Cyclone dust collector blower position

[Carl Beckett]

Its hard to imagine this hasnt been covered already, so just ignore if so.

But shouldnt the blower go BEFORE the cyclone, and not after?

Blowers can push more than pull, so any pressure drop through the cyclone would be handled better by putting the blower in between the equipment and the cyclone (and as close to the machine as possible - to where it 'T''s off to other machines) - to put as much of the pressure drop on the outlet side of the blower.

(yes, there is convenience of mounting the blower right to the cyclone)

I wonder how much effect this would have? Maybe the cyclone itself is negligible pressure drop?

[Michael O'Neill]

It can be done..... But do you really want all the chaff going through the blower??? If it gets ahold of a big knot or a tool of some kind, it could-most likely would, damage the impeler.... Imagine a tape measure passing through the blower........

Might not be to good for the tape.....


Michael

[David Kumm]

It can be done..... But do you really want all the chaff going through the blower??? If it gets ahold of a big knot or a tool of some kind, it could-most likely would, damage the impeler.... Imagine a tape measure passing through the blower........

Might not be to good for the tape.....


Michael

They are made both ways. Alan Schaffter has a push through. Performance doesn't change all that much and there are likely a million other factors that you would have to get exactly right for the difference to be apparent. If you look at the Aget systems with the impeller set along side the cyclone you will have a push through. Dave

[Clint Olver]

A proper cyclone can suck up a 25' tape measure. I wouldn't want something that size hitting the impeller. For that reason alone, I'd put the blower AFTER the cyclone.

C

[Bruce Wrenn]

First I don't put tape measures in my DC system. (I don't flush golf balls down my commodes either.) A blower can "push" no more air than it can "suck." As for trash though impeller, most if not all, two bag systems are through the impeller first. Manufacturers figured out early on that some one is going to suck stuff up that isn't chips or fines. That is why inlet side of impeller blades are tapered, plus they usually have those "cross hairs" in the inlet to stop large items from entering blower. A simple "drop box" could take care of large items. It could have inlet and outlet straight across from each other to reduce suction losses due to changes in direction.

[Michael W. Clark]

This premise is not true. A fan does not push more than it pulls. What goes in the inlet, comes out the outlet. The fan is on the outlet so it handles minimal material. When mounting a fan on top of a cyclone, make sure it is rotating the proper direction, or your air volume will be reduced.

Mike

[Carl Beckett]

Ok.... as much as I dislike starting another DC question thread - here it is:

Does anyone know of a good (meaning cheap/simple, without use of a hot wire anemometer) way to measure air flow?

I would like to test some different configurations - with the hope of increasing air flow and improving separation of the cyclone. (at least my thinking is that the system can benefit from better (higher) air flow - the cyclone isnt doing a great job at separation)

(although this rotation effect has me wondering.... I dont have it mounted on top, but there might be an effect going on there so that another consideration)

In trouble shooting mode.

[Bruce Seidner]

you can buy or make a water manometer.

I did a quick Google and found this: http://www.obairlann.net/reaper/moto...manometer.html

[David Kumm]

you can buy or make a water manometer.

I did a quick Google and found this: http://www.obairlann.net/reaper/moto...manometer.html

I use a fan blade hand held anemometer. You can find them for $75-125 and well worth it to know what velocity you really have at each machine port. The only cfm or velocity numbers that mean much are measured at each machine. Get the type that allow for speeds of 6000+ fpm so you don't shatter the blades. I try to be consistent and hold it against the edge of the flex or fitting and if larger than 5" you need to move it around the opening and average out the readings. If I read from 5100-5500 on a 6" port I assume the flow to be 5200 and do the math to convert to cfm. You don't need absolute numbers here but a range that you can convert. You will find that the ports closest to the cyclone read higher than those farther away and a pattern develops that allows you to judge how the bends and pipe affect velocity. I found that I could pull the same velocity through a 7" pipe that I could through a 6" which increased my cfm by about 1/3. You do need to measure amp draw as well to determine whether you are running the motor at capacity as the gates open. Dave

[Alan Schaffter]

They are made both ways. Alan Schaffter has a push through. Performance doesn't change all that much and there are likely a million other factors that you would have to get exactly right for the difference to be apparent. If you look at the Aget systems with the impeller set along side the cyclone you will have a push through. Dave

Yup, as David says, I've been doing that for over 10 years. While I haven't intentionally tested my fan/impeller I have sucked up many chunks of wood, and yes, at least one tape measure and a DP chuck key, with no detriment to my 14" steel impeller.

Unlike water pumps some of which push better than they pull, our material handling DC blowers work the same both ways.

[Michael W. Clark]

For airflow measurements, try a Pitot tube and manometer if you don't want the anemometer. Dwyer Instruments has some of this stuff that I have used. There may be some other places that have something similar, but cheaper.

Dwyer Pitot Tube #166-12 http://www.dwyer-inst.com/PDF_files/124.pdf
Dwyer manometers http://www.dwyer-inst.com/PDF_files/430.pdf
Instead of the manometer, you could use a magnehelic gauge http://www.dwyer-inst.com/PDF_files/2000.d.pdf If you are only doing flows, get the 2002AV with the velocity scale. If you want to measure SP, then maybe 12" range or whatever you think your collector can develop. A lot of people use two gauges, one for flows, the other for SP measurements.

[Carl Beckett]

Thanks for all the ideas (simple home made manometer is more my speed(budget))

The basic problem is this: I purchased a Clearvue cyclone and connected my current 2hp blower to it. The separation is not good (I think it may be inadequate air flow - just too low!). I do have a lot of 4" pipe, including substantial flex tubing (all stuff I got for free)

I took a chance on trying to get all the free stuff working before going out and spending another $1000 on a 5hp, 15" impeller and 6" ducts everywhere. I dont need perfect separation (I do vent to the outside), but its pretty dismal at the moment and not adequate at the tool anyway (all my tools have 4" ports, and upgrading these would not be trivial - but I would do this if it allowed the current blower to work).

Yes I may be fighting a no win battle, but its a tricky (and easily philosophical) topic. I want to see just how close I can get with the current equipment at hand (currently unacceptable, so wanting to learn if I can upgrade it to acceptable status). Maybe start with a very minimal run of pipe and if that doesnt do it then nothing will. (the bare blower/clearvue combination). The clearvue gets good reviews so I know its possible, but I havent found any direct data on how the clearvue does with low flow rates.

[Alan Schaffter]

Cyclones are sized to the blower. 2 hp with what is likely a 12" impeller is not sufficient to properly drive a ClearVue.

[Carl Beckett]

Cyclones are sized to the blower. 2 hp with what is likely a 12" impeller is not sufficient to properly drive a ClearVue.

I think this is the fundamental problem. ( kinda thought was up against some fundamentals)

I do think the impeller is 12" ( or maybe 12.5.... But definitely not 15)

Hmmm.... Might have to back up a bit and look at choices of a different cyclone, or different blower ($$$)

[David Kumm]

don't spend money on a different cyclone. You need to look for a 3 hp blower with a 14" fan or something like the clearvue 5 hp 15". Look at Pennstate as well. they have a 3.5 blower unit that would fit as well. Dave