GB703712A - Improvements relating to liquid level gauges - Google Patents

Abstract

703,712. Radio-active liquid-level gauges. ANGLO-IRANIAN OIL CO., Ltd., and McLENNAN, K. F. April 10, 1952 [April 20, 1951], No. 9264/51. Class 40 (3) The level of liquid in a tank is determined by means of a radio-active float mounted on a vertical wire inside the tank and an ionization chamber mounted for vertical movement outside the tank and provided with a lead shield over its upper portion facing the radiation source so that when the lower edge of the shield is coincident with the liquid level substantially all rays to the ionization chamber are cut off. As shown, the float 10 containing cobalt 60 is threaded on a wire 11 passing over pulleys 12, 13 so that it moves parallel to the wall of the tank. A collar 17, which may be magnetic so as to grip the bottom of the tank is provided to enable the float to be raised to the top of the tank. Outside the tank an ionization chamber 20, Fig. 2, is fastened to a wire 23 passing over pulleys 24, 25 and is so counterbalanced the chamber tends to rise to the top of the tank. The chamber is formed inside a lead block 27 the front thickness of which is greatly reduced at the point 33. In use, the wire 23 is electrically driven so that the chamber descends, the current in the chamber gradually increasing as it approaches the radioactive material. When it is level with the source the thickened part of the lead chamber housing is inserted in the radiation path so that the chamber current falls sharply. This fall operates a relay which applies a brake 31 to the drive, the position of the chamber being read against a calibrated scale 21. In an alternative arrangement a small slit is provided in the chamber housing so that radiation enters the chamber only when it is opposite the source.