ASTM D5391

ASTM D5391 is a test method for measuring the electrical conductivity and resistivity of a flowing high purity water sample. It provides a standardized way to evaluate key water-quality indicators that are often used to judge cleanliness, ionic contamination, and system performance. For operations where water purity is critical, this standard helps support consistent testing, comparison of results, and more reliable quality control. ASTM D5391 is especially useful when a flowing sample must be assessed under controlled laboratory or process conditions.

Overview of ASTM D5391

The ASTM D5391 standard focuses on the electrical conductivity and resistivity of flowing high purity water, two properties commonly used to indicate the presence of dissolved ionic material. As a test method, it helps define a consistent approach for measuring water that is expected to be very low in impurities. This makes the standard relevant wherever high purity water quality must be monitored with precision. ASTM D5391 supports repeatable testing and helps users compare results across equipment, locations, or operating conditions.

Common use cases of ASTM D5391

This standard is commonly used in settings where high purity water must be checked during production, treatment, or distribution. It is relevant for testing flowing water samples in laboratory systems, process water loops, and other controlled environments where conductivity and resistivity are important indicators. ASTM D5391 may also support routine verification, troubleshooting, and acceptance testing when water quality needs to be documented with a recognized method. Its value is strongest when accurate, repeatable measurement is needed for low-conductivity water.

Benefits of using ASTM D5391

Using ASTM D5391 helps promote consistency in measuring high purity water properties that can affect product quality, system reliability, and compliance documentation. A recognized test method can simplify procurement decisions, support internal quality control, and reduce ambiguity when comparing test results. It also helps organizations communicate using a common technical reference for conductivity and resistivity measurements. For users working with sensitive water systems, ASTM D5391 provides a practical basis for reliable evaluation and monitoring.

• Measures conductivity and resistivity of flowing high purity water
• Supports repeatable, standardized testing
• Useful for quality control and verification
• Helps document low-ionic water conditions
• Applies to controlled process and laboratory samples