Endress+Hauser FMR50, FMR51 and FMR52: Understanding the Differences Before Selecting a Radar Level Transmitter

When engineers search for an Endress+Hauser Micropilot radar level transmitter, three model names that frequently appear in existing plant documentation are FMR50, FMR51 and FMR52.

However, these models should not be selected simply by comparing their model numbers or measuring ranges.

The actual process conditions, product properties, installation requirements, material compatibility and the status of the existing instrument all need to be considered.

FMR50: Basic Level Measurement and Existing Installations

The Micropilot FMR50 was designed for basic continuous level measurement in liquids, pastes and slurries.

Endress+Hauser specifies the FMR50 as a K-band, approximately 26 GHz, free-space radar device with a standard measuring distance of up to 30 m and up to 40 m with Advanced Dynamics. Its historical applications included basic level measurement where changing media, temperature changes, gas blankets or vapor were present.

However, there is an important procurement consideration today:

Endress+Hauser currently lists FMR50 as no longer available and identifies Micropilot FMR60B as its successor.

Therefore, FMR50 is particularly relevant when:

• Identifying an existing installed instrument

• Checking an old plant configuration

• Sourcing a replacement for an existing FMR50

• Reviewing historical documentation

• Comparing an existing FMR50 with the current-generation successor

For a new project, the current successor should be evaluated rather than assuming that FMR50 is still a standard new-product selection.

FMR51: Demanding Liquid Level Measurement

The Micropilot FMR51 is positioned by Endress+Hauser as a sensor for demanding liquid level measurement applications.

Its published specifications include a standard measuring distance of up to 40 m and up to 70 m with Advanced Dynamics. Depending on configuration, the FMR51 supports process temperatures extending to very high and very low ranges, and process pressure up to 160 bar.

The FMR51 also supports a range of process connections, materials and communication options, including:

• 4...20 mA HART

• PROFIBUS PA

• FOUNDATION Fieldbus

• Optional Bluetooth operation

• 316L and Alloy C materials

• PTFE and ceramic components

• Threaded and flanged connections

• Hygienic Tri-Clamp options

The exact specification depends on the selected configuration and order code.

When Is FMR51 Particularly Relevant?

One important point in the Endress+Hauser application information is the relationship between dielectric properties and model selection.

The official application limits identify low dielectric constant applications with FMR51.

This is an important distinction when engineers are selecting between Micropilot models.

Instead of asking only:

“Which model has the longer measuring range?”

the more useful question is:

“What are the actual dielectric, process and installation conditions?”

For demanding liquid applications, these parameters can have a direct influence on the appropriate radar configuration.

FMR52: When PTFE and Hygienic Requirements Matter

The FMR52 belongs to the same free-space radar family but has a different application focus.

Endress+Hauser's official application information identifies:

Only PTFE resistant → FMR52

and also identifies:

Hygiene requirements → FMR52 / FMR53

The FMR52 technical documentation specifies a PTFE-clad antenna, with the PTFE material identified as being in accordance with FDA 21 CFR 177.1550 and USP <88> Class VI for the relevant configuration.

This makes FMR52 particularly relevant when material compatibility and hygienic process requirements are central to the application.

The exact configuration should still be verified against the actual product, cleaning process, temperature, pressure and required approvals.

FMR50 vs FMR51 vs FMR52

This should be used as a starting point rather than as a substitute for checking the complete Endress+Hauser order code.

What About FMR50 Replacement?

This is especially important for maintenance departments.

If an existing plant is equipped with FMR50, the procurement team should first identify the complete original configuration.

Useful information includes:

• Complete order code

• Serial number

• Antenna configuration

• Process connection

• Communication protocol

• Measuring range

• Process temperature

• Process pressure

• Existing certificates

• Installation dimensions

Endress+Hauser currently identifies Micropilot FMR60B as the successor to FMR50. FMR60B is an 80 GHz radar sensor with a maximum measuring range of 50 m and is designed for free-space applications, including vessels with many internal fittings.

Therefore, an FMR50 replacement project should be treated as a technical replacement verification, rather than simply ordering another instrument based on the old model number.

Radar vs Other Level Measurement Technologies

Selecting FMR51 or another Micropilot model also requires consideration of the measurement principle.

Free-Space Radar

The radar transmitter measures the distance to the product surface without requiring a probe to extend into the process.

This can be useful for many liquid level applications and can reduce direct mechanical contact with the process.

Guided Radar

Guided radar uses a probe to guide the radar signal.

It can be appropriate for certain vessel geometries and process conditions, but probe installation and process interaction need to be considered.

Ultrasonic Level Measurement

Ultrasonic instruments use sound waves rather than electromagnetic radar waves.

For applications involving vapor, changing atmospheric conditions or other difficult process environments, the suitability of ultrasonic measurement should be evaluated against the actual application.

Differential Pressure

Differential-pressure level measurement determines level from hydrostatic pressure.

It can be suitable for specific vessel configurations, but process connections, pressure conditions and changes in liquid density need to be considered.

The correct technology therefore depends on the complete process rather than the instrument category alone.

A Practical Selection Workflow

For an Endress+Hauser Micropilot selection or replacement project, a practical workflow is:

1. Identify the existing or required instrument

Determine whether the project concerns an existing FMR50, a new FMR51 application or another Micropilot configuration.

2. Identify the process

Check the medium, dielectric properties, temperature, pressure, vapor, foam and product build-up.

3. Check the vessel

Review tank height, nozzle position, agitators, pipes, heating coils and other internal structures.

4. Check material requirements

Determine whether standard materials are sufficient or whether PTFE, Alloy C, ceramic or other specific materials are required.

5. Check communication

Confirm HART, PROFIBUS PA, FOUNDATION Fieldbus or other required interfaces.

6. Verify the complete order code

Do not rely on FMR50, FMR51 or FMR52 alone. The complete configuration determines the actual instrument supplied.

Final Selection Principle

The most useful way to approach these three model numbers is not to think of them as a simple “low / medium / high” product hierarchy.

Instead:

FMR50 → Important for existing installations and replacement identification; currently listed as no longer available, with FMR60B identified as successor.

FMR51 → Demanding liquid level measurement, including applications where low dielectric properties are an important selection factor.

FMR52 → Applications where PTFE resistance and/or hygienic requirements are important selection considerations.

For an existing installation, always verify the original order code before purchasing a replacement.

For a new application, start with the process conditions and then select the appropriate Micropilot configuration.

This approach helps engineers, system integrators and procurement teams avoid selecting a radar level transmitter based solely on the model name and instead match the instrument to the actual measurement requirements.

Related Keywords: Endress+Hauser FMR50, Endress+Hauser FMR51, Endress+Hauser FMR52, FMR50 replacement, FMR60B successor, Micropilot FMR51, FMR51 vs FMR52, radar level transmitter, free-space radar, liquid level measurement

Contact us for competitive pricing on E+H items by providing the complete model number, for example:

FMR43 FMR43-AABADFNX1X2JGFC+TC

FMR20B FMR20B-AABADTBMVCGVEEB

FMR10B FMR10B-AAAADTBMWDGWEEB

FMR30B FMR30B-AABAKHBMXQ0VEE3

FMR67 FMR67B-AABAFBCJGPEBESJD1+EH

FMR62 FMR62-NBBCAAGMF5MRK

FMR60 FMR60-AAALAAGAA3XJG

FWR30 FWR30-AA1B1B7B0+PC

FMR20 FMR20-AAABNWDEXR01

FMR10 FMR10-AAQBMWDEWFE2

NMR84 NMR84-IC1BB1C2B1ACABFB1AHJITD

NMR81 NMR81- BC2BA1A2X0ACEACB2AFJNTC+AALAR1R3

FMR67B FMR67B-AABAENAFGAJCRBFD3

FMR66B FMR66B-AABAEDAHBSI1WFEA

FMR62B FMR62B-AABACAAJGNEBEUKB+AA

FMR60B FMR60B-AABAEJAFBSJCRCFA+LA

FMR54 FMR54-AAACCABDD1AJJ+AAEHJALA

FMR52 FMR52-BCACCBBPAGK+AA

FMR51 FMR51-BBACCABCA5AGJ

FMP50 FMP50-BCACCBAAA1GDJ+AAF371,2M

FMP51 FMP51-BAACCABCB3ARJ+AA, 7000MM

FMP52 FMP52-AAACCAOACHK+AAIJZ1 (2050MM)

FMP53 FMP53-AAACCADAB5TDJ L=560 mm

FMP54 FMP54-BCEEBBAED1AHJ+EBEHF4JAJBKEOAPBZ1 (LENGTH:2030MM)

FMP55 FMP55-BAACBACAATK +AAEHF4I7JBJDOEPBZ1 CA=2750MM

FMP56 FMP56-AAAAAALAABGDE

FMP57 FMP57-AAACCAAEA4GGE (2000mm)

FMU40 FMU40-ARB2A2

FMU41 FMU41-1NB2A2

FMU42 FMU42-AVB2A42A

FMU44 FMU44-ATB2A23A

FMU30 FMU30-AAHEAAGGF

FMG50 FMG50-AABADJACA

and so on.....

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