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

摘要

698,237. Automatic control systems. CROCKATT & SONS, Ltd., W., and CROCKATT, W. C. Oct. 20, 1950 [Oct. 19, 1949], No. 26815/49. Class 38 (iv). [Also in Group XXXVI] Apparatus for maintaining the water in a boiler tank 47 below a certain impurity level comprises a relay 17 in series with an electrode cell 5 containing a sample of the feed water, supplied with a constant voltage through a potentiometer 8 and temperature compensating resistance 11, so that when the impurities in the feed water increase to a maximum value the increased current through the relay 17 causes it to operate, thereby energizing a warning lamp 29 and bell 23, also closing a further relay 26 which operates a control valve 32 to modify the supply of feed water through a pipe 45. A second cell 6 measures the conductivity of the water in the boiler 47, and opens a blow-down valve 33 when the maximum degree of impurity is exceeded, the boiler being refilled by pump 49 from the boiler feed tank 46.