Copolymer Sheath in Instrumentation Cables

[HIRENRP]

Dear Friends,

Pls explain if any one knows what is adavantage of providing copolymer sheath in Instrumentation Cables below inner sheath.

Especially for cable conductor having foamed PE insulation e.g. foundation fieldbus cables, what important role is played by copolymer sheath.

What is the construction of copolymer sheath.

Thanks in advance..

[amshah]

if i am not wrong is is a Moisture Barrier :

"A layer of aluminium tape coated with PE-copolymer on one or both sides is applied longitudinally with overlap over the cable core to provide 100% electrical shielding coverage and ensure a barrier against water vapor"