Information on the Gastech Model RI-411, infrared CO2 indicator (letter to the editor).
Huebener-DJ; Gorman-RW; Holcom-B
Appl Ind Hyg 1989 Jan; 4(1):F6-F8
Information on a problem discovered in the use of the Gastech Model R1-411, Infrared CO2 Indicator for evaluations of indoor air quality was provided. The approximate time constant and magnitude of the drift effect seen when the instrument was taken into a high carbon- dioxide (124389) (CO2) area were determined. Evaluation showed a problem exists in the instrument due to a dead air space between the infrared source and the active/reference cell. Changes in the concentration of CO2 in this space during a measurement caused the reading to change. Movement of the instrument from one area to another to measure CO2 levels may cause the data to be inaccurate. Possible fixes were investigated: pumping zero air into the dead air space; and pumping sample air into the dead air space. Although either fix will improve the precision, neither fix was entirely satisfactory. In a reply from the maker of the unit, possible modifications to the unit and alternative instruments for use in measuring CO2 for indoor air quality evaluations were discussed.
NIOSH-Author; Air-sampling-equipment; Air-quality-monitoring; Testing-equipment; Indoor-air-pollution; Analytical-instruments; Air-samplers; Air-quality-measurement; Indoor-environmental-quality
Applied Industrial Hygiene