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What is a solenoid valve?

A valve that is opened and closed by an electromagnet is called a solenoid valve. A solenoid valve converts an electrical signal into a mechanical opening or closing movement, which makes it possible to control the flow of both liquid and gaseous media.

The solenoid that controls the valve can be either an AC solenoid or a DC solenoid. Compared to DC solenoids, AC solenoids offer faster switching and a short drop-out delay. However, their switching time cannot be influenced. With DC solenoids, the switching time can be reduced by overvoltage, but they must be protected by a switching element when they are turned off.

How does a solenoid valve work?

When current flows, a magnetic field forms inside the coil. When current flows through the coil, the magnetic circuit strives to reduce its magnetic resistance and close the air gap. Therefore, the inductance increases. A voltage is thus induced in the coil which has the same polarity as the supply voltage.

What types of solenoid valves exist and what are their characteristics?

Solenoid valves can be directly controlled, servo-controlled or force-controlled.

With directly controlled solenoid valves, the force of the solenoid is used directly to open or close the valve. This type of valve is mainly used for low pressures as well as smaller nominal values.

The servo-controlled solenoid valve requires a pressure difference of the operating pressure to be able to open and close. This mode of valve operation allows a higher flow rate at higher pressure without increasing the power consumption of the coil.

Force-operated valves offer a combination of servo-operated and direct-operated valves. If there is differential pressure, the valve operates as a servo-controlled valve. If there is no differential pressure - or only a very small one - it works as a directly controlled valve.

What does NC and NO mean?

"NC" means that the valve is closed in the idle position, i.e. in the de-energised state. "NO" valves, on the other hand, are open in the idle position.

Why do I need a dirt strainer?

Strainers protect valves and other pipelines from contamination. The liquids and gases that flow into the pipes can contain impurities. These impurities can clog both the pipes themselves and their valves. To counteract this, dirt traps are installed at the beginning of the pipeline to prevent dirt from entering the pipe system.