●功能參數同等于雙向節流閥但包含一個回轉方向的自由流單向閥。
●依靠他們在回路中的位置，可提供量入量出和旁伸控制。
●孔口流量正比壓降平方根(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。
●Performance parameters are sinilar to the bi-directional reedle valve but inelude a high capacity free flow check in the return directon.
●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.