SIST EN ISO 5814:2013 PDF

Overview

EN ISO 5814:2012 - "Water quality - Determination of dissolved oxygen - Electrochemical probe method" specifies an electrochemical probe technique for measuring dissolved oxygen (DO) in water. The method uses a probe with an electrochemical cell isolated from the sample by a gas‑permeable membrane and reports results in mg/L and/or % saturation. It is applicable for in‑field measurements, continuous monitoring and laboratory analysis of drinking, natural, saline and waste waters.

Key topics and technical requirements

• Measurement principle: Probe (galvanic or polarographic) reduces oxygen at a noble‑metal electrode; resulting current is proportional to oxygen partial pressure through the membrane.
• Sensor types: Examples given include galvanic (e.g., lead/silver) and polarographic (e.g., silver/gold) probes; built‑in temperature compensation is required because temperature affects membrane permeability and electrode reactions.
• Measurement range: Designed for 1% to 100% saturation; most instruments can read above 100% (supersaturation). Special handling is required to measure supersaturated samples without outgassing.
• Calibration: A calibration procedure using water‑saturated air is specified (edition change vs previous methods). Routine checks: daily calibration at air saturation and after significant ambient changes (temperature/pressure).
• Sampling and handling: Prefer in‑situ measurement. If sampling is needed, use gas‑tight, laminar transfer (dip sampling, water‑displacing submersible pumps, flow‑through cells). Avoid air bubbles and turbulence to prevent oxygen exchange.
• Interferences and maintenance: Gases (chlorine, H2S, bromine, iodine, amines, ammonia) and substances (solvents, oils, sulfides, biofilms) can diffuse through or foul the membrane and affect readings. Ensure membrane integrity, adequate polarization time and follow manufacturer maintenance.
• Compensation requirements: Correct for temperature, atmospheric pressure, and - for saline waters (sea/estuarine) - salinity.

Applications and users

EN ISO 5814:2012 is widely used for:

• Field and continuous monitoring of rivers, lakes, estuaries and coastal waters
• Wastewater treatment process monitoring and control
• Drinking water and distribution system checks
• Research on oxygen dynamics, eutrophication and algal blooms (including supersaturation events) Primary users:
• Environmental and water quality laboratories
• Water and wastewater treatment operators
• Regulatory agencies and environmental consultants
• Researchers conducting aquatic monitoring and process control

Related standards

• ISO 5813 - iodometric (Winkler) method for dissolved oxygen (reference for samples where electrochemical probes are unsuitable)
• ISO 3696 - water for analytical laboratory use (reagents/grade)
• EN ISO 5814:2012 supersedes EN 25814:1992

Keywords: EN ISO 5814:2012, dissolved oxygen, electrochemical probe, water quality, DO measurement, field monitoring, calibration, salinity correction.