Aqueous chemical leak detection cable

Abstract

Disclosed are aqueous chemical leak detection cables that provide protection to sensor wires by using a conductive polymer coating that is resistant to corrosion by aqueous chemicals. In addition, non-conductive, liquid pervious layers may surround one or more of the sensor wires to assist in preventing false detection of a aqueous chemical leak as a result of various non-liquid contaminants. The non-conductive, liquid pervious layer may comprise braided, non-hygroscopic, non-conductive fibers, or a continuous, non-conductive pervious coating.

What is claimed is: 
     
         1 . A method of making an aqueous chemical leak detection cable for sensing aqueous chemicals comprising:
 forming a base member that is made from non-conductive polymer that is resistant to corrosion by said aqueous chemicals, said base member having two insulating lobes that form two interstices on opposite sides of said insulated lobes, said base member having at least one conductor wire in at least one lobe of said base member;   placing sensor cables in each of said two interstices that have a conductive polymer coating that is resistant to corrosion by said aqueous chemicals, said sensor cables having a sensor wire disposed in each of said sensor cables that is protected from said aqueous chemicals by said conductive polymer coating that is resistant to corrosion by said aqueous chemicals;   surrounding at least one of said sensor cables with a non-conductive, aqueous chemical pervious layer that is resistant to corrosion by said aqueous chemicals and that substantially covers an outer surface of said conductive polymer coating, said non-conductive aqueous chemical pervious layer having openings that allow said aqueous chemicals to pass through said non-conductive, aqueous chemical pervious layer and contact said conductive polymer coating, while preventing non-aqueous conductive substances from contacting said conductive polymer coating;   twisting said base member to alternately expose said sensor cables along a length of said aqueous chemical leak detection cable so that said aqueous chemical leak detection cable is capable of detecting the presence of said aqueous chemicals on a surface when said aqueous chemicals contact said sensor cables and create a conductive path between said sensor cables resulting in said conductive polymer coating on said sensor cables creating a conductive path to said sensor wires.   
     
     
         2 . The method of  claim 1  wherein said process of forming a base member further comprises:
 forming a base member that has at least one conductive wire in each of said two lobes. 
 
     
     
         3 . The method of  claim 1  wherein the process of forming a base member further comprises:
 forming a base member that has more than one conductive wire in each of said two lobes. 
 
     
     
         4 . The method of  claim 1  wherein said process of placing sensor cables in each of said two interstices comprises:
 placing a sensor cable in one of said two interstices that has braided, non-conductive, non-hygroscopic fibers surrounding an outer surface of said conductive polymer coating of sensor cables that allows aqueous chemical liquids to pass through openings between said fibers while preventing non-liquid substances from contacting said conductive polymer coating on said sensor cables. 
 
     
     
         5 . The method of  claim 1  wherein said process of placing sensor cables in each of said two interstices comprises:
 placing a sensor cable in one of said two interstices that has a continuous, non-braided, non-conductive, aqueous chemical porous coating that surrounds an outer surface of said conductive polymer coating of said sensor cable and that is resistant to corrosion by said aqueous chemicals, and that allows aqueous chemical liquids to pass through openings in said porous coating while preventing non-liquid substances from contacting said conductive polymer coating on said sensor cables. 
 
     
     
         6 . The method of  claim 4  wherein said process of placing a sensor cable in said two interstices comprises placing a sensor cable that is surrounded by non-conductive, non-hygroscopic fibers that comprise poly-meta-phenylene isophthalamide.