Dust Collection: How Much is Too Much?

There are drawbacks to a dust collection and vacuum system that is bigger than your shop needs. August 21, 2006

I am in the process of trying to decide what system is appropriate for our operation. We have come to the conclusion that a 15 HP machine with approx. 5,000 CFM is adequate. Now I have the option to purchase a much larger used system, i.e. 25 HP 7,500 CFM, for less than what the new 15 HP system would cost. Now the question is, at what point is it too much dust collection? If our current need is 5,000 and no real need to increase in the near future, does it make sense to have a 7,500 CFM system? Is it less than efficient when it is being used at only 2/3 capacity? Any thoughts or suggestions are appreciated.

Forum Responses
(Dust Collection and Safety Forum)
From Curt Corum, forum technical advisor:
If the 25 hp blower is belt drive you can have the pulley arrangement set up to draw 15 BR horsepower. Then, you can size system as if it were a 15 hp. If it's a single stage unit with a direct drive blower you will have to size as a 25 hp system. You will have a few more branches under suction on machines you are not using to allow the full amount of air flow and you will be paying to run a 25 hp motor. For a shop that plans to hire more employees in the near future, it's a way to build for expansion, but that's not your situation.

From contributor A:
I thought a fan would only use the HP required to move the available air, up to what its designed for, and then, if its not a backward incline wheel, would start to draw more amps if more air than what the fan is designed for is allowed to be drawn into the inlet.

From contributor B:
Another thing to consider are your electric peaks which set your multiplier in calculating your electric bill. Starting a 25 hp versus 15 hp will give a higher momentary peak use which inflates your multiplier, which inflates that nasty old electric bill.