ASTM D5391-23 PDF

Overview

ASTM D5391-23 is an international standard published by ASTM International, titled "Standard Test Method for Electrical Conductivity and Resistivity of a Flowing High Purity Water Sample." This method outlines procedures for accurately measuring the electrical conductivity and resistivity of high purity water samples below 10 μS/cm (above 0.1 Mohm-cm). These parameters are vital for monitoring minute levels of ionic contaminants in water, crucial to industries where high purity water is essential. The method specifically requires samples to be flowing, as static grab samples are unsuitable due to potential contamination, ensuring representative results for both continuous and periodic measurement scenarios.

Key Topics

• Measurement Scope: Targets high purity water with very low ionic content; applicable to samples below 10 μS/cm.
• Flowing Sample Requirement: Only applies to flowing samples; static or grab samples cannot provide reliable results at these purities.
• Significance: Conductivity and resistivity measurements are the primary indicators for identifying trace levels of ionic contamination.
• Special Considerations:
  • High temperature coefficients of pure water can reach up to 7% per °C.
  • Extreme care required to prevent trace contamination from sample handling, cell surfaces, and atmospheric exposure.
  • Instrument design and temperature compensation must be validated for high purity conditions.
• Interference Factors:
  • Atmospheric CO₂ can alter results; closed or in-line measurement is essential.
  • Alkaline contamination (e.g., NaOH) at low levels can falsely indicate higher water purity due to ion exchange effects.
  • Leadwire capacitance and cell design can introduce errors if not properly managed.

Applications

This standard offers practical value for monitoring high purity water systems in several key sectors, including:

• Power Generation: Essential for boiler feedwater and cycle chemistry control, ensuring the performance of demineralization processes and detection of ionic contamination which can cause corrosion or scaling.
• Microelectronics: Used to monitor rinse and process water, where even trace ions can impact product yield.
• Pharmaceuticals: Utilized for process water purity validation, helping ensure regulatory compliance.
• Industrial Water Treatment: Assesses demineralized water quality in settings requiring ultra-low ionic content.
• Process Control: Enables real-time, online verification of water purity in critical process lines.
• Reference for Compliance and Quality Control: Supplements other ASTM methods for water quality assessment and aligns with international best practices established through the World Trade Organization Technical Barriers to Trade (TBT) guidelines.

Related Standards

Several other ASTM standards, guides, and practices support or complement ASTM D5391-23 and may be referenced in the context of conductivity and resistivity measurement in water:

• ASTM D1125: Test Methods for Electrical Conductivity and Resistivity of Water
• ASTM D2186: Test Methods for Deposit-Forming Impurities in Steam
• ASTM D4519: Test Method for On-Line Determination of Anions and Carbon Dioxide in High Purity Water
• ASTM D1129: Terminology Relating to Water
• ASTM D1193: Specification for Reagent Water
• ASTM D1066, D1192, D2777, D3370, D3864: Additional guidance on sampling, equipment, precision, and on-line analytical systems for water quality assessment

Keywords: high purity water, electrical conductivity, water resistivity, monitoring ionic contamination, ASTM D5391-23, boiler water quality, power plant cycle chemistry, microelectronics water, pharmaceuticals water testing, continuous water sampling, water temperature compensation, water quality standards.

By adhering to this standard, organizations can ensure reliable, interference-free assessment of water purity, maintain stringent operational requirements, and uphold regulatory and industry quality standards.