# Can a Cyclone be too large for the motor?



## ChuckH (Jul 25, 2013)

if I hook a very large cyclone separator that's about 4 feet tall with 6 or 8 inch in/output, is it possible it will be too large for a moderately powered collector, like a 1HP 600CFM unit to power?

Someone has a large Torit cyclone, no impeller just the cyclone and frame for sale locally for about $100. Considering the cyclones for sale on ebay/amazon are around that price or more, it seems like it could be a good deal but I'm not in a position to get a very powerful collector at the moment.

Thanks,
Charles


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## Loren (May 30, 2008)

Choke the input to 5" or 4" and you'll get some usage I think.

I have a shop-made cyclone from the Wood Magazine plan. 
Somebody else made it and I bought it used. It has
the 110v impeller from Penn State. It's really not that
high powered and I'd like to upgrade to a 220v blower
but I'd have to run a new circuit for it and that's a hassle.


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## MrRon (Jul 9, 2009)

Using a small DC with a large cyclone will result in low volume and pressure.


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## wapakfred (Jul 29, 2011)

You are going to be so disappointed with the performance of that combo you'll wish you hadn't thought of doing it. Cyclones introduce a lot of drag (resistance to air flow) to a system, then adding a blower that barely moves air anyway means you aren't moving any air. If that sounds harsh, I apologize. But it's what will happen.


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## crank49 (Apr 7, 2010)

It will work in a limited fashion.
The velocity of the air entering and spinning around inside the cyclone is critical to proper function.
What happens if the flow is too slow, as it would be with an undersized fan, is that the heaviest material will still drop out of the flow as it should, but because the air does not form a proper vortex and increase velocity it will not spin out the finest dust.

The cyclone, in this case, becomes what is referred to in pollution control speak, as a drop out box. You could do virtually the same thing with a 55 gallon drum and a couple of fittings.

On the positive side, there will be very little burden on the fan for increased flow resistance so you won't have hardly any pressure drop.


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## bigblockyeti (Sep 9, 2013)

When you install a cyclone on a blower, you now have drag not only from the attached duct work, but also from the entire inner surface area of the cyclone. This can be substantial. With even a 6" intake port into the cyclone, your velocity will be to low for all but the lightest dust, planer shavings won't have a chance.


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## ChuckH (Jul 25, 2013)

Harsh? No way, I appreciate the feedback. Harsh is the reality of dropping real dollars on a bunch of junk that doesn't do what I want.

Thanks for all the feedback everyone, I recalculated my DC needs using a different guide - which indicated I could get away with using 4" pipe. The first guide I used (both were by Wood magazine, go figure) indicated I would neat 6" pipe and I was panicking that there are no collectors in my price range that take a 6" input. 4" is much more workable, so I'm working on that assumption now.


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## Bluepine38 (Dec 14, 2009)

One thing that no one mentioned. A lot of the older, and some newer cyclones were not properly designed
and are best used as scrap at a recycling center. Not saying this is one of them because the new Torits are
very well designed, but before buying any cyclone, take a good look at the designs and specs on newer good
cyclones and then compare what you want to buy to them, it could save you money and a lot of grief.


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## shawnmasterson (Jan 24, 2013)

Don't waste your money just build a top hat separator.


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## kizerpea (Dec 2, 2011)

Well…throw rock in what ever directions you like my cyclone works..its 51 in to the bottom of the cone..so that's over 4ft…with a jet 1200 cfm blower an 30ft of 6 in pipe …I have tried to choke it up….but not yet!!!15 in grizz planer cutting as hard as it can at the very end of the run…sure …I have some friends that said it was to big an not going to work…..two of them have built there own just like it …..so crunch all the numbers you like …an pull out the slide rule to….it works….my friends say I need to post a video…mite just do that….


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## REO (Sep 20, 2012)

crank49 hit the nail squarely on the head. anything can be used for a drop out box for large coarse chips but the fines are best removed by proper flow through the cyclone.


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## Bluepine38 (Dec 14, 2009)

kizerpea, not throwing rocks, just wondering how does it do on separating the fine dust? Do you exhaust
through a bag or a big filter? At 1200 CFM that must be the 2hp model. Thank you.


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## ChuckH (Jul 25, 2013)

Bluepine, what sort of specs do you look for on a cyclone to be "good"? I just look to see if it's shaped like a cone 

Shawn, thanks, I will probably do this - I did not realize until your reply that there was any kind of 2 stage other than a cyclone.


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## Bluepine38 (Dec 14, 2009)

The newer better cyclones have some type of ramp directing incoming air down and around the outside of
the cyclone, the inlet extends down into the intake chamber at least 1/2 the diameter of the intake pipe or
further. The older Deltas and some others just stopped the intake at the outside diameter of the cyclone
and the intake was flush with the top. This did not generate a good air flow and too much dust and 
particles went right through and out the exhaust. This is a simplified idea, for a lot better idea visit Bill Pentz,
Clearvue and the Bill Thien sites.


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## crank49 (Apr 7, 2010)

Killer, what is the diameter of your cyclone?
That is the important dimension relative to air volume.
I have designed and built a cyclone that was 29 ft tall but only 5 ft diameter. It catches silica dust in a foundry grinding operation and made the EPA guys happy.
It's all about air velocity.


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## wapakfred (Jul 29, 2011)

Pentz's tests indicate the internal air ramp and neutral vane (what Bluepine mentioned) is important, but the body diameter to height ratios is as well (what Crank designed), along with the squared sloping inlet. All these are important to separating the finest particles, less so for the large stuff. Now, if you talk to Bill Witter (founder of Oneida) he poo-poo's this criteria. I do not, and to this day call my Oneida a POS because it doesn't follow any of this.


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