GB744453A - Automatic air volume control for a liquid supply system - Google Patents

Abstract

744,453. Regulating liquid levels KRACHT PUMPEN-UND MOTORENFABRIK GES. Dec. 11, 1953 [Dec. 15, 1952] No. 34525/53. Class 123(1) In a low or medium pressure liquid supply system wherein the liquid, for example, oil or water, is stored under pressure in a tank 2 to which it is supplied by a pump controlled by means responsive to the variations in pressure of the air cushion 6 trapped above the liquid surface, apparatus is provided which serves automatically to replenish the air cushion which, in service, tends to decrease in volume over a period of time. In one form, Fig. 1, the apparatus consists of an auxiliary tank 1 the upper and lower portions of which are respectively connected by pipes 18, 13, to the air and liquid spaces of tank 2. In tank 1 is axially disposed a vertical rod 4 carrying a float 3 at a point on the rod corresponding to the level 5 in tank 2 whichis defined by an air cushion of the correct volume, the rod being formed at its lower end as a valve member 7 which, at the lowest position of the rod, closes a drain valve 8. The liquid flow in pipe 13 is controlled by a valve 9 mounted on a bell crank lever 11 the longer arm of which engages in a slot 10 in the rod 4. Near its lower end, the rod 4 has an annular recess 22 which can be engaged by a pawl 16 when the rod is in its uppermost position, the pawl forming the end of one arm of a second bell crank lever the other arm of which supports a float 15. Pipe 18 has a non-return valve 17 through which air flows from tank 1 to tank 2, whilst tank 1 has an air inlet provided with a non-return valve 24. In service, when the volume of air cushion 6 decreases, the liquid level in tanks 1, 2 exceeds the normal level 5 and rod 4 is raised by float 3 thus closing valve -9 and opening valve 8, the pawl 16 retaining the rod in its raised position whilst the liquid in tank 1 drains off through pipe 12, air being sucked into the tank through valve 24. When the float 15 is no longer supported by the liquid, rod 4 is released, valve 8 is closed and valve 9 opened, allowing liquid to enter from tank 2. The air in tank 1 is compressed until it has sufficient pressure to pass through valve 17 to replenish the air volume in tank 2, the cycle being repeated until the normal volume of the air cushion has been restored. In a modification, rod 4 is retained in its uppermost position magnetically whilst in further modifications tank 2 is provided with an external level gauge inwhich is disposed a pipe whose open upper end terminates at level 5, the lower end of the pipe being connected to a regulator device operating in the manner described -above.