Siemens SITRANS LH100 Hydrostatic Pressure Transmitter

The Siemens SITRANS LH100 is a hydrostatic pressure transmitter designed as a compact submersible level probe. It is used for continuous level measurement in liquids and is particularly suitable for applications in basins, tanks, canals, wells and dams. The probe measures the hydrostatic pressure of the liquid column and converts it into an electrical output signal.

Thanks to its robust construction and IP68 degree of protection, the SITRANS LH100 is designed for permanent use in liquids. The device is easy to install and can be supplemented with accessories such as a cable terminal box and suspension clamp. Different measuring ranges and explosion protection versions allow adaptation to various application requirements.

Key benefits

• Compact design for easy installation
• Robust construction for use in liquids
• Hydrostatic level measurement without moving parts
• Low measuring deviation of 0.3 %
• IP68 protection for permanent submersion
• Suitable for water, wastewater and industrial liquid applications
• Integrated moisture filter to protect against condensation
• 4 … 20 mA output signal for easy integration into control and monitoring systems

Typical applications

The SITRANS LH100 is used wherever liquid levels need to be measured reliably and continuously. Typical applications include:

• Level measurement in wells
• Water and wastewater supply
• Measurement in open or unpressurized tanks
• Shipbuilding and marine applications
• Canals, basins and dams
• Level monitoring in water management systems

Design and construction

The pressure transmitter contains an integrated ceramic sensor with a Wheatstone resistance bridge. The sensor and the electronics are installed together in a stainless steel housing. This creates a compact and resistant unit suitable for continuous use in liquids.

A vent tube is integrated into the connection cable. It is connected to a moisture filter, which prevents condensation from forming. The measuring diaphragm is protected from external influences by a protective cap. The electrical connection and the connection cable are housed in a compact enclosure.

Operating principle

The hydrostatic pressure of the liquid column acts on the sensor diaphragm. This pressure is directly proportional to the immersion depth of the probe. At the same time, the hydrostatic pressure is compared with atmospheric pressure. Pressure equalization is achieved via the vent tube in the connection cable.

The deformation of the diaphragm is detected by the Wheatstone resistance bridge in the sensor. The output signal is then processed by the electronics and converted into a 4 … 20 mA current signal. The protective conductor connection or equipotential bonding is connected to the housing.

When is the SITRANS LH100 a suitable choice?

The SITRANS LH100 is particularly suitable when a simple, robust and permanently submersible solution for level measurement is required. Compared with mechanical float systems, hydrostatic measurement works without moving parts and is therefore low-wear. The probe is well suited for continuous level monitoring and easy integration into existing control systems.

Technical overview

Practical benefit

With the SITRANS LH100, liquid levels can be monitored reliably in many water and process engineering applications. The combination of ceramic sensor, stainless steel housing, IP68 protection and 4 … 20 mA output makes the probe a simple and robust solution for continuous level measurement.