Peculiar Cyclone Question

[Phisherman]

If the reject is open you will lose accept (return) flow and the cyclone will serve no purpose. Fasten the reject (bottom of the cone) to an air-tight container. Be concerned about leaks.

[Gung Ho]

Depending on your climate you might consider insulating the unit to reduce condensation in cold months.

Also consider explosion/fire hazards - i.e. explosion hatches.

A shaker will limit accumulation of debris.

Better check with your local codes i.e fire/building/engineering, especially if this is for an industrial establishment. Non certified equipment poses legal/liability insurance problems. If you ever have a fire down the line you might discover your claim being denied or worse law suits.

Cheers,

[Howard Ruttan]

Hi all,

I am preparing to construct a cyclone of my own design for my next shop. I have most of the design ideas worked out but I have one odd question I need to ask, assuming there is anyone out there with a similar setup. My cyclone is going to be mounted to the building on the outside (the return air and filtration will be directed back into the building so there are no makeup air requirements) and will be a push through design. Under the cyclone I plan on having no bag. I plan on dumping the contents directly on the ground. This appears to leave me open to the problem of rodents or other pests crawling into the system. I could place screen door screen over the outlet I suppose, but what about the inlet? Hang it from the body so that they have to climb down the steel sides to get in? Grease around the exterior of the chip chute at the bottom? I was wondering if anyone else operated this way or had any suggestions? Am I worrying for nothing?

[Steve Knight]

lets ask some questions why a pusher system? you have all of the stuff hitting the impeller. so you can use a floorsweep. if you leave the bottom open everything will come out of it including all of the air you want to return. you will need some kind of container under it for the air problem.

[Howard Ruttan]

Shouldn't be problematic on a push through cyclone, according to the literature, although the return airflow will be reduced.

[Larry C in Auburn, WA]

Two questions: Why not put a drum under the cyclone to catch the debris? It will be a lot easier to clean up than a pile of chips laying on the ground. Not to mention the rodent issue you're concerned about. You're going to have to monitor the pile of chips anyway because eventually they would pile up to the bottom of the cyclone so you might as well check the drum instead. I vote against your current plan (I did get a vote didn't I?).

[Swingman]

He might be basing the idea on the one David J. Marks has. IIRC, when "Wood Works" did the show on David's shop, they showed his cyclone emptying onto a big pile out behind the shop ... if you have the room, and make a lot of sawdust, it's not a bad idea.

[Silvan]

I wouldn't worry about rodents. I'd worry about *termites*. They'd have a field day with a big pile of wet shavings, then decide while they were in the neighborhood anyway, my shop looks pretty tasty.

Might depend on where you live though. Like if you're in a desert or something, maybe this is a non-issue.

[Howard Ruttan]

Yeah, I saw a picture of that in one of the books I have, but I took some notes from an article I read SOMEWHERE (forgot to write down where I found it) on a push through system where you didn't need a drum. I'm not the biggest chip maker in the world but I have 360 acres of room and I hate dumping out those damn cans. It's worse on my allergies than just living with the dust. I'd rather use the bobcat to scoop it up whenever I pass by with it. Then I can throw the stuff on the manure pile to compost. No-one else has seen this, or any info on doing it? Appreciate the help so far.

[Bob Summers]

How are you going to control the air pressure at the dust outlet?

If it's negative (i.e. less than atmospheric) you risk sucking the dust back up and into your final filter. This is possible with a 1D3D design because they can generate a strong low pressure area at the bottom of the cone; c.f. PSI and their comments about collapsing metal dust bins.

One report described a push through 1D3D design (with a standard cone) that got a vacuum of about an inch or two of water at the dust exit depending on the inlet velocity.

When the cone was modified to have a linear flighting (vertical vane) in the lower third of the cone, the dust exit pressure became very slightly positive (i.e. a little air flowed out the dust exit).

So, that part should work out as long as you're willing to put up with wind blown wood dust.

I don't understand what you mean by keeping rodents out of the inlet; won't that and the air return be terminated inside your shop?

Putting a screen over the dust exit would risk clogging which would probably fill your cyclone and clog your filter in short order.

Grease will rapidly fill up with dust.

Maybe a down tube with a weighted flap at the end? A spring to hold it closed might be better. With the cyclone producing a positive pressure at the dust exit and the weight of the wood dust it should open and let the dust fall out. A flap should also help with those times the wind blows and overwhelms the positive pressure at the dust outlet.

Or, how about something like an eco-gate on the dust outlet?

Or, how about an pneumatic cylinder operated gate on the dust exit? When the cyclone is in operation, the inlet pressure will be higher than atmospheric pressure (this being a push through design). You could use that pressure to operate a bellows (maybe a few feet of large diameter, cheap flex hose or even flexible dryer hose would expand enough) to operate the gate. If the connection between the inlet and the bellows were small enough then the air flow in the inlet wouldn't be affected much. If the hose/bellows were vertical, the dust should fall back into the inlet instead of building up in the bellows.

Good luck. Let me know how it turns out.

Bob S

[Mark & Juanita]

Nope, termites live in the desert too. :-(

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