●依賴它們在回路中的位置可作量入，量出，旁伸控制。
●孔口流量正比壓降平主根(由于非補償設計)因此只適合固定負載,變動負載要用壓力補償閥。
●流路可正反向由1到2口或2到1口。
●當節流閥關閉時可關閉流量,關閉時零泄漏。
●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.