The Prince valve models RD-100 is pressure compensated adjustable flow control valves. By rotating the handle, the flow out the ?CF?, or controlled flow port, can be varied from approximately 0 to the maximum controlled flow shown in the chart below. Any remaining flow is bypassed to the ?EF? or excess flow port. This flow can be used to power another circuit or can be returned to tank. Once the controlled flow is set it will remain nearly constant with variations in pressure on either the controlled or excess flow ports. Please note: If during operation the controlled flow port is blocked the valve will compensate in such a way as to shut off flow to the excess port. These valves can also be used as a restrictive flow control by plugging the excess flow port. The Prince valve models RDRS-100 have a built in adjustable pressure relief. For these models the excess flow port must be connected to tank.