US 5,015,958 A · Elongate sensors comprising conductive polymers, and methods and apparatus using such sensors

Abstract

Detection of events, e.g. liquid leaks and other changes in varibles. The event causes two conductors to become electrically connected, and thus creating a system in which the connection point can be located by measuring the potential drop from one end of one of the conductors (called the locating member) to the connection point. Preferably a fixed current flows through the connection, so that the result is independent of the resistance of the connection. The locating member can be a continuous resistive wire, preferably coated with a conductive polymer; such a locating member can form part of a sensor cable in which the elongate components of the circuit are in a wrapped configuration, or part of a cable in which the conductors are separated by a member shaped to prevent capillary action of a liquid from connecting the conductors. Alternatively the locating member comprises a plurality of discrete resistors. Preferably the system is arranged so that the sensitivity of the system is not dependent on the location of the fault and/or is such that only connections within a certain range of resistance will activate the system. The voltage drop is preferably calculated by comparing it to the voltage drop over a resistor of known size. Particular event-sensitive connection means are preferably employed for the detection of hydrocarbons and for the detection of acids.

Claims28

Dependent claims

An elongate sensor for use in a method for detecting and locating the presence of an electrolyte, the sensor comprising

(1) a first elongate electrical connection means which has a near end and a far end;
(2) a second elongate electrical connection means
(i) which has a near end adjacent the near end of the first connection means and a far end adjacent the far end of the first connection means,
(ii) whose impedance, from the near end to each point thereon, is characteristic of its length from the near end to that point, and
(iii) which is electrically insulated from the first connection means between its near end and its far end in the absence of the electrolyte and which, in the presence of the electrolyte, becomes electrically connected to the first connection means, the connection being effective at a first point whose location is defined by the location of the point or points at which the electrolyte is present;
and
(3) a third elongate electrical connection means which has a near end adjacent the near ends of the first and second connection means and a far end adjacent the far ends of the first and second connection means and which is electrically insulated from said first and second electrical connection means between its near end and its far end in the absence of the electrolyte and in the presence of the electrolyte;
the first, second and third connection means being physically secured together;
at least one of the first and second connection means comprising an elongate metal core which is electrically surrounded by a jacket of a composition which comprises a polymeric component and, dispersed in the polymeric component, a sufficient amount of a particulate conductive filler to render the composition conductive at ambient temperature;
and at least one of said first, second and third connection means having a wrapped configuration.

7 more elements

An elongate sensor for use in a method for detecting and locating the presence of an electrolyte, the sensor comprising

(1) a first elongate electrical connection means which has a near end and a far end;
(2) a second elongate electrical connection means
(i) which has a near end adjacent the near end of the first connection means and a far end adjacent the far end of the first connection means,
(ii) whose impedance, from the near end to each point thereon, is characteristic of its length from the near end to that point, and
(iii) which is electrically insulated from the first connection means between its near end and its far end in the absence of the electrolyte and which, in the presence of the electrolyte, becomes electrically connected to the first connection means, the connection being effective at a first point whose location is defined by the location of the point or points at which the electrolyte is present;
(3) a third elongate electrical connection means which has a near end adjacent the near ends of the first and second connection means and a far end adjacent the far ends of the first and second connection means and which is an insulated wire which is electrically insulated from said first and second electrical connection means between its near end and its far end in the absence of the electrolyte and in the presence of the electrolyte;
and
(4) an overbraid of an insulating material which physically secures the first, second and third connection means together;
each of the first and second connection means comprising an elongate metal core which is electrically surrounded by a jacket of a composition which comprises a polymeric component and, dispersed in the polymeric component, a sufficient amount of a particulate conductive filler to render the composition conductive at ambient temperature;
and
at least one of said first, second and third connection means having a wrapped configuration.

8 more elements

A method for detecting and locating the presence of an electrolyte, which method comprises

(A) providing a system
(a) which comprises
a power source;
a voltage-measuring device;
and
an elongate sensor for detecting and locating the presence of an electrolyte, the sensor comprising
(1) a first elongate electrical connection means which has a near end and a far end;
(2) a second elongate electrical connection means
(i) which has a near end adjacent the near end of the first connection means and a far end adjacent the far end of the first connection means,
(ii) whose impedance, from the near end to each point thereon, is characteristic of its length from the near end to that point, and
(iii) which is electrically insulated from the first connection means between its near end and its far end in the absence of the electrolyte and which, in the presence of the electrolyte, becomes electrically connected to the first connection means, the connection being effective at a first point whose location is defined by the location of the point or points at which the electrolyte is present;
and
(3) a third elongate electrical connection means which has a near end adjacent the near ends of the first and second connection means and a far end adjacent the far ends of the first and second connection means and which is electrically insulated from said first and second electrical connection means between its near end and its far end in the absence of the electrolyte and in the presence of the electrolyte;
the first, second and third connection means being physically secured together;
at least one of the first and second connection means comprising an elongate metal core which is electrically surrounded by a jacket of a composition which comprises a polymeric component and, dispersed in the polymeric component, a sufficient amount of a particulate conductive filler to render the composition conductive at ambient temperature;
and at least one of said first, second and third connection means having a wrapped configuration;
and
(b) in which system, when an electrolyte is present,
electrical connection is made between the first connection means and the second connection means through said conductive polymer composition;
the connection to the second connection means being effective at a first point whose location is defined by the location of the point or points at which the electrolyte is present;
the making of the connection enabling the formation of a test circuit which comprises (i) that part of the second connection means which lies between the first point and a second point at the near end of the second connection means, (ii) the connection, and (iii) the power source, the power source causing an electrical current of known size to be transmitted between the first and second points on the second connection means;
and
the current and the second connection means being such that, by measuring the voltage drop between the first and second points, the spatial relationship between the first and second points can be determined;
(B) monitoring the system continuously or on a schedule to determine when a said connection has been made, said test circuit being in existence while said monitoring is taking place if a said connection has been made;
and
(C) when it is determined that a said connection has been made, using the voltage-measuring device to determine the voltage drop between the first and second points;
and
(D) obtaining the location of the point or points at which the electrolyte is present from the measurement made in step (C).

25 more elements

Apparatus for detecting the presence of an electrolyte which comprises

(A) an elongate sensor for detecting and locating the presence of an electrolyte, the sensor comprising
(1) a first elongate electrical connection means which has a near end and a far end;
(2) a second elongate electrical connection means
(i) which has a near end adjacent the near end of the first connection means and a far end adjacent the far end of the first connection means,
(ii) whose impedance, from the near end to each point thereon, is characteristic of its length from the near end to that point,
(iii) which is electrically insulated from the first connection means between its near end and its far end in the absence of the electrolyte and which, in the presence of the electrolyte, becomes electrically connected to the first connection means, the connection being effective at a first point whose location is defined by the location of the point or points at which the electrolyte is present;
and
(3) a third elongate electrical connection means which has a near end adjacent the near ends of the first and second connection means and a far end adjacent the far ends of the first and second connection means and which is electrically insulated from said first and second electrical connection means between its near end and its far end in the absence of the electrolyte and in the presence of the electrolyte;
the first, second and third connection means being physically secured together;
at least one of the first and second connection means comprising an elongate metal core which is electrically surrounded by a jacket of a composition which comprises a polymeric component and, dispersed in the polymeric component, a sufficient amount of a particulate conductive filler to render the composition conductive at ambient temperature;
and at least one of said first, second and third connection means having a wrapped configuration;
(B) a voltage-measuring device for determining the voltage drop between the first point and a second point which is at the near end of the second connection means;
and
(C) a power source which is electrically connected to the second point on the s means and, in the absence of an electrolyte is not otherwise connected to the second connection means, so that, when the presence of an electrolyte, causes an electrical connection to be made between the first and second connection means, this results in the formation of a test circuit which comprises (a) that part of the second connection means which lies between the first and second points, (b) the connection, and (c) the power source, and in which test circuit a current of known size is transmitted between the first and second points on the second connection means.

11 more elements

A method for detecting and locating the presence of an electrolyte, which method comprises

(A) providing a system
(a) which comprises
a reference impedance which has a known impedance,
a power source, and
an elongate sensor for detecting and locating the presence of an electrolyte, the sensor comprising
(1) a first elongate electrical connection means which has a near end and a far end;
(2) a second elongate electrical connection means
(i) which has a near end adjacent the near end of the first connection means and a far end adjacent the far end of the first connection means,
(ii) whose impedance, from the near end to each point thereon, is characteristic of its length from the near end to that point, and
(iii) which is electrically insulated from the first connection means between its near end and its far end in the absence of the electrolyte and which, in the presence of the electrolyte, becomes electrically connected to the first connection means, the connection being effective at a first point whose location is defined by the location of the point or points at which the electrolyte is present;
and
(3) a third elongate electrical connection means which has a near end adjacent the near ends of the first and second connection means and a far end adjacent the far ends of the first and second connection means and which is electrically insulated from said first and second electrical connection means between its near end and its far end in the absence of the electrolyte and in the presence of the electrolyte;
the first, second and third connection means being physically secured together;
at least one of the first and second connection means comprising an elongate metal core which is electrically surrounded by a jacket of a composition which comprises a polymeric component and, dispersed in the polymeric component, a sufficient amount of a particulate conductive filler to render the composition conductive at ambient temperature;
and at least one of said first, second and third connection means having a wrapped configuration;
and
(b) in which system, when an electrolyte is present, electrical connection is made between the first and second connection means through said conductive polymer composition;
the connection to the second connection means being effective at a first point whose location is defined by the location of the point or points at which the electrolyte is present;
and
the making of the connection resulting in the formation of a test circuit which comprises (i) the reference impedance and (ii) that part of the second member between the first point and a second point at the near end of the second connection means and in which an electrical current is transmitted between the first and second points on the second connection means and has a known relationship with the current through the reference impedance;
and the current, the reference impedance and the second connection means being such that, by obtaining a ratio between a first voltage drop across the reference impedance and a second voltage drop between the first and second points on the second connection means, the spatial relationship between the first and second points can be determined;
(B) monitoring the system to determine when a said connection has been made;
(C) when it is determined that a said connection has been made, obtaining the ratio of the first and second voltage drops;
and
(D) obtaining the location of the point or points at which the electrolyte is present from the ratio in step (C).

22 more elements

Apparatus for detecting and locating the presence of an electrolyte which comprises

(A) an elongate sensor for detecting and locating the presence of an electrolyte, the sensor comprising
(1) a first elongate electrical connection means which has a near end and a far end;
(2) a second elongate electrical connection means
(i) which has a near end adjacent the near end of the first connection means and a far end adjacent the far end of the first connection means,
(ii) whose impedance, from the near end to each point thereon, is characteristic of its length from the near end to that point, and
(iii) which is electrically insulated from the first connection means between its near end and its far end in the absence of the electrolyte and which, in the presence of the electrolyte, becomes electrically connected to the first connection means, the connection being effective at a first point whose location is defined by the location of the point or points at which the electrolyte is present;
and
(3) a third elongate electrical connection means which has a near end adjacent the near ends of the first and second connection means and a far end adjacent the far ends of the first and second connection means and which is electrically insulated from said first and second electrical connection means between its near end and its far end in the absence of the electrolyte and in the presence of the electrolyte;
the first, second and third connection means being physically secured together;
at least one of the first and second connection means comprising an elongate metal core which is electrically surrounded by a jacket of a composition which comprises a polymeric component and, dispersed in the polymeric component, a sufficient amount of a particulate conductive filler to render the composition conductive at ambient temperature;
and at least one of said first, second and third connection means having a wrapped configuration;
and
(B) a reference impedance which has a known impedance and which is connected in series with said second connection means;
(C) a power source which, at least when the presence of an electrolyte causes electrical connection to be made between the first and second connection means, causes a current to be transmitted (i) between the first point and a second point which is at the near end of the second connection means, and (ii) through said reference impedance, the size of the current transmitted through the reference impedance having a known relationship with the current transmitted between the first and second points;
(D) a first voltage-measuring device for determining a first voltage drop across said reference impedance,
(E) a second voltage-measuring device for determining a second voltage drop between the first and second points;
and
(F) a divider which provides a ratio between said first and second voltage drops.

15 more elements

Dependencies are inferred from the claim text.

Elongate sensors comprising conductive polymers, and methods and apparatus using such sensors

Life of this patent

Elongate sensors comprising conductive polymers, and methods and apparatus using such sensors

Life of this patent

Abstract

Claims28