Abstract:
A leak detector includes a fabric having a conductor. The fabric has an electric property between the conductor and a reference. The electric property has a first value in response to the fabric being in a non-wetted state with regard to a working fluid and the electrical property has a second value different than the first value in response to the fabric being in a wetted state with regard to the working fluid.

Description:
BACKGROUND 
       [0001]    This disclosure relates to improvements in leakage detection. 
         [0002]    General usage leak detectors are known and used to detect leakage of relatively low temperature fluids in a system, such as water. A typical leak detection system utilizes an electric capacitor on the exterior of a pipe within the system. Water that leaks from the pipe contacts the capacitor, changing the capacitance and indicating a leak. 
       SUMMARY 
       [0003]    A leak detector according to an exemplary aspect of the present disclosure includes a fabric including a conductor, the fabric having an electric property between the conductor and a reference, the electric property having a first value in response to the fabric being in a non-wetted state with regard to a working fluid and the electrical property having a second value different than the first value in response to the fabric being in a wetted state with regard to the working fluid. 
         [0004]    In a further non-limiting embodiment of the foregoing example, the working fluid is a high temperature working fluid. 
         [0005]    In a further non-limiting embodiment of any of the foregoing examples, the fabric is selected based on the high temperature working fluid. 
         [0006]    In a further non-limiting embodiment of any of the foregoing examples, the working fluid is molten salt. 
         [0007]    In a further non-limiting embodiment of any of the foregoing examples, the fabric is adjacent a conduit. 
         [0008]    In a further non-limiting embodiment of any of the foregoing examples, the conduit contains the working fluid. 
         [0009]    In a further non-limiting embodiment of any of the foregoing examples, the reference is a second conductor of the fabric. 
         [0010]    In a further non-limiting embodiment of any of the foregoing examples, the reference is ground. 
         [0011]    In a further non-limiting embodiment of any of the foregoing examples, the reference is a conduit. 
         [0012]    A leak detection system according to an exemplary aspect of the present disclosure includes a conduit for carrying a working fluid, and a detector on the outside of the conduit, the detector including a fabric with a conductor having an electrical property that changes responsive to contact with the working fluid. 
         [0013]    In a further non-limiting embodiment of the foregoing example, the fabric is a sleeve configured to fit on the outside of the conduit, the sleeve extending around a central axis and between axial ends and an inner surface and an outer surface relative to the central axis. The conductor has a portion that is embedded within the fabric between the inner surface and the outer surface. 
         [0014]    In a further non-limiting embodiment of any of the foregoing examples, the sleeve includes at least one groove on at least one of the outer surface or the inner surface. 
         [0015]    In a further non-limiting embodiment of any of the foregoing examples, the at least one groove is elongated and extends along a longitudinal axis that is perpendicular to a longitudinal axis defined by the sleeve. 
         [0016]    A leak detector according to an exemplary aspect of the present disclosure includes a porous sleeve configured to fit on the outside of a conduit, the porous sleeve extending around a central axis and between axial ends and an inner surface and an outer surface relative to the central axis, and an electrical circuit having at least a portion that is carried by the porous sleeve, the electrical circuit having an electrical property that changes responsive to contact with a leaked fluid. 
         [0017]    In a further non-limiting embodiment of the foregoing example, the electrical circuit includes a controller configured to activate an indicator in response to change in the electrical property. 
         [0018]    In a further non-limiting embodiment of any of the foregoing examples, the porous sleeve is a fabric. 
         [0019]    In a further non-limiting embodiment of any of the foregoing examples, the electrical circuit includes a portion that is dissolvable in the leaked fluid. 
         [0020]    In a further non-limiting embodiment of any of the foregoing examples, the electrical circuit is open when free of any contact with the leaked fluid. 
         [0021]    In a further non-limiting embodiment of any of the foregoing examples, the electrical circuit is closed when free of any contact with the leaked fluid. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The various features and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. 
           [0023]      FIG. 1  shows an example leak detection system. 
           [0024]      FIG. 2  shows a modified leak detection system having an electrical circuit that is normally closed. 
           [0025]      FIG. 3  shows a cross-section through a conduit and portion of a leak detector. 
           [0026]      FIG. 4  shows an example of a sleeve of a leak detector having a groove on an outer surface. 
           [0027]      FIG. 5  shows another example sleeve of a leak detector having a groove on an inner surface. 
           [0028]      FIG. 6  shows another example of a sleeve of a leak detector having multiple grooves that run parallel to electrical leads. 
           [0029]      FIG. 7  shows an example of a porous sleeve of a leak detector. 
           [0030]      FIG. 8  shows another example of a leak detector in which a conduit serves an electrical lead. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]      FIG. 1  illustrates an example leak detection system  20  including a leak detector  22 . In this example, the leak detection system  20  is adapted for a system that carries a relatively high temperature fluid, such as molten salt in a concentrated solar power plant. It is to be understood, however, that some or all of the embodiments disclosed herein can be also used in other systems or systems that utilize lower or higher temperature fluids. Other examples are the use of the leak detection system  20  for in-situ medical devices to detect leaking body fluids after surgery. 
         [0032]    In the illustrated example, the leak detection system  20  includes a conduit  24  that carries a working fluid. The working fluid can be a molten salt, such as potassium nitrite salt, sodium nitrite salt, fluoride salt or a mixture of salts. The leak detector  22  is mounted on the outside of the conduit  24  and has an electrical property that changes in response to contact with the working fluid. Thus, the change in the electrical property indicates a leak of the working fluid from the conduit  24 . In this regard, the leak detector  22  can be located on a portion of the conduit  24  where leaked working fluid is likely to flow to. For instance, the leak detector  22  can be located at a vertically low portion on the conduit  24  such that any leaked working fluid gravitationally flows downward and over the leak detector  22 . 
         [0033]    In the illustrated example, the leak detector  22  includes an electrical circuit  26  that has a conductor, first electrical lead  26   a,  and a reference conductor, second electrical lead  26   b.  The electrical leads  26   a / 26   b  are connected to a controller  28 . For example, the controller  28  can include an indicator  30 , such as a visual indicator, audible indicator, etc., control logic, a power source or other additional features for controlling the operation of the leak detector  22 . 
         [0034]    The electrical leads  26   a / 26   b  are carried on a fabric  32  that is configured in this example as a sleeve to fit on the outside of the conduit  24 . As an example, the fabric  32  includes fibers  32   a  that are arranged in a fiber network and pores  32   b  extending between the fibers  32   b . The fibers  32   a  can be natural, organic fibers, synthetic polymer fibers or other fibers suitable for the intended use. That is, the fabric  32  is selected based on the type and temperature of the working fluid. The fiber network is a woven structure, for example. The fabric  32  sleeve has an inner diameter corresponding to the diameter of the conduit  24  to enable the fabric  32  to be slid over the conduit  24 . 
         [0035]    In this example, the fabric  32  sleeve is cylindrical and extends around a central axis A between axial ends  34   a / 34   b  and an outer surface  36   a  and an inner surface  36   b.  As can be appreciated, the electrical leads  26   a / 26   b  can be attached on the outer surface  36   a  of the fabric  32 , attached on the inner surface  36   b  of the fabric  32  or embedded within the fabric  32  between the outer surface  36   a  and the inner surface  36   b.    
         [0036]    In this example, the electrical circuit  26  is open when free of any contact with the working fluid. Leaked working fluid from the conduit  24  flows into the fabric  32  and bridges the electrical leads  26   a / 26   b  to complete the circuit. In the completed circuit, electrical current can flow between the electrical leads  26   a / 26   b  and change the state of an electrical property of the leaked detector  22 , to indicate a leak. 
         [0037]    Alternatively, as shown in  FIG. 2 , a modified electrical circuit  26 ′ is closed when free of any contact with the working fluid. In this example, the electrical circuit  26 ′ includes a portion  26   c  that changes electrical properties when in contact with the working fluid. Thus, when there is no leak, current flows between the electrical leads  26   a / 26   b  through the portion  26   c.  However, upon leakage of the working fluid from the conduit  24 , the leaked working fluid dissolves or changes the electrical properties of the portion  26   c  to change the state of the electrical circuit  26 ′. The change from one state to the other state indicates a leak. 
         [0038]      FIG. 3  illustrates a cross-section showing a further example in which there is a layer of thermal insulation  40  between the conduit  24  and the leak detector  22 . In this example, the fabric  32  is mounted on the outside of the layer of thermal insulation  40 . Specifically, in systems such as concentrated solar power plants that carry working fluid at temperatures typically in excess of 500° F./260° C., the conduit  24  includes the layer of thermal insulation  40  to reduce thermal losses. 
         [0039]      FIG. 4  illustrates another example fabric  132  that can be used in the leak detector  22 . In this disclosure, like reference numerals designate like elements where appropriate and reference numerals with the addition of one-hundred or multiples thereof designate modified elements that are understood to incorporate the same features and benefits of the corresponding elements. In this example, the fabric  132  includes at least one groove  150  on the outer surface  36   a  thereof. The groove  150  is generally larger than the pores between the fabric fibers. The groove  150  facilitates directing any leaked working fluid into contact with the electrical leads  26   a / 26   b.  For example, any leaked working fluid flowing over the sleeve  132  is caught within the groove  150  and thereby directed into contact with the electrical leads  26   a / 26   b.  The groove  150  thus enhances leak detection where the fluid or molten salt might not otherwise contact the leads  26   a / 26   b.    
         [0040]      FIG. 5  shows another example sleeve  232  having a groove  250  on the inner surface  36   b  thereof. The groove  250  operates similar to the groove  150  described above. 
         [0041]      FIG. 6  illustrates a further example of a fabric  332  that includes multiple grooves  350  on the outer surface  36   a.  It is to be understood, however, that the grooves  350  may alternatively may be on the inner surface  36   b.  Although only two grooves  350  are shown, additional grooves may be used. In this example, the grooves  350  are elongated in a direction that is generally parallel to the central axis A of the fabric  332  sleeve. The electrical leads  26   a / 26   b  generally extend in a direction parallel to axis A′, which is perpendicular to the central axis A. Orienting the grooves  350  to be perpendicular to the electrical leads  26   a / 26   b  facilitates directing any of the leaked working fluid into contact with the electrical leads  26   a / 26   b.    
         [0042]      FIG. 7  illustrates another example fabric  432 , or porous sleeve in this example, that can be used in the leak detector  22 . In this example, the electrical leads  26   a / 26   b  (only electrical lead  26   a  shown) are embedded within the fabric  432  between the inner surface  34   b  and the outer surface  34   a.  The fabric  432  includes pores  460  through which any leaked working fluid can flow to contact and bridge the electrical leads  26   a / 26   b.  The size of the pores  460  in the fabric  432  can be tailored to the viscosity of the working fluid, to provide a wicking action that facilitates leakage detection. Further, the fabric  432  protects the electrical leads  26   a / 26   b  from outside damage. 
         [0043]      FIG. 8  illustrates another example in which the conduit  24  serves as an electrical lead in place of the electrical lead  26   b.  The conduit  24  is grounded at G such that any leaked working fluid from the conduit  24  bridges the fabric  532  to complete the circuit between the electrical lead  26   a ′ and the conduit  24 , which thus serves as the reference. 
         [0044]    Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments. 
         [0045]    The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.