Yes you control the speed of liquid movement with the ball valve on the pump output. If you have the kettle valve that feeds the pump partially closed, you run the risk of starving the pump and losing prime.
Also, if you try to throttle the flow farther past the pump than the discharge you may blow the hose off. Like if you are pumping through a valve at the destination. Always use a valve at the pump discharge.
Originally Posted by D_Struct
I would've made a crayon schematic if I thought this was going to hang people up.