CORROSION RATE METER

1357573 Electro-chemical analysis-corrosion rate BETZ LABORATORIES Inc 5 Oct 1971 [21 June 1971] 46205/71 Heading G1N In a three-electrode corrosion rate meter the corrosion potential between the test electrode 10 and reference electrode 12 is initially stored in a capacitor 38. Then switch contacts 22, 28, 32 are actuated to connect a small polarizing potential (about 10 m.v.) from potentiometer 34 in series with the stored corrosion potential in capacitor 38 as an input to operational amplifier 20 to energize the auxillary electrode 14. The resulting current is proportional to the corrosion and the ammeter 24 may be calibrated in corrosion units. A recorder may be connected across resistor 26. Several minor variations of this circuit are illustrated in Figs. 2..5, (not shown). In the simplest Fig. 3, (not shown) the corrosion voltage amplifier 18 and the potentiometer 34 are omitted, the polarizing voltage being provided by off-set bias in amplifier 20. Fig. 6, (not shown) illustrates a power supply and switch-actuating timer-motor.