Effect of Uhle Box Variables on Press Fabric Moisture Ratio, 1994 Papermakers Conference Proceedings

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Much discussion has occurred on the subject of the proper air flow, vacuum level and uhle box slot sizes for good felt conditioning, leading to the need for a controlled technical study. Slot size and number, as well as applied vacuum airflow, were varied on a press stand uhle box to determine the effect on press fabric moisture ratio. Fabric permeability and style were also varied to determine the effect on moisture ration. Shower volumes were also varied to determine water removal characteristics. This paper charts the required vacuum airflow and slot dwell times required to achieve various ratios of moisture to felt weight. A statistical analysis was conducted to establish the significance of the variables. The effect of slot number, vacuum airflow, felt permeability and shower water quantity will also be discussed. The results have been compared in a few mill applications and correlate well. This work will be incorporated into an update of TAPPI TIS 0404-27, Air Flow Requirements for Conditioning Press Felts at Suction Pipes.