FCR51 series valves are pressure compensated adjustable flow control valves. By rotating the handle, the flow out the “CF” or controlled flow port can be varied. Any remaining flow is bypassed to the “EF” or excess flow port. Once the controlled flow is set, it will remain nearly constant with variations in pressure on either the controlled or excess flow ports. There is a pressure relief valve integrated in valve body. EF port must be connected to oil tank.