How to choose the liquid level transmitter?

A liquid level transmitter is a type of liquid level instrument. There are a wide variety of liquid level transmitters. They include: Submersible level sensor, Magnetic level sensor, Magnetostrictive liquid level sensor, Radio Frequency Admittance Material Level Sensor, Ultrasonic level meter, Radar level meter, Guided wave radar level meter, etc.

You can use a transmitter to measure the level of liquid media such as water, viscous fluids and fuels, or dry media such as bulk solids and powders. The liquid level measuring transmitter can be used in various working conditions such as containers, tanks and even rivers, pools and wells. These transmitters are commonly used in the material handling, food and beverage, power, chemical, and water treatment industries. Now let's take a look at several commonly used liquid level meters.

Types of liquid level transmitter

Submersible level sensor

Basedon the principle that the hydrostatic pressure is proportional to the height of the liquid, submersible level sensor uses the piezoresistive effect of diffused silicon or ceramic sensor to convert the hydrostatic pressure into electrical signal. After temperature compensation and linear correction, it is converted into 4-20mADC standard current signal output. The sensor part of submersible hydrostatic pressure transmitter can be directly put into the liquid, and the transmitter part can be fixed with flange or bracket, so that it is very convenient to install and use.

Submersible level sensor is made of advanced isolation type diffused silicon sensitive element, which can be directly put into the container or water to accurately measure the height from the end of the sensor to the water surface, and output the water level through 4 – 20mA current or RS485 signal.

Ultrasonic level meter

Ultrasonic level meter is a digital level instrument controlled by microprocessor. In the measurement, the pulse ultrasonic wave is sent out by the sensor, and the sound wave is received by the same sensor after being reflected by the object surface, and converted into an electrical signal. The distance between the sensor and the object under test is calculated by the time between the sound wave transmitting and receiving.

The advantages are no mechanical movable part, high reliability, simple and convenient installation, non-contact measurement, and not affected by the viscosity and density of liquid.

The disadvantage is that the accuracy is relatively low, and the test is easy to have blind area. It is not allowed to measure pressure vessel and volatile medium.

Radar level meter

The working mode of radar liquid level meter is transmitting reflecting receiving. The antenna of radar liquid level meter emits electromagnetic waves, which are reflected by the surface of the measured object and then received by the antenna. The time of electromagnetic waves from transmitting to receiving is proportional to the distance to the liquid level. The radar liquid level meter records the time of pulse waves, and the transmission speed of electromagnetic waves is constant, then the distance from the liquid level to the radar antenna can be calculated, so as to know the liquid level of the liquid level.

In practical application, there are two modes of radar liquid level meter, namely frequency modulation continuous wave and pulse wave. The liquid level meter with frequency modulated continuous wave technology has high power consumption, four wire system and complex electronic circuit. The liquid level meter with radar pulse wave technology has low power consumption, can be powered by two-wire system of 24 VDC, easy to achieve intrinsic safety, high accuracy and wider application range.

Guided wave radar level meter

The working principle of the guided wave radar level transmitter is the same as that of the radar level gauge, but it sends microwave pulses through the sensor cable or rod. The signal hits the liquid surface, then returns to the sensor, and then reaches the transmitter housing. The electronics integrated in the transmitter housing determines the liquid level based on the time it takes for the signal to travel along the sensor and return again. These types of level transmitters are used in industrial applications in all areas of process technology.

A liquid level transmitter can be evaluated by its accuracy, reliability, responsiveness, adaptability, and ease of maintenance and calibration. Choose the right liquid level transmitter for your specific application needs and perform regular testing and maintenance to ensure its proper operation and accuracy. Types of liquid level transmitters include pressure type level transmitter, ultrasonic level transmitter, capacitive level transmitter and float level transmitter. To judge the level transmitter needs to consider its accuracy, reliability, adaptability, safety and easy maintenance. Then we choose which type of liquid level transmitter is suitable for our liquid level measurement. If you have difficulty in product selection, please feel free to contact us!