What Is A Submersible Level Transmitter

What Is A Submersible Level Transmitter

Working Principle

The submersible level transmitter is based on the principle that the measured static pressure of the liquid is proportional to the height of the liquid. It utilizes diffusion silicon or ceramic sensitive components with the piezoresistive effect to convert static pressure into an electrical signal. After temperature compensation and linearity correction, this signal is converted into a standard 4-20mA DC current signal output.

The sensor part of the input hydrostatic level transmitter can be directly submerged into the liquid, while the transmitter part can be fixed using a flange or bracket, which is extremely convenient for installation and use. The input liquid level meter is constructed with advanced isolated diffusion silicon sensitive components. This allows it to be submerged directly into a container or body of water to accurately measure the height from the end of the water level meter to the water surface. It outputs the water level value to the outside world through a 4-20mA current signal.


This two-wire submersible level transmitter consists of a special air-conducting cable with a built-in capillary hose, a pressure-resistant connector, and a probe. The probe of the submersible level transmitter is constructed as a stainless steel cylinder core with a diaphragm at the bottom and is covered by a perforated plastic shell. Level measurement is achieved by measuring the static pressure of the liquid at the probe head and the actual atmospheric pressure difference. This information is then converted into a 4~20mA output signal by the ceramic sensor and electronic components.

LCD display submersible level transmitter

Main Applications

The static pressure submersible level transmitter is suitable for level measurement in various media in petrochemical, metallurgical, electric power, pharmaceutical, water supply and drainage, environmental protection, and other systems and industries. It features a compact structure, simple adjustment, and flexible installation, allowing users to conveniently utilize standard signal outputs such as 4~20mA, 0~5V, 0~10mA, and others according to customer requirements. The submersible level transmitter’s stainless steel sensor is equipped with a cable covered in extendable polyurethane shell material. Additionally, the transmitter can be selected with a heavy anchor sensor, suitable for use in liquid environments with fluctuation or rapid flow.


  1. Good stability and high precision.
  2. The submersible level transmitter is directly immersed into the measured medium, making it quite convenient to install and use.
  3. It features a solid-state structure with no moving parts, ensuring high reliability and a long service life. It can accurately measure a wide range of mediums, from water and oil to high-viscosity paste, without being affected by blistering, deposition, or electrical characteristics. It also incorporates temperature compensation to account for variations in temperature. The input level meter includes reverse polarity protection and overload current limit protection.
  4. It can convert measurements into a standard current signal for remote transmission to the operation and control room, enabling centralized display, alarm, or automatic control using secondary instruments or computers. Due to its robust structure and easy installation, it is suitable for use in high-temperature, high-pressure, corrosive, crystallizing, clogging-resistant, cold-resistant, and solid powder or granular material environments. It can be employed for continuous level detection and control in various industrial processes.

Installation Points

  1. The level transmitter should be restored to its original packaging during transport and storage, and stored in a cool, dry and ventilated warehouse.
  2. If any abnormality is found in use, the power supply should be switched off, stop using and check.
  3. When connecting the power supply, it should be connected strictly according to the wiring instructions.
  4. When the level meter is installed in a static deep well or pool, a steel pipe with an inner diameter of Φ45mm (containing several small holes at different heights to allow water to enter the pipe smoothly) is typically anchored in the water. Subsequently, the input level transmitter is placed into the steel pipe and is ready for use.
  5. The installation direction of the transmitter is vertical, and the installation position of the input type should be far away from the liquid inlet and outlet and agitator.
  6. In large vibration situations, you can wrap steel wire around the transmitter to absorb shocks, preventing the cable from being pulled off.
  7. When measuring the level of flowing or stirring liquid, usually, a steel pipe with an inner diameter of approximately Φ45mm is placed in the water. Small holes are made at different heights on the opposite side of the liquid flow direction to allow water to enter the pipe smoothly. Next, the input level transmitter is inserted into the steel pipe, and then it can be used.

Smart submersible level transmitter

Use Precautions

  1. When installing the hydrostatic submersible level transmitter, the pressure pipe must be vertically inserted into the measured medium.
  2. For media with impurities or crystallisation, the head of the collector must be cleaned regularly to prevent clogging.
  3. Regular cleaning is recommended once a month.
  4. When cleaning, first open the screw cap of the iron pipe of the input water level meter and take out the level meter carefully. Then remove the debris (such as water plants, plankton, etc.) attached to the level meter.
  5. When cleaning the pilot hole, use trichloroethylene or alcohol to inject the pilot hole to half of its depth and soak it for about 5 minutes. Then, shake it slightly and repeat the process several times until it is clean. Do not use any equipment to clean the pilot hole to avoid damaging the sensitive pressure-sensitive core diaphragm.
  6. When cleaning the transmitter pressure interface and pilot hole, avoid using hardness brush or metal tools to avoid damage to the sensitive core and pressure interface threads.
  7. After cleaning the level meter, slowly put it back into the iron pipe. Once it feels it has been placed at the low part of the iron pipe, the screw cap can be installed back into its original position. After unloading, cleaning, and reinstallation, due to potential changes in installation depth, it is necessary to compare the sluice gate with the water level at the time of the water level meter scale. This is to correct the detection value of the secondary instrumentation and ensure the accuracy of the sampling data.
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