. The Bell System technical journal . Fig. 15—-Vacuum driers. cable, while the latter single tank is used for drying submarine cables oflong lengths. The drying ovens are arranged so that the loading end is located inthe cable room proper, and the unloading end in the dehumidifiedcable storage room (Fig. 17). To prevent the exfiltration of dry airfrom the storage room through joints between oven and brick wall anovel type of seal is used. This consists of a flexible sheet of copper,to allow for tank expansion, fastened and gasketed on the inner cir- 8 For further discussion and detailed factor
. The Bell System technical journal . Fig. 15—-Vacuum driers. cable, while the latter single tank is used for drying submarine cables oflong lengths. The drying ovens are arranged so that the loading end is located inthe cable room proper, and the unloading end in the dehumidifiedcable storage room (Fig. 17). To prevent the exfiltration of dry airfrom the storage room through joints between oven and brick wall anovel type of seal is used. This consists of a flexible sheet of copper,to allow for tank expansion, fastened and gasketed on the inner cir- 8 For further discussion and detailed factory layout of this system, see paper byJ. C. Hanley, Mech. Engg., March, 1931. LEAD-COVERED PAPER-INSULATED TELEPHONE CABLE 447 cumference to the tank, and on the outer circumference to the brickwall of the storage oven. Auxiliary equipment used with the vacuum drying ovens consistsof two welded vacuum lines (twelve inches in diameter) vacuumpumps, condensers and receiver tanks. A general view can be obtainedfrom Fig. 16,. Fig. 16—^Auxiliary equipment for vacuum driers. One vacuum line is used to establish vacuum in a new tank load ofcables, and the second is used for maintaining vacuum in the tanksonce they have reached the proper point. The pump equipmentconsists of four reciprocating feather valve vacuum pumps. Thepistons on these pumps have a diameter of twenty-nine inches and astroke of eighteen inches or a displacement of ten hundred and twentyfive The pumping capacity has been based on maintainingabsolute pressures of one-half to one inch in the vacuum values are based on a vacuum tank activity of eighty-five percent and on maximum leakage of approximately twenty pounds of airinto each tank through the door gaskets. Two two hundred and twenty five surface condensers areincorporated in the layout ahead of the pumps to condense moisturegiven off by the insulated paper. Three thousand pounds of watermay be extracted in twenty-four hours. New feat
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