Thread: Dust extractor filter - required after cyclone?

Thanks. Is the 2” loss at 600 you are talking about between pics 1 and 3?
My impellor outlet is modified to 150mm as is the entrance pipe to the collector ring. The original 125mm inlet to the collector is now utilised as an outlet and goes to a Thien unit in a 200litre drum. I had to do that because the single pleated filter outlet was insufficient for the 150mm modified system.

Originally Posted by dmorse

You have to do more than just remove or replace the bag. That won't be enough (unless the bag is nearly plugged). That separator ring needs to go. It has as much flow resistance as 38 m of 150 mm PVC.

Is the "separator ring" the angled ring in picture 4 that slopes downwards towards a hole in its centre?

Originally Posted by RSD

Is the "separator ring" the angled ring in picture 4 that slopes downwards towards a hole in its centre?

It's the whole drum shaped Green object. There's an entrance on the side. The sloped top is the small particle exit. The open bottom of the drum is the large particle exit. It's a very rudimentary centrifugal particle separator.

Originally Posted by dmorse

It's the whole drum shaped Green object. There's an entrance on the side. The sloped top is the small particle exit. The open bottom of the drum is the large particle exit. It's a very rudimentary centrifugal particle separator.

Cheers. Would be hard to get rid of the whole thing I imagine but it wouldn't be too hard to cut that inside sloping ring out if you think that would help?

Originally Posted by RSD

Cheers. Would be hard to get rid of the whole thing I imagine but it wouldn't be too hard to cut that inside sloping ring out if you think that would help?

It's not hard to get rid of it. With the cyclone in the system it only functions as a bag holder. If you're venting outside there's no need for the bag so no need for a holder. Venting inside preferably uses a pleated filter and you can then just feed the filter canister directly, no need to spin the air again just to send it out.

Originally Posted by dmorse

It's not hard to get rid of it. With the cyclone in the system it only functions as a bag holder. If you're venting outside there's no need for the bag so no need for a holder. Venting inside preferably uses a pleated filter and you can then just feed the filter canister directly, no need to spin the air again just to send it out.

Cheers - makes sense. Can't just vent outside unfortunately but do have two of the big pleated cartridge filters (have the H&F DC-7 twin system)

Originally Posted by RSD

... have two of the big pleated cartridge filters (have the H&F DC-7 twin system)

In that case I wouldn't worry too much about loss in those separators. With the flow split in two the pressure loss drops by a factor of four. Keeping the filters clean is more deserving of your attention than messing with the rings.

so out of pure curiosity which is the more efficient system (or the lesser of two evils)

1.
modified 2 or 3 hp dusty
inline cyclone
no plastic/filter bags or separators
vented straight outside with an adapter from DC outlet through a wall

2.
modified 2 or 3 HP dusty
no cyclone
plastic collector bags, and pleated filters
enclosed and vented outside


basically does having a cyclone but nothing on the tail end of the DC provide better CFM then the separators and filters?

can only assume going off a lot of Bobs advice that #2 will actually provide the best benefit in terms of air movement.

Originally Posted by havabeer69

so which is the more effecient system (or the lesser of two evils)

Either COULD be the more efficient. It would depend a lot on any number of design factors and equipment options. Not all dc's and cyclones are equal.

The real question is which is better for you. In either of those options you are exhausting all your heated or cooled air from your shed anyway. If you are going to use pleated filters you might as well make them good ones vent back into the shed to save heating/cooling energy.

I hate plastic bags and filters and use my dust producing machines in the un-airconditioned compartment of the shed so i go with option 1. I empty a bin when needed and don't need to clean filters.

If you love cleaning filters and dealing with dust bags go with option 2.

Just decided to measure my system. It’s described in Post #17.

The system measured is basically 6 metres of 150mm PVC pipe and 3 metres of Flexi going to a table saw.

All hooked up - 620.4 cfm

Thein filter hose disconnected - 649.8 cfm so it’s pipe is pumping straight to the air.

Outlet pipe from the impellor disconnected from separator ring and pleated filter so pumping straight to air. - 720.9 cfm

As I'm currently redoing my own extractor system, I'd like to know whether my attempts are achieving anything. To that end, can I ask how people are measuring their airflow?

I have a hot wire anemometer . I also have a calibrated pitot tube used with an electronic “manometer”.

I prefer the anemometer as it talks to my iPad so I can capture and store readings.

Originally Posted by Lappa

I have a hot wire anemometer . I also have a calibrated pitot tube used with an electronic “manometer”.

I prefer the anemometer as it talks to my iPad so I can capture and store readings.

OK, thanks! I've just looked at the price of these things....... more than my extractor cost!

Where abouts in NSW are you?