ASTM B117-26a: Residual Chlorine Update

When ASTM D1193 added a residual chlorine limit to its reagent-water requirements, some laboratories questioned whether that limit introduced a new wrinkle to the ASTM B117 practice. ASTM B117 has long required laboratories to measure and control the pH of the collected salt solution without specifying a separate residual chlorine measurement. The latest ASTM B117 update formally resolves the question raised by the D1193 change.

Why the D1193 change raised a question

ASTM B117 references ASTM D1193 Type IV reagent water for preparing its sodium chloride solution. Section 8.1 already allowed the D1193 limits for sodium and chloride to be ignored for that preparation.

D1193’s 2024 revision introduced a residual chlorine limit that had not appeared in earlier editions. B117’s existing exceptions did not name residual chlorine, leaving laboratories to determine how the new requirement applied to their salt spray procedures.

What ASTM B117-26a changes

Published as B117-26a, the revision adds residual chlorine to the exceptions in Section 8.1.

For salt-solution preparation under Section 8.1, the D1193 limits for sodium, chloride, and residual chlorine may now be ignored.

This makes the treatment of residual chlorine explicit. Laboratories preparing solution under Section 8.1 do not need to introduce a separate residual chlorine measurement to demonstrate compliance with the D1193 limit.

The requirement to use Type IV water, subject to the stated exceptions, remains in place. The exception applies to salt-solution preparation under Section 8.1; it should not be read as a blanket exception for every use of water in the practice.

pH requirements and the established exposure controls remain in place. The other principal exposure conditions also remain unchanged.

Working with ASTM B117 in the laboratory

Auto Technology Company actively participates in ASTM standards development. We work with the committees and with the labs and manufacturers who rely on these practices every day, and we’re happy to discuss how changes like these affect real-world testing and interpretation.

The latest ASTM B117 practice is available from ASTM International.