A fluid-operated needle valve having a fluid displaceable actuator reciprocable in one housing and a needle valve reciprocable in another housing. The two housings are detachably secured to each other.Instrumentation Ball Valves One or more plungers act between the actuator and the tip of the needle valve so that movement of the actuator seats or unseats the needle valve. Known valves which are capable of automatic operation commonly suffer the drawback that fluid under high pressure at the orifice of the valve tends to bypass the plug when the valve is closed. Many such automatic valves are of the solenoid or magnetic type, Needle Valvesand when such valves are subject to more than 150