sensing liquid flow in pipe

Hi

Can you suggest the type of sensor to be used in my project.

My project is to control a valve in a pipe based on whether liquid is flowing or not.
"if liquid flow means valve turns on,
if no liquid flow means valve turns off."

Thanks in advance
marco

fire_marco said:

My project is to control a valve in a pipe based on whether liquid is flowing or not.

Click to expand...

This statement imply that you will change the position of the valve depending on the liquid flowrate in the pipe.

fire_marco said:

"if liquid flow means valve turns on,
if no liquid flow means valve turns off."

Click to expand...

These statements imply that you want to infer the position of the valve from the liquid flowrate.

Your statements contradict each other, what is it that you really want to do?

A few other relevant questions:
How big is the pipe?
What material is it made from?
What is the liquid?
What is the pressure?
What is the flowrate?
How much money do you want to spend?

JimB