Hi, @bin1234
What is your project?
Are you trying to keep a constant head of water in a pipe?
If so, why not just keep a tank at that head height full with an overflow.
Tom... 
Hi, @bin1234
What is your project?
Are you trying to keep a constant head of water in a pipe?
If so, why not just keep a tank at that head height full with an overflow.
Tom...