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wallace chapman
09-26-2005, 2:44 AM
Nic Obie showed several pictures of his dual configuration cyclone and Bill Pentz replied to an earlier query with this post. Awesome to hear from Bill pentz on this,he seems to be the authority on this.

"Dual Blower Cyclone
<hr style="color: rgb(209, 209, 225);" size="1"> <!-- / icon and title --> <!-- message --> You can use a couple of blowers to power a cyclone, but then should always check the motor amperage to ensure you are not trying to move more air than the motors can handle. Mostly this means blowers in series will burn up motors, so we have to put the blowers in parallel. To do this go from your main to a wye, then to each blower, then back to a wye. Jim Halbert did this ages ago and it worked fairly well, but he did have some motor problems, so please check.

bill"


I tried to do a search on this archive and the Badger pond archive (no longer exists) but this doesn't look as popular as I previouslly thought.

Bill, I don't see any alternate configurations like dual blowers on your site, would you know of any plans or test data for this type of setup?

Does anyone else have a setup similar to Nic Obie's dual configuration?

Wallace

Bill Pentz
09-28-2005, 3:49 AM
Wallace,

This is one of those areas that easily can get you into trouble, meaning burned up motors, fires, flattened ducting, ruined cyclones, etc. It also is an area not at all well covered in either the vacuum engineering or HVAC air engineering worlds because it falls roughly in between the two.

Yes you can use two blowers to provide very high pressures or high airflows depending upon ducting size, system resistance, and blower configurations. The best way to set these up is in series, but doing so will in many cases force both blowers to move so much air they both will quickly burn up from drawing too many amps. They likewise exceed the pressure that most HVAC ducting and cyclones can handle, so expect flattened parts. Still, these very high pressures can move much larger volumes of air through smaller ducting. With enough pressure, a 4" duct run will carry the 800 to 1000 CFM that many health experts and air engineers recommend for good fine dust collection.

Jim Halbert way back when was frustrated with the terrible performance of his 1.5 hp cyclone in his large shop. Owing a Jet 1.5 hp dust collector he simply added it in series with his cyclone. The result was nothing short of incredible producing about 21" of pressure and moving more overall air than any current 3 hp hobbyist cyclone design does. Both motors strained hard from moving too much air so he eventually upgraded both to 2 hp Baldor motors powering 12" impellers. He has run the result for years and it provides better total performance than my cyclone design with a 3 hp motor turning a 14” impeller. I duplicated his effort with larger ducting and found both of my motors immediately overloaded.

Unlike most, Jim Halbert is a very sharp electrical engineer who knows motors and electronics. Many benefit from his designs to control their dust collectors using a doorbell transformer based remote activated relay that he published on my web pages ages ago. Although a few have now copied those circuits, I long ago pulled down those remote circuits for the same reasons I don't recommend dual blower configurations. Most hobbyists lack the skills or tools to accurately setup and monitor a dual blower configuration and could easily hurt themselves or burn up their shops or homes.

Moreover, predicting performance and appropriately sizing the blowers is a math nightmare. The calculations depend upon so many poorly understood factors that I have repeatedly given up trying to come up with a good estimated. Instead, I simply start with a closed port on the end of the size test pipe I want to use and slowly open the airflow until the first of the two motors reaches maximum safe operating amps. If you don't know what you are doing and have good amperage guages, this is not something to go playing with unless you are willing to permanently let the smoke out of one or both motors.

Using two identical blowers works better as both peak at near the same point instead of one loafing along while the other is near burning up. I’m tempted to buy a couple of HF so called 2 hp blowers (really 1.5 hp 11" impeller units) and test them in series to see if they will together move enough air to power a cyclone. I think they might, but the overall costs both for purchase and operation will be higher than a single motor based blower.

I guess the only time this approach is really usable is when you have something too small and want to beef its performance up.

Not sure if this helps at all..

Bill

nic obie
09-28-2005, 2:28 PM
I agree with Mr. Pentz's evaluation of using two blowers in series. It seemed to me that the middle blower motor would blow up from trying to move too much air.

That's why I mounted mine in parallel. In essence what this did is turn two 10.5" blowers into a single (?)" blower. There is nothing really complicated about it. I've used my DC daily for over a year now with those cheap HF motors and haven't burnt up anything yet.

wallace chapman
09-28-2005, 11:36 PM
Bill, two of my neighbors are retired Engineers and have just about every tool you can imagine (I lean on their knowldege all the time).
I am very intrigued by this design, especially after you commented on huge volume of air it produced.

Of course given the further warning of potential fire and motor burnout, I don't know if I would be willing to tackle this myself given my limited knowledge in this area.


What do you think of Nic's usage of HF motors in parallel with the wye connection lending to overall increase in air volume and pressure?


I’m tempted to buy a couple of HF so called 2 hp blowers (really 1.5 hp 11" impeller units) and test them in series to see if they will together move enough air to power a cyclone. I think they might, but the overall costs both for purchase and operation will be higher than a single motor based blower.


I'm sure you're very busy with the site and other pursuits, However I would be willing to donate to this endeavor.

It would give me a further reason to donate to your excellent site that has helped so many of us in this area.

Let me know if you do give in to that temptation of the two HF blowers and I will send a small amount to help. I will also talk to my neighbors to see what they think would be the limits of the motors and protection needed for either configuration.

I would also like to post a question on the forum to see who would be interested in a test of this kind, but would like to know your opinion first.


Wallace

Bill Pentz
09-29-2005, 12:02 AM
Wallace,

The two HF 2 hp DC in series will work, you just have to carefully monitor amperage and if needed put a restrictor in place (a partially shut blast gate) on your closest, most open run.

I came close today to using my 20% off HF coupon to buy those units, but then looked at the pile of blowers, impellers, and motors already in my limited space and said, nope, this is just not a high enough priority project for me to take on right now.

The only reall interest for me is would this move enough air through a 4" pipe with the extra pressure?

bill

wallace chapman
09-29-2005, 4:30 PM
I don't think that may be worth a 20% off coupon. Thanks for the info.

Wallace

bill walton
09-29-2005, 7:26 PM
I just picked up on this thread and it intrigues me. I hava two Shopfox "2hp 220V" dc units both with wynn filters. I dont think either is up to the task of powering a 6" dc network. I want a cyclone but just can't see it happening for another year or so. This has me thinking of a way to use the two units to suck through a 6" network into a separator of some kind and then through the two wynn filters stacked. Any thoughts?

Bill Pentz
09-30-2005, 1:27 AM
Bill,

Those two blowers setup in series should generate 18 to 20 inches of pressure. The only way to test them would be with a good amp meter on each and start with an 8' long piece of 6" ducting that is sealed with a blast gate on the end. Slowly open the gate watching both amp meters and call time when your comfort level is reached. I'd be guessing, but would not be comfortable with Grizzly motors at much over 90 to 95% of maximum rated amps.

At that point you need to measure differential pressure to find out the FPM being generated. You would then convert that into CFM.

I'd then do this all over again this time with a 6' long piece of 5" pipe and then once again with a 5' long piece of 4" pipe. I suspect the pressure will be ample to move 800+ CFM through both the 4" and 5".

Based on my own testing with one unit smaller than yours and one slightly larger, you will move plenty of air to power a cyclone. If you decided to go with a cyclone, don't get something that does not do good fine dust separation. Build or buy one based on my plans and use a couple of good large cartridge filters.

bill

bill walton
09-30-2005, 6:02 AM
I decided several months ago to purchase a Clearvue unit for my new shop. Probably the purchase will be during the 2nd half of next year. In the meantime, I want to minimize the investment in DC pipe, etc., that will be superfluous when I make that purchase which is why this thread was interesting to me. What would beyour thoughts be on a parallel motor arrangement?

Echoing others, thanks again for all of the contributions you've made on the subject.

Bill Pentz
09-30-2005, 12:53 PM
Bill,

Jim Halbert shared the following with me on dual blower setups.

“Motor burn out in series can be a problem with some motors. If the max amp rating is correct and you don't exceed it no problem. My dual blower cyclone (in series) with 12" impellers is very old, like me, and in very good health. I switched to Baldor 2 HP motors years ago. They run at 11 Amps each. Max SP on the system is 21". That moves a lot of air. I tested ..." your cyclone design "and it was close, but not better then mine."

"If I every redo mine I would use a single 15" impeller, er maybe. A lot simpler. At the time mine was built 15" blowers were not available so that's why I went the route with two 12" impellers. I'm thinking about twin 14", 3 HP blowers. Never enough air you know..."

It makes no sense to buy two HF blowers. Not cost effective. You now can.." build a bigger cyclone 15" blower for under $400. “Now two of these in series with 3 HP motors would be something to behold. If it ain't broke don't fix it, so I won't make the effort."

Jim went on to say he disagrees with running blowers in parallel because the low static pressure they have would not move much more air then a single blower.

He also added, “Here is something worth mentioning - I have done this on several Oneida units and the CFM doubles.”

“The original Onieda 1.5 with the built in filter had relative low CFM. A check on their Leeson motor with duct work installed showed it was just coasting at about half it's rated amps. Adding an 11" Jet Blower in series brought the amps up to max and makes this unit flow better then their new Gorilla! Just check the amps with the ducts installed!! If it overloads, which I have never seen, place a restrictor in the line. This works even with 4" duct because of the very high SP pressure. Kiss the HD metal duct good bye however with this puppy. Only use this with the much heavier PVC SD duct! Install the blower with ducting right after the original blower. I never tried the HF blower. It might work but on the other hand the motor might blow. For $150 probably worth a try. You will find out real quick about motor quality, hopefully while still under warranty.”

“I don't know why I still get heat on the dual series set up. It works. I'm using a similar dual blower in series setup on my son’s mini-cyclones with a push through mode. It runs on 120V and flows way more air then the original 1.5 Oneida.”

“Another point of interest is the Jet 12" impeller is a drop in fit to replace the stock Jet 11". Same bore size etc. Big jump in CFM! No problem on excessive amp draw when installed on a cyclone. These made a very good installation. Got some bad PR on this thing too. Hard to figure since no one ever saw them in action."

Bill

wallace chapman
10-01-2005, 11:39 PM
I will will also be purchasing a clearvue cyclone in the future.

Bill Pentz, the response from Jim gave me more hope in this design other than the cost effectiveness.
I have seen the HF blowers as low as $140.

I still can't figure out why he was getting so much pushback on this design if his results show the increased pressure through smaller ducting. With a restrictor in place this sounds like a very sound setup with massive airflow given the motor sizes.

I did assume that metal ducting would be out of the question with a setup like this and may decrease the overall cost of the DC design.


Bill Walton, I don't know how well this will work with a separator. Seems like you would need a much taller can to offset the increased airflow and keep items from going to the impeller.

Wallace

Bill Pentz
10-02-2005, 1:17 AM
Wallace,

Jim uses 6" ducting because the 4" just wastes your money wasting most of the air and hp overcoming the ducting resistance. If you do the calculations, 4" ducting is ideal for 349 CFM, no more. That's why our 2 hp blowers that through a test pipe will move 1200 CFM can barely pull 450 CFM through a 4". Adding enough horsepower and big enough impeller will overcome that resistance, but unless your ducting is buried under a slab floor, does not make sense to stay with the 4".

bill

Dino Makropoulos
10-02-2005, 1:36 AM
Hi Bill.
I use your advice today. Rout outside and use a blower instead of a vacuum.
With no hose and no dust, the job was 50% faster, much easier and better the same time. :cool:
Thanks Bill.
YCF Dino

Bill Pentz
10-02-2005, 2:09 AM
Dino,

I'm helping my daughter build a desk and we have been working outside for most of the project. Our local weather has been great, no dust problems, and kind of nice being outside with the puppies to make sure we do all just right.

*smile*

bill

Stephen Lawrence
04-24-2013, 12:14 PM
I know this thread is years old, but I feel compelled to reply.

I came across two grizzly dust collectors for cheap: a 3hp and a 2hp. After reading this thread, and getting some additional guidance from Bill, I built a cyclone, and used the blowers in series to power it. I put the 2hp first, then the 3hp, figuring that the anchor blower should be stronger. Seems to work for most sports :)

I must say it moves a lot of air! I've put permanent amp meters on each blower, and I've never seen an over-amp. I'm using the original blower housings, connected in series, so I think the 5 inch port between the blowers, plus the cyclone resistance, limits the amount of air that can get through it.

The static pressure is really great. If I need to rig some 4" ducting for a temporary setup, I can still pull a lot of air. Because my shop is a continuous work-in-progress, this is a great feature. I've not done any scientific measurements.

It is really loud, but I think that is mostly because the 3hp blower is not designed very well, and it vibrates too much. The 2hp blower is not very loud by itself. One day I will build a new series blower enclosure, and get some better impellers.

I did manage to reduce the noise a lot by going all the way to the floor with insulated flex-duct, to an mdf baffle box, and then to the filter-stack (air flowing up). I have the blowers and cyclone on a free-standing frame (4 legs), with some vibration-isolated safety straps to the wall and ceiling. Some vibration isolating feet for the frame might help as well.