LIQUID LEVEL INDICATING DEVICE

1,154,217. Indicating liquid level. PILKINGTON BROS. Ltd. and J.J. JAGO. Nov.22, 1967 [Nov.25, 1966], No.52988/66. Heading G1H. In a device for indicating the surface height of a liquid such as molten glass, a hollow probe 29 having an inclined lever end, is supplied with air under pressure from a tube 11 through a regulator 31, a restrictor 32, a vessel 33 and a flexible tube 34 and the arrangement is such that as the probe end 37 is moved towards the liquid level L-L, by air pressure, supplied from tube 11 through a regulator 12, restrictor 13, a solenoid valve 14, a vessel 23, and a pipe 24, acting on a spring loaded piston 26, the air pressure in the probe 29 increases, as the probe 29 nears or immersed in the liquid to a pre-determined value to cause a switch 41 to actuate solenoid valves 14, 19. The valve 14 on actuation terminates the air supply to tube 15 and connects tube 15 to an exhaust 16 so that the cylinder 25 begins to exhaust and the spring 27 raises piston to lift probe 29 clear of the liquid surface. The air pressure, when the probe 29 is clear of the liquid surface, escapes to atmosphere and the air pressure in vessel 33 falls to a pre-determined minimum and the switch 41 deenergizes valves 14, 19. The valve 19 when energized, terminates the air supply through tubes 15, 18, restrictor 20 and a vessel 21 to an indicator such as a pressure recorder 22. When switch 41 is again de-energized valves 14, 19 due to the elivation of probe 29 the valve 14 connects the air supply to tube 15 to instigate a further sensing cycle and the valve 19 opens to place the indicator in communication with the cylinder 25. The lower end of the probe 29 may be provided with a number of notches or vertical slids. The probe 29 may alternatively be fixed to obtain an indication of the liquid reaching a predetermined level.