GB1047092A - Apparatus for regulating the flow of a liquid - Google Patents

Abstract

1,047,092. Automatic control. MILES ELECTRONICS Ltd. May 27, 1965 [May 15, 1964], No. 20436/64. Heading G3R. In a system for maintaining a constant level of liquid in a chamber, the liquid forms the dielectric of a capacitor in an AC bridge circuit controlling an on-off valve in a liquid conduit coupled to the chamber. To maintain a constant flow of liquid, e.g. fuel to a burner, a constant level is maintained in a supply tank with the aid of immersed electrodes forming a capacity with the liquid as dielectric. When the level rises so that the electrodes are immersed to a predetermined extent, the increase of capacity balances a high frequency A.C. bridge circuit to operate a thermionic or semi-conductor switch which closes a solenoid-operated valve in the tank supply conduit until the level falls sufficiently. To guard against failure of the valve, a second valve in the supply conduit closes when the level rises and increases the capacity to a value higher than normal. For conducting liquids the electrodes are insulated from the liquid. When the burner is utilized for central or domestic hot water heating, an expansion device responsive to ambient or water temperature is arranged to adjust the vertical position of the electrodes automatically to maintain the temperature constant. Alternatively a temperature responsive resistor may modify the output of the bridge circuit to achieve the same purpose.