5 advantages of Optical level switch water compared to float switch

- Dec 19, 2019-

We will discuss the following five aspects: compact structure, solid state, sensitivity, scope of application, customization, and float switch working principle.


The float switch is installed with one or more reed switches in a closed non-conductive tube, and then passes this tube through one or more hollow floating balls with ring magnets inside. The rising or falling of the liquid will drive the floating balls together. Move up and down, so that the reed switch in the non-conductive tube can attract or disconnect, and output a switching signal, also called a passive contact signal. Float switches are one of the most cost-effective but well-proven technologies in level sensing.

The working theory of optical level switches:


The optical level switch is a new type of contact point liquid level measurement and control device developed using the principle of reflection and refraction at the interface between two different media. The working principle is that the product contains a near-infrared light-emitting diode and a photosensitive receiver. The light from the light-emitting diode is directed into a lens on top of the sensor. When the liquid immerses the lens of the optical level switch, the light is refracted into the liquid, so that the receiver cannot receive or can only receive a small amount of light. The photoelectric level switch senses this change, and the receiver can drive the internal electrical switch to activate an external alarm or control circuit. If there is no liquid, the light from the LED is reflected directly from the lens back to the receiver.

5 advantages of optical level switch compared to float switch

The optical level switch has the advantages of simple structure, high positioning accuracy, no mechanical parts, no debugging, high sensitivity, corrosion resistance, low power consumption, small size, and many other advantages. It is stable and has little effect on the measured medium. The specific embodiment is as follows:

Compact structure:


Only the sensor tip is required, which is ideal for applications where space is tight or obstacles (such as agitators) are inside the tank.

Solid state:

EPTSensor's optical sensor liquid level are solid-state, so no moving parts are blocked, damaged or corroded.



Everyone knows that the sensitivity of a sensor is directional. When the measured is a single vector, and its directivity requirements are high, you should choose a sensor with low sensitivity in other directions; if the measured is a multi-dimensional vector, the smaller the cross-sensitivity of the sensor, the better. The optical sensor liquid level provided by EPTSensor requires directional liquid to change the sensitivity of the sensor. Similarly, this is not possible for a floating switch.

Note: special circumstances

There are often high temperature and pressure in the liquid level sensor container, or the liquid has a large viscosity, or contains a large amount of suspended solids, which adversely affect the measurement. Usually within the linear range of the level sensor, the higher the sensitivity of the sensor, the better. Because only when the sensitivity is high, the value of the output signal corresponding to the measured change is relatively large, which is conducive to signal processing.

Scope of application:

EPTSensor offers a variety of chemically compatible plastics and glass, which can be used to detect almost all liquids. At the same time they can be used in a very high temperature and pressure range. In addition, the photoelectric liquid level sensor has nothing to do with other characteristics of the medium including temperature, pressure, density, and electrical parameters, so the sensor liquid level is accurate, the repeat accuracy is high, the response speed is fast, and the liquid level control is very accurate. Therefore, the optical sensor liquid level can be used for accurate and reliable measurement and monitoring of critical points, upper and lower limit points or multi-point liquid levels of various low-viscosity clean liquids, display alarms, fixed-point control, and identification of gas / liquid two-phase or oil-water interfaces.


FS-IR1902 optical sensor liquid level / photoelectric level switch provided by EPTSensor can provide single-point liquid level detection, TTL compatible push-pull output. The sensor design contains an infrared emission source and a detector, and the installation position is accurate. When the tapered end of the sensor is immersed in liquid, infrared light will be transmitted out of the tapered surface, and the intensity of the light reaching the detector will become weak. This optical sensor liquid level (industrial grade, photoelectric flooding sensor) is designed for industrial applications. Capable of heavy-duty environments in industrial applications. This series of products are suitable for a wide voltage range power supply environment, and the driving current can reach 250mA. Therefore, this series of sensors can directly drive alarms and other devices.