How do RPM changes affect CFM and pressure in a Roots blower?

[aravind5995]

Hi,

I would like to know how the RPM of a root blower will affect the CFM and pressure created by the blower. The confusion that I have is this: Generally when RPM is decreased, both the CFM and pressure decreases. But according to Bernoulli's principle, should not one decrease and the other increase?

Pls help.

 

[Baluncore]

A Roots Blower is a positive displacement pump so CFM multiplied by Pressure will be proportional to RPM.

What has Bernoulli's principle got to do with a positive displacement pump ?