Development of HCl and HF Detection System

The Gas Filter Correlation (GFC) technique for detecting HCl and HF has been demonstrated in the laboratory. The basic idea of this technique is that a sample of gas can provide an efficient selective filter for absorbing infrared radiation emitted from a polluted mixture of atmospheric constituents. In optical instrument terms, spectral resolutions of better than 0.1/cm may be achieved. Thus, a high specificity is attained for the detection of a particular pollutant. A laboratory GFC instrument has been developed and applied to detect HCl and HF over a concentration range of 0.1 to 2500 PPM and demonstrated to be insensitive to other possible interfering propellant vapors. The test procedures for conducting the experiments are described. Serious problems were encountered in the sample cell of the instrument namely, wall absorption and chemical reaction effects. These problems will arise in any type of instrument that uses a sample cell or sampling system. Recommendations are made as to how these problems may be eliminated in a properly designed GFC field instrument that does not require a sample cell or sampling system. (Author)