Gas-phase measurement of oil-like vapor in SF/sub 6/ using FTIR

Fourier transform infrared spectroscopy (FTIR) can be a useful tool for the precise determination of the concentration of oil-like contaminants in SF/sub 6/. The presence of oil vapor in SF/sub 6/ has detrimental effects on its dielectric strength. Thus the study of the critical concentration responsible for dielectric breakdown becomes important. For that matter, we have carried out experiments using ethyl benzene (C/sub 8/H/sub 10/) as a contaminating agent in SF/sub 6/. The absorbance was recorded as a function of the measured vapor pressure in the frequency range where the stretching mode could be observed. Calibration curves of the oil concentration estimated from reference IR intensities were obtained within the pressure range 0.5