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What Is a 3-Way Solenoid?

Andrew Kirmayer
Andrew Kirmayer

A 3-way solenoid is a valve with three connections for pipes. It also has two ports for liquid or gas to flow through. The electromagnetic part of the valve is the solenoid and includes a coil, core, and enclosure. Also included are two openings that alternate being in open and closed positions, so that pressure can be applied accordingly; an actuator or cylinder controls the valve. Various manufacturers sell 3-way solenoid valves in different configurations, including Normally Closed (NC), Normally Open (NO), and universal.

Inside the valve housing, a movable armature is capped by fluid sealing parts on either end. The various solenoid parts include a ring near one seal to contain fluid, as the spring on that end is in the right position. While the 3-way solenoid is de-energized, fluid passes through the sealing ring from one port to a second. A bore is aligned with a hole in the ring to allow fluid or gas to pass through. The armature mechanism changes position when the valve becomes energized, stopping the fluid from passing through this point and opening a third port for the medium.

Woman holding a book
Woman holding a book

Solenoids with three ports also include a rolling diaphragm seal to ensure that fluid or gas does not pass unintentionally to the wrong port. One port is always open, enabling control of the direction of flow. This design is suitable for use with tools as well as equipment such as hydraulic cylinders. Using a 3-way solenoid requires knowledge of the port size needed for the application. The model chosen also depends on the media being affected by the valve, the voltage applied to the valve, and factors such as operating pressure and location.

Types of solenoids can include NC 3-way solenoid valves. De-energizing these causes the pressure port to close and the exhaust port to open, while the exhaust port closes and pressure port opens when the valve is energized. In NO valves, the exhaust port closes when the system is de-energized, while the pressure port is closed in an energized valve. Solenoids that can be operate either way are known as universal.

A 3-way solenoid can support various types of gas or fluid. It is used in industries that utilize process equipment and those that build and maintain transportation infrastructure and vehicles. Medical and energy facilities use solenoids as well. Depending on the application, the valve can be connected to pressure controls, gauges, and electrical equipment.

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