Overview
EN ISO 20456:2019 (ISO 20456:2017) provides guidance for the measurement of fluid flow in closed conduits using electromagnetic flowmeters for conductive liquids. It applies to industrial full‑bore meters driven by either alternating current (AC) or pulsed direct current (DC) excitation and covers instruments powered from mains, batteries or other sources. This is a guidance standard (not a safety standard) and does not apply to insertion‑type meters, partially filled/open‑channel systems, magnetically permeable slurries or liquid metals.
Key topics and technical requirements
- Scope and limitations: Clear definition of applicable meter types and excluded applications (insertion meters, open channels, slurries, liquid metals).
- Theory and symbols: Fundamental electromagnetic measurement principles and basic formulae used for volumetric flow calculation.
- Sensor and transmitter construction: Design considerations for sensors (liner and electrode materials) and transmitters (signal processing for AC and pulsed DC excitation).
- Installation practice: Sizing, mounting conditions, electrical connections, potential equalization, flange dimensions and recommended lay lengths to ensure accurate readings.
- Operational influences: Effects of liquid conductivity, Reynolds number and velocity profile on measurement performance.
- Calibration, verification and performance: Guidance on flowmeter calibration, in‑situ electronic verification, performance evaluation and uncertainty analysis.
- Informative annexes: Practical guidance on materials, AC/DC excitation considerations, cathodic protection and conversion tables.
Practical applications and users
EN ISO 20456:2019 is intended for professionals involved in specifying, installing, commissioning and maintaining electromagnetic flowmeters in industries handling conductive liquids, including:
- Water and wastewater treatment
- Chemical and process plants
- Food & beverage and pharmaceutical production (where full‑bore conductive liquid lines are used)
- Utilities and industrial process control
Typical users include plant engineers, instrumentation designers, flowmeter manufacturers, calibration laboratories and metrology/testing organizations seeking consistent best practices for flow measurement accuracy, verification and uncertainty estimation.
Benefits and SEO keywords
Using EN ISO 20456:2019 helps ensure reliable flow measurement with electromagnetic flowmeters, improves installation design, and supports traceable flowmeter calibration and performance evaluation. Relevant keywords: electromagnetic flowmeter, EN ISO 20456:2019, ISO 20456:2017, conductive liquids, closed conduits, flow measurement, AC excitation, pulsed DC, calibration, installation practice.
Related standards
- Supersedes: EN 29104 and EN ISO 6817 (earlier editions cited in the document).
- Developed by ISO/TC 30 (Measurement of fluid flow in closed conduits) - consult national standards bodies for national adoption and implementation details.