Alternate Cyclone Layout and duct layout

[Anthony Whitesell]

I am playing with a duct layout to upgrade to a cyclone DC. I noticed that most cyclones have the cyclone body in the vacuum or inlet side. Some folks here have the cyclone body in the pressurized or outlet side.

In the case of the cyclone body before the impeller, I have noticed the inlet is not a convenient height. The duct must come out, then angle up, run to the ceiling, and then angle back to horizontal. This takes both length and two more bends. I was thinking with the blower before the cyclone body, it could be mounted such that the inlet of the cyclone and the blower outlet were at the same height. Then orient the blower with the motor down and on a 45 degree angle, thus aiming the inlet upwards at a 45 degree angle. This would result in the blower inlet aimed towards the ceiling and the ductwork run overhead. I see two advantages. (1) lose some of the duct run and one 45 degree bend (2) the motor-blower combination is taller than the elbow so I can accommodate a taller bin. The down side is the increase in the "width" of the cyclone.

Anyone have a reason why this would not work? Anyone see any problems with it?

[Jim Becker]

Pre-separation (before the blower) insures that material being moved isn't passing through the blower. That's what you want for sure if you plan for things like floor sweeps, etc., to insure no metal comes in contact with the fan blades. Most "small shop" cyclones are built this way if they are integral units.

As to your specific question, you have to remember that the inlet is spooling material in at the exact point needed for the air vortex in the cyclone body to be ideal for separation via friction. The outlet (for air) is ascending up and out of the center of that air vortex. This should be clear if you take a look at the internal design of a cyclone separator. It would likely be very difficult if not impossible to have the inlet (which must be horizontal) be at the same level as the outlet (which is vertical until it hits the blower or takes a 90º bend out in the case of a separate cyclone/blower design).

What many of us have done to accomodate the larger 55 gallon bin is to get the motor of the cyclone up between the joists. This also makes the inlet closer to the ceiling height which results in less of a ramp to the inlet on the cyclone.

[Anthony Whitesell]

What many of us have done to accomodate the larger 55 gallon bin is to get the motor of the cyclone up between the joists. This also makes the inlet closer to the ceiling height which results in less of a ramp to the inlet on the cyclone.

I still don't have enough height. I'm stuck with building my own bin.

As to your specific question, you have to remember that the inlet is spooling material in at the exact point needed for the air vortex in the cyclone body to be ideal for separation via friction. The outlet (for air) is ascending up and out of the center of that air vortex.

So far I'm with you

This should be clear if you take a look at the internal design of a cyclone separator.

Still good.

It would likely be very difficult to have the inlet (which must be horizontal) be at the same level as the outlet (which is vertical until it hits the blower or takes a 90º bend out in the case of a separate cyclone/blower design).

Lost me.

I'm thinking of not using the cyclone as a pre-separator, but as a downstream filter. Downstream of the blower. In this way the outlet of the blower could be mounted at the same height as the cyclone body with the blower inlet facing upwards. But I want to rotate the blower inlet 45 degrees on the axis of the blower outlet-cyclone inlet. I'm trying to draw a picture, but sketchup isn't cooperating. Has anyone mounted a blower on an angle other than horizontal or vertical?

[James Gunning]

The blower could be mounted at varying places and angles and connected to the cyclone by piping. It's the cyclone body that needs to be vertical. Not having the cyclone vertical would work against gravity and interfere with the internal operation of the cyclone. I would suggest you place the cyclone before the blower as Jim suggested to reduce the chances of hitting the impeller with anything larger than sawdust. If you mount the blower at some place other than close to the cyclone and connect with hose, you will likely suffer some drop in performance, especially if the connecting hose has 90 degree bends in it. Building a bin isn't difficult and you can have one as large (or small) as your space permits. Just remember it needs to be sealed with the bottom of the cyclone body so there are no air leaks.

Here is the portable unit I built. http://www.sawmillcreek.org/showthre...able-SDD-build As you can see, it is not that tall, approximately 75" overall.

[Michael W. Clark]

Also, if you put the blower on the inlet, you need to watch fan rotation and you should space the blower back some from the cyclone inlet. Turbulence and blower direction (turning opposite of cyclone rotation as seen in plan view) will reduce collection efficiency in the cyclone.

[Chris Parks]

I'm thinking of not using the cyclone as a pre-separator, but as a downstream filter. Downstream of the blower. In this way the outlet of the blower could be mounted at the same height as the cyclone body with the blower inlet facing upwards. But I want to rotate the blower inlet 45 degrees on the axis of the blower outlet-cyclone inlet. I'm trying to draw a picture, but sketchup isn't cooperating. Has anyone mounted a blower on an angle other than horizontal or vertical?

There is a low height installation method for a Clearvue cyclone that is basically what you describe. Wander over to the CV forum and have a search or get in contact with them for further information.

[Anthony Whitesell]

There is a low height installation method for a Clearvue cyclone that is basically what you describe. Wander over to the CV forum and have a search or get in contact with them for further information.

A little help. Can you be more specific? I am not finding any information in their instructions or their forum.

[Jim Andrew]

I bought an Aget Dustkop cyclone dust collector, and it is a blow through design. It does allow the motor to be lower than the blower on top design. Found it on Nextech classified at a juco a few miles from here. Turned out to be an excellent machine for me. Although it has a small impeller, it is a straight blade, and moves much more air than my 2hp cyclone did.

[Peter Aeschliman]

Here's one mounted on a severe angle, but with the motor and impeller on top:

http://www.gallery2.clearvuecyclones...CVMax/David-L/

I'd search more, but I'm on my phone.

[John K Jordan]

ClearVue sells their cyclones in either a left-hand or right-hand configuration causing the chips to spiral in one direction or the other. The inlet from the machines is below the impeller. The outlet to the filters is on the level as the impeller. With this design, it doesn't matter which way the impeller turns - it can be opposite the spiral into the collection can. ClearVue said the efficiency is the same for either direction with this design since the extremely fine dust is exiting the high in the center of the cyclone, far from the spiral stream of chips on the outer diameter of the cone. I think mine turns opposed and the efficiency of collection is amazing. After a couple of years I get almost nothing in the filters.

I can't imagine how it would work if the inlet directly in line with the impeller blades. Seems like you would risk sparks from metal pieces inadvertently striking the impeller blades. The thing has amazing suction. (ClearVue had a video showing their cyclone picking up a 30' measuring tape and dumping in into the can.)

JKJ

[Anthony Whitesell]

Remember that all bag style dust collectors have the impeller in front of the filters. It is not like I am putting the blower/impeller in a location that no one else does. What I am trying to determine is if the motor/housing can handle being mounted on an angle over the long haul.

[Michael W. Clark]

Remember that all bag style dust collectors have the impeller in front of the filters. It is not like I am putting the blower/impeller in a location that no one else does. What I am trying to determine is if the motor/housing can handle being mounted on an angle over the long haul.

I think everyone is trying to say there is no free lunch. Sure, you can mount it in front of the cyclone and the cyclone doesn't care. However, you lose the pre-separator aspect of protecting the fan from large pieces, for what that is worth to you.

As far as the fan goes, I would want it turning the same direction as the cyclone, as viewed from above. If you can go vertical straight out the top for your outlet for outlet air, this could be a good setup. If you have to go horizontal out of the top to filters or to discharge outside, then you would have less of a height decrease.

[David Kumm]

Push through systems like the Aget are not all that unusual but I don't think it has been mentioned that the impeller should be rated for material handling. Typically that means a heavy steel radial. Mine is so rated but also weighs 20-30 lbs. A taper lock bushing is preferable to a set screw locking the shaft to the impeller. Dave

[Wade Lippman]

I had an Oneida portable (or something like that) years ago that had the cyclones (there were two small ones) after the impeller. It worked okay, but emptying those tiny bins and cleaning the filters got old fast.
Don't really know about the 45* motor question. Ask the manufacturer what they think.

I use 8" pipe to get to the ceiling and then go down to 6". I tell myself that the 8" makes for less turbulence than 6" would. I don't know if that is true.

[Dan Hintz]

I took my PSI DC2 blower and modified it. Built a plywood box that raised the motor to the height of the input collar on the bag and flipped it sideways. That got rid of the flex hose that was there previously, as well as a 90 degree turn. The fan now essentially blows right into the metal collar. Inside the collar I built a cyclone, so it's all pretty self-contained.