Cyclone Filter Clogging and Duct Sizing

Troubleshooting a clogging situatin in pleated air filters for a cyclone dust collection system. Is too-small ducting the problem? January 23, 2012

I have had a 2hp cyclone for about six months now and am having problems with the pleated filter getting clogged. I recently purchased a double drum sander and suspect that the fine dust may be clogging the filters. I have cleaned them thoroughly with the internal brush.

The problem I am experiencing is reduced airflow. Also, the bag on the bottom of the filter is very hard (compared to being fairly low pressure when new.) I think the clogged filters are reducing the airflow.

Can anyone else comment on this or have similar experience? Cyclone is Grizzly 2hp. It is located inside my shop and has runs of 20-30 feet of 6" steel pipe. I talked to Grizzly and they said this is first time they have heard of this type of issue. They seem willing to replace $300 filter under warranty, but am waiting to hear back from them.

Forum Responses
(Dust Collection and Safety Equipment Forum)
From contributor U:
Make sure that you are running a big enough air line to the sander. You want max velocity in the cyclone to spin out as much dust as possible. You might also try blowing the filters from the outside with compressed air. Having said this, I gave up on pleated filter media a couple of years ago. Once it is loaded with very fine dust, you have to replace it.

From the original questioner:
I do have inadequate piping to my drum sander (only one 4" line that goes into a "Y" at the sander). I dadn't thought about the additional airflow helping the separation process. I guess for now I'll open a downstream port as well.

I had been running the cyclone for six months with excellent airflow and separation (hadn't even needed to empty filter bag). I think it must be the recently acquired drum sander that is the culprit. Also good to hear confirmation that pleated filters can't be cleaned 100% once loaded with fine dust, as this is what I am finding as well.

From contributor F:
I have a 24" double drum sander and it requires 2 - 4" ports which are wyed into a 6" drop. Your piping is far too small for effective collection. Once you solve that problem your cyclone should (if well designed) separate most of the dust before it ever hits the filters. I agree that the cartridges filters are way overhyped. If it needs replacing I'd recommend going with a good quality bag a little oversized for your needs.

From contributor B:
I have cleaned/blown-out the pleated cartridge filter on my Onieda 3 hp system installed in 2003 many, many, many times when I have had reduced air flow. After cleaning the pleated filter, all is well again in regards to air flow.

From the original questioner:
Grizzly has informed me they won't replace filter under warrantee, and I have tried cleaning more with internal brush and banging filter housing to loosen dust. Suction has actually returned to a point that I am happy with it (not sure if it is same as new).

On another note, I have always been bothered by the loud noise the cyclone makes, too loud for even brief exposure without hearing protection. That said, I recently attempted wrapping the filter with fiberglass insulation. It made a big difference, as most of the noise comes from the filter. Just wondering how you find the noise level on your Oneida 3hp cyclone, and if you have tried anything to make it quieter?

From contributor B:
To thoroughly clean my filter, I completely remove it, take it outside, blow it out completely inside and out with the air compressor. This might help if you haven't done it already.

As far as loudness is concerned, it is loud, and I haven't tried to muffle it. Putting fiberglass around the filter sounds good but I wonder if it reduces your airflow as well?

One aspect of my shop is that I heat with a wood stove at one end, the dust collection at the other end, so it actually re-circulates the heat in the shop. Covering the filter, for me, would reduce that air flow.

As preventative build up, once a week I bang the filter and blow the pleats and empty the canister on the bottom of the cartridge filter. I do not know how large your filter is on your system - my filter is approximately 14" diameter by 72" tall.

From contributor F:
Are we talking pink fiberglass insulation? If so not only will it reduce your airflow, it will also fill your shop with insulation dust which is probably worse for you than wood dust, and completely eliminating any benefit the filter may have provided.

From the original questioner:
Yes I'm talking about pink fiberglass bat insulation. I had some kicking around from a previous reno and decided to try wrapping it around the filter to absorb some of the roar of the DC. I only wrapped the top 2/3, loosely. I agree that it could block airflow, but I did not wrap tightly and air is easily escaping. The actual air velocity isn't high, so I don't know if it'll fill shop with fiberglass remnants. I don't think it will, but will watch. I did cover filter with a piece of melamine so it should keep most of it in the corner of my shop. The sound reduction was quite noticeable, are indeed effective at reducing noise.

From contributor R:
Cyclone efficiency is affected by a lack of air. If you are running too small of duct and/or starving the cyclone for air it will not function properly. You need to make sure those bases are covered your cyclone will drop out the dust instead of pushing it into the filters.