Patent GB-923236-A (GB)
Title: Improvements in or relating to devices for measuring the level of an electrically conductive liquid in a container
IPC: G01F23/24
Filed: 1959-08-11
Abstract: 923,236. Indicating liquid levels. PHILIPS ELECTRICAL INDUSTRIES Ltd. Aug. 11, 1959 [Aug. 14, 1958], No. 27476/59. Class 123 (1). A device, particularly for measuring the level of molten glass 1 in a closed container 2 and which is not influenced by prevailing high temperatures, is light in weight, and compact so as to be mountable on the container 2, comprises a vertical gauge rod 3, which projects down into the casing 2 through an opening in its upper end wall and is connected to the rod 4 of a piston 5 which works in a pneumatic cylinder 6. The cylinder spaces below and above the piston 5 are alternately connectable, through lines 7, 8 respectively and a reversing device 11, to a highpressure source of air. As the gauge rod 3 descends and contacts the molten glass 1 an electric circuit, consisting of a source of direct current 9 and a coil 10, is completed so that a relay 14 is operated to energize a coil 12 and switch over the supply of compressed air to the line 7 leading to the space beneath the piston 5. When the piston 5 attains its highest position the supply of compressed air is again reversed a contact 16 on a member 15 slidable, with little friction supplied by a spring-loaded friction element 34, on the cylinder 6 being pushed down by a stop 17 to complete a circuit through a coil 13 which changes over the reversing device 11. In order to record the liquid level the member 15 is connected to the piston rod 4 through a lostmotion mechanism which comprises a rod 20, which is free to slide through the member 15, is connected to the piston rod 4 by a cross bar 21, and carries lower and upper stop members 22, 25. The latter, after the lost motion has been taken up, carry the member 15 respectively upwardly and downwardly with the piston rod 5 the motion of which is damped by a dash-pot 31, 32. The level of the molten glass, determined by the lowest position of the piston 5, is recorded by a member, not shown, adjusted by a motor 30 which receives a voltage from an an amplifier 29 corresponding to the displacement of a recorder 28. The latter is actuated by one arm of a lever which is rockable about a pivot 27 and whose other arm carries, at its upper end, an inclined edge 26 which co-operates with a projection 33 on the sliding member 33 the degree of displacement being proportional to the downward travel of the member 15. The level is recorded during each time interval which exists between a contact of the rod 3 with the liquid 1 and the take-up between the lower stop member 22 and the sliding member 15. Fingers on the stop members 22, 25 ensure that one or other of two contacts 23, 24, in series with the signals supplied to the motor 30, are open when the sliding member 15 is moving so that the motor 30 is inoperative, the upper contact 24 being held open by a stop member 18 while the member 15 is at rest in its uppermost position and the stop member 25 is descending to make contact with the member 15 and take over the operation of the switch 24. The assembly is surrounded by a heat-insulating jacket 19. Lateral movement of the rod 3 may be limited by stops.