MEASUREMENT OF OXYGEN PARTIAL-PRESSURE USING FULLY-SEALED ZIRCONIA PUMP GAUGE DEVICES OPERATED IN THE TRACKING MODE .2.

The instrument incorporated a miniature oxygen sensor operated in an a .c. mode. Signal processing of the periodic gauge e.m.f. enabled deter mination of the oxygen partial pressures both within the enclosed volu me of the sensor (P0) and in the surrounding sample gas (P1). The devi ce was operated in a closed loop in order to control P0. The mean gaug e e.m.f. was maintained equal to zero resulting in a well-defined rela tion between P0 and P1. P1 was then computed from a measurement of the amplitude of the gauge e.m.f., determined using simple circuity. Furt hermore, theory indicated that linearity of the output should be maint ained at high values of the amplitude of the gauge e.m.f. resulting in high signal-to-noise ratio: this was confirmed for peak-to-peak value s up to 50 mV.