●依赖它们在回路中的位置可作量入，量出，旁伸控制。
●孔口流量正比压降平主根(由于非补偿设计)因此只适合固定负载,变动负载要用压力补偿阀。
●流路可正反向由1到2口或2到1口。
●当节流阀关闭时可关闭流量,关闭时零泄漏。
●Dependant on their position in the circuit they can provide meter-in,meter-out or bleed-off control.
●Needle valves are non-compensating devices the orifice sige will regu late the flow through the valve in proportion to the sgure root of the pressure differential across port 1 and 2,therefore naking these valves suitable only where the load remains constant.
●Flow path is bi-directional i.e.1 to 2 or 2 to 1.
●Positive shut off of flow when needle is closed.