Endress+Hauser FMU41 Modules

Technical Dossier

Product Details And Specifications

Endress+Hauser FMU41 Series: Comprehensive Module Range and Technical Overview

The Endress+Hauser FMU41 (Micropilot M) is a pulse radar level transmitter engineered for continuous, non-contact level measurement of liquids, pastes, and bulk solids. Deployed across global heavy industry — including petrochemical refineries, nuclear auxiliary systems, offshore platforms, and large-scale chemical processing plants — the FMU41 series holds a significant installed base in applications where process reliability and measurement accuracy under harsh conditions are non-negotiable. Its 5.8 GHz pulse radar technology enables reliable measurement independent of vapor, dust, temperature fluctuations, and pressure variations, making it a standard reference instrument in DCS-integrated process environments worldwide.

The Evolution of FMU41 Architecture

The FMU41 belongs to Endress+Hauser's Micropilot M generation, introduced in the early 2000s as a successor to earlier TDR (Time Domain Reflectometry) and ultrasonic level instruments. Operating at 5.8 GHz with a pulse radar principle, the FMU41 offered a significant leap in measurement reliability over its ultrasonic predecessors (FMU40, FMU42 series) by eliminating sensitivity to acoustic interference and condensation.

The FMU41 architecture is built around a two-wire 4–20 mA HART loop-powered design, enabling direct integration into existing DCS and PLC infrastructure without additional power supplies. Early variants (circa 2003–2008) featured basic HART 5 communication; later firmware revisions introduced HART 7 compatibility, enabling advanced diagnostics and remote configuration via FieldCare or DeviceCare software. The series also offered PROFIBUS PA and Foundation Fieldbus variants, broadening its integration scope in digital process bus architectures.

As the FMU41 series has entered its mature/end-of-active-production lifecycle, Endress+Hauser has positioned the Micropilot FMR5x series (FMR51, FMR52, FMR54, FMR56, FMR57) as the modern replacement platform. However, the FMU41 remains in active service at thousands of installations globally, and long-term spare parts and repair support remain critical for plant operators committed to lifecycle extension strategies.

FMU41 Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly sourced configurations within the Endress+Hauser FMU41 Micropilot M series. Units are classified by antenna type, process connection, housing, and output configuration:

FMU41-ARB2A2: 5.8 GHz pulse radar, PVDF drop antenna, 4–20 mA/HART, polycarbonate housing, G1½ process connection — standard liquid level measurement in chemical tanks.
FMU41-ARB2A2A: Variant of ARB2A2 with extended temperature approval, suited for elevated ambient conditions.
FMU41-AGB2A2: 5.8 GHz pulse radar, PTFE rod antenna, 4–20 mA/HART, aluminum housing, G1½ — general-purpose liquid and slurry applications.
FMU41-ARB2B2: PVDF drop antenna, 4–20 mA/HART output, stainless steel housing, G1½ — corrosive media and washdown environments.
FMU41-ARB2C2: PVDF drop antenna, PROFIBUS PA output, polycarbonate housing — digital fieldbus integration in PA segment architectures.
FMU41-ARB2D2: PVDF drop antenna, Foundation Fieldbus (FF) output, polycarbonate housing — FF-based DCS integration.
FMU41-AGB2B2: PTFE rod antenna, 4–20 mA/HART, stainless steel housing — robust construction for aggressive process environments.
FMU41-AGB2C2: PTFE rod antenna, PROFIBUS PA, aluminum housing — PA fieldbus variant for bulk liquid measurement.
FMU41-ARB2A2/EX: ATEX-certified explosion-proof variant, Zone 1/Zone 2 rated, 4–20 mA/HART — hazardous area liquid level in refineries and chemical plants.
FMU41-ARB2B2/EX: ATEX Zone 1/2, stainless steel housing, HART output — Ex-rated variant for corrosive and flammable media.
FMU41-AGB2A2/EX: ATEX-certified, PTFE rod antenna, aluminum housing — Ex-rated general-purpose radar for Zone 1 classified areas.
FMU41-ARB2C2/EX: ATEX Zone 1/2, PROFIBUS PA, PVDF antenna — Ex-rated PA fieldbus transmitter for hazardous liquid service.
FMU41-ARB2D2/EX: ATEX Zone 1/2, Foundation Fieldbus, PVDF antenna — Ex-rated FF transmitter for DCS-integrated hazardous areas.
FMU41-AGB2B2/EX: ATEX-certified, PTFE rod antenna, stainless steel housing, HART — Ex-rated robust variant for aggressive and flammable process media.
FMU41-AGB2C2/EX: ATEX Zone 1/2, PROFIBUS PA, aluminum housing, PTFE antenna — Ex-rated PA fieldbus for bulk chemical and refinery service.
FMU41-ARB2A2/FM: FM/CSA-approved variant for North American hazardous locations, Class I Div 1/2, 4–20 mA/HART — NEC-compliant installation in US/Canadian refineries and chemical facilities.

Sourcing Hard-to-Find & Obsolete FMU41 Parts

The FMU41 series is classified as a mature product line by Endress+Hauser, with active production of certain configurations discontinued or subject to extended lead times. For plant operators running DCS environments built around FMU41 instrumentation, sourcing replacement units, spare electronics modules, and antenna assemblies through standard distribution channels is increasingly difficult.

DriveKNMS maintains a dedicated inventory program for FMU41 series instruments, including pulled-from-service units, refurbished transmitters, and new-old-stock (NOS) configurations. Our sourcing network covers HART, PROFIBUS PA, Foundation Fieldbus, and ATEX/FM-rated variants. For plants requiring lifecycle extension beyond the manufacturer's active support window, DriveKNMS provides a documented supply chain with full traceability, enabling continued operation without forced migration to newer platforms.

Customers operating in petrochemical, nuclear auxiliary, water treatment, and bulk chemical sectors have relied on DriveKNMS for FMU41 continuity sourcing across multiple plant turnaround cycles.

Quality Control for the FMU41 Range

The FMU41 transmitter integrates a radar front-end module, signal processing electronics, and a HART/PA/FF communication stack within a compact housing. Quality verification for sourced or refurbished FMU41 units at DriveKNMS follows a structured protocol:

Each unit undergoes loop calibration verification across the full 4–20 mA output range. HART communication integrity is confirmed using a HART communicator (275/375/475 series) or FieldCare software, verifying device identity, tag, and measured value transmission. For PROFIBUS PA variants, segment coupler connectivity and GSD file compatibility are validated. Antenna condition — including PVDF drop antenna integrity and PTFE rod antenna surface condition — is inspected for chemical attack, mechanical damage, or deposition buildup that would affect beam angle and signal return. Housing seal integrity (IP67/IP68 rating) is verified by inspection of O-ring condition and cable entry sealing. Firmware version is documented and cross-referenced against known compatibility matrices for the target DCS platform. All test results are recorded and supplied with the unit upon shipment.