Promag W 400 Electromagnetic Flowmeter

Overview

The Endress+Hauser Promag W 400 is a full-bore electromagnetic flowmeter (also called a magmeter or mag flow) designed specifically for water, wastewater, and general-purpose liquid applications. Operating on Faraday's law of electromagnetic induction, the meter generates a magnetic field across the pipe diameter — as conductive fluid flows through, it generates a measurable voltage proportional to the fluid velocity. With no moving parts, no pressure drop, and no obstruction to flow, electromagnetic meters offer superior long-term reliability compared to orifice plates, turbine meters, or vortex meters in clean and dirty liquid applications.

Heartbeat Technology is E+H's built-in diagnostic and verification system. It continuously monitors sensor health indicators (coil resistance, electrode impedance, liner condition) and transmits status via HART secondary variables, Profibus diagnostic blocks, or IIoT through the Netilion Cloud platform. Heartbeat Verification allows in-situ calibration verification against traceable standards without removing the meter from service — meeting FDA, ISO 9001, and custody transfer re-verification requirements.

The Promag W 400 is available in compact (transmitter on sensor) or remote (transmitter up to 30 m from sensor via cable) configurations. The W designation indicates a hard rubber or PFA liner suitable for water and wastewater applications; the P model uses PFA liner for chemical service, and the H model uses hard rubber for abrasive slurries and mining applications. Nominal diameter range spans DN 25 (1") to DN 2400 (96") — covering everything from chemical dosing lines to large water main metering.

Key Features

• No pressure drop, no moving parts

  Full-bore design with no restriction means zero additional pressure drop compared to orifice-based meters. No mechanical components wear — a properly specified electromagnetic flowmeter can operate for decades without performance degradation, making it the lowest total cost of ownership option for large-diameter liquid metering.
• Heartbeat Technology — in-situ verification

  Heartbeat Verification generates a traceable verification report (PDF) documenting sensor performance against factory calibration values — without removing the meter from service or interrupting production. This satisfies annual verification requirements for custody transfer, pharmaceutical, and food industry installations at fraction of the cost of traditional wet calibration.
• Bidirectional flow with totaliser

  The Promag W measures both forward and reverse flow simultaneously, with independent totalisers for each direction. Backflow detection is essential in water distribution networks and pump recirculation loops. The pulse output and Modbus totalisers allow direct integration with utility billing and water audit systems.
• IP68 — fully submersible

  IP68 (2 m, 168 hours) rated sensor makes the Promag W suitable for permanent installation in flooded pits, below-grade valve chambers, and outdoor locations subject to flooding — without the expensive instrument shelter required by non-submersible alternatives.

Technical Specifications

Typical Applications

• Municipal water distribution: OIML R49 custody transfer metering at district metered areas (DMAs)
• Wastewater treatment: Influent and effluent flow measurement in submersible pit installations
• Food & beverage: CIP flow monitoring; hygienic liner options for direct product contact
• Mining slurry pipelines: Promag H variant with hard rubber liner and tungsten carbide electrodes
• Chemical dosing: Small DN 25–50 installations with remote transmitter in safe area