Here's a crazy DC question

[Fred Voorhees]

I simply haven't broached this subject with anyone and I'm very curious. I just connected my last blast gate tonight and the thought occured to me - should a gate be open BEFORE the dust collection unit is turned on? I made sure that my ductwork system was very tight up to the gates and this is why I'm asking. I'm figuring that if the ductwork is very tight, it would make the fan unit work pretty hard while no gates are open. I guess this would also answer the question "should the unit run while you are not using any machine that would require it to be run?" I'm thinking no. :confused:

[Terry Hatfield]

Fred,

Actually the opposite is true. The motor/fan works less when all the gates are closed. running it with the gates closed will certainly do no harm. I do it all the time. I just leave the cyclone running as I open and close gates and move from one machine to another. If you've got an ammeter, you can check this out for yourself. The motor will pull the least amps with the gates all closed and the most with them all open.

Terry

[Spence DePauw]

Fred, as I understood it when I got my system designed, the blower motor current goes up with air volume moved, so when the blast gates are all closed, power is lower. Since the gates are closed, there is no work performed to move large volumes of air, it just stirs the air around in the impeller.

That's my understanding anyway.

Spence

[Fred Voorhees]

Now THAT is a surprise. Caught me off guard with that one. Now, I have another question. I could have tested it myself tonight, but I didn't. When I started up my cyclone, I noticed that for a minute or so, it kind of cycled through a moment or two of higher suction and then lower suction, then higher suction, the lower suction. Then it kind of leveled out and kept an even suction level. Is this normal? I thought that it might have had something to do with starting it with the gates closed and it was just "catching" up to itself. I was going to test this theory tomorrow and start it up with the gates all closed and then again, with a gate open. But, can anyone shed any light on why this minute of higher and lower pressure cycles?

[Terry Hatfield]

Fred,

Hmmm...that doesn't sound right. I have no idea what to tell you on that one...oh wait....yes I do........It's gotta be Becker's fault. :D

Seriously, sounds like a question for your buds at Oneida.

Terry

[Jack Diemer]

Good one, I agree, got to be Beckers fault.

[Dale Thompson]

Fred,
The above posters are right! A DC is totally different than a shop vac when it comes to the kind of "air pump" that they use. A shop vac can survive for a while with the input plugged but it's a good idea not to "push" it.

Dale T.

[Jim Becker]

It's gotta be Becker's fault.
Good one, I agree, got to be Beckers fault.
I love you, too, guys... :rolleyes:

"Seriously", I'd have to hear what's going on, but it could merely be the effects of a rather lengthy column of air flow stablizing after the fan turns on and gets it moving. His main trunk is pretty long due to the nature of the building and location of the unit. I'll try to stop by Fred's next week when I am back in the country and give a listen.

BTW, Fred's duct work installation is incredible...a real pro-job. We should all have duct work that looks so great. And his implementation of Terry's blast gates is awesome. 'Wait 'til you see the pics of those!

[Terry Hatfield]

Jim,


"I love you, too, guys"

Right back at ya there Jim. :D :D :D

Can't wait to see the pics of Fred's system!!!!!

Terry

[Bill Pentz]

Fred,

Although turning on your dust collector with all gates closed will not hurt the motor or impeller, it does put a heavy strain on your cyclone and ducting. Even worse is quickly closing the last open gate when all is running strong. The 30 gauge HVAC snap-lock pipe will collapse and 26 gauge HVAC snap-lock pipe can collapse. Likewise the Wood Magazine cyclones can collapse. My web pages give you the various collapsing pressures for metal ducting. Both 26 and 30 gauge can be collapsed by a 2 hp or bigger motor turning a 12" or bigger impeller. You should not have a problem with either metal spiral duct or PVC.

bill