ISA TR92.06.03

Introduction

This report has been written to provide support to the work ofthe ISA92.06 Subcommittee responsible for drafting a performancestandard for chlorine detection instruments. The scope of thestandard is limited to those instruments intended for thedetermination of chlorine gas in air to enhance workplace safety.In Committee discussions two technical questions were raised; thefirst was the feasibility of generating chlorine gas concentrationswith sufficient accuracy and precision necessary for theperformance tests. The second question was whether there was asignificant reaction between chlorine and water in the vapor phasesince the extent of this reaction would impact the validity of theproposed humidity performance test.

The first part of the report discusses issues related to thequestion of the possible interaction of chlorine with water vaporin the gas phase. The latter part of the report discusses thegeneration of chlorine gas.

This report is divided into several sections. The first sectionprovides a brief overview of the chemistry of chlorine and relatedcompounds. This section is intended to provide an outline of thechemical basis for later discussions and to summarize the resultsobtained from literature searches. Since a standard is by necessitybased on the current technology, the available information fromsensor manufacturers is summarized so that a comparison between theproposed specifications and manufacturers’ specifications can bemade. Several instrument tests have been performed by both theNCASI and several manufacturers using both Draeger and CityTechnology chlorine sensors. These tests were aimed at finding theeffect that humidity has on the response of the instrument to anominal chlorine concentration. Lastly, a theoretical approachusing free energy calculations was used to estimate thethermodynamic feasibility of the proposed vapor-phase reactionsbetween chlorine and water.

The second part of the report addresses sources of chlorine testgas and the feasibility of generating chlorine test gas mixtureswith sufficient accuracy and precision necessary to do theperformance testing called for by the standard (ISA-92.06.01-1998).This section also provides information about the analysis ofchlorine test gas mixtures and a short section with some practicalexperimental recommendations for working with chlorine.

Edition:

08

Published:

07/07/2008

ANSI:

ANSI Approved

Number of Pages:

30