Products Ultrasonic Level Transmitters and Switches

Ultrasonic Level Transmitters and Switches


Ultrasonic Level Transmitters and Switches
This technology relies on sound waves to determine material level by gauging the distance between a topof-tank transducer and the surface of the material, whether liquid, solid, or slurry. The transducer emits short ultrasonic impulses (sound waves) that represent mechanical energy. The waves bounce off the top of the material like an echo and return to the transducer which calculates the “time of flight” to determine the height of the material in the tank. The transducer emits a relatively narrow beam, so obstructions in the tank typically don’t impair its applicability or accuracy.
Due to inherent limitations of ultrasonic measurement, this technology is used primarily in water/wastewater and aggregate applications.
The ultrasonic meter is also unaffected by changes in material density or specific gravity.
There are two general types of ultrasonic meters. The integrated version encompasses both the sensor and the electronics in a single, compact instrument. There is also a remote version that separates the two components, enabling remote level monitoring.


Our offering


Ultrasonic Level Transmitter LST400

The LST400 is an Ultrasonic Level Transmitter capable of measuring liquid level or solid applications up to 50 ft. / 15 meters or flow rates in all types of open channel flow applications. The transmitter has a single 4-20 mADC analog output with HART 7 and five (5) relay outputs. A transducer is fitted to the top of a silo or tank, facing down towards the material being measured.

The transmitter’s microprocessor simultaneously fires an electronic pulse to the transducer and starts a timer. The transducer converts this electronic pulse to an acoustic pulse, which is directed toward the surface of the material being measured. When the acoustic pulse contacts the surface of the material, energy is reflected back to the transducer, which converts this reflected energy back to an electronic pulse. This pulse is sent back to the microprocessor, which stops the timer and determines the “time of flight” of the signal. By combining the speed of sound through air and the “time of flight” of the pulse, the microprocessor accurately determines the level of the product. Powerful software removes false echoes from the signal and electronic filters remove ambient noise. 

Compact ultrasonic level transmitter LST300

The LST300 is a high performance ultrasonic level transmitter that accurately measures level, distance and open channel flow in ranges up to 10m (30ft). It is a non-contact, level measuring instrument designed for use on liquid level in a wide range of applications and industries. 

• Maintenance free, non-contact continuous level sensor
• 2-wire instrument with HART digital communication
• Up to 10 m measurement range
• Wide temperature range of -40 to 85 ˚C
• Accuracy of ±2 mm or 0.2 % of full span (the larger one)
• Beam angle as low as 5˚ with false echo filtering for narrow spaces
• Easy installation with graphic echo display, advanced diagnostic and easy setup menu
• Unique GAP technology ensures the best performance under any condition
• IP66/67 and NEMA 4X (can submerge to 1 m depth for 30 minutes)
• ATEX, IEC & FM Intrinsic safe and non sparking approved

— Through the Glass (TTG) buttons, standard push buttons or without HMI interface
— 6 m (20 ft.) or 10 m (32 ft.) measurement range
— FM, ATEX, IECEx or NEPSI approved, intrinsically safe or non‑sparking
— Standard, extendable or floor mounted brackets available for easy installation
— TFlange mounting options


Ultrasonic level transmitter LST200

Level measurement is a key requirement in many industries where accurate data on liquid levels is needed for purposes ranging from managing storage through to reporting. In water and wastewater treatment applications, where dozens of level devices may be used, a product that offers simple commissioning, reliable operation, fast delivery and easy maintenance offers tremendous customer value.

Developed in conjunction with our customers and drawing on ABB’s extensive experience in level measurement, the LST200 ultrasonic level transmitter offers a simple, smart and reliable level measurement solution. Featuring a modular design, the LST200 utilizes the latest developments in digital sensing technology, including built-in smart chip and an interface for upgrading with future modern data acquisition methods such as NB-IoT, offering the full benefits of digitalization for improved measurement and sharing of data.                                                              

Key features 
Typical water and wastewater applications
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