Method and apparatus for controlling the liquid level in a tank.

摘要

1. A process for monitoring the level of liquid contained in a tank using the variation in dependence on temperature in the resistance of a resistive element which has a high temperature coefficient and which is immersed in the liquid, the level of which is to be measured, comprising passing a reference current pulse of predetermined strength lo and duration which are sufficiently low as to cause only negligible heating of the element and measuring the initial voltage Vo produced at the terminals of the element by the reference current lo , characterized by then : - passing into the element a measurement current lo corr whose constant strength is dependent on said voltage Vo such that the difference between the voltage generated at the terminals of the element by the current lo corr at each moment and said voltage Vo is substantially independent of said voltage Vo , and - determining the level of liquid from the comparison between the final voltage Vm generated at the terminals of the element by the current lo corr at a given time tm and the initial voltage values Vo or V'o generated at the terminals of the element upon the respective establishment of the reference current lo or the measurement current lo corr.