GB1085825A - Improvements in or relating to the measurement of gas dissolved in liquid - Google Patents

Abstract

1.085,825. Determining gases in liquids. FOXBORO-YOXALL Ltd. June 24, 1966 [July 9, 1965], No. 29187/65. Heading B1X. The concentration of a gas dissolved in a liquid is determined by measuring the temperature at which bobbles are formed when the liquid is heated to above the saturation temperature. In a first embodiment (Fig. 1) liquid is circulated between an upper reservoir 2, and a lower chamber 4 containing a heater 5 transmitting a constant quantity of heat to the liquid, by means of the lift imparted in a duct 7 by bubbles rising therethrough and the concentration of gas inferred from the temperature difference between the liquid in the reservoir and in the vicinity of the heater. When the concentration is large, the number of bubbles is greater, the circulation more rapid and the temperature difference smaller. In a second embodiment (Figs. 3 and 4, not shown), a generally similar circulation system comprises a transparent upflow tube (7) and a photocell detector system (7-9) detects the scattering due to bubbles in the tube and controls the heater by means of an amplifier and relay to provide a constant rate of bubble production: the concentration is inferred from the temperature in the vicinity of the heater. In a third embodiment (Fig. 5), a device comprising metallic strips 16, 17 embracing a heat ing element 15 is rigidly attached to support 12. Current is supplied to the element through contacts 14, 18 when the device is immersed in a liquid and some of the bubbles of gas which are released when the liquid is warmed, are entrapped under strip 17 which consequently becomes hotter than strip 16. The device distorts and contacts 14, 18 part, to cut off the current. A thermistor 19 measures the temperature of the bubble interface, from which the gas concentration is inferred.