FMR51 Radar Tank Gauge

FMR51 Radar Tank Gauge

The FMR51 Radar Tank Gauge (RTG), with an accuracy rate of ±2 mm and ideally suited for inventory control applications, is used for continuous, non-contact level measurement in bulk liquid storage tanks.

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  • Specifications
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Accurately Measure Your Inventory

The FMR51 RTG uses 26 GHz band microwaves to measure liquids to an accuracy of ± 2 mm (0.08″). Changing process conditions inside your tank, such as temperature changes, gas blankets, pressures or vapors, have negligible effect on radar measurement.



Touch Screen Operations

Easy onsite operation using built-in touch control display without having to open the enclosure. A remote display is also available so that you can read and operate the gauge from the tank side.



Simple Device-to-Device Configuration

When setting up your system, the HistoROM module can be used to quickly transfer configuration settings from one gauge to the next. It can also be used to access historic data from device integrated memory.



Worldwide Approvals

Each radar gauge is approved for use in explosion hazardous areas to ATEX, FM, CSA, TIIS and IECEx standards. They are also SIL 2 and SIL 3 rated for overfill prevention.


Key Features

  • 2-wire technology: Reduces on tank wiring costs and allows easy implementation into existing systems.
  • Non-contact measurement: Tank top is almost independent from product properties.
  • Small horn antenna 1½” to 4″ (40-100 mm) is ideally suited for small vessels.
  • Standard range to 131 ft (40 m). Extended range to 230 ft (70 m) using Advanced Dynamics.
  • Easy onsite operation using built-in touch control display without opening enclosure (or optional push button display with cover removed).
  • Access historic data from device integrated memory (HistoROM) and transfer configuration setting from device to device.
  • Easy commissioning and diagnostics using Windows® based software.
  • HART, PROFIBUS PA or FOUNDATION Fieldbus protocols.
  • High temperatures: Suitable for process temperatures from -321 °F (-196 °C), up to 842 °F (450 °C) with high-temperature
  • High pressure: Suitable for pressures up to 2320 PSI (160 bar).
  • Approved for use in explosive hazardous locations.
  • Integrated over voltage protection.
  • SIL 2 approved for overspill protection system applications or SIL 3 for standalone applications.
  • Optional remote display (FHX50).
Maximum Measured Error

Standard Range Digital: ± 2 mm (0.08″) plus ±0.02 % of analog value
Extended Range Digital: ± 3 mm (0.12″) plus ±0.02 % of analog value

Power Consumption

min. 60 mW, max. 900 mW

Current Consumption

HART: 3.6 to 22 mA
PROFIBUS PA: max. 14 mA
FOUNDATION Fieldbus: max. 15 mA


4 – 8 kg (9 – 18 lb) plus antenna


IP 66, NEMA 4X
(IP20, NEMA 1 with open housing)
Housing GT18: 316L, stainless steel
Housing GT19: plastic
Housing GT20: aluminium, seawater repellent, powder coated


IP 68 (NEMA 6P)

Conduit Entries

Cable gland: M20x1,5 (for EEx d: cable entry)
Cable entry: G ½ or ½ NPT
Fieldbus Foundation M12 or 7/8″ plug

Ambient Temperature

Unit: -40 °F and +176 °F (-40 °C and +80 °C)
Display: -4 °F and +158 °F (-20 °C and +70 °C)

Operating Frequency

K-band 26 GHz, Up to 8 devices can be installed in the same tank

Dielectric Constants

– er 1.9 in free-field applications
– er 1.4 in stilling well

See specifications document for more information.

Approvals & Certifications


Antenna & Seals

1½”, 3″, or 4″ (40 mm, 80 mm or 100 mm) Encapsulated PVDF or PP cladded horn antennas

Process Connections

1½” thread
Optional mounting bracket with slip-on (DN80, DN100 or
DN150) flange

Output Options

HART, PROFIBUS, and Foundation Fieldbus

Gland Entry

Metric, NPT, G


Over 20 national languages available


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Application Checklists

Radar Tank Gauging Checklist
Checklist for Radar Tank Gauging needs.
Temperature Tank Gauging Checklist
Checklist for Temperature Tank Gauging needs.


Advanced Tank Gauging
High Accuracy Inventory Management and Custody Transfer Applications
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Integrate Field Instruments and Software for Complete Asset Management


FMR51 Radar Tank Gauge Manual
Please visit the Endress and Hauser website to access the parts and accessories information for the FMR51 Radar Gauge.
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