# Parallel dc on thein separator



## han0522 (Jan 4, 2013)

I have a crazy idea. I'm currently renovating my shop and making it temperature controlled. I'd also like to control dust. I originally wanted a stationary unit with ~20 ft of 6" piping to tools with blast gates all with a thein separator between the tools and the collector. Then I looked in to the cost to do this and seeing that systems designed to be stationary with long runs start at ~1500 and go up from there and portable solutions are more in the 400-500 range - I honestly don't think I'll use a portable solution as much as I should, but if the below doesn't work, then I'll probably go with this.

Of course, there's also the 2hp HF solution that is 199 without coupon. So here's my crazy idea: Still have 6" piping to each tool which leads to a large drum thein but instead of 1 "suction" port on the lid to 1 dc, what if I had 2 ports on the lid (4" each) each leading to a cheap HF 2hp dc. 

I've done some research this morning and understand that the pressure difference won't change but that flow would increase and given a large enough pipe for pulling in dust into the thein separator, then the combo won't be restricted. My goal is having a stationary dust collection solution with piping to 3-4 blast gates around the shop with flex hose from there to the tools.

Thoughts?
Chris

P.S. 

Here's a (not to scale) sketchup drawing of what I'm thinking:


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## ryan50hrl (Jun 30, 2012)

Why not use one outlet, and tee it off from there. That would reduce turbulence in the collector.


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## Dave Paine (May 30, 2012)

ryan50hrl said:


> Why not use one outlet, and tee it off from there. That would reduce turbulence in the collector.


I think good idea for single outlet in the collector, but I would use a "Y" instead of "T" to split the stream, since a "Y" will have less pressure drop.


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## rrbrown (Feb 15, 2009)

I still have doubts about the effectiveness of two collectors working together. Now by the time you buy two from HF you would need separate circuits for them to run on and spend more then just going with one of these 3HP Grizzly collectors. At first I wasn't sure about the aluminum impeller on these but if you use a separator to prevent anything from hitting it, it should be fine. 
















They have one with the canisters for $704 shipped and without is $474 I would suggest with canisters. 

Buying the HF models even at the best price I've heard with a coupon was like $150 each the Wynn Filters are like $160 each so your at around $620 for two set up with canisters. I think the extra $85 for the Grizzly would be worth it in performance. Just my .02


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## rrbrown (Feb 15, 2009)

Dave Paine said:


> I think good idea for single outlet in the collector, but I would use a "Y" instead of "T" to split the stream, since a "Y" will have less pressure drop.


I agree but to get any benefit out of 2 blowers the Y used and ducts would need to be larger. otherwise your restricting it somewhere.

Example. 

A Wye with 6"x6"x8" to separator may work with 6" duct to tools. because you have some loss in the separator. Yet the pull from the blowers should be more then whats needed and should increase the suction. If you only have 6"x6"x6" wye your only pulling through a 6" port still restricting any advantage the dual blowers give the system. You can't pull double the air needed through the same size duct.

Again just my .02


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## rrbrown (Feb 15, 2009)

If you go with the two blower set up, I'd be interested in the difference running one blower compared to two. 

Everything is just theory until it was attempted.:thumbsup:


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## han0522 (Jan 4, 2013)

I like the idea of a single 6 inch outlet from the separator with a Y connection to the two collectors. I guessed 6 inches would be adequate due to the collectors having 4 inch inlets. The area of those 4 inch inlets on the collectors are 3.14*2*2 (12.56 sq in) multiplied by 2, or ~25 square inches total for both. Equivalent single pipe in area alone would be ~5.6 in in diameter (3.14*2.8*2.8 = 24.6 sq in) so I figure a 6 in pipe would provide more than the equivalent area for both collectors while reducing resistance to flow. As I understand it, increasing from 2 to 3 in radius pipe will decrease the resistance to flow by a factor of 5 (resistance increases by the inverse of the radius to the fourth power, or 1/16 times some constant for 2in pipe vs 1/81 times some constant for 3 in pipe, so the 2 inch radius pipe will have 5x the resistance as the 3 in pipe, all else being equal).

It's been awhile since I took physics, so some of the above may not be accurate - please let me know if I'm incorrect.

I'll admit, that I'm intrigued enough to proceed unless someone who has tried it can tell me that it definitely won't work. 

I will need to keep my perspective and keep in mind that there are 3 hp solutions that ought to work, although from the research I've done over the last couple of days, most people recommend keeping those solutions portable and not stationary. Seems like effective stationary solutions are pricey.

-Chris


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## rrbrown (Feb 15, 2009)

Those 4" connectors are reduced down from like 5" if you remove that adapter. It actually restricts the flow, removing it will improve efficiency by as much as 50%. So make your Wye 6x5x5 and remove those adapters. It will work much better.:thumbsup:


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## rrbrown (Feb 15, 2009)

han0522 said:


> I will need to keep my perspective and keep in mind that there are 3 hp solutions that ought to work, although from the research I've done over the last couple of days, most people recommend keeping those solutions portable and not stationary. Seems like effective stationary solutions are pricey.
> 
> -Chris


Mine and many others on here are using 1 1/2 -3hp models as a stationary system, including the HF 2hp model that many on here have. 

I have the 1.5 hp Shop Fox model with 6" duct. It works pretty good but I have been looking to move up to a 3hp maybe a 4hp model here recently.


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## han0522 (Jan 4, 2013)

Here's a post of someone who did this:

http://www.dewalt.com/blogs/post/2009/03/2-Stage-Dust-Collector.aspx

I've contacted him on lumberjocks to see if he has any further information.

Chris


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## Fred Hargis (Apr 28, 2012)

This is only a guess, but I'm betting the 2 might work better in series than parallel. The may be fighting each other in parallel. In series they work together, so to speak. Stumpy nubs did that on something he built, and watched the amperage of both motors to make sure one didn't overwork the other. I'll be interested to hear how whatever you do works out.


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## han0522 (Jan 4, 2013)

Fred Hargis said:


> This is only a guess, but I'm betting the 2 might work better in series than parallel. The may be fighting each other in parallel. In series they work together, so to speak. Stumpy nubs did that on something he built, and watched the amperage of both motors to make sure one didn't overwork the other. I'll be interested to hear how whatever you do works out.


Interesting. I've emailed stumpy and bill pentz to get advice, but I didn't fully appreciate the fire hazard aspect of this project. I might need to rethink this experiment.

If I monitor the amount of amps the motor is drawing, is that the main thing I need to do and make sure it doesn't go above the stated max for the motor, or is it more involved than that?

-Chris


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## rrbrown (Feb 15, 2009)

Fred Hargis said:


> This is only a guess, but I'm betting the 2 might work better in series than parallel. The may be fighting each other in parallel. In series they work together, so to speak. Stumpy nubs did that on something he built, and watched the amperage of both motors to make sure one didn't overwork the other. I'll be interested to hear how whatever you do works out.


In series you gain nothing by using two blowers. Same duct same output nothing better. I believe it would actually make one or both amp higher.


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## Fred Hargis (Apr 28, 2012)

Well, I disagree with you...but do not feel strongly enough about it to debate the issue; like I said I was only guessing. I did find this note from Bill Pentz on another forum...and think it's pertinent to the OP's question, he was responding to a question about using 2 blowers on a common system (a little lengthy, apologies):
Quote:
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 
end quote ​


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## TimPa (Jan 27, 2010)

i think 2 vacuum sources will not play well together, parallel or series. i would connect one dc to some machines and the other dc to other machines. this way you are only running what you need. or, buy one larger dc to handle it all.


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