Venturi Suction question

[Johan111]

TL;DR Summary

I have suction problems on a venturi connected across a centrifugal pump.

Good day

I am trying to use a venturi across a centrifugal pump. The pressure at suction side is about 2 bar and the discharge pressure about 6 to 7 bar. This pump supply drippers and the delivery is about 180 cub/h. I need to inject entrainment air into the suction side and try to use a venturi across the high (discharge) and low (suction) pressure sides of the pump.

I get little to no suction on the venturi. I have a throttling valve to play around with the flow through the venturi. The setup have also quite a lot of bends.

Can the low suction be the pressure loss on these bends and relative low diameter pipe between the high and low pressure.

Thank you for feedback!

 

[bigfooted]

A bit difficult to say what happens here... do you have a sketch of the setup that shows what's going on, with some dimensions? Do you have a measurement of the pressure at the Venturi throat?

 

[russ_watters]

A diagram would definitely help, but I can't envision how a Venturi for air entrainment could be added anywhere in a system like this.