Thread: Bill Pence cyclone build

This is the link to Bills spreadsheet http://billpentz.com/woodworking/cyc...etac160629.xls
simply put in the Hp of the motor, and the size of the ducting... it will recalculate the dimensions for you.

For a 7.5Hp motor the cyclone will be 18" diameter

While using any impeller will separate something the BP designed impeller is really worth using since it pairs optimally with the BP cyclone design.

Clearvue no longer supply the impeller from their cyclone a separate part.

Yes, it will work as is. You can make it bigger to get less airflow reduction but will have lower collection efficiency.

I don't really understand why you expect a cyclone to solve an uneven bag distribution problem but your 18" fan at 50Hz should have about the same performance as the CV 15" fan at 60Hz.

Any cyclone design can be scaled. Pressure loss and particle cut size vary in a (somewhat) predictable manner with scale factor for a given geometry.

Simplistically, the scale factor is picked to meet the desired cut size (determined by dust size distribution and collection efficiency requirements) at the specified air flow rate. This then determines the pressure loss. The fan is then "matched" to the required total system pressure needs at the air flow rate by picking a fan size and RPM that put those near it's efficiency peak. This optimizes operating cost.

I am not sure what the question is. Is it that a cyclone might solve the debris distribution problem or is it that you want to remove the bag system and go to a cyclone with drum collection?

I think it’s both Chris

Yes its a bit of both. If we put a cyclone in it will remove the bag problem. ie. only one bag/drum to empty. Have had another look at the motor plate and it is 5.5hp @2800 rpm at 50hz so I guess the 18" cyclone should work.

Any chance it is a 3 phase motor? If so you could use a variable frequency drive (VFD) to spin it to 3450 rpm at 60 hertz getting a boost in airflow if the ducts are big enough. What are the present ducting sizes?

Pete

Yes it is a 3ph motor. The ducting starts at about12" and reduces down to 10" and 8" on the main trunk. Unfortunately then drops down to 4" ( I know!) lines to each machine.

Originally Posted by Flintlock

Yes it is a 3ph motor. The ducting starts at about12" and reduces down to 10" and 8" on the main trunk. Unfortunately then drops down to 4" ( I know!) lines to each machine.

Pity, until you swap the 4" to 6" on the bigger machines you won't be able to utilise the performance of the big impeller and cyclone.
What effectively happens is the fine dust is not being collected at source.
Its so fine you may not even realise its not being collected.

I think your biggest priority as you acknowledge is fixing the duct system and getting rid of the 100mm parts of it then worry about the other end. Just as an outside random guess the debris distribution might be inadequate due to not enough air flow caused by the 100mm inlets at the machines. You could try installing a port in the main duct that was open just venting the work area and seeing if that improves matters, it would be open at all times. It seems to me that an 18" impeller will require a large amount of air and honestly I wonder if the ducting has a build up of debris in it. Would it be possible to open up the main ducting by disconnecting at a point where it was still full size and firstly inspecting for build up and then operating the DE allowing the maximum air flow to see if that releases any build up that can't be seen. These are just off the wall suggestions that might not do anything but I think it is worth a try.

I advise anyone with a Max or bigger to always have one port permanently open as this scrubs the air and keeps the duct air flow higher than it would normally be. Doing this causes a turn over of air even when the machines are not in use. A smaller DE would not have the spare capacity to have an open duct.

Originally Posted by Chris Parks

I think your biggest priority as you acknowledge is fixing the duct system and getting rid of the 100mm parts of it then worry about the other end. Just as an outside random guess the debris distribution might be inadequate due to not enough air flow caused by the 100mm inlets at the machines. You could try installing a port in the main duct that was open just venting the work area and seeing if that improves matters, it would be open at all times. It seems to me that an 18" impeller will require a large amount of air and honestly I wonder if the ducting has a build up of debris in it. Would it be possible to open up the main ducting by disconnecting at a point where it was still full size and firstly inspecting for build up and then operating the DE allowing the maximum air flow to see if that releases any build up that can't be seen.

It depends what dust has settled out of suspension in the trunk line. To pick up the denser larger more compact chip/dust requires ~4000 FPM so with a 12" trunk line that requires a nominal 3142 CFM.To get this with 4" ports would require 8 or more such ports to be open.

Flintlock

Would you know if the system you have was put together by club members years ago or was it designed and installed by a dust collection company as a system? Can you tell us what the make and model of the dusty is? I'm curious.

Pete

Originally Posted by BobL

Pity, until you swap the 4" to 6" on the bigger machines you won't be able to utilise the performance of the big impeller and cyclone.
What effectively happens is the fine dust is not being collected at source.
Its so fine you may not even realise its not being collected.

Oh I know it is not being collected but getting anyone else to see that is hard work.