Improvements relating to apparatus for measuring the properties of liquids, the electrical conductivity of which varies with said properties

摘要

522,488. Determining physical qualities of materials; resistance measurements, compensating instruments for temperature errors. CROCKATT & SONS. Ltd., W., and CROCKATT, W. C. Dec. 13, 1938, No. 36263. [Class 37] A salinometer has a potentiometer or transformer for providing points of predetermined potential difference and a current rectifier interposed between these points and the measuring instrument. A potentiometer 1 has adjustable output tappings 2, 3 which are connected to a full-wave rectifier 15. In the output circuit of the rectifier is a detector cell 4 with electrodes 5, 6 between which flows the liquid under test. In series with this cell are a milliammeter 9 and relays 7, 8 with a temperature compensating shunt resistance 10 controlled by the mercury in a thermometer arranged in a pocket in the supply pipe to the cell 6. The relay 8 closes the circuit of a warning lamp 16 when there is a predetermined degree of impurity, and the relay 7 shortcircuits the milliammeter 9 if the degree of impurity continues to cause an increase of current. In a modification the cell 4 is arranged in the input circuit of the rectifier 15 so that the cell receives alternating current while the milliammeter and relays receive rectified current.