How Does a Tuning Fork Level Switch Work?

What is a tuning fork level switch device?

A tuning fork device combines two metal tuning forks in a circuit that oscillates and is known as the tuning fork level switch. This circuit is usually put inside large vessels with liquids to check their levels or their presence. These devices are commonly present inside water tanks for monitoring purposes and to activate switch contacts. The piezoelectric oscillator’s tuning or oscillation of the forks makes the device vibrate in the default frequency, which is air.

How does it work?

The forks vibrate in the known frequency of the default medium that is air. Since all the mediums’ viscosity differs, they also affect the vibration of the tuning fork. Generally, in water, which has a higher density than air, the tuning fork will vibrate with a lower frequency representing water in the tank. In a general setting, the fork juts out from the switch housing and direct contact with the medium.

Thus, the material compatibility with the fork’s material is a crucial factor to take into deep consideration. These oscillating tuning forks are set straddling inside vessels’ e the vessels’ tops or with the fork jutting out in a horizontal alignment to the tank.

Where are they in use?

It is an efficient instrument that is frequently in-use for monitoring the general elevation of a liquid in a tank. The liquid is usually water. The device transmits a solid-state relay output in the form of an alarm, pump, or valve when the liquid gains a specific level inside the tank. It is not possible to physically observe the fluid levels of tanks since they are usually set up in areas with low access, and this is where this instrument comes in handy!

Additionally, in a vessel, when the fork is oscillating, the natural frequency. Its vibration is constant, but as soon as it comes in contact with a medium with a varying viscosity than air, there is a sudden change in its vibration recorded by the device and sends a signal to the output device. Almost every water tank comes with a vibrating tuning fork liquid level switch that keeps the liquid levels in check and lets the output unit know if there are any changes.

What are the advantages of using it?

This instrument has many benefits that make its use efficient and reliable. There are no effects of turbulence, foaming, and oscillation on the delivery and detection of the switch. Another great advantage is that since none of the instrument’s sensitive components come in contact with the liquid but are safe inside the switch box, there is no adverse effect of high temperatures.

The switch’s installation is not hard because it easily mounts inside the vessel because of its small compact size. The performance of the instrument does not affect even if the vessel has a pressure sealing inside it.

Are there any limitations?

The general compatibility of the liquid has to be taken into account so that the fork works without any disruption and sends a signal at the required levels. Over time and frequent use, there can be a development of a thick substance outside the probe that can affect its vibrations.

Moreover, regular cleaning and maintenance will help eliminate this problem and help in the device’s smooth running. Sometimes, fouling can also cause interference with the frequency recordings that can give wrong switch activations. The tuning fork cannot vibrate in very thick mediums, and for this, there can be a problem if the device is set up where the liquid is too viscous. To get the best results, ensure that the instrument is set up in the tank in the best position to give optimal results. There should be regular maintenance of the switch because replacing one can be a little expensive if it breaks down.


Conclusively, a tuning fork level switch is a beneficial instrument that utilizes frequency changes to signify level changes of liquids in the tanks. Robust materials are used to construct these switches that make them capable of working even in containers that have pressure controlling effects.

Slight modifications can allow these devices to sound the signals at the right time, according to the changes in liquid levels. Regular maintenance ensures that the instrument gives perfect results, and there are no extra costs of replacing it. Now, you know everything about how a tuning fork level works. Next time you will use it, you will undoubtedly find it more comfortable to use.