if buying a larger commercial cyclone is its shape. None of them seem to publish good data on their fine dust retention capability, but as David has said there are some longer/taller units about that seem to more closely mirror industrial practice, and other more squat ones. It's hard to know if this is significant, but it's hard to think that the industrial units are not the way they are for a reason...

ian

David Kumm

03-19-2012, 1:56 PM

Hi Ian. It's tough to figure out the curve numbers with any consistency. The 5 hp belt driven straight fan curve on the Oneida site tops out at less SP than the entire 5 hp system curve for their 2000. The difference in blowers might account for it but the fan curve shows a max of 10 sp and the DD system curve goes over 12" before adding the cyclone that runs about 3". The chart says the readings are without filters but the numbers are the same as the cfm with filters posted. As to cyclone design it seems that most hobby units are sized to fit under an 8' ceiling and that limits the effectiveness in fine dust removal. I think that is one reason the clearvue uses an 18" diameter for their systems as the relationship between the cone length and diameter seems to be key. The problem in fabricating the smaller diameter with a bigger unit is the need then to convert the 8" inlet to a rectangular shape about 13" x 4" to maintain the area but keep the flow against the outer wall and between it and the inner neutral vane. cyclones with a round or square intake need to be larger diameter to avoid the turbulence created if the air flows directly against the vane. That in turn means the cone must be proportionaely shorter and separation suffers. How much I don't know because it takes a lot smarter guy than me to figure it out. Dave

Ole Anderson

03-19-2012, 2:22 PM

Speaking of fan curves, could someone please post or link the data for the 5 hp CV cylcone?

ian maybury

03-19-2012, 3:51 PM

There sure doesn't seem to be a lot of consistency in test methods David, or comparability of test numbers. It's as you say why it's a bit risky to sail too close to the wind in estimating CFM and pressure drops without being able to draw on experience of a very similar installation. Add in that there's a shortage of pressure drop info on filters and cyclones and it gets even less precise. I've a suspicion too that there's possibly a trade off like what you say - but likewise rely on hearsay.

One of the issues Ole with the 16in Clear Vue fan is that there isn't a curve published for it. (at least not that I've seen) I've encouraged the new owners to get the necessary testing done and publish the data. Likewise on the retention performance of their cyclone. It seems a pity that it hasn't been done, in that if the cyclone actually does perform better than the shorties it's a pity not to be in a position to be able to quantify it.

None of the cyclone makers seem to do so. Perhaps it's because it risks creating a hostage to fortune in circumstances where the type of dust, conditions of use and nature of installations are not well controlled. I've a feeling too that minor variations in the set up can have significant effects when the issue is the dropping out of very fine dusts which are right at the limits of cyclone capability. The industrial manufacturers seem to (?) do it on an application specific basis - starting with a particle size count and other analysis of a sample of your dust.

David has made the point before that it'd make sense to use a credible and independent third party test house, in that it should strip out the 'you would say that, wouldn't you' perception from the situation.

I've relied on Bill Pentz's numbers, and on the curves for similar size and RPM fans published by Cincinatti fan - they seem to correspond pretty closely. The cyclone is reportedly based on a well proven industrial model (he mentions the source somewhere), it's longish proportions are certainly pretty similar to those done by some of the industrial suppliers for use on fine dusts.

ian

Michael W. Clark

03-19-2012, 4:11 PM

Todd,
FYI, if you have 45' of straight duct, 360 degrees of elbows, and pull 1000 CFM through a 6" duct, you will need about 5"wg at the cyclone inlet. I'm like others, I find it hard to believe that the Oneida unit can develop 6"wg SP at the cyclone inlet with only a 2HP motor. If you need 5" SP at the cyclone inlet, and you need another 5"DP for the cylone, filter, and ducting between, you will need at least a 3HP motor and then you are probably into the safety factor of it (I get 3.14 BHP at 50% efficiency).

Have you looked at the Grizzly cyclone units? They are also all metal construction and look to have a good L/D ratio (tall and skinny).

If the CV is getting the small dust, it will also do better on the big dust as long as the cone discharge and inlet arrangement does not create a plugging concern for large chips.

There was a mention earlier on this thread about energy consumption. If you go David's route and locate the fan after a good cyclone, you may be able to use a more efficient fan. A BI (backward inclined) fan wheel will deliver more CFM at less HP than the Radial fan wheel types. The BI fan cannot handle large chunks of material without damage, but if its after the cyclone this shouldn't be an issue. It will be handling some particulate after the cyclone, but it is doubtful that you will use it enough as a hobbiest to errode the fan wheel. For example, if you use a BI fan at 70% efficiency, you only need 2.3 BHP at the flow and loss conditions above, so a 3HP would work.

David, I am still not familiar with the "nuetral vane". I looked at the Pentz site and it looks like an extension of inlet to get the airstream past the outlet pipe. This is probably necessary on the tangential inlet style of the hobby cyclones. Otherwise, you would errode the outlet pipe and could get some "short-circuiting" of the inlet air straight into the outlet pipe. The industrial cyclones I'm familiar with have involute inlets where the inside of the inlet is actually on the OD of the cyclone body.

I think the smart Oneida system is some type of HP control using a VFD. I think the fan speed changes to maximize current draw. Thus, you would always have the maximum suction available at the flow being delivered. They probably have a larger fan than the motor can handle under normal circumstances (dust collection). They can then increase speed under low volume conditions (floor vacuuming) and increas the SP. Not sure, I saw this before and was curious how it worked. This is a common concept used on hydraulic pumps where you need power under load (low flow and high pressure), and a quick return under no load (high flow and low pressure).

Mike

Todd Brewer

03-19-2012, 7:54 PM

Todd,

Have you looked at the Grizzly cyclone units? They are also all metal construction and look to have a good L/D ratio (tall and skinny).

Mike

Mike, thanks for the tip. I just checked out the Grizzly's. From what I'm reading, I don't think I will get anything other than a 5 HP.

For the price of the 5HP Grizzly I would spend a few hundred more to get the Oneida Smart Pro, or spend a lot less and get the Clear Vue.

Fascinated by this discussion, wish I understood 1/2 of it. :)

David Kumm

03-19-2012, 8:03 PM

Mike, thanks for the tip. I just checked out the Grizzly's. From what I'm reading, I don't think I will get anything other than a 5 HP.

For the price of the 5HP Grizzly I would spend a few hundred more to get the Oneida Smart Pro, or spend a lot less and get the Clear Vue.

Fascinated by this discussion, wish I understood 1/2 of it. :)

Cyclone design is pretty similar to Oneida and Pennstate. Downside would be the motor and perhaps the filter material. Dave

Rod Sheridan

03-19-2012, 8:43 PM

Rod, I see what you are saying. The Oneida system curves are supposed to have taken the cyclone and filters into account so when they show 730 cfm at about 7+" they are only speaking of the duct and flex loss. My mistake. I do have some suspicion however about those system curves as they have always seemed in line with the Cincinnatti fan curve data which led me to believe - evidently in error- that you had to add the cyclone and filter pressure to the totals. I went on the CF direct drive backward inclined fan table and could find a bunch of 12" diameter fans that provided 800 cfm at 7" at 2hp but could find none that came even close at 10-11". The ratings at 2" on the CF table seemed similar to the Oneida system ratings at 2.3" which to be comparable should be about 5" on the fan rating chart.

Rod, I'm agreeing that you were using the Oneida tables correctly but I'm going to look more at the numbers. Pentz always argued that the DC companies juiced their ratings by running the motors over amperage and using larger particle filters. I always discounted that analysis but there is something that needs more explination. Dave

Hi, having installed and measured the airflow on two different Oneida models, I found their curves to be accurate.

I was extremely impressed with the sophisticated blade shape on the impeller, it has a changing radius and profile, something I haven't seen on other impellers.

The better the fan efficiency, the less power it needs to produce the same airflow and pressures. In my opinion you really are getting a better designed machine for your money...........regards, Rod.

Michael W. Clark

03-19-2012, 9:19 PM

Oneida must have a BI wheel and a low DP cyclone design to get the performance.

ian maybury

03-19-2012, 9:20 PM

That's interesting Rod. There's certainly scope for a lot more output from a 2HP fan if the impeller is significantly more efficient - the typical item is only about 40% it seems.

ian

Rod Sheridan

03-19-2012, 9:25 PM

Oneida must have a BI wheel and a low DP cyclone design to get the performance.

Hi, the wheel is backward inclined..............Rod.

Michael W. Clark

03-19-2012, 9:29 PM

Hi, the wheel is backward inclined..............Rod.
So you have 70%+ efficiency instead of 40%, makes a difference.

David Kumm

03-19-2012, 9:40 PM

Thanks, Rod. I knew the Oneida fans were BI because I use one on my system but didn't give them credit for that kind of increase in efficiency. Makes me think that when I get less busy I need to put my straight blade Torit fan in the housing and try to measure the difference. The cfm at higher resistence is the issue. The Oneida 5 hp system curve looks to be much closer to my expectations than did the 2 hp one. It would be really helpful to know all the companies test. What length of input pipe, type of filters, and amp draw at various cfm and sp. Might only be interesting to me. Dave

Todd Brewer

03-19-2012, 11:26 PM

Cyclone design is pretty similar to Oneida and Pennstate. Downside would be the motor and perhaps the filter material. Dave

Thanks Dave.

I own a Grizzly table saw and 8" joiner. I am happy with them. The cost of their DCs seems somewhat high. I think of Grizzly as a good bang for the buck manufacturer. I wouldn't pay that much for their 5 HP DC when I could pay a few hundred more for the Oneida Smart Pro or save a bunch and get the Clear Vue 1800.

I am torn between the Clear Vue and the Oneida Smart Pro. A less expensive 5 HP Oneida would be acceptable but I'm worried about the Oneida Pro 2000, it has an 8" inlet port compared to the Smart Pro with a 7" input port. I am concerned that reducing 8" to 6" will be a problem. If I shouldn't worry about 8" -> 6" please let me know. I could save about $1000 and get the 5 HP Oneida Pro 2000.

I have nothing against the Clear Vue, except it's "home-made" looks. Please don't take this the wrong way, it's a flaw in my personality. :) I really wish I could accept the "home-made" look as it would save me about $1000, but I will have to look at the DC every time I pull into my garage. I know, it makes no sense, I'm weird. :) I'm not dismissing the Clear Vue, so many people love it and that says a lot! And the $1000 savings would buy another nice tool. :)

David Kumm

03-19-2012, 11:44 PM

Todd, buy whatever you prefer but the smart system doesn't warrant the $1K extra. I see the 8" inlet as a plus for the ability to upgrade later. I would save the money and spend a few bucks of it for spiral pipe and large radius fittings rather than PVC. As I have said before I would get the three phase motor and put on my own vfd. Motor will pull more air than the single phase version although you don't need that. You will have soft start and won't have to worry about too many starts per hour being hard on the capacitors. You can slow the rpms down a little when you don't need the flow and quiet things down. The 3 hp would likely be fine but for $200 extra and the hepa option thrown in the 2000 is a pretty good deal. Of course with my tendency toward used I would look at the Dust Vent industrial on ebay with all kinds of Norfab pipe for $1200. The vfd will set you back another $500 or so. In the straight 5 hp 15" impeller configuration the clearvue cyclone is hard to beat if looking just at fine dust separation for the price but a three phase option isn't available at this time. Clear as mud. Dave There is also a clear vue 5 hp with extras on CL at $1000.

Michael W. Clark

03-20-2012, 1:04 AM

Todd, I would love to have your problem.:D

It looks to me like the 5 HP Grizzly is more expensive than the 5HP Pro 2000? $2200 vs. $2500 excluding shipping? Oneida shipping is more and there are some options to add to compare apples to apples.

I would be torn between these two if these were my top choices. Just to make your decision harder, since I am not fortunate enough to have your problem...The Oneida has the HEPA filter which is great, but I would think that it would tend to plug fairly quickly. The grizzly filter is pretty good and there is twice the cloth area. Air:cloth (A/C) ratio is a concern especially when you have gotten out all of the big pieces with the cyclone. People debate about putting cyclones before baghouses (think large after filters with compressed air pulse cleaning) because all the small particulate that comes out of the cyclone can embed in the filter media and there are no larger particles to help knock it out or to cover sections of the media to prevent it from blinding. If the A/C is too high, small particles can be forced too far into the filter media and cause it to blind because it can't be cleaned. The way around this is a lower A/C (reduced velocity through the filter media) to prevent the particles from embedding too far into the material. The Oneida A/C would be at about 9:1 (1000 CFM/110 ft2) and the Grizzly would be at about 4.4:1 (1000 CFM/226 ft2). If I were designing new, I would try to get the customer to buy something in the 3:1 A/C range.

Its late and maybe I am reading too much into it. I know in industrial systems, you would not put a HEPA filter after a cyclone, unless you want the Maintenance staff to have job security. You will get very good particle filtration through the HEPA, but if it blinds over (blinding meaning that you will not be able to clean it), your outlet SP on the blower will be increased causing you to lose CFM and reduce capture at the hoods. This can launch additional dust into the air and create a dusty shop until you replace the filter. Maybe it is not an issue with home shop systems or this particular system. Maybe others have some experience with this setup. My experience is mostly industrial. I only have a single stage unit at home with a cartridge canister filter. I notice a huge increase in flow when I take the canister off and clean it out with the vacuum, then replace it. I'm aware that the filter cake actually can improve collection efficiency, but blinding is a separate issue.

David Kumm

03-20-2012, 1:10 AM

Mike's point is good about the filters especially if you are discharging into the garage rather than the shop. Kind of eliminates the need to hepa filtration. Dave

ian maybury

03-20-2012, 10:55 AM

The story goes to the effect that if you have a high performing cyclone that HEPA filters last well - there doesn't seem to have been kick back to the effect that blinding is an issue on the ClearVue forums or here. But who knows for sure.

Interesting this business of backwards inclined impellers, and variants of them.

Looking closely at the picture of the impeller in the spec sheet linked via 'technical specs' at the bottom of this page http://tiny.cc/bk1gbw it does have more blade depth and backwards curve than a typical BC - although it's more like an adaptation of a BC impeller than a typical shrouded BI item like no. 4 here: http://www.cincinnatifan.com/blower-wheels.htm Ditto on the 5HP unit, although it looks very like it could be the same impeller in the picture so it may or may not be an exact representation.

Cincinatti get about 1,000CFM from 2HP at 8in WG at 3,450RPM, so the figure in the curve of 785CFM at 8in off 2HP looks do-able with a BI impeller. It's not going to get to the 1,000+CFM or so at 15in WG of a 5HP unit, especially not with a dirty filter on top, but it's probably going to do a lot better than a BC.

Bill P it seems did some playing with BI impellers, but reportedly ran into problems with stalling and buffeting at high pressure drops/lower air speeds. Looks like O found a way around it, at least at this size anyway - maybe that's why it look a bit different to the usual BI.

There's a write up on the basic pros and cons of the various (traditional) types here: http://tiny.cc/t70gbw

ian

Michael W. Clark

03-20-2012, 12:06 PM

The Oneida wheel looks like the Cincinnati Fan Type 6, backward curved radial fan. I can't imagine Oneida has a special wheel design proprietary to them. They are likely buying the wheel and assembling it. A lot goes into the wheel construction and testing. There are many fan companies that make their living doing only fans (Cincinnati, Twin City, New York Blower, Clarage, Robinson, etc.). Its doubtful that a manufacturer serving a nitch retail market of hobbyists in the woodworking industry has spent the R&D $$ to develop a new fan.

I think a typical BI would be more efficient. The backward curved radial is probably somewhere between the radial type and BI, probably closer to the radia type, if I had to bet.

Ian, its probably that no-one actually knows how the SP builds. The low use of the home shop collector and variation in dust particulate size probably helps the situation. Also, with the low use rate, there would be a slow build up and maybe hard to notice a reduction in volume because you get used to it. The only time I have ever seen HEPA filters in industry is on the outlet of a baghouse. Ther may be some application on the outlet of a cyclone, but I would imagine the cyclones are dealing with a very high percentage of larger particulate. The baghouse is usually filtering down to 99.9% on 1 micron. A cyclone will not do that in the size cyclones available to home shop users, regardless of the claims. CV has done some lab tests, but these are lab tests at specific conditions. If your flow and dust particles are different, the cyclone efficiency will be different. Even with the baghouse, the systems are almost always equipped with a divert damper to allow the facility to vent to atmosphere and bypass the HEPA filter bank. This is common practice in the summers for most facilities. The HEPAs are there to reduce gas costs associated with make-up air in the winter. They do not want to replace plugged HEPA filters in the Summer months.

My home furnace does not have a HEPA filter. It has a pleated furnace filter that still plugs every few months. I may be wrong, but I would venture that the return air to my HVAC unit has lower PM than the effluent from a cyclone that is connected to a woodworking machine (especially a sander).

Pricewise, I might ask Oneida if they can furnish the unit with a different after filter. I can't recall what the filtration range should be, but my understanding is that the very small stuff is not a problem. There is a range of particulate size that gets breathed in, but does not come out. You want the coarsest filter that gets the range that you need. Any finer, and you are adding needless expense, potential blinding problems, and could cause performance issues. If you loose flow and can't get the dust in the hood, it doesn't matter how good the collector filters.

David Kumm

03-20-2012, 12:19 PM

Michael and Ian, I've been studying- liberal use of the word- the fan numbers over at the CF site and struggling with how to compare. The BI fans seem to deliver less cfm at much lower hp than the typical blade for the same size. I'm looking mainly at the 14-16" range and trying to stay within the limits of the 5 hp motors at 4-5" sp as I suspect the motors are sized to be fully loaded at about that resistence. I agree that the fans are likely sourced elsewhere. Given the number of sizes it would seem unlikely that they are all specially made so there should be some comparables out there. It looks like the BI fans have a range where they deliver most efficiently and then taper off at higher rpms or higher airflow so that overamping the motor is less of a problem. Anyone who knows about air delivery at different levels of resistence for different types of fans can chime in here and help me to understand the trade offs. Dave

Michael W. Clark

03-20-2012, 1:10 PM

David,
Can you provide a link to the page?
Thanks,
Mike

David Kumm

03-20-2012, 1:26 PM

David,
Can you provide a link to the page?
Thanks,
Mike

I'm sort of a Klutz on links but if you go to the Cincinnatti site and go to fans all types come up. I look at PB fan catalog and the info is part of the catalog. Hope that helps. Dave

David Kumm

03-20-2012, 1:58 PM

My latest info is that Oneida does indeed cast their own blades. The wider blade they use allows for more airflow at low SP but causes the cfm to drop off more quickly at high resistence than more narrow ones. I can't verify any of that as I'm in over my head. seems that the design of the blower housing also impacts the airflow efficiency. I have also been told that the industrial type blades like those from Cincinnatti fan are a step up in both quality and efficiency from the hobby level ones used in DCs we buy. Again not verified by multiple parties- yet. Dave

ian maybury

03-20-2012, 4:00 PM

I didn't look at BI impellers until this thread came up David as they typically are ruled out for dust system use. Like in most things we have a tendency to think in terms of clear distinctions when we refer to this sort of stuff, but in practice it starts to look like there are what you could almost call hybrid impellers about - ones as you say Michael that are half way between BC and full BI.

It's a bit less marked than on the Oneida, but even the blades on the ClearVue impeller http://www.clearvuecyclones.com/supporting-products/45-15-inch-impeller.html are curved along their full length - unlike the more traditional BC which just has the tips set back a bit. Which latter basically trades a little less performance (especially at higher pressures) for a little less noise. (see the pictures and tables in the Cincinatti Fan SPB catalogue)

Even though they look fairly similar (BC and BI) they potentially operate very differently - so heaven knows what's going on in a hybrid. Radial and BC types impart kinetic energy to 'fling' packets of air that the inlet has deposited between the blades out the exhaust, whereas on the BI type the blade is described as 'flying' - as functioning like an aerofoil. Which is presumably why when the angle of attack get too steep at low airspeeds on a BI impeller it stalls. They are also much more speed/RPM specific in their design.

The aerofoil function probably also explains the use of a shroud/annulus to bridge between the tips on the traditional BI impellers - as well as helping the tall blades structurally it probably reduces tip losses. (like the winglets on the tips of the wings of the latest jets)

The next step in performance it seems actually uses a true aerofoil section blade version of the flat plate blade in the BI, but is even more sensitive in terms of its only functioning within an even narrower range of conditions.

The Kruger technical bulletin linked at the bottom of my post above (or another piece I read recently - can't remember for sure) says that for radial and BC type fans the clearances between the impeller and the fan housing don't (within reason) much influence fan performance - but that the situation is different for BI fans which need to run tighter clearances.

It also confirmed the two disadvantages attributed to BI fans before - a risk of stalling at low airspeeds/with too many blast gates closed and a tendency to get clogged with shavings if they are not dropped out before the fan.

I suspect that as before Michael that cyclone performance on the fine dust is indeed a bit of a variable feast, and that it probably depends on stuff like phases of the moon and so on. :) Or at least that there will be a particle size range and weight, and inlet velocity and turbulence that's going to suit a specific cyclone layout best. That as you say (and as I've seen written elsewhere) that very small changes in the set up and even build may well make quite large differences to retention performance. My system is set up as you describe - opening a blast gate allows it to exhaust outside. I've not run it that mode yet though.

It seems by the way (again reportedly) that the HEPA standard defines retention performance at a particle size of 0.3 micron because this is the size that is most difficult for the body to deal with....

ian

Michael W. Clark

03-20-2012, 4:00 PM

Maybe they do have their own design. I did not see anything about AMCA on their website, maybe I missed it. Many industrial fan manufacturer's are members of AMCA (Air Movement and Control Association). They have specific test standards for fan performance. If a company is not a member of them, it doesn't mean their product is not good or is necessarily inferior. It just means the performance was developed with a different test method and may not be comparing apples to apples with the performance of AMCA fans. At the end of the day, energy is conserved and it takes "X" amount of eneryg to move a volume of air, at a given rate, across a system with a known resistance. The mechanical efficiency of the fan wheel will reduce the BHP required.

David,I would think you would want the CF that is rated at about 9-10" SP. On page 9, there are several options for the 3450 RPM direct drive model in the 1500 CFM range (8" duct at 4300 FPM).

I think Oneida probably makes a great product, and definitely like that it is Made in the USA. They would be one of my first ones to consider if buying new. What about Penn State Industries? I know a few who have their cyclones and are quite pleased with them.

Todd, I feel like I am living vicariously through you today. :)

Mike

Ryan Mooney

03-20-2012, 4:11 PM

http://www.cincinnatifan.com/fan-selector.htm is how I found the "interesting fans". I plugged in 1000 CFM and 10 for SP (figuring 4" for the piping in the OP's setup which is long but not unusual plus 3-4" for the cyclone plus 1-2" for the filter plus some amount of me not knowing things, 10" seemed relatively safe anyway - I don't claim correctness on anything here).

At 8" the suggested fans are quite a bit different .. and at 100CFM @12" you get some really interesting results.

The PB series seems to be the most overlapping with ~many? of what I can figure commercial cyclones use, the HP series is.. interesting.. (practical? maybe not, I don't know enough to say.. interesting yes :rolleyes:)

I left that list even more confused than I started with though :D

It looks like you can (in theory) get 12" of pressure with a 23" wheel at ~2.5 HP (steady state, not counting spinup), I suspect that there are stall and spinup issues at that size though... and its the most expensive fan and you need a big honkin motor just to get it to spin up in direct drive mode, and well... the SP we're interested in isn't even on its curve (looking at the HP-10F23 for example). More "useful" looking is perhaps the HP-4A and HP-4C models, again we're below the interesting pressure curve so its possible that they don't even work well at the lower pressure. The recommended model in that line would probably be something like the HP-6B, but then you're well back into 5HP range.

Rod Sheridan

03-20-2012, 5:18 PM

Hi, in my post I calculated that the OP needed 1000CFM at 4" WC.

Using the Cincinnati fan catalogue you can select a fan that requires .94HP for that task.

As you noticed from the Oneida cyclone curve, the cyclone fan at 2 HP was capable of much more than the OP needed.

If you select a fan with really poor efficiency you need a big motor, however that's not what Oneida do.

The Oneida cyclone the OP purchased was more than adequate for his needs, unfortunately instead of doing the calculations, he sold it because he was getting anecdotal evidence that you need at least 4 HP.

As I indicated previously, only the fan designer needs to know the HP, it's a useless specification as can be seen from the selection of a good versus poor fan design.

Regards, Rod.

David Kumm

03-20-2012, 5:53 PM

Rod, since the CF ratings are straight fan curves, how much did you add to the 4" for cyclone and filter loss? Dave

Salem Ganzhorn

03-20-2012, 6:57 PM

David,
When I was looking for a cyclone I was disappointed that Oneida did not list specs on their fans. I ended up getting a deal that was just too good to pass up on a 2HP Super Dust Gorilla. I took pictures when I took it apart. The impeller is 13.5"x4":
http://farm8.staticflickr.com/7065/6859983231_dd51b9a3a5.jpg (http://www.flickr.com/photos/93434731@N00/6859983231/)
Untitled (http://www.flickr.com/photos/93434731@N00/6859983231/) by eyekode (http://www.flickr.com/people/93434731@N00/), on Flickr

http://farm8.staticflickr.com/7202/6859982617_24da26d28b.jpg (http://www.flickr.com/photos/93434731@N00/6859982617/)
Untitled (http://www.flickr.com/photos/93434731@N00/6859982617/) by eyekode (http://www.flickr.com/people/93434731@N00/), on Flickr

I don't have all my duct up yet and most of my runs are short but I have been pleased with the dust collection and noise level. One of these days I would love to borrow a dylos and see how it really does. But I still wear a mask when using my TS and bandsaw because I don't have DC above the table yet. And no amount of suction from below will fix that.

Good luck guys!
Salem

Todd Brewer

03-20-2012, 6:59 PM

I spoke to Oneida today. In a nut shell I told him my longest run was around 50'. He didn't ask about bends and I didn't have a lot of time today. He recommended a 3HP unit. He also recommended large pipe at the DC, for 8" inlet, run 8" about 7' then 7" for around 12' then reduce to 6". Use 5" on verticals and 4" connecting to machine. Lot's of folks seem to think 6" all the way. Completely different recommendations. Oneida claims the smaller diameter pipe prevents the material form falling out of the stream.

This evening I was planning on changing out the 5" lines for 6" lines. I have two 5" lines off the 6"main line, the 5" runs about 18' across the ceiling where it will come down to a drill press. Another one just like it goes to the band saw. If I use 6" then machines could move around (be relocated) I would have more air flow, unless of course Oneida is correct and I want smaller pipe as i get farther away.

Should I swap out the 5" for 6"?

Current contenders: Clear Vue 1800 and Oneida Pro 2000, both 5HP. Worried Oneida 3HP may be borderline and I don't want to swap them out again, that's why I lean toward the 5HP. Some are now saying the 2HP I had may have been enough. ??? :)

I couldn't sleep last night, thinking about duct design.

David Kumm

03-20-2012, 7:34 PM

David Kumm

03-20-2012, 7:47 PM

"Todd, don't lose sleep yet. If Oneida recommended a 3hp unit with 8" to 7" to 6" pipe they were worried that the restrictions of using 6" all the way would bring their 3 hp unit below what you want. I do that with with my 5 hp unit for the same reason. If you can save 1" sp that can get pretty significant on the resistence side of the curve and when you can increase the size of the ell you may gain a couple. The wide blade BI design -I've been told- provides lots of cfm at low resistence but tops out a little earlier than a larger diameter narrower blade design so saving sp is a big deal. Whether you go Oneida or Clearvue you will save some resistence by graduating the pipe size. 2.5 radius ells on the horizontals adds up too. If you do it right you can juice the 3 hp to work fine. For $200 I would avoid the problems and have a system I could put any machine I wanted on. But you can make the 3 hp work. Dave

Salem Ganzhorn

03-20-2012, 8:17 PM

I would Dave but I dont have an amp meter :(.
Salem

Rod Sheridan

03-20-2012, 8:18 PM

Rod, since the CF ratings are straight fan curves, how much did you add to the 4" for cyclone and filter loss? Dave

David, that's what happens when I don't read all my notes, at 6.5" it's 1.95 HP. I added 2.8" WC for the cyclone and filter...............Which is very similar to the Oneida design, remember that the Oneida blowers are optimised for their application, it makes an enormous difference.........Rod.

David Kumm

03-20-2012, 8:51 PM

David, that's what happens when I don't read all my notes, at 6.5" it's 1.95 HP. I added 2.8" WC for the cyclone and filter...............Which is very similar to the Oneida design, remember that the Oneida blowers are optimised for their application, it makes an enormous difference.........Rod.

Hey Rod, been there done that. I would argue though that 2.8 is a little light. Very few cyclones go less than 3" and filters if new go 2" unless they really don't filter. I'm thinking 5" might be more best case than worst. Have no way to check though. Although i think the Oneida systems are really well made for the price point I'm not sure they can be designed or manufactured to outperform industrial use or priced blowers. Again, no proof though. Dave

Todd Brewer

03-20-2012, 9:40 PM

David, if it were you, would you get the 3HP or 5HP?

Salem Ganzhorn

03-20-2012, 9:47 PM

David Kumm

03-20-2012, 9:47 PM

David, if it were you, would you get the 3HP or 5HP?

Todd, you are asking the guy with the 24" planer, 16" jointer, and 5 hp DC. I'm biased to overcapacity. I have never regretted paying $200 more for something I liked but have regretted the opposite. I do have an 18" planer and 12" jointer in storage for proof. Dave

ian maybury

03-20-2012, 10:27 PM

Thanks Salem, good to know. That is a big impeller for 2HP....

ian

Todd Brewer

03-20-2012, 10:47 PM

I have a 2 HP Super Dust Gorilla that I am pretty happy with. That said if you are buying new I would go for the 5 HP. It is only 200$ more which is not much considering the overall cost of the system. Just make sure you have the extra 3" of height. Another consideration is the electrical. You will need 30A instead of 20A for the 5HP.

<edit> the manual says to use a 20A receptacle for the the 5HP model. And they say it only draws 19.5A. But I have never seen a 5HP motor be specified for a 20A circuit...

Also one other thing that was mentioned previously is with either system if you want to locate it in a different room you must make sure you have a way to get makeup air into your shop. And you better not have any gas burning appliances in there otherwise you could very well be sucking carbon monoxide into your shop!
Salem

Thanks Salem,

I agree, for a little more money, why not get the more powerful system? I have a 10ga. wire roughed into the attic of my shop. Very easy to route to the DC. I wouldn't run a 19.5A motor on a 20A circuit.

I'll provide a path for the make-up air. In the winter I will probably route it through the attic. With a black roof, I will get some warmth for no addition cost. :) In the summer I will probably provide for an alternate path.

I don't have any gas burning appliances in my shop. No heat no A/C.

Thanks for the tips!

Todd

Carl Beckett

03-21-2012, 8:39 AM

I couldn't sleep last night, thinking about duct design.

Classic. :) I have spent way too much time thinking about DC design.......

Just last night was in another part of my shop where there is no DC - routing MDF. What a huge mess (and yes I used a respirator and a fan with the doors/windows open). Will be satisfying when I get this all hooked up and functioning at a high level.

In fact, I think this stuff might be the best test of DC you can do - just cut some on the tablesaw, or on the router setup, as a test on how well your DC system works. Its almost impossible to keep from making a mess (and the dust is nasty - maybe formaldehyde in it??)

Carl Beckett

03-21-2012, 8:48 AM

That impeller looks pretty nice. You see a curved vane design - many of the impellers are straight vaned and this could make a big difference.

I havent designed vanes for air handling. I have designed vanes for centrifugal pumps. On the larger HP units the vane geometry, and 'volute' geometry (the housing the vane runs in) can make a big difference in performance. The pressure/volume/RPM curves would tell. (you need the RPM's tracked to be sure its not motor related speed changes). You can put a crappy motor on a good pump head and get poor performance. And a good motor (vs a poor one) might be capable to driving a higher diameter impeller (simply because it demands relatively less power at a given rate). But ultimately, you can check overall system by mapping pressure, flow rate, speed, and motor current (and voltage - or true power would be ideal) draw. Deep into the design work of the manufacturer, and Im not sure why they would publish this info (typically not selling into highly engineered applications, although thats what its become to this community).

Michael W. Clark

03-21-2012, 2:45 PM

That impeller looks pretty nice. You see a curved vane design - many of the impellers are straight vaned and this could make a big difference.

I agree, the curved impeller blades should be more efficient. I thought all of them were straight blades. I still don't think it is as efficient as a BI though.

Deep into the design work of the manufacturer, and Im not sure why they would publish this info (typically not selling into highly engineered applications, although thats what its become to this community).

Carl, as you know from your experience, the overall system performance depends on the pump performance and its interaction with the piping system losses. In a large system, these losses are typically known when selecting and sizing the pump. This is also true with "most" industrial ventilation systems. We design the hoods and get CFM required, then size the duct for the proper velocity, then select the collector and determine its losses, design the stack (if applicable), and finally select the fan and motor to deliver the CFM necessary at the required SP.

When buying a system for home/hobby use, you are not buying an engineered system. You are buying an "off-the-shelf" DC to match up to your duct system. In home shops, like industrial applications, each duct/piping system is different. In a home shop, we have to figure out the best match of "off-the-shelf" equipment to work with our system. Each model of equipment has its window where it performs best. However, we typically do not know our system requirements (which are often depateable), we have little information about the equipment for sale, and even less information about how the published performance was obtained to comapare other manufacturer's. This presents a very challenging problem to purchasing and installing a succesful home dust collection system. Even the term "successful" is subjective in this case.

When a question is posted, and we give a response, someone else always has a different view and opinion. This is good because it allows us to learn from others and realize the value in their opinions. However, sometimes facts need to separated from misconceptions. I, for one, definitely have plenty of misconceptions and always appreciate the chance to learn. I have a better appreciation of Oneida from this thread and have learned about nuetral vanes from this forum. I even had a customer ask me about nuetral vanes the other day and was able to respond. We may get a little too technical sometimes when trying to illustrate a point. But, I would rather be talked over than talked under. I don't have a problem asking someone to explain it in layman's terms so my simple mind can understand it.;)

Carl Beckett

03-21-2012, 3:32 PM

Michael W. Clark

03-21-2012, 5:35 PM

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. :)

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.

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

David Kumm

03-21-2012, 6:12 PM

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.

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

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

ian maybury

03-21-2012, 10:00 PM

Carl Beckett

03-22-2012, 7:27 AM

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

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.....

ian maybury

03-22-2012, 1:43 PM

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

David Kumm

03-22-2012, 1:59 PM

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

Michael W. Clark

03-22-2012, 3:11 PM

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.

David Kumm

03-22-2012, 3:39 PM

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

Carl Beckett

03-22-2012, 9:23 PM

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?

Michael W. Clark

03-22-2012, 9:27 PM

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/documents/productbrochures/cyclone_08.11.pdf

Todd Brewer

03-22-2012, 9:35 PM

(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.....

I'm still here. :) I'll chime in when I think I have a plan. Please keep discussing, I'm enjoying and learning too. Lot's of thoughts, opinions and suggestions, loving it!

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.

David Kumm

03-22-2012, 9:45 PM

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/documents/productbrochures/cyclone_08.11.pdf

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

Michael W. Clark

03-23-2012, 6:44 AM

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.

ian maybury

03-23-2012, 7:12 AM

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

David Kumm

03-23-2012, 9:36 AM

I think you guys have hit on something with the inlet speed. The Clearvue was designed specifically for 6" mains with an inlet velocity in the 5-6000 fpm range. The 55-60 sq inch inlet on the Torit is likely to reduce the speed to the same range when running with 8". The working range of my unit is between 1200-1600 cfm . Higher is possible but not with a 5 hp motor so to hit the higher numbers the system would need the 7.5 hp motor and then Torit moves to a 24" cyclone to again slow the speed down. As to the filters, I built my own plenum but if it worked out I would use the one supplied by Torit and replace two of the four tubes with cartridges and run a combination of both. The 100 sq ft that Torit comes with works much better if expanded and filtration is improved when the air isn't forced through. I run one 100 sq ft cartridge and four tubes equalling another 100 sq ft on mine and am considering replacing one of the tubes with another cartridge. My cartridge is spun bond rather than hepa but the Dylos stays so low I don't know what I would really gain with the Hepa and of couse I would have to change them all or it wouldn't make sense. Dave

Michael W. Clark

03-23-2012, 3:30 PM

There are two primary things that affect cyclone efficiency. Ther first is pressrue drop (DP). DP is representative of the force being exerted on the particles to move them to the outside wall where they can be collected. The higher the DP, the greater the force, and the higher the efficiency. The second is the size of the cylone (diameter and height). The size is representative of the retention time in the cyclone. The more time the particle has to move to the outside wall, the greater the chance that it will be collected. Of these two things, cyclone size has a larger impact on efficiency. Of course, this is a general statement and there are a lot of variables that affect efficiency.

Ian, the company I work for developed some computer programs like you are referring to for our cyclones. Our cyclones are high efficiency industrial cyclones, but have some significant differences from the cyclones avaialble to us retail. We developed these computer models through about 5 years of emperical testing and correlating the data. In my opinion, emperical testing is the only way to truly get cyclone efficiency. This allows us to guarantee and warranty our efficiency. To my knowledge CFD (computational fluid dynamics) computer analysis does not give repeatable/reliable results for cylones, but maybe it is close enough for what you are suggesting. I think you would still have to do some emperical testing to prove the CFD analysis worked. The biggest problem for CFD is that no-one has been able to mathematically describe the flow patterns inside a cyclone accurately and repeatably.

That being said, I am not surprised by the efficiency listed for the 1 micron particles on the Donaldson units. I am more surprised by the efficiencies quoted for the retail units. It is very difficult for a cyclone to get high efficiency on 1 micron dust. Usually, when you are trying to filter this low, you either have a fabric filter or wet scrubber. A cyclone is usually not practical for this type of efficiency on this dust size. If we were talking about 99% on 5 micron, then a high efficiency cyclone would probably do that on wood dust. I'm not saying it can't be done, just saying that I doubtful that you could buy it for the prices advertised and the sizes given.

I'm not sure why we need 99% on 1 micron from the cyclone when there is an afterfilter. The only reason to have a high efficiency cyclone is to reduce the cleaning of the afterfilter, correct? Obiviously, if the filter goes too long without cleaning, your system volume drops due to the back pressure, and you lose collection at the hoods. Just thinking, which is dangerous, why not use a static pressure gauge after the fan outlet to monitor backpressure from the afterfilter? Once it gets to a set pressure, then you clean it.

David Kumm

03-23-2012, 4:17 PM

Michael W. Clark

03-23-2012, 5:42 PM

good info Michael. I watch the amp draw on my vfd to determine filter effectiveness. I know the amp draw with certain ports open when the filters are clean and when the draw goes down a few tenths I clean them and it returns to normal. Not really scientific but makes me feel better. Is there a website with info on your cyclones. Would be interesting to read even if not relevent for our use. Dave

http://www.fkinc.com/cyclones.htm

There are also some technical articles on the site regarding cyclone operation and design. Some of the project examples are pretty interesting too. (for geeks like me anyway)
Mike

ian maybury

03-23-2012, 7:35 PM

What you have to say on size Michael doesn't bode well for the shortie cyclone types we see around. That said extra delta P presumably stops helping eventually - otherwise it'd be a case of the faster the inlet air speed the more efficient a cyclone would be??

My muttering about 99% cyclone efficiency is mostly a reflection of the claims I've seen about - it sounds like the reality may be that they don't get near that. For sure the issue filter life, but being tight, and again being influenced by what one reads on some of the forums I guess I'd been hoping that my nice new Donaldson cartridges might last for a long time. Cleaning is fine, but it sounds like there's only a limited number possible before the filter blinds up and/or the media starts to leak.

I was thinking CFD models Mike, but have no experience. It wouldn't surprise me too much if there isn't still an element of the unpredictable black art about cyclones - that like in most other engineering calculations it's often necessary to get an empirical value or two to get calibrated. That said I saw a paper recently by a European university group which seemed to suggest they were modeling cyclones, but it's quite likely I read more into it than was advisable.

If predicting performance entails a lot of testing then the chances are that most cyclone makers would regard the output as proprietary information, and probably wouldn't be very inclined to release it to a bunch of DIY-ers - at least not for any price we could reasonably hope to pay. :) Do you have a good R&D guy in your company that we could kidnap?

ian