GB/T 6904-2026Determination of pH in water for industrial recirculating cooling systems and boilers (English PDF)

3 Terms and definitions

4 Principle

5 Reagents or materials

6 Apparatus and equipment

7 General requirements

8 Test procedure

9 Reporting of the results

10 Permissible difference

Foreword

This document was issued on 2 July 2026 by the State Administration for Market Regulation and the Standardization Administration of the People's Republic of China, and takes effect on 1 February 2027.

It replaces GB/T 6904-2008, which remains in force until that date.

The document is under the responsibility of the China Petroleum and Chemical Industry Federation.

Classification: ICS 71.040.40, CCS G 76.

3 Classification and status

GB/T 6904-2026 is classified under ICS 71.040.40, in the field of chemical technology. ICS is the International Classification for Standards, the same scheme used by ISO and by the national bodies of most countries, which is what allows a Chinese standard to be placed beside its foreign counterparts on subject rather than on number.

Its Chinese Standard Classification code is CCS G 76. CCS is the domestic scheme, a letter for the sector and two digits for the subject within it, and it is the code by which the standard is filed and searched in China.

The GB/T prefix marks a recommended national standard. It is not, in itself, law: it becomes binding when a contract names it, when a regulation or a mandatory standard refers to it, or when a producer declares conformity with it. In practice that covers most of the cases in which it will be read — a purchase specification, an inspection agreement or a certification scheme.

The document is under the responsibility of the China Petroleum and Chemical Industry Federation, which is the body that maintains it and that will answer a formal question about its interpretation.