Gas Generation Systems for the Evaluation of Gas Detecting Devices

摘要

This report summarizes work concerned with the development of gas generation systems for use in verifying the performance of gas detection devices or for the calibration of gas analysis instrumentation. The systems were designed to provide mixtures of a number of different gases and vapors in air at concentrations representing fixed proportions of the threshold limit value. Furthermore, they furnish a sufficient volume of gas to allow continuous testing of devices while maintaining a predetermined concentration level. The substances for which gas generation systems were developed are: carbon dioxide, carbon monoxide, ozone, sulfur dioxide, hydrogen sulfide, nitrogen dioxide, benzene, carbon tetrachloride, trichloroethylene, ammonia, and chlorine. The systems are of 4 basic types: direct delivery from cylinders of known concentration. Dynamic blending of high concentrations with air, permeation tubes, and generation of the substance directly in an air stream. Monitoring systems are suggested to allow confirmation of the quantities generated. Details of construction are given.