Diameter of impeller housing inlet on CVMax?
- Thread starter NeilS DE
- Start date
Pete, many thanks for providing that detail. Much appreciated!
If also 9" on the CVMax I don't need to do any further calculations on that.
I'm currently thinking about matching up the impeller unit from the CV1800 with a cyclone body (see attached photo) that I built years ago and whether the CV1800 impeller unit that I have will do the job.
The long cone on the cyclone in the photo may not look familiar, but it does conform to Bill Pentz' specifications (his 3:1 cone ratio). When installed that cyclone is too high to fit into most workshops, but if that is not an issue it is an excellent performer.
You're welcome.
I've seen the 3 to 1 cone before and somewhere I have a link to a student (L Wang) thesis written about agricultural cyclones with several ratios. Math in it is way over my head.
Back in 2006 there was a discussion in the old Fine Woodworking Forum, Knots, that in part discussed tilting the CV over on an angle to reduce the height needed to install one. They will separate properly even horizontally except bigger chunks won't go uphill in the cone so they just rattle around inside but tilted to 45 degrees has no effect on the separation.
As far as I know the only difference between the CV 1800 and the Max was the bigger impeller and the 8" inlet adaptor rather than a 6".
Pete
I've seen the 3 to 1 cone before and somewhere I have a link to a student (L Wang) thesis written about agricultural cyclones with several ratios. Math in it is way over my head.
Back in 2006 there was a discussion in the old Fine Woodworking Forum, Knots, that in part discussed tilting the CV over on an angle to reduce the height needed to install one. They will separate properly even horizontally except bigger chunks won't go uphill in the cone so they just rattle around inside but tilted to 45 degrees has no effect on the separation.
As far as I know the only difference between the CV 1800 and the Max was the bigger impeller and the 8" inlet adaptor rather than a 6".
Pete
Likewise, I don't try to get my head around cyclone calculations since Bill Pentz did all of his research and put his spreadsheet out into the public domain. I went with the 3:1 cone ratio as Bill found that to be the optimum ratio for wood dust provided you could fit it into your workshop. For most their home workshops weren't high enough, thus the 1.64:1 ratio (from memory) which he found was the the next sweet spot. There is better separation with the 3:1 cone length, but with some downside with more pressure loss. See highlighted text in the following link.
https://www.sciencedirect.com/topics/engineering/cyclone-size#:~:text=In general, a cyclone with, decreases%20the%20pressure%20drop%20increases.
Down here in Australia, where the climate is milder, many CVs are vented outside (and thus the degree of separation is not as important) the shorter cone size works well and would probably work even better with a 17" impeller that could be run quieter at lower Hz. The noise levels from venting outside can be an issue if neighbours/neighbors are close.
I built my 3:1 cyclone 15yrs ago before the CVs were available down here and probably would have gone with one of those had they been available back then. Getting hold of an impeller with more than 13" diameter that would run on our single phase supply with max of 15A 240v 50Hz was/still is the an issue here. Using 3 phase motors (with Delta wiring) running through a single to 3ph VFD that have become more affordable has been a critical development for us.
The above link shows an image (further up the page) of a 'gang' of cyclones set at about 45°, so definitely a practical implementation in industry.
Interesting! As CV has the Pentz stamp of approval I'm confident that their models are close to being optimised.
It is my understanding that if you don't go up to an 8" main trunk on the ducting, you will not get the full benefit from going with a Max. There is only so much air you can pull through 6" ducting regardless of how much larger the impeller is, the hp on the motor or the speed you run it at. More static pressure yes, but not more CFM.
I also understand that 7" (175mm) ducting would be beneficial with a CV1800, but that isn't a size available down here in fixed PVC ducting. Going up to 8" on the main duct with the CV1800 brings in the potential for load drop and plugging. The Max is needed to maintain the FPM in an 8" main duct.
If you don't have more than one 6" port open at a time the only benefit that I can see in going with a Max in a one person workshop is the lower noise level generated with a 16" impeller running at lower Hz. The other situation where a Max is needed is if you have a very long main duct run, in which case the accumulated drag in the 6" duct will slow down the air flow needed for the machines at the far end of the runs. I have that situation in the community shed I'm involved with, but home workshops would have much shorter runs.
Of course, the ports on a machine have to be open to at least a 6" diameter equivalent with matching inflow of air into machine cabinets for all of this to apply. The following thread on dust ports has a lot of useful information on dust ports for different machines.
https://www.woodworkforums.com/f200/...t-ports-187936
Now I know who you are Neil. I go under QC Inspector name on the Aussie forum. Small world.I knew I'd seen your cyclone before but wasn't sure.
Pete
Touché, Pete.
Yes, small world!
Knowing now who you are I'll avoid telling you how to suck eggs in any future posts... : ~}
Will do.
Neil