GB1312244A - Liquid level detection apparatus - Google Patents

Abstract

1312244 Liquid level detection SERCK INDUSTRIES Ltd 9 March 1970 [25 March 1969] 15509/69 Heading G1H [Also in Division G3] An apparatus for detecting the level within a container of a relatively dense first liquid 22 submerged in a less dense second liquid 23, comprises a first float 10 (intended to sink in the second liquid) connected to a hollow second float 16 more buoyant than the first, an indicator element 14 attached to the second float so as to project in use above the surface of the second liquid, the indicator element having a bore through which a liquid may be introduced into the second float to reduce the buoyancy so that the apparatus rests in use at a position such that the first float is at or about the interface of the first and second liquids. This apparatus is used in an arrangement controlling discharge of sediment from a settling tank 21 to a further tank 27. The tanks are connected via air operated diaphragm valves 25, 26, and air supplies to the valves are controlled by solenoid valves 33, 32. Indicator 14 carries a washer (19) Fig. 1, (not shown) to actuate a micro-switch (39) to indicate when level of liquid 22 is low and has a magnetic portion which interacts with induction coil 40 of oscillator 41 to operate a relay 42 to open valve 25 to discharge sediment when the level of sediment is at a derived level. Float switch 38 in tank 27 prevents such discharge from tank 21 as would cause overflowing of tank 27.