File:Bell telephone magazine (1922) (14752979581).jpg

Identifier: belltelephonevol3132mag00amerrich (find matches)
Title: Bell telephone magazine
Year: 1922 (1920s)
Authors: American Telephone and Telegraph Company American Telephone and Telegraph Company. Information Dept
Subjects: Telephone
Publisher: (New York, American Telephone and Telegraph Co., etc.)
Contributing Library: Prelinger Library
Digitizing Sponsor: Internet Archive

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high-grade preventive mainte-nance treatment. Some years ago, a very successfulmeasure was developed. These ca-bles are filled with dry nitrogen gasheld at a pressure of 6 to 10 pounds,pumped up, in effect, just as we pumpup a tire on our car. Pressure-sensi-tive switches are provided at variouspoints along the cable run and,should a sheath break develop, thedrop in gas pressure will close aswitch to give an alarm at some cen-tral point, thus drawing the attentionof maintenance people to the failure.In addition, the gradual escape ofgas through a small break will pre-vent moisture from entering the ca-ble to interfere with service, untilrepairs can be made. Although this system is the bestso far devised for maintaining cableplant in good condition, it is toocostly for general use on the distribu-tion cables serving customers. Morerecently, a trial continuous flow gaspressure system was installed on thedistribution cables at Caldwell, New 1952-53 FDidbig Troubles Before They Happen 213
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Digging down to telephone wires, to free the))i from their unaccustomed bnrde)i of snow, is an unusual form of preventive mainte)ia)ice Jersey. At the central office, an aircompressor and dehydrator supplydry compressed air at 6 to 9 poundspressure to the cables leaving thebuilding. Before entering the cables,this air is passed through gas flowmeters similar to those which measurethe gas used for cooking, so thatmaintenance people can tell how muchair is entering each cable. Althoughall ends of the cable have been sealedwith air-tight plugs, some air is al-ways flowing into the cables becauseof minute leaks, and a normal weeklyconsumption through the meter foreach cable was established. Centraloffice men, keeping an eye on themeters each week for excessive airflow, can readily observe when abreak occurs in a cable, and can dis-patch a cable repairman to fix it be- fore service is affected. And againwe have the advantage that, in mostsheath breaks, escaping air will pre-vent moisture f

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