PORTABLE DETECTOR FOR MIXED HYDRAZINES PROPELLANT FUEL VAPORS AT LOW CONCENTRATION.

Paradimethylaminobenzaldehyde DMABA was examined as a color forming agent for the colorimetric determination of mixed hydrazines propellant fuel vapor in air. Contaminated air was drawn through a filter paper disc which had been moistened with DMABA solution. The reaction between the fuel vapor and the indicator produced a yellow color. Air was drawn through the indicator until the yellow color matched an arbitrarily selected standard yellow color. The volume of air required to produce the standard color was related to the concentration of fuel vapor in the air over the range of 0.5 to 10 ppm. Several gases which might be found in the air at least occasionally were examined for interference with the fuel vapor test. Ammonia at 50 ppm did not interfere, but higher concentrations either decreased the indicator sensitivity or completely inhibited color formation. Sulfur dioxide at 500 ppm did not interfere with the test higher concentrations did interfere. Carbon dioxide at concentrations up to 50,000 ppm 5 did not affect the test. Chlorine at 2 and 5 ppm reduced the sensitivity of the test indicator. Fifty ppm and higher concentrations of chlorine formed brown or green colors with the indicator, thus interfering with the fuel vapor test. Author