High specific speed Vertical turbine pumps

Dear friends...

I am supposed to prepare the control logics for he starting and operation of a vertical turbine pump. In case of high specific speed pumps it is not recommended to start the pump with the closed discharge valve and use of open discharge valve or partially open discharge valve is preferred. Now, i would like to know is there any difference in the starting torque for partially open and completely open discharge valve...

Thanks ...

Hello:
Yes, typical high specific speed pumps require the maximum pump power required at shut off these is the reason to avoid starting against a closed valve.
Usually the pump should be started when the discharge valve position allows starting the pump at minimum flow
However in same systems configurations such as cooling water in power stations,the starting sequence should be performed with the discharge valve closed to avoid reverse running.
Regards

Thanks for ur reply...