Methods and apparatus for locating hidden or buried non-conductive pipes and leaks therefrom

Abstract

Methods and apparatus for locating a hidden or buried non-conductive fluid pipe and leaks therefrom are presented in which a current signal is injected into fluid in a hidden or buried non conductive pipe and the resulting induced magnetic field is detected to determine the location of the pipe and leaks therefrom according to the spatial variation of the intensity of the magnetic field. In one approach, a pulser injects a plurality of individual electrical current pulses directly into water in pipe. The pulsed currents in the pipe can be returned to the pulser by a wire conductor independent from ground. A coil detector senses the magnetic fields created in the water in the pipe. Leak detection can be enhanced by providing a current path through earth ground for leakage current due to water leaks in the water pipe and utilizing a variable resistor to control the amount of current returning to the pulser.

1 . A method for locating a hidden or buried non-conductive fluid pipe, comprising:
 injecting a plurality of individual electrical current signal pulses into fluid in a hidden or buried non-conductive pipe;   detecting a plurality of magnetic field pulses, induced by said plurality of electrical current pulses, and emanating from fluid in said pipe; and   determining the location of said pipe according to the spatial variation of the intensity of said magnetic field pulses.   
     
     
         2 . The method of  claim 1 , wherein injecting a plurality of electrical current pulses into said fluid comprises injecting into said fluid a plurality of electrical current pulses having a predetermined pulse repetition rate and/or predetermined pulse shape. 
     
     
         3 . The method of  claim 1 , wherein injecting into said fluid a plurality of electrical current pulses comprises injecting into said fluid a plurality of electrical current pulses having a predetermined pulse repetition rate of about 1 to 100 Hertz. 
     
     
         4 . The method of  claim 1 , wherein injecting into said fluid a plurality of electrical current pulses comprises injecting into said fluid a plurality of electrical current pulses each having a pulse duration of about 10-500 microseconds. 
     
     
         5 . The method of  claim 1 , further comprising
 wherein injecting said plurality of individual electrical current signal pulses comprises   providing an electrical current signal forward path, independent from earth ground, from a signal terminal of said pulser to fluid in a first end of said pipe,   providing a current signal return path, independent from earth ground, from fluid in a second end of said pipe back to a return terminal of said pulser;   injecting said plurality of individual electrical current signal pulses into said fluid via said current signal forward path; and   returning said plurality of electrical current signals from said fluid to said pulser via said current signal return path.   
     
     
         6 . The method of  claim 5 , wherein providing said current signal return path independent from said earth ground comprises electrically connecting a conductive return wire between said fluid at said pipe second end and said pulser return terminal. 
     
     
         7 . The method of  claim 6 , wherein electrically connecting said conductive wire between said fluid at said pipe second end and said pulser comprises
 connecting one end of a connective wire to said pulser; and   either inserting the other end of said conductive return wire into the fluid inside said second pipe end; or   attaching said conductive return wire to a second conductive member at said pipe second end, said second conductive member being in physical contact with said fluid inside said pipe first end.   
     
     
         8 . The method of  claim 1 , wherein injecting said plurality of electrical current signal pulses into said fluid comprises:
 providing a pulser for applying high voltage pulses;   applying said plurality of high voltage signal pulses from said pulser across said pipe fluid extending between said pipe ends.   
     
     
         9 . The method of  claim 1 , wherein
 wherein injecting said plurality of individual electrical current signal pulses comprises   providing an electrical current signal forward path from said pulser to fluid in first end of said pipe,   providing a current signal return path from fluid in a second end of said pipe back to said pulser; wherein either said forward current signal path or said return current signal path is via earth ground;   injecting said plurality of individual electrical current signal pulses into said fluid via said current signal forward path; and   returning said plurality of electrical current signals from said fluid to said pulser via said current signal return path.   
     
     
         10 . The method of  claim 1  further comprising determining the location of at least one leak from said pipe according to the spatial variation of the intensity of said magnetic field pulses. 
     
     
         11 . The method of  claim 10 , wherein determining the location of at least one leak from said pipe according to the spatial variation of the intensity of said magnetic field pulses comprises:
 adjusting the amount of electrical resistance between earth ground and a return terminal of a pulser for injecting said plurality of individual electrical current pulses in order to control the current exiting the pipe through said at least one leak and returning to said pulser through earth ground; and   determining a location at which the detected magnetic field pulse strength is substantially reduced or becomes undetectable as a result of reducing said current returning to said pulser to thereby determine the location of a fluid leak from said pipe.   
     
     
         12 . The method of  claim 1 , further comprising detecting a hidden or buried conductive fitting or valve, carried on said pipe and in electrical contact with said pipe fluid inside said pipe, according to said detected spatial variation in said magnetic field. 
     
     
         13 . The method of  claim 1 , wherein injecting a plurality of individual electrical current signal pulses into fluid in a hidden or buried non-conductive pipe comprises injecting said plurality of individual electrical current signal pulses into water in said hidden or buried non-conductive pipe. 
     
     
         14 . A method for locating a hidden or buried non-conductive fluid pipe comprising:
 providing an electrical current signal forward path, independent from earth ground, from a power supply to fluid in a first end of a hidden or buried non-conductive pipe,   providing a current signal return path, independent from earth ground, from fluid in a second end of said pipe back to said power supply;   injecting an electrical current into said pipe fluid via said current signal forward path;   returning said electrical current from said fluid to said power supply via said current signal return path;   detecting a magnetic field induced by said electrical current and emanating from fluid in said pipe; and   determining the location of said pipe according to the spatial variation of the intensity of said magnetic field.   
     
     
         15 . The method of  claim 14 , wherein injecting said electrical current into said pipe fluid comprises injecting a plurality of individual electrical current pulses from a pulser to said pipe fluid via said current signal forward path; and
 wherein returning said electrical current from said fluid to said power supply comprises returning said plurality of electrical current pulses from said pipe fluid to said pulser via said current signal return path.   
     
     
         16 . A pipe locator apparatus for locating a hidden or buried non-conductive pipe, said apparatus comprising:
 a pulser for injecting a plurality of individual electrical current signal pulses into fluid in a hidden or buried non-conductive pipe; and   a detector for detecting a plurality of magnetic field pulses, induced by said plurality of electrical current pulses, and emanating from said fluid in said pipe;   whereby, in use, operation of said pulser injects said plurality of electrical current pulses into fluid in said pipe, and whereby movement of said detector over a surface area in the vicinity of said pipe detects said corresponding magnetic field pulses emanating from the pipe fluid, and the spatial variation of the intensities of said magnetic field pulses, to indicate the location of said hidden or buried pipe. and/or the location of a leak in said pipe.   
     
     
         17 . The apparatus of  claim 16 ,
 wherein said pulser is configured to inject into said fluid a plurality of electrical current pulses having a predetermined pulse repetition rate and/or predetermined pulse shape.   
     
     
         18 . The apparatus of  claim 17 , wherein said pulser is configured to inject into said fluid a plurality of electrical current pulses comprises having a predetermined pulse repetition rate of about 1 to 10 Hertz. 
     
     
         19 . The apparatus of  claim 17 , wherein said pulser is configured to inject a plurality of electrical current pulses each having a pulse duration in about the 10 to 500 microsecond range 
     
     
         20 . The apparatus of  claim 16 , further comprising
 an electrical current signal forward path from said pulser to fluid in a first end of said pipe, said electrical current signal forward path being independent from earth ground;   an electrical current signal return path from fluid in a second end of said pipe back to said pulser; said electrical current signal return path being independent from earth ground; and   wherein said pulser is configured to inject said plurality of individual electrical current signal pulses into said fluid via said current signal forward path and return said plurality of electrical current signals from said fluid to said pulser via said current signal return path.   
     
     
         21 . The apparatus of  claim 16  further comprising a variable resistor device operably coupled between said pulser and earth ground for adjusting the amount of electrical resistance between the pulser and earth ground to control the current exiting the pipe through said at least one leak and returning to said pulser through earth ground; whereby, in use,
 adjusting said variable resistor device to reduce the current returning to said pulser results in the detected magnetic field pulse intensities being greatly reduced or becoming undetectable at a location of said at least one fluid leak. 
 
     
     
         22 . The apparatus of  claim 16 , wherein said pulser is a portable battery powered pulser and/or wherein said detector is a battery powered portable detector.