GB865505A - Improvements in and relating to level gauging devices - Google Patents

Abstract

865,505. Indicating liquid levels. FEIGENBAUM, H. May 19, 1959, No. 17028/59. Class 123(1) A liquid-level indicating device comprises two electric coils 22, 23 disposed within a casing 1.1 around a vertical through-pipe 15 which slidingly receives, with slight friction, a float rod formed of a part 17 of high permeability magnetic metal or alloy which is secured, e.g. by screwing 19, to a part 18 made of non- magnetic material, e.g. brass. The casing 11, open to the outside and sealed within an opening in a side wall of a container 10 by screws 14, has an internal lining of thermo-plastic insulating material 32 and, as with the pipe 15, is made of non-magnetic material. The coils 22, 23 acting as primary and secondary windings of a transformer, are connected respectively by conductors 24, 25 and 26, 27 to a low voltage source of alternating current 29 and an amplifier relay 30 designed to control a warning, pump, or valve circuit, not shown. When the float rod 17, 18 is raised sufficiently, in response to a rise in the level of liquid 20 in the container 10, the high-permeability part 17 of the rod increases the mutual conductance between the coils 22, 23 and a voltage of corresponding magnitude is induced in the secondary winding 23 to operate the relay 30. The device may be mounted in the lower part, to limit the draining of a container, the parts 17, 18 of the rod in this case being made respectively of non-magnetic and magnetic material. Alternatively the float 20 and its rod 17, 18 as shown could be arranged above the casing 11. In the case of a container having a moving cover the casing 11 is provided with a chimney which carries the electric wires 24- 27 and passes in a liquid-tight manner through the cover. When a moving roof can act as a float the lower end of the rod 17, 18 rests upon the upper face of the roof. The chimney may pass through a stuffing box in the cover and be graduated to enable the height of the casing 11 in the container to be adjusted as required. The casing may contain three windings, one primary and two secondaries, preferably arranged in opposition to actuate a differential relay.