Siemens Radar level transmitters / SITRANS LR 400

7ML5421-0TD03-0BQ1- (liquid,and slurries.)

The SITRANS LR 400 works by using Frequency Modulated Continuous Wave (FMCW) radar technology to continuously measure the level of liquids, slurries, and solids. It emits a 24 GHz radar signal, and by comparing the transmitted and reflected signals, it calculates the distance to the material's surface, providing accurate level data. Its 24 GHz frequency and high signal-to-noise ratio allow it to penetrate difficult conditions like dust, high temperatures, and low dielectric materials, ensuring reliable performance.

How it works:

1. FMCW Principle: The device emits a radar beam that is continuously varied in frequency.
2. Reflection: When this signal hits the surface of the material in the vessel, it is reflected back.
3. Signal Comparison: The SITRANS LR 400 compares the frequency of the transmitted signal with the frequency of the reflected signal.
4. Distance Calculation: The difference in frequency is directly proportional to the time it takes for the radar signal to travel to the material and back.
5. Level Measurement: By measuring this frequency difference, the device calculates the distance to the surface, which is then converted into a level measurement

Key features for effective operation:

• High Frequency (24 GHz): This higher frequency provides a narrower beam, which reduces sensitivity to vessel interferences and helps in penetrating dust and other challenging media.  
• High Signal-to-Noise Ratio: This ensures that weak signals, which can be produced by certain materials or in difficult conditions, are still detected and processed reliably.
• Robust Design: The unit features a robust housing, flange, and horn designed to withstand various process and atmospheric conditions, including high temperatures and pressures.
• Advanced Processing: The device incorporates features like Auto False-Echo Suppression and advanced echo processing to filter out unwanted reflections from vessel walls or other obstructions.

 Full Datasheet

Transmitter & Antenna Feature  

• Manufacturer :  Siemens
• Product No. : 7ML5421-0TD03-0BQ1
• SITRANS LR400 Radar level tr ansmitt er with PTFE rod:  7ML5421 - 4-wire, 24 GHz FMCW radar level transmitter for continuous monitoring of liquids and slurries in storage and process vessels including high temperature and high pressure, to a range of 50 m (164 ft); ideal for low dielectric media.
• Process temperature range:  0 - -40 °C ... +200 °C (-40 ... +392 °F), standard
• Process connection: T -  DN 100, PN 16, Type A, flat faced
• Antenna: D  -  Horn antenna, long 93 mm (3.66 inch) diam. for 100 mm (4 inch) nozzles
• Antenna purging system : 0  - None
• Process seal/gasket: 3  - FKM for -20 ... +200 °C (-4 ... +392 °F) flange temperatures²)
• Output/communication: 0  - 4 ... 20 mA, HART
• Power supply/cable inlet: B - 2 x M20x1.5
• Approvals: Q  - ATEX II 2G
• local display: 1  - with

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

Basic Ordering Information Transmitter

ABM Temperature -40°C to + 65°C