An evaluation of a cross section ionization detector suitable for mine air analysis

Abstract

Describes the detection of the permanent gases in mine air using the cross section ionization detection system. A dual chamber ionization cross section detector, with a tritium source, was designed and the results of analysis compared with the results obtained from an argon detector, with an 90Sr source, in its cross section mode of operation. The performance characteristics of both the detectors suggest that the ionization cross section method is precise and reliable and capable of detecting a minute quantity of the test gas in the parts per million range or less. The performance characteristics have been compared with those of other reported designs, but using carbon dioxide as the test gas instead of propane. The performance was measured by the exponential decay method of calibration and the construction of a dilution chamber containing a magnetically driven stirrer is described. It is suggested that a series or parallel column method of a balanced pair cross section detector system would reduce the random noise level and improve its performance characteristics still further.