Troubleshooting a Cyclone Setup

A woodshop owner struggles with a dust collector whose filter quickly clogs with fine sanding dust. October 26, 2011

We've had our Oneida Pro 2000 5ph system in place for a couple months now. When we first hooked it up, and before any dust was drawn through it, the pressure gauge between the cyclone and exhaust filter cartridge had a reading of "2" on a gauge that goes from "0" to "5".

Once we started using it, the bottom end of the gauge reading when running the system became "3". Tech support at Oneida said that was normal as the filter fabric would be initially embedded with fine dust, thus slowing down the air flow somewhat.

What we are finding, though, is that after we clean it and get the gauge reading of "3", it only takes about 30 minutes of Timesaver use to bring the gauge all the way up to "5", making it time to clean the filter again.

Does anyone have similar experience with this filter system? Is the cyclone not separating the fine dust the way it should be?

Forum Responses
(Dust Collection and Safety Equipment Forum)
From contributor E:
Make sure that you have no leaks at all in the cyclone setup. Any small leak can affect the cyclone's separating ability. I know you're playing with a RAL below so that could be the culprit.

Other than that, it shouldn't be clogging your filters that quickly, or at all really. I have a different setup using a 7-1/2 hp cyclone with 3 - 2' x 8' filter bags (1 more than needed, but I like the idea of overdoing it). I can run my dual drum sander all day long and never have a problem with loss of suction or clogging filters. In fact I clean my bags out every 6 months or so, not because of any noticeable loss of flow, just to keep them somewhat clean.

From contributor B:
I spoke with Andy at Oneida and he gave me pretty much the same feedback. It's nice to know that you go so long without cleaning... Gives me a goal to work towards.

I was going to use an elaborate secondary blower system but now I'm afraid it will leak too much air through the air lock. I may be back to a single very tall bag below the unit (cyclone on 1st floor, bag in basement) and just eliminate the rotary air lock completely.

From contributor E:
I know from your posts you're limited on space, but you may have a couple options.

First, you could have your blower system from the RAL on completely sealed. Not sure how difficult it would be to do, but if the entire system was air tight it should (theoretically anyway) eliminate the problem.

Second, if you cannot completely seal the system, but it still separates the majority of waste, then keep the RAL and add a small baghouse in the basement as a replacement to your cartridge filter? Just run the exhaust duct to the basement into a plenum with as many of whatever size bags you want. I originally had a very nice 3 stage filter for my collector, but I knew it would be more difficult to clean if (more like when) I got blowby from overfilling the drum. So I had a plenum made and added 33% more area by adding 1 more bag than what was needed. Fairly inexpensive to have done in the overall scheme of things. You wouldn't fix the separation problem, but you also shouldn't have to stop to clean the filters very often.

Third, don't know how tight your space really is, but I know you do a lot of molding work, correct? This last idea, if you had the room, would be to add a separate cyclone for the widebelt only. You could have the first cyclone service the rest of your shop with the heavy stuff through the RAL, etc., then the cyclone for your widebelt could be a completely sealed system which would give you good separation to keep the filters clean and also allow you to do quite a bit of sanding before filling the 55 gallon drum. Wouldn't be too much of an expense, as I see the smaller Torit cyclones come up in our area every so often in the $500 range. The shop I worked in previously did this. They had a huge outdoor system for most of the shop including an old Timesaver. But when they bought a second 53" widebelt they also added another collector inside just for that one machine.

From the original questioner:
Thanks for the good ideas. Option 3 is what I'm leaning towards. I told the guys yesterday to hook up our portable Delta 1-bag collector to the Timesaver for a week or two to see what we think. It actually does a pretty good job there, as we've done this during the dust collection system construction. Pending the results of that, I can use the Delta or a smaller cyclone.

I've also been thinking about pulling the rotary air lock out of the system and just dropping straight down into two 5' to 6' tall bags through a Y-split. I'll be a bit hard pressed to get both bags in place, but I probably can pull it off. Again, not much room given the location of the cyclone drop into the corner of the basement. Plus I'd be stuck with a 2 bag system instead of the 3 or 4 bags I was looking to build.

From contributor G:
What condition are the paddles of your RAL in? The system as you designed in your previous post should work. The RAL should not leak enough air to affect the system that much. What you propose to do is exactly what RALs are designed for. Check the condition of the paddles and replace them if needed. How tight is the seal between the RAL and cyclone? I wouldn't give up on it yet.

From contributor J:
When I had a cartridge system, I blew up several filters due to back pressure from sanding dust. I ended up with a baghouse instead. Then I put a separate blower and small baghouse (Dantherm with Beane filter media) on my widebelt. We had a small loft area that worked to avoid taking up floor space. The main cyclone system benefited by not having to deal with an extra line. We just bag the fines. A local HVAC company owner has been taking them to burn in a furnace that he is designing. He is amazed that I have to pay someone to collect my shavings dumpster. The times are changing, and hopefully we will be able to sell wood dust as energy soon.

From the original questioner:
Unfortunately the rotary air lock was rebuilt prior to the installation. It is acting pretty much just as Donaldson-Torit and Oneida say it should. It's letting just enough air by to keep the sanding fines from separating, but doing a great job with table saw sawdust and shavings.

I will say that I'm a bit annoyed by all this. When I bought the Oneida I expected it to solve all dust collection issues. And it would have if I could have lived with the single 55 gallon collection barrel below the cyclone. That of course is totally inadequate though. I kind of wish I knew then what I know now!

From contributor G:
Would replacing the cartridge filters with bag or sock filters make a difference? Unfortunately the only way to know is to spend yet more money to find out. It worked for a local shop here that did just that. I have not heard much good about cartridge filters, which leads me to believe they are not what they are cracked up to be. The manufacturers seem to keep pushing them and I know they have a lot of surface area in a small package, but from what I've read and heard they just don't seem to perform as well as fabric filters.
I used to have my sawdust barrels under the cyclone but now have a RAL with a blower transfer system and wouldn't go back, especially with the amount of sawdust a moulder can make. I would really like to see yours work.

From contributor C:
When we were upgrading our DC I looked at the Oneida 20 HP with the cartridge filter and talked to a few shops with that system. They all said the same thing about WBS dust plugging these and being labor intensive to maintain. We ended up with a Belfab baghouse.

Contributor J is right about cyclone systems needing a baghouse or hanging filter bags downstream to handle the fines.