valvesdirectional

Directional valves, also called directional control valves, regulate the path of a fluid within a hydraulic or pneumatic circuit. By connecting source pressure, actuated, and exhaust ports in different ways, they determine which actuator receives flow and in what direction.

Most directional valves are multi-port and multi-position devices. Common configurations include 3/2, 4/2, and 5/2 valves, with two or more working ports and one or more exhausts. The numbers indicate ports and actuation positions. They can be monostable (spring-return) or bistable (latching) and may be operated by a variety of actuators.

Actuation methods: solenoid (electrical), manual lever or knob, spring return, pneumatic or hydraulic pilot signals, or mechanical actuation. Internal designs are primarily spool valves and poppet valves. Spool valves route flow through a bore with slots; poppets use seals at ports with a moving disc.

Operation: in one position certain ports are pressurized or vented; in another position different connections are made. Movement between positions is achieved by actuation and may be held by springs or latching mechanisms. Symbols for directional valves are standardized (ISO 1219) to show port arrangement and actuation.

Applications: used to control cylinders, motors, and other actuators in automation, manufacturing, robotics, process control, and automotive systems. Selection considerations include port size and pressure rating, required number of positions, response time, leakage, and environmental conditions.