Accession Number : AD0458550


Title :   ACCUMULATION OF MOISTURE IN A PLASTIC SHEATHED CABLE,


Corporate Author : BELL TELEPHONE LABS INC MURRAY HILL NJ


Personal Author(s) : Hladik, W M


Report Date : Jan 1964


Pagination or Media Count : 14


Abstract : Information from the field has indicated the presence of water in some plastic insulated cables having alpeth sheath (single polyethylene jacket over aluminum tape). Although water trouble is generally due to simple causes such as holes in the sheath, the entry of water through the polyethylene jacket in the form of water vapor has been considered as a possible explanation for some time. Accumulation of water by way of a permeation-condensation cycle requires a nonreversible action which has been the subject of much speculation. This paper describes a simple experiment which shows that water may be ''pumped'' by permeation in combination with temperature cycling and thus made to accumulate inside a space enclosed with intact polyethylene. A plausible explanation of the phenomenon has been developed. Calculations bracket the results of laboratory measurements on thin-wall sealed bags and on samples of actual cable. Quantities in the range of 1 gram of water per foot of cable per 30 years may accumulate with a daily temperature cycle of =1 C around 21 C and with an external relative humidity of 100%. (Author)


Descriptors :   MOISTURE , PERMEABILITY , CONDENSATION , WATER VAPOR , WATER , UNDERGROUND , TEMPERATURE , EXPERIMENTAL DATA , POLYETHYLENE PLASTICS , BAGS


Distribution Statement : APPROVED FOR PUBLIC RELEASE