Information on High-Purity Water

As a manufacturer of measuring systems (transmitter/controllers and sensors) for resistance/conductivity and pH measurement, we are confronted almost every day with the uncertainty prevailing among customers, end users and project planners when it comes to the proper measurement techniques and equipment for high-purity water.We have written this booklet to provide assistance and information in this field. It is intended to give you a generally understandable background and explanation of the fundamental terminology used in high-purity water measurement, and thus contribute to demystifying the subject. Furthermore, it also presents the procedure that is generally valid (at the time of going to press) for calibrating and testing a high-purity water measuring system, and is currently still firmly based on the American regulations (USP/ASTM).We are concerned to keep this “Information on high-purity water measurement” up to date, and therefore appeal to the readers for feedback and the sharing of knowledge and experience. Any comments or contributions to the discussion will be most welcome.

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Table of contents :
6 Concluding remarks 29……Page 3
7.2 Literature (German) 33……Page 4
Preface……Page 5
1 Basics……Page 6
2 Measuring conductivity……Page 8
2.2 Instrumentation: transmitter/controller……Page 9
2.2.1 Temperature compensation……Page 10
2.2.2 USP contact……Page 12
2.2.3 Ph. Eur. limits……Page 13
2.2.5 Test certificates……Page 14
2.3.1 Cell constant……Page 15
2.3.2 Factory procedure for determination of the cell constant……Page 16
2.3.4 Quality assurance in the manufacture of measuring cells……Page 17
2.5 On-site test options……Page 19
3.2 TOC principle of measurement……Page 20
3.3 TOC in high-purity water in the pharmacopeia: USP and Ph. Eur…….Page 21
4 pH measurement of high-purity water……Page 22
4.1 Instrumentation for pH measurement……Page 24
5 Points to be observed in handling high-purity water……Page 26
6 Concluding remarks……Page 27
7.1.1 ASTM-Standards……Page 28
7.1.2 Pharmacopeia……Page 29
7.1.4 DIN / ISO / EN standards (mostly German)……Page 30
7.2 Literature (German)……Page 31