▼
Posts: 2,574
Threads: 0
Joined: Feb 2001
I know that the great conundrum with DC vs vacuum, is that DC provides more airflow at a lower velocity and shop vacs provide more static pressure with less actual air flow.
As I understand part of the reason for this, is the ability for universal motors on vacs to turn at much higher speeds.
With the higher horsepower required to run a DC impeller you can’t really use a universal motor.
With the availability of variable frequency drives these days, why could you not design a DC that used 5hp 3 phase motor, and rather than run it at 3450 RPM run it faster and get more static pressure?
Duke
▼
Posts: 1,996
Threads: 1
Joined: Aug 2016
(07-03-2023, 11:31 PM)JDuke Wrote: I know that the great conundrum with DC vs vacuum, is that DC provides more airflow at a lower velocity and shop vacs provide more static pressure with less actual air flow.
As I understand part of the reason for this, is the ability for universal motors on vacs to turn at much higher speeds.
With the higher horsepower required to run a DC impeller you can’t really use a universal motor.
With the availability of variable frequency drives these days, why could you not design a DC that used 5hp 3 phase motor, and rather than run it at 3450 RPM run it faster and get more static pressure?
Duke
Make sure the impeller is rated for the rpm you are wanting to run it at. Most are made for 3450 rpm. Roly
▼
Posts: 15,440
Threads: 0
Joined: Feb 2002
Location: Northeastern MA
(07-04-2023, 07:46 AM)Roly Wrote: Make sure the impeller is rated for the rpm you are wanting to run it at. Most are made for 3450 rpm. Roly
and balancing that monster. a 14" impeller doing 3500 RPM has something like a 150mph rim speed.
You are frequently puzzled by things you tell us you fully understand. - Bob10 to EH 9/22/16
Too much has been made out of my mostly idle comments - Cletus 12/9/15
You sound like one of those survivalist, hoarder, tin foil hat, militia, clinger, wackjobs. - Fear Monger 1/30/13
Posts: 12,871
Threads: 0
Joined: Jan 2010
Location: Lewiston, NY
Onieda has solved that design conundrum: Supercell
If you watch the video, you'll see that they used 3 small diameter fans, rather than try to turn a one large fan at high speed, which, as others have pointed out, is not easily or safely done.
John
Posts: 2,574
Threads: 0
Joined: Feb 2001
I figured someone had tried to make this leap, just didn’t assume it would be Oneida.
Given their track record, I’m a little hesitant to make the leap until it’s been out a while.
Now off to find some YouTube videos that aren’t paid shills…
▼
Posts: 12,871
Threads: 0
Joined: Jan 2010
Location: Lewiston, NY
(07-07-2023, 07:18 AM)JDuke Wrote: I figured someone had tried to make this leap, just didn’t assume it would be Oneida.
Given their track record, I’m a little hesitant to make the leap until it’s been out a while.
Now off to find some YouTube videos that aren’t paid shills…
"Given their track record, ....." What is it that prompted you to say that? I love how well the Dusty Deputy works to keep my CNC shopvac clean.
John
Posts: 2,574
Threads: 0
Joined: Feb 2001
John
If you dig into the weeds on Bill Pentz (if I recall correctly) research on dust collection and the reason for the design choices that led to the clearvue cyclone you may or may not find some history of Oneidas resistance to bringing their design up to the current standard in cyclone technology.
As I recall their ignoring Pentz is what led to him pushing his design to the public and it’s adoption by clearvue.
My memory may be cloudy as this was over 10 years ago, before your time on woodnet.
They also went back to an internal filter on this design, that has been a challenge to their efficiency as well as filter cleaning in the past, hopefully this design has addressed those issues.
Their marketing says they have a reverse flow to clean filter, perhaps that’s enough with a higher static pressure machine.
Now I’m wondering if you could gang a few whole house vacs together and get similar performance to the supercell.
Duke
▼
Posts: 12,871
Threads: 0
Joined: Jan 2010
Location: Lewiston, NY
(07-08-2023, 03:00 AM)JDuke Wrote: John
If you dig into the weeds on Bill Pentz (if I recall correctly) research on dust collection and the reason for the design choices that led to the clearvue cyclone you may or may not find some history of Oneidas resistance to bringing their design up to the current standard in cyclone technology.
As I recall their ignoring Pentz is what led to him pushing his design to the public and it’s adoption by clearvue.
My memory may be cloudy as this was over 10 years ago, before your time on woodnet.
They also went back to an internal filter on this design, that has been a challenge to their efficiency as well as filter cleaning in the past, hopefully this design has addressed those issues.
Their marketing says they have a reverse flow to clean filter, perhaps that’s enough with a higher static pressure machine.
Now I’m wondering if you could gang a few whole house vacs together and get similar performance to the supercell.
Duke
You're right, I'd didn't know that history. I would suspect that Oneida has sold 100 DC units for every Clearvue sold so, right or wrong, Onieda is doing something right. My friend has a 5 hp ClearVue, probably one of their early designs because he had to build a contraption to mount the motor and fan from. The filters have clogged up so badly at least twice that he's had to replace them, so the cyclone isn't spinning out the really fine stuff. I don't remember seeing any type of filter cleaning system on his unit, so maybe ClearVue has addressed the problem in newer designs.
Yeah, if you put several whole house vacs in parallel, you'd have something similar to the Supercell. Or you could just buy a Supercell.
John
Posts: 24,331
Threads: 0
Joined: Feb 2002
Location: Elizabethtown, KY
My two scents --
Moving air is difficult above certain speeds and the big reason for the difference in "vacuum" and "dust collector" impellers is driven by that difference.
Dust collectors use a very coarse, open impeller for two reasons -- low pressure and big particles. Vacuum motors use finer, compartmentalized impellers to move the air under higher differential pressures. Big impellers spill air but have more than enough left to move the dust; vacuums don't have the excess capacity so they need better impellers.
Kirby vacuums are an interesting mix between the two types --which was part of the reason the noise of a Kirby was so irritating as a kid.
Look inside a vacuum and study the impeller, compare it to a dust collector. I once had to engineer a 3-hp air mover that used a small-cell impeller and had to limit the intake to prevent the 10-in impeller from overloading the 3-hp motor. It moved a LOT of air but took a lot of power.
Bottom line -- big loose impeller for big particles and lots of air moving; small, compartmented impeller for big pressure differential and small particles.
HTH
"Truth is a highway leading to freedom" --Kris Kristofferson
Wild Turkey
We may see the writing on the wall, but all we do is criticize the handwriting.
(joined 10/1999)
Posts: 2,574
Threads: 0
Joined: Feb 2001
John,
I’m not as interested in the unit number of sales Oneida has, I’m more interested in the performance of the one unit in my shop.
As I’m sure you know big companies like Oneida don’t let the engineers have free reign to build the best, they are constrained by the accounting department.
So while they have sold a lot of units I’m not convinced they are the best.
The early clearvue weren’t Pentz designs.
I’m not completely convinced that even Pentz design is the best, but his explanation of things like the slanted intake make enough since to me that I’d make a cyclone of his design before I bought a standard Oneida cyclone.
This is one of the reasons I like to see head to head comparisons on YouTube etc. I know that even that is subject to bias based on support.
Duke
|
