GB497282A - Improvements in and relating to vacuum producing apparatus for paper making machinesor the like - Google Patents

Abstract

497,282. Suction boxes for paper-making machines. POIRIER, E. June 15, 1937, No. 16639. Convention date, May 6. [Class 96] For extracting water from a travelling web in paper-making machines or the like, the web runs in water extracting relationship over a vacuum box 2 with which communicates a vacuum casing 6 into which water extracted by the box is delivered, and a drop leg 7, divided into a plurality of sections so arranged that the number of such sections utilized at any time to carry away water from the casing automatically changes in accordance with changes in the volume of water disclosed, leads downwardly from the vacuum casing to a well 8 with adjustable weir 10 and outflow 12. Usually several boxes are arranged side by side each connected by a pipe 4, containing valve 5, to the vacuum casing 6. In the Figure, the drop leg is shown divided into three sections a, b, c, by baffles 14, two inch pipes leading from sections a, b and a four inch pipe from section c. A small flow of water runs almost exclusively through pipe a, a larger flow overflowing the first baffle and being led away by pipes a and b while pipe c is only used when the water in the casing is sufficient to overflow both baffles. To provide a higher vacuum when required, e.g. when starting up a line 15 from an external source of suction, e.g. suction pipe 16 running to the couch roll leads into casing 6. A spring operated valve may be provided in this pipe to open when the pressure in the casing 6 rises above a predetermined point. The lip d of pipe 15 is upturned so as always to be above the water level. In a modification, the pipe 15 may be left open and projecting into the bottom of pipe 4. Normally this pipe will be submerged in water and its diameter being small, it will merely carry off a small volume of water. When the flow of water is small however and the pressure is tending to rise, the pipe 15 will carry off a relatively large amount of air and hence reduce the pressure. The tip of the pipe 15 may be disposed at any desired level. An adjustable spring controlled valve 20 open to the air is provided in a pipe leading into the box at a point remote from the pipe 4, but inside the baffles 3 provided for adjusting the effective width of the box. This valve prevents the vacuum in the box rising to too high a degree.