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BELL SYSTEM TECHNICAL JOURNAL 



length of eleven hundred and twenty feet of pipe. This type of coil 

 not only makes a much neater appearance in the heating system due to 

 its rigidity, but also insures positive draining, with the elimination of 

 steam hammer, and also more uniform heating in all portions of the 

 tank. The tanks are completely welded instead of riveted. This 

 method of assembly insures a better average vacuum as well as elimi- 

 nating considerable maintenance work in caulking rivets, which 

 become loosened by the repeated expansion and contractions of the 

 drier. 



Cable Storage Prior to Lead Covering 

 The air conditioned room (Fig. 17) is provided for the storage of cable 

 prior to lead sheathing in order to facilitate the covering of varying 



Fig. 17 — Air conditioned cable storage room. 



diameters of cable with a minimum of lead-press die-block changes, 

 and also to act as a reservoir for the fluctuating delivery of large 

 quantities of vacuum-treated cable. An alternative, that of storing 

 cable in the vacuum driers until ready for lead covering would require 

 an excessive investment in vacuum drying tanks and their operation. 

 The storage room, from which the cable is paid out directly to the 

 presses, is approximately 270 ft. long, 50 ft. wide and 12 ft. high, 

 and has been designed to prevent infiltration of moisture. Without 

 moisture proofing, the outside wet air would penetrate a concrete or 

 brick wall since the vapor pressure in the storage room is only approxi- 

 mately .007 in. Hg as compared to 1.02 inch outside the room on a hot 

 humid day. The moisture proofing was accomplished as follows: An 

 aluminum foil was placed over the inner surface of the outer portion of 

 the brick wall. This foil was suitably protected by a layer of saturated 

 rag felt and roofers asphalt. The remainder of the brick wall was 



