The Trafag gas density sensor type 8775 was specifically designed for monitoring SF6 insulation gas. The gas density is measured with an oscillating quartz with excellent long-term stability. The constant resonant frequency of a quartz oscillator under vacuum is compared with the resonant frequency of an identical quartz situated in the sample gas. The difference in the resonant frequency is proportional to the density of the sample gas.
The RS485/MODBUS output enables continuous density and temperature measurements. For 100% SF6 gas is the pressure measured as well.