Abstract
A laboratory method has been developed by which to determine the accuracy of techniques for measurement of airborne pollutant concentrations in diluted diesel exhaust. The method involves dilution of the hot exhaust from a diesel engine operated at various controlled speeds and loads and sampling the exhaust-air mixture in a manner designed to simulate sampling in air surrounding diesel equipment operated in confined spaces such as in an underground mine. The method developed was applied to detector tubes for CO, CO2, NO, N02, and SO2. This included recalibration of the detector tubes with certified gases which had been checked alongside NBS Standard Reference Gases. Detector tube diesel exhaust measurements were compared with simultaneous measurements by portable instruments which earlier tests had indicated were specific for the pollutant of concern. The differences between detector tube and instrument readings were assumed to be made up of detector tube calibration and interference errors. The calibration errors were subtracted from the total error to obtain the interference error. All of the detector tubes tested were found to have significant diesel exhaust interference errors.