ASTM D5464-25 PDF

Full title and description

Standard Test Method for pH Measurement of Water of Low Conductivity — ASTM D5464-25. This procedure specifies a static (grab-sample) technique, electrodes, and sample-handling practices to determine pH in water of low conductivity while minimizing contamination from atmospheric CO₂ and loss of volatile sample components.

Abstract

ASTM D5464-25 provides a laboratory test method for measuring the pH of low-conductivity waters (nominally 2 μS/cm to 100 μS/cm) over the pH range 3 to 11. It emphasizes special sample containers and measurement techniques to avoid atmospheric contamination and volatile losses, and describes electrode and apparatus considerations and temperature-compensation needs for accurate pH readings when an on-line flowing measurement is not practicable.

General information

• Status: Active.
• Publication date: Edition D5464‑25 — last updated January 20, 2025.
• Publisher: ASTM International.
• ICS / categories: 13.060.50 (Examination of water for chemical substances).
• Edition / version: D5464‑25 (current active edition; earlier editions include D5464‑16, D5464‑11, D5464‑07, etc.).
• Number of pages: 10.

Scope

This test method applies to pH measurement of water samples with conductivity from 2.0 μS/cm up to 100 μS/cm and a pH range of approximately 3 to 11. It is intended for static (grab-sample) laboratory determinations where on-line, real-time measurement (see Test Method D5128) is not practical; the method reduces atmospheric CO₂ uptake and prevents loss of volatile trace components while addressing electrode and reference-junction considerations and temperature compensation.

Key topics and requirements

• Applicability: low-conductivity waters (2 μS/cm to 100 μS/cm) and pH 3–11.
• Sample handling: use of sealed/sample-protecting containers to limit CO₂ absorption and volatile losses.
• Electrodes and reference system: guidance on pH electrodes and liquid-junction/reference arrangements appropriate for unbuffered, high‑purity waters.
• Temperature compensation: compensation and measurement close to sample stream temperature to reduce solution temperature coefficient errors.
• Limitations and interferences: static grab sampling is more prone to contamination and time/temperature effects than on-line flowing methods; Test Method D5128 is preferred when a real-time flowing sample can be obtained.

Typical use and users

Common users include power-plant water chemistry laboratories, steam-cycle and condenser monitoring teams, high‑purity/pure‑water treatment facilities, contract testing laboratories, and manufacturers of pH instrumentation and electrodes. The method is often applied to condensed steam samples, boiler/power generation low‑conductivity streams, and intermediate streams in ultrapure water systems where on-line sampling is impractical.

Related standards

Closely related ASTM methods include Test Method D5128 (preferred on-line, flowing-sample pH measurement), Test Method D6569 (on‑line measurements for waters ≥100 μS/cm), and Test Method D1293 (laboratory pH for waters ≥100 μS/cm). International pH determination standards such as ISO/EN pH determination (for broader water categories) may also be used as complementary references depending on application.

Keywords

pH measurement, low conductivity water, high‑purity water, grab sample, sealed sample container, pH electrode, reference electrode, liquid junction, temperature compensation, power plant water chemistry.

FAQ

Q: What is this standard?

A: ASTM D5464‑25 is a standardized test method that specifies procedures for measuring the pH of water with low electrical conductivity using static (grab) samples and specialized sampling/measurement techniques to reduce contamination and volatile loss.

Q: What does it cover?

A: It covers pH measurement for waters with conductivity between about 2 μS/cm and 100 μS/cm across a pH range of roughly 3 to 11, including requirements for sample containers, electrodes, reference systems, and temperature-compensation practices.

Q: Who typically uses it?

A: Water‑chemistry laboratories in power generation, ultrapure/pure‑water treatment facilities, contract test labs, and pH instrument/electrode manufacturers and calibrators commonly use this method.

Q: Is it current or superseded?

A: As published, D5464‑25 is the current active edition (last updated January 20, 2025). Earlier editions (for traceability) include D5464‑16, D5464‑11, D5464‑07, etc.

Q: Is it part of a series?

A: D5464 is part of the ASTM D19 committee activity on water and environmental test methods; it references and is used together with related ASTM test methods (D5128, D6569, D1293) and with international pH-determination standards where applicable.

Q: What are the key keywords?

A: pH, low conductivity, high‑purity water, grab sample, sealed container, electrode, reference junction, temperature compensation.