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Recently, very good quality papers have appeared: low weight and high density papers. These papers are very good heat transmitters and, therefore, are very sensitive to warm-ups. Heat transfer to the glue is so efficient that crystallization occurs at the very beginning of the double backer, before there is time for the glue to penetrate the liner. Zero section: The zero section is formed by combining the double backer preheater and the first two steam chests of the first Hot Plates Section. The zero section is made independent, becoming a small fourth section of the Double Backer. The zero section is named that way after its location. The greatest advantage of the zero section is that, by regulating very low its pressure (around 1 bar, in any case, below 2 bar), the problem of the glue crystallization is easily avoided. Also, the zero section is a great aid for lowering corrugating temperatures in the direction of ‘cool corrugating’ conditions, permitting important glue and steam consumption reductions. Since only two steam chests of the first Hot Plate Section are “sacrificed”, the Double Backer remains with enough heat transfer capacity for the heaviest qualities. The following sketch shows the creation of a zero section starting from a conventional three sections Double Backer. |
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ZERO SECTION |
