Abstract
In response to a request from the Joint American Conference of Governmental Industrial Hygienists-American Industrial Hygiene Association Committee on Direct-Reading Gas-Detecting Tube Systems, a study of the precision and accuracy of tubes for the measurement of carbon monoxide at concentrations near the threshold limit value was undertaken. The test concentration was generated by the dilution of a standard carbon monoxide in nitrogen mixture of known concentration with a stream of purified air. The concentration was verified by analysis with an infrared analyzer. A tube type was considered acceptable unless the difference between its mean reading and the true concentration was over 50% and statistically significant and unless its reproducibility was significantly poorer than the population of tubes as a whole. Eight tube models manufactured by four companies were found to be acceptable.