Siemens Radar level transmitters / SITRANS LR250

7ML54310BD200BA1 (liquid,solids, and slurries.)

The Siemens SITRANS LR250 is a 2-wire, 25 GHz pulse radar level transmitter that works by emitting a focused microwave pulse from its antenna. The pulse travels to the liquid or slurry surface and reflects back to the antenna. By measuring the time it takes for the pulse to travel to the surface and return, the device calculates the distance to the material, and thus, its level. Its Process Intelligence signal processing and dynamic time-varying threshold (TVT) help it reliably measure level even with obstructions or varying process conditions.

How the SITRANS LR250 Works

1. Pulse Emission: The transmitter emits a narrow, high-frequency (25 GHz) microwave pulse in a focused beam towards the surface of the material in the vessel.
2. Reflection: When the microwave pulse strikes the surface of the liquid or slurry, it reflects back towards the antenna.
3. Signal Reception: The antenna receives the reflected pulse.
4. Time Measurement: The transmitter measures the exact time interval between the emission of the pulse and the reception of the reflected echo.
5. Distance Calculation: Based on the speed of light and the measured time, the LR250 calculates the distance to the material surface.
6. Level Determination: Knowing the total vessel height, the device determines the level of the material.

Key Features Supporting its Working Principle

• 25 GHz Frequency: The high frequency allows for a narrow beam, which reduces interference and enables the use of smaller antennas.
• Process Intelligence: This advanced echo processing technology uses a dynamic time-varying threshold (TVT) to adapt to changing process conditions, ensuring reliable measurements even with internal obstructions.
• Non-Contact Measurement: As a radar device, the LR250 is a non-contact transmitter, meaning it does not physically touch the process material, avoiding issues like membrane fouling associated with pressure transmitters.
• Diagnostic Support: The device features a graphical local user interface (LUI) that can display echo profiles, providing diagnostic information to support setup and operation.

 Full Datasheet

Transmitter & Antenna Feature  

• Manufacturer :  Siemens
• Product No. : 7ML54310BD200BA1
• SITRANS LR250 Radar level tr ansmitt er with PTFE rod:  7ML531 -Continuous, non-contact, 20 m (66 ft) range, for liquids and slurries.
• Process Connection and Antenna Material:  0 - 316L (1.4435 or 1.4404) stainless steel, PTFE emitter, FKM seal1)
• Process Connection Types (all types have TFM1600 PTFE lens): BD -  2" Class 150 ASME B16.5, raised face4)
• Communication/Output: 2  - 4 ... 20 mA, HART, start-up at < 3.6 mA
• not use: 0  - none
• Enclosure/Cable inlet : 0  - 2 x ½" NPT
• Antenna: B  - 2" horn (fits 2" ASME or DN 50 nozzles)
• Approvals: A - Ordinary Locations/General Purpose (Non-Ex), CE, UKCA, CSA, FM, FCC, RED, RCM
• Pressure rating: 1  - 0.5 bar g (7.25 psi g) maximum7)

There are several Model of pressure transmitters, for more details read the PDF below 

Basic Ordering Information Transmitter

ABM Temperature -40°C to 80°C