# Duct work for collector



## bandman (Jan 15, 2009)

Just picked up a nice Powermatic, 3hp, double bag collector and want to ask some questions about it. I understand that keeping the duct work as large as possible from the collector to the dust source is important. This collector has a triple 4" coupling on top so you can run three separate runs. Since I never use more than one machine at a time I see no reason to use three runs. My question, when I remove the 3-way coupling I see the opening is 8" into my collector. Would I be wise to try and run an 8" main line as close to my dust sources as possible? Am I going to have trouble finding 8" duct work for this?
Thanks for your help,

Bandman


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## raskgle (Dec 10, 2007)

*i have he same collector*

i have used this for the last 22 years. i used the 4" port in the beginning and hac no trouble with the collector. i have 6 machine on it with 6" pipes now and have lots of power. blast gates will make it better, but i can use it without any. i did change the bags filters to the big horn filters and have good filteration. you should be happy with the collector. carl.TE=bandman;639338]Just picked up a nice Powermatic, 3hp, double bag collector and want to ask some questions about it. I understand that keeping the duct work as large as possible from the collector to the dust source is important. This collector has a triple 4" coupling on top so you can run three separate runs. Since I never use more than one machine at a time I see no reason to use three runs. My question, when I remove the 3-way coupling I see the opening is 8" into my collector. Would I be wise to try and run an 8" main line as close to my dust sources as possible? Am I going to have trouble finding 8" duct work for this?
Thanks for your help,

Bandman[/QUOTE]


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## jdonhowe (Jul 25, 2014)

Yes, if I were you, I'd remove the 4" coupling, but with a caveat.

I did something similar, on a smaller scale: a Delta 1.5 hp DC, with a 6" opening and 2 x 4" coupling. Between the opening and the impeller a restrictor plate was spot welded, with a 4" diameter opening. I read someplace that this was added to prevent motor burnout.

The current draw (amps) of a DC motor is proportional to the air flow (cfm). It is my understanding that if there is no resistance, either at the input port, or the exhaust (no filter), the motor will draw more amps than it's designed for and there is the risk that it will burn out.

I think that Delta added the restrictor plate because some users of earlier model versions removed the 4" coupling, and burned out their motors when they didn't have any duct or filter attached.

Bottom line: when you remove the 4" coupling, make sure you have some duct work attached. A long duct run, esp. with a 4" or 6" adapter and hose at the far end should provide enough resistance to flow to prevent burnout.

If you have trouble finding or affording 8" ducts and fittings, you could just attach an 8" to 6" reducer fitting to the DC intake port, and use 6" ducts- readily available at the big box stores. You should still have plenty of performance, since you're using just one machine at a time.

One final thought: with that amount of DC power available, you should consider a two stage system, with a Thien or cyclone separator to capture most of your dust.

just my .02 :smile:


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