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 an aqueous chemical leak as a result of various non-liquid contaminants. The non-conductive, liquid pervious layer may comprise spirally wrapped or braided, non-hygroscopic, non-conductive monofilament 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 a 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 base member, said base member having at least one conductor wire disposed 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;   wrapping at least one non-conductive, non-hygroscopic monofilament fiber, that is resistant to corrosion by said aqueous chemicals, in a spiral around an outer surface of at least one of said sensor cables to form a non-conductive monofilament outer insulating layer that substantially covers said outer surface of said conductive polymer coating and substantially prevents detection of non-aqueous conductive substances, said non-conductive monofilament outer layer having interstitial openings that allow aqueous chemical liquids to pass through said non-conductive, monofilament outer layer and contact said conductive polymer coating while preventing said non-aqueous conductive substances from contacting said conductive polymer coating on said sensor cables;   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 comprises:
 forming a base member having at least one conductive wire in each of said two lobes. 
 
     
     
         3 . The method of  claim 2  wherein said process of forming a base member comprises:
 forming a base member having more than one conductive wire in each of said two lobes. 
 
     
     
         4 . A method of making an aqueous chemical leak detection cable for sensing aqueous chemicals comprising:
 forming a base member that is made from a 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 base member, said base member having at least one conductor wire disposed 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;   surrounding an outer surface of at least one of said sensor cables with braided, non-conductive, non-hygroscopic monofilament fibers to form a non-conductive, braided fiber outer insulating layer that is resistant to corrosion by said aqueous chemicals and that substantially covers said conductive polymer coating, said non-conductive, braided fiber outer insulating layer having interstitial openings that allow said aqueous chemicals to pass between said braided, non-conductive, non-hygroscopic monofilament fibers, while preventing non-liquid substances from contacting said conductive polymer coating on said sensor cables;   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 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.   
     
     
         5 . The method of  claim 4  wherein said process of forming a base member comprises:
 forming a base member having at least one conductive wire in each of said two lobes. 
 
     
     
         6 . The method of  claim 5  wherein said process of forming a base member comprises:
 forming a base member having more than one conductive wire in each of said two lobes.