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What Are Solenoid Valves and How They Function?

Understanding the concept behind a device or tool is crucial before actually using it. It becomes more important when we are talking about mechanical stuff. Here in this article, we will understand all about what is a solenoid valve, what are its types, and how it functions.

What is a solenoid valve?

A solenoid valve is an electrically powered mechanical device. As the name says, it is a valve that is used to control flow. A solenoid valve is used to manage the flow of gas or liquid. Solenoid valves perform a major function in the machinery field and make an important part of many devices. It is used quite widely and can be easily replaced by experts when required.

What are the types of solenoid valves?

There are majorly two types of solenoid valves.

  1. Pilot operated
  2. Direct-acting

Pilot operated

The pilot-operated valve uses pressure to function. These are the most widely used solenoid valves. The best thing about them is that they use less electricity, however, system line pressure is required for functioning. The pilot-operated solenoid valve uses a smaller coil which again cuts cost and thus it is quite affordable as compared to the direct acting valve.


The spring coil remains at a default position until electricity is powered. The direct-acting valves offer only two positions which are open and closed. Once the electricity supply is maintained, the valve can be set in any required position. As the name suggests, the direct-acting valves don’t have a very complex mechanism. The coil does all the work by shifting the valve seat with either a push or pull depending on the instruction provided. The size of the coil is usually larger than a pilot-operated valve. The fluid runs out when the pressure is released with the opening of the valve and that’s how it functions. Apart from it, the valves also come in different types to suit individual needs. You can have 2-way, 3-way, and even 4-way valves to make your system effortless. Depending on functions, the solenoid valves are divided into many categories which you will get to know over time.

How does the solenoid valve work?

The solenoid valve works with three important parts which include a coil, a plunger, and a sleeve assembly. It works either in a fully closed or fully open mode depending on what instructions are fed. The solenoid valves offer a good replacement to manual valves with buffer efficiency.

Since the job of the valve is to control the flow of liquid, the opening or closing mechanism is all it has. The solenoid coil can either be normally open or normally closed. Opening means the liquid or gas will flow and a closed position will enclose it. The function will reverse when the coil is energized.

When the position is normally closed, the plunger is made to block the passage of flow with the help of a spring. Once the coil is energized, increasing the magnetic field, the valve will enable the flow.

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