Abstract:
An insert apparatus for installing a transducer assembly in a sensor port of a flow cell is disclosed. The transducer assembly is installed in the cavity of the insert body without the use of glues or adhesives to bond the transducer assembly to the cavity.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to an insert apparatus for installing a transducer assembly in a sensor port of a flow cell. 
         [0002]    Flow meters, including ultrasonic flow meters, are used to determine the characteristics (e.g., flow rate, pressure, temperature, etc.) of liquids, gases, etc. flowing in conduits of different sizes and shapes. Knowledge of these characteristics of the fluid can enable other physical properties or qualities of the fluid to be determined. For example, in some custody-transfer applications, the flow rate can be used to determine the volume of a fluid (e.g., oil or gas) being transferred from a seller to a buyer through a conduit to determine the costs for the transaction, where the volume is equal to the flow rate multiplied by the cross sectional area of the conduit. 
         [0003]    In one type of ultrasonic flow meter employing transit time flow metering, one or more pairs of ultrasonic transducer assemblies can be installed in sensor ports of a flow cell. Each pair of ultrasonic transducer assemblies can contain transducer assemblies located upstream and downstream from each other forming an ultrasonic path between them at particular chordal locations across the conduit. Each transducer assembly, when energized, transmits an ultrasonic signal (e.g., a sound wave) along an ultrasonic path through the flowing fluid that is received by and detected by the other transducer assembly. The path velocity of the fluid averaged along the ultrasonic path at a particular chordal location can be determined as a function of the differential between (1) the transit time of an ultrasonic signal traveling along the ultrasonic path from the downstream transducer upstream to the upstream transducer against the fluid flow direction, and (2) the transit time of an ultrasonic signal traveling along the ultrasonic path from the upstream transducer downstream to the downstream transducer with the fluid flow direction. 
         [0004]    Transducer assemblies can be installed in sensor ports of flow cells using insert assemblies that are mounted within the sensor ports. Since the transducer assemblies are bonded to the cavity of the insert body using glue or another adhesive, when the transducer assembly fails or must be replaced, the transducer assembly cannot easily be removed from and replaced within the insert assembly. For example, after removal of the transducer assembly, the remaining glue or adhesive will negatively impact the performance of any replacement transducer assembly installed within the insert assembly. Accordingly, the entire or a substantial part of the insert assembly often must be removed in order to replace a transducer assembly. The removal of the insert assembly may require a shutdown of the system that the flow cells are monitoring to remove the fluid and pressure from the flow cell. 
         [0005]    The discussion above is merely provided for a general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0006]    An apparatus for installing a transducer assembly in a sensor port of a flow cell is disclosed. The transducer assembly is installed in the cavity of the insert body without the use of glues or adhesives to bond the transducer assembly to the cavity. An advantage that may be realized in the practice of some of the disclosed embodiments of the sensor port insert apparatus is that a transducer assembly can be more easily replaced in the field without having to remove the fluid and pressure from a flow cell. 
         [0007]    In one embodiment, an apparatus for installing a transducer assembly in a sensor port of a flow cell is disclosed. The apparatus comprises an insert body configured for insertion into the sensor port, the insert body defines a cavity having a opening located at a first end of the insert body and an ultrasonic buffer at a second end of the insert body, a transducer assembly located in the cavity of the insert body, the transducer assembly comprises a housing having a first end, a second end proximate to the ultrasonic buffer opposite of the first end of the housing, and a piezoelectric crystal located in the second end of the housing, a holding nut located in the cavity proximate to the first end of the housing applying a compressive force to the housing to keep the second end of the housing proximate to the ultrasonic buffer, a coupling material in fluid form located in an area between the second end of the housing and the ultrasonic buffer, and a first o-ring located in the cavity proximate to the housing to assist in preventing the leakage of the coupling material from the area between the housing and the ultrasonic buffer. 
         [0008]    In another embodiment, the apparatus comprises an insert body configured for insertion into the sensor port, the insert body defines a cavity having a opening located at a first end of the insert body and an ultrasonic buffer at a second end of the insert body, a transducer assembly located in the cavity of the insert body, the transducer assembly comprises a housing having a first end, a second end having an exterior surface in contact with an interior surface of the ultrasonic buffer opposite of the first end of the housing, and a piezoelectric crystal located proximate to the interior surface of the second end of the housing, and a holding nut located in the cavity proximate to the first end of the housing applying a compressive force to the housing to keep the second end of the housing in contact with the ultrasonic buffer, wherein the exterior surface of the second end of the housing and the interior surface of the ultrasonic buffer are polished to eliminate voids between the exterior surface of the second end of the housing and the interior surface of the ultrasonic buffer when the exterior surface of the second end of the housing is in contact with the interior surface of the buffer. 
         [0009]    This brief description of the invention is intended only to provide a brief overview of subject matter disclosed herein according to one or more illustrative embodiments, and does not serve as a guide to interpreting the claims or to define or limit the scope of the invention, which is defined only by the appended claims. This brief description is provided to introduce an illustrative selection of concepts in a simplified form that are further described below in the detailed description. This brief description is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    So that the manner in which the features of the invention can be understood, a detailed description of the invention may be had by reference to certain embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the drawings illustrate only certain embodiments of this invention and are therefore not to be considered limiting of its scope, for the scope of the invention encompasses other equally effective embodiments. The drawings are not necessarily to scale, emphasis generally being placed upon illustrating the features of certain embodiments of the invention. In the drawings, like numerals are used to indicate like parts throughout the various views. Differences between otherwise like parts may cause to those parts to be indicated with different numerals. Different parts are indicated with different numerals. Thus, for further understanding of the invention, reference can be made to the following detailed description, read in connection with the drawings in which: 
           [0011]      FIG. 1  is a perspective view of an exemplary flow cell assembly; 
           [0012]      FIG. 2  is a cross-section of the exemplary flow cell assembly of  FIG. 1 ; 
           [0013]      FIG. 3  is an exploded view of an exemplary sensor port insert apparatus; 
           [0014]      FIG. 4  is a cross-section of the exemplary sensor port insert apparatus of  FIG. 3 ; 
           [0015]      FIG. 5  is a cross-section of another exemplary sensor port insert apparatus; and 
           [0016]      FIG. 6  is a cross-section of yet another exemplary sensor port insert apparatus. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]      FIG. 1  is a perspective view of an exemplary flow cell assembly  100 .  FIG. 2  is a cross-section of the exemplary flow cell assembly  100  of  FIG. 1 . The exemplary flow cell assembly  100  includes a flow cell  110  having a flow cell bore  112  through which fluid can flow. The flow cell  110  has a plurality of sensor ports  114  in which a sensor port insert apparatus  300  ( FIG. 3 ) is installed. As seen in  FIG. 2 , the sensor port  114  of the exemplary flow cell  110  is shaped so as to receive and place the exemplary sensor port insert apparatus  300  in physical contact with the fluid in the flow cell bore  112  of the flow cell  110 . An ultrasonic signal transmitted from one sensor port insert apparatus  300  travels through the fluid within the flow cell bore  112  and is received by the other sensor port insert apparatus  300 . The plurality of sensor port insert apparatuses  300  are connected to the flow meter  110  to determine the flow rate of the fluid. 
         [0018]      FIG. 3  is an exploded view of an exemplary sensor port insert apparatus  300 .  FIG. 4  is a cross-section of the exemplary sensor port insert apparatus  300  of  FIG. 3  in one configuration. The sensor port insert apparatus  300  is designed to be installed into the sensor ports  114  of the exemplary flow cell  110  of  FIG. 1 . 
         [0019]    In one embodiment, the sensor port insert apparatus  300  includes an insert body  310  configured for insertion into the sensor port  114  of the flow cell  110  ( FIG. 1 ). The insert body  310  can have an external surface that includes threads  319  or concentric grooves designed to dampen acoustic reflections/ring downs in the ultrasonic buffer  318  of the insert body  310 . In one embodiment, the threads  319  of the insert body  310  can be designed to be engaged with an interior threaded surface of a sensor port  114 . One or more o-rings  311  can be installed on the exterior of the insert body  310  to provide a seal between the exterior of the insert body  310  and the sensor port  114 . 
         [0020]    The insert body  310  defines a cavity  316  ( FIG. 4 ) having an opening  315  located at a first end  312  of the insert body  310 . The second end  314  of the insert body includes an ultrasonic buffer  318 . A transducer assembly  330  is located in the cavity  316  of the insert body  310  proximate to the ultrasonic buffer  318  for transmitting and receiving ultrasonic signals that travel through the fluid within the flow cell bore  112 . In one embodiment, the transducer assembly  330  includes a housing  340  having a second end  344  proximate to the ultrasonic buffer  318  and a first end  342  opposite of the second end  340 . In one embodiment, the first end  342  of the housing  340  is proximate to the opening  315  of the cavity  316 . As used herein, where a first component is referred to as being located in another component, it will be understood that only a portion or all of the first component can be located in the other component. The transducer assembly  330  also includes a piezoelectric crystal  332  located in the second end  344  of the housing  340 . The face  333  of the piezoelectric crystal  332  can be installed proximate to the interior surface  348  of the second end  344  of the housing  340 . The exterior surface  346  or face of the second end  344  of the housing  340  is proximate to the ultrasonic buffer  318 . The transducer assembly  330  can transmit and receive ultrasonic signals into and from the fluid to be measured through the ultrasonic buffer  318  of the insert body  310 . 
         [0021]    The first end  342  of the housing  340  can include a back stem  338  for routing a wire  336  from the piezoceramic crystal  332  to a connector  339  (e.g., a BNC connector). In one embodiment, a backing member  334  (e.g., made from epoxy) can be attached to the piezoelectric crystal  332  and located in the housing  340  of the transducer assembly  330 . The wire  336  can extend from the piezoelectric crystal  332  through the backing member  334  to the back stem  338  of the transducer assembly  330 . 
         [0022]    Referring again to  FIGS. 3 and 4 , the transducer assembly  330  can be held in place by a transducer holding nut  350  located in the cavity  316  proximate to the first end  342  (e.g., the back stem  338 ) of the housing  340  applying a compressive force to the housing  340 . The compressive force of the transducer holding nut  350  against the housing  340  keeps the second end  344  of the housing  340  proximate to the ultrasonic buffer  318 . The transducer holding nut  350  can have an external surface that includes threads designed to be engaged with an interior threaded surface of the insert body  310 . In one embodiment, a disc spring  352  (e.g., Bellville washer) and a washer  354  can be installed between the transducer holding nut  350  and the first end  342  of the housing  340 . In the event the transducer holding nut  350  loses some of its compression against the first end  342  of the housing  350  (e.g., if it rotates backwards out of the cavity  316  of the insert body  310 ), the disc spring  352  can provide additional compression against the housing  340  to keep the second end  344  of the housing  340  proximate to the ultrasonic buffer  318 . In another embodiment, a transducer holding nut o-ring  324  can be installed between the transducer holding nut  350  and the first end  342  of the housing  340  to keep external elements (e.g., moisture, air) from entering the cavity  316  of the insert body  310 . An insert holding nut  372  can be threaded into the interior of the sensor port  114  to hold the insert body  310  in place. A plug  370  can be used to seal the sensor port  114 . 
         [0023]    Referring to  FIG. 4 , in one embodiment, a coupling material  360  is located between the second end  344  of the housing  340  and the ultrasonic buffer  318 . The coupling material  360  can provide a conductive medium for the ultrasonic signals between the exterior surface  346  of the second end  344  of the housing  340  and the ultrasonic buffer  318  by effectively coupling the piezoelectric crystal  333  to the ultrasonic buffer  318 . In one embodiment, the coupling material  360  is fluid form (e.g., liquid, gel, etc.), and can fill voids and displace air that could otherwise be located between the housing  340  and the ultrasonic buffer  318  that would interfere with the transmission quality of an ultrasonic signal passing through this location. 
         [0024]    In one embodiment, the coupling material  360  is a composition including a room temperature vulcanizing (RTV) silicone material. Other types of coupling materials  360  can be employed as long as the material does not cause any significant interference with the quality of ultrasonic signals passing through it. In addition, the coupling material  360  should not have high adhesive properties to avoid bonding between the transducer assembly  330  and the insert body  310  to allow replacement of the transducer assembly  330 . 
         [0025]    Since the coupling material  360  remains a fluid, it may be susceptible to leakage from the area between the second end  344  of the housing  340  and the ultrasonic buffer  318 . As discussed, the transducer holding nut o-ring  324  can be installed between the transducer holding nut  350  and the first end  342  of the housing  340  to keep external elements (e.g., moisture, air) from entering the cavity  316  of the insert body  310  and potentially causing evaporation of the coupling material  360 . As shown in  FIG. 4 , a face o-ring  320  can be located within the cavity  316  of the insert body  310  proximate to the second end  344  of the housing  340  to assist in preventing the leakage of the coupling material  360  from the area between the second end of the housing  344  and the ultrasonic buffer  318 . In one embodiment, the face o-ring  320  wraps around the perimeter of the exterior surface  346  of the second end  344  of the housing  340 . In one embodiment, the face o-ring  320  is located in a groove in the exterior surface  346  of the second end  344  of the housing  340  to accommodate engagement between the face o-ring  320  and the housing  340 . In another embodiment, the face o-ring  320  is located in a groove in the insert body  310  on the ultrasonic buffer  316 . 
         [0026]      FIG. 5  is a cross-section of another exemplary sensor port insert apparatus  400 . As shown in  FIG. 5 , a groove  317  in the cavity  316  of the insert body  310  proximate to the exterior surface  346  of the second end  344  of the housing  340  is provided. A insert groove o-ring  322  is installed in the groove  317  to assist in preventing the leakage of the coupling material  360  from the area between the second end of the housing  344  and the ultrasonic buffer  318 . In other embodiments, the insert groove o-ring  322  and associated groove  317  can be located closer to the transducer holding nut  350  (e.g., anywhere proximate to the transducer housing  340 ) to enable more coupling material to be stored within the cavity  316  of the transducer assembly  300  while surrounding the exterior surface  346  of the second end  344  of the housing  340 . In another embodiment, the insert groove o-ring  322  could be located between the holding nut  350  and the first end  342  of the housing  340  (e.g., between the holding nut  350  and the back stem  338 ) to provide the required sealing. 
         [0027]      FIG. 6  is a cross-section of yet another exemplary sensor port insert apparatus  500 . Unlike the embodiments shown in  FIGS. 4 and 5 , the sensor port insert apparatus  500  of  FIG. 6  does not use coupling material  360 , eliminating the need for a face o-ring  320  or an insert groove o-ring  322 . The face  333  of the piezoelectric crystal  332  can be installed proximate to the interior surface  348  of the second end  344  of the housing  340 . As in  FIGS. 4 and 5 , transducer assembly  330  can be held in place by a transducer holding nut  350  applying a compressive force to the housing  340  to keep the exterior surface  346  of the second end  344  of the housing  340  in contact the ultrasonic buffer  318 . In the event the transducer holding nut  350  loses some of its compression against the first end  342  of the housing  350 , the disc spring  352  can provide additional compression against the housing  340  to keep the exterior surface  346  of the housing  340  in contact with the ultrasonic buffer  318 . Instead of using the coupling material, the exterior surface  346  of the second end  344  of the housing  340  in contact with the interior surface  313  of the ultrasonic buffer  318  is polished, and the interior surface  313  of the ultrasonic buffer  318  in the cavity  316  is polished. The polishing eliminates voids and displaces air that could otherwise be located between the exterior surface  346  of the second end  344  of the housing  340  and the interior surface  313  of the ultrasonic buffer  318  when the exterior surface  346  of the second end  344  of the housing  340  contacts the interior surface  313  of the buffer  318 . 
         [0028]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.