At present, there are many different liquid level sensing technologies to choose from in the market, some of which have existed for decades and run in food and beverage, manufacturing, automobile and white household appliances industries.

In this article, we will introduce the main differences and considerations when choosing point type liquid level switch or continuous type liquid level sensor.

1. Working principle

Liquid level switch:

Liquid level switch is a device to detect whether there is liquid when it reaches a predetermined liquid level. In most cases, they work as an on / off switch. When the liquid level of the tank or container rises or falls to a certain level, a function will be activated. This may be to alert or activate a device. Essentially, when the liquid reaches the desired point, the switch will detect it and act as a switch to activate the necessary response.

Liquid level sensor:

When we need to measure every possible intermediate liquid level of tank or container, we need a continuous liquid level sensor, which is called continuous liquid level measurement. This means that the sensor can provide feedback regardless of the level of the liquid.

2. Measurement task

Liquid level switch:

Liquid level switch is generally used in the process of monitoring high or low liquid level. Prevent overfilling, dryness and leakage.

Liquid level sensor:

A continuous level sensor transmits the exact level to be monitored. It is very suitable for the process that needs to improve the accuracy and the application that needs to know the liquid level.

3. Environmental factors

In addition to distinguishing between continuous level sensor and point level switch, there are also some environmental factors that can determine which type of sensor is most suitable for application. These factors include:

Temperature and pressure: depending on the working temperature and pressure in the application environment, liquid level switches and sensors of different materials and designs may or may not be suitable.

Chemical compatibility: the type of enclosure material of the sensor or switch shall be selected according to the liquid medium to be tested. You must consider whether the liquid medium will accumulate or smear on the surface; in this case, it is better to choose a solid-state sensor without moving parts.

Measurement range: the depth of the container or tank and the distance between the liquid level and the sensor will help to determine the correct sensor.

Type of response or output: different sensors are more suitable to produce different outputs: analog, relay, digital, etc.

Tank size and shape: special requirements will be required for very wide or narrow tanks and tanks that cannot be fitted with sensors on the side, top or bottom. For example, ultrasonic sensors will not be suitable for narrow shaped tanks.

4. Type of liquid level sensor and point type liquid level switch

Although most level sensor technologies fall into these two categories (continuous level sensors or point level switches), there are many different types of devices to choose from in each category, which are suitable for endless applications.

Examples of point level switches are listed below:

Optical level switch

Horizontal float switch

Vertical float switch

Ultrasonic level sensor

Examples of continuous level sensors are as follows:

Submersible liquid level sensor

Ultrasonic level sensor

Capacitive liquid level sensor

Editor in charge: CC

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