Abstract:
A process instrument having a wafer-style body for mounting between an upstream flanged pipe and a downstream flanged pipe has a flow passage, a transmitter connected to the body, and first and second end plates fixed to the body. The first end plate has a first set of cams for engaging a plurality of threaded fasteners extending between the upstream flanged pipe and the downstream flanged pipe. The second end plate has a second set of cams for engaging the plurality of threaded fasteners such that the first set of cams and the second set of cams center the flow passage with respect to the upstream flanged pipe and the downstream flanged pipe.

Description:
BACKGROUND 
     The present invention relates generally to fluid processing and, more particularly, to process instruments. Specifically, the invention concerns the alignment of wafer-style devices installed in a flow line. 
     Process instruments are used in a wide range of fluid handling systems. While the present invention will be described in the context of a flow measurement device, it is to be understood that the invention could be applied to other types of wafer-style process instruments. Flow measurement devices are used to monitor and control the flow rate or quantity of process flow within a conduit and come in many varieties, including positive displacement and magnetic flow meters, suited for use in numerous applications. The different types of meters employ technology based on the system in which they are installed. For example, a magnetic flow meter is advantageous when the use of moving parts within a flow line is not ideal or practical. While the present invention will be described in the context of a magnetic flow meter, it is to be understood that the invention could be applied to other types of flow meters. 
     Standard flow meters are interposed between upstream and downstream pipes, each pipe having an end flange. In order to secure the device between the pipes, traditional flow meters are equipped with a flange on each end, each flange having a circle of bolt holes that aligns with bolt holes on the end flanges of the pipes. While flow meter flanges ensure the flow passage of the meter is centered with respect to the flow passage of the conduit, flanged flow meters are relatively large and expensive. Moreover, there a number of possible bolt hole patterns in existing flanged pipelines, requiring flanged flow meters to have distinct bolt hole circles. One solution to reduce cost and simplify installation is to remove the flanges from the flow meter body. While flangeless, or wafer-style, flow meters save money and time, without bolt hole circles on the flanges, these meters can suffer from misalignment issues giving rise to local turbulence and inaccurate meter readings. 
     Current methods of resolving flow meter alignment issues include providing camming devices positioned between the pipe flanges and the flow meter body during the installation process. Such devices take advantage of existing hardware used to bridge the gap between the upstream and downstream pipes. By rotating camming devices with respect to the flow meter body, the bolts are forced to their extreme positions within the bolt holes, thus ensuring the flow passage of the meter is centered with respect to the flow line. Examples of existing alignment devices are disclosed in U.S. Pat. No. 4,345,464 and U.S. Pat. No. 5,632,632. While these devices can be used to center wafer-style flow meters installed in flanged pipelines having a variety of bolt hole patterns, the additional hardware is problematic both from a production and installation standpoint. Not only is the added equipment less cost-effective and more time-consuming than it could be, the additional hardware, such as camming sleeves or rings and the gaskets required to seal the flow meter between the pipe ends, can easily be ineffectively installed or inadvertently discarded. 
     SUMMARY 
     A process instrument having a wafer-style body for mounting between an upstream flanged pipe and a downstream flanged pipe has a flow passage, a transmitter connected to the body, and first and second end plates fixed to the body. The first end plate has a first set of cams for engaging a plurality of threaded fasteners extending between the upstream flanged pipe and the downstream flanged pipe. The second end plate has a second set of cams for engaging the plurality of threaded fasteners such that the first set of cams and the second set of cams center the flow passage with respect to the upstream flanged pipe and the downstream flanged pipe. 
     A method of centering a wafer-style body of a process instrument between an upstream flanged pipe and a downstream flanged pipe includes inserting a plurality of threaded fasteners into a plurality of corresponding holes in the upstream flanged pipe and the downstream flanged pipe, and positioning the wafer-style body of the process instrument between the upstream flanged pipe and the downstream flanged pipe such that a first set of cams on a first endplate fixed to an upstream end of the wafer-style body and a second set of cams on a second endplate fixed to a downstream end of the wafer-style body engage the plurality of threaded fasteners. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is an exploded view of a wafer-style flow meter. 
         FIG. 1B  is a perspective view of the wafer-style flow meter of  FIG. 1A . 
         FIG. 2A  is a plan view of a wafer-style flow meter positioned between an upstream flanged pipe and a downstream flanged pipe. 
         FIG. 2B  is a plan view of the wafer-style flow meter of  FIG. 2A  installed between an upstream flanged pipe and a downstream flanged pipe. 
         FIG. 3A  is a perspective view of an end plate of a wafer-style flow meter aligned with a pipe flange having four holes and a plurality of threaded fasteners in loose positions. 
         FIG. 3B  is a perspective view of the end plate aligned with a pipe flange of  FIG. 3A  with the threaded fasteners in outer limit positions. 
         FIG. 4A  is a perspective view of an end plate of a wafer-style flow meter aligned with a pipe flange having eight holes and a plurality of threaded fasteners in loose positions. 
         FIG. 4B  is a perspective view of the end plate aligned with a pipe flange of  FIG. 4A  with the threaded fasteners in outer limit positions. 
         FIG. 5A  is an exploded view of a flexible neck attached between a wafer-style flow tube and a transmitter housing of a magnetic flow meter. 
         FIG. 5B  is a perspective view of the flow meter of  FIG. 5A . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1A  is an exploded view of wafer-style process instrument (flow meter)  10 , and  FIG. 1B  is a perspective view of wafer-style flow meter  10 . Flow meter  10  includes meter flow passage  12 , flow meter body (or flow tube)  14 , transmitter (or remote junction box)  16 , neck  18 , wrappers  20 , electrical components  22 , end plates  24 , and cams  26 . In the embodiment shown in  FIGS. 1A-1B , flow meter  10  is a magnetic flow meter. In other embodiments, flow meter  10  can be any type of flow meter, including but not limited to other velocity flow meters, positive displacement flow meters, and mass flow meters. In other embodiments, flow meter  10  can be any type of process instrument that uses a wafer-style mounted in a pipe line. 
     Meter flow passage  12  forms a tube for directing flow through flow meter body  14 . Transmitter  16  is connected to flow meter body  14  by neck  18 . Wrappers  20  are two arcuate halves joined together to form the outer cylinder or housing of flow meter body  14 . Electrical components  22  (such as field coils and electrodes) can be connected as appropriate to meter flow passage  12 , and can be housed within the cylinder formed by wrappers  20 . End plates  24  are joined to each end of the cylinder formed by wrappers  20 . End plates  24  have a series of evenly-spaced cams  26  extending radially outward from flow meter body  14 . Cams  26  can be arcuate and gradually increase in size as they extend outward from flow meter body  14  to produce a desired angle (discussed further in  FIGS. 3-4 ). 
     Flow meter  10  can be assembled by welding wrappers  20  together around meter flow passage  12  to form flow meter body  14 . Transmitter  16  can be connected to flow meter body  14  by neck  18 , which can be flexible to allow for repositioning of transmitter  16  (discussed further in  FIG. 5 ). End plates  24  can then be welded to either side of the cylinder of flow meter body  14 . In this manner, the components of flow meter  10  can be cut from the same material and welded into a single, leak-proof housing for electrical components  22  of flow meter  10 . Further, flow meter body  14  and end plates  24  can be cut to various sizes and shapes to accommodate pipe lines having different sizes and bolt hole patterns. 
       FIG. 2A  is a plan view of wafer-style flow meter  10  positioned between upstream flanged pipe  28  and downstream flanged pipe  30 .  FIG. 2B  is a plan view of wafer-style flow meter  10  installed between upstream flanged pipe  28  and downstream flanged pipe  30 . Upstream flanged pipe  28  and downstream flanged pipe  30  include flanges  32  and pipe flow passages  34 . Flanges  32  include lower holes  36  and upper holes  38  for receiving threaded fasteners  40 , which are threaded to receive nuts  42 . For simplicity, only one upper hole  36  and one lower hole  38  are shown on each flange  32  in  FIGS. 2A-2B . Flanges  32  can have any number of lower holes  36  and upper holes  38 . Threaded fasteners  38  span the distance between upstream flanged pipe  28  and downstream flanged pipe  30  and, together with nuts  42 , hold flow meter  10  securely in place. 
     Threaded fasteners  40  can be placed in lower holes  36  and fastened by nuts  42  to form a preliminary connection between upstream flanged pipe  28  and downstream flanged pipe  30 . Flow meter  10  can then be installed between upstream flanged pipe  28  and downstream flanged pipe  30  such that end plates  24  are flush with flanges  32 . Threaded fasteners  40  can then be placed in upper holes  38  and fastened by nuts  42 . Nuts  42  can be tightened such that flow meter  10  is suspended between upstream flanged pipe  28  and downstream flanged pipe  30  while still allowing flow meter  10  to be rotated to a desired position to align meter flow passage  12  with pipe flow passages  34  (described further in  FIGS. 3-4 ). After flow meter  10  has been rotated into the desired position, nuts  42  can be tightened, securing flow meter  10  between upstream flanged pipe  28  and downstream flanged pipe  30  and forming a leak-proof seal between end plates  24  and flanges  32 . Neck  18  can be made adjustable such that transmitter  16  is readable as necessary following rotation of flow meter  10 . In this manner, installation of flow meter  10  involves utilizing existing hardware to align meter flow passage  12  and pipe flow passages  34  and creating a leak-proof seal between flow meter  10  and flanges  32 , eliminating the need for additional hardware. 
       FIGS. 3-4  illustrate the compatibility of the present invention with a variety of flange bolt hole patterns. For simplicity, a single end plate  24  of flow meter  10  is shown with flange  32 .  FIG. 3A  is a perspective view of an end plate of a wafer-style flow meter aligned with a pipe flange having four holes and a plurality of threaded fasteners in loose positions.  FIG. 3B  is a perspective view of the end plate aligned with a pipe flange of  FIG. 3A  with the threaded fasteners in outer limit positions.  FIG. 4A  is a perspective view of an end plate of a wafer-style flow meter aligned with a pipe flange having eight holes and a plurality of threaded fasteners in loose positions.  FIG. 4B  is a perspective view of the end plate aligned with a pipe flange of  FIG. 4A  with the threaded fasteners in outer limit positions. 
     Flange  32  has lower holes  36  and upper holes  38 . In the embodiment shown in  FIG. 3 , flange  32  has two lower holes  36  and two upper holes  38 . In the embodiment shown in  FIG. 4 , flange  32  has four lower holes  36  and four upper holes  38 . In other embodiments, flange  32  may have any number of lower holes  36  and upper holes  38 . End plate  24  has equally spaced cams  26  extending radially outward. 
     In  FIG. 3A  and  FIG. 4A , threaded fasteners  40  are loosely held in lower holes  36  and upper holes  38  of flange  32 . Lower holes  36  and upper holes  38  are sized such that threaded fasteners  40  are given limited play when initially installed to facilitate connection of pipe flanges  32  on either side of flow meter  10 . In  FIG. 3B  and  FIG. 4B , threaded fasteners  40  are pushed to the outer limit of lower holes  36  and upper holes  38  of flange  32 . 
     When flow meter  10  is rotated, cams  26  of end plate  24  engage threaded fasteners  40 . The arcuate surface of cams  26  push against threaded fasteners  40  such that flow meter  10  can rotate until threaded fasteners  40  reach the outer limit of lower holes  36  and upper holes  38  of flange  32 . The arcuate surface of cams  26  can extend radially outward from end plate  24  in a variety of angles. The angle required can differ based on the number of lower holes  36  and upper holes  38  of flange  32 . In this manner, a variety of end plates  24  having cams  26  extending radially outward at different angles can be joined to flow meter  10  depending on the bolt hole pattern of flanges  32 . Cams  26  can thus enable rotation of flow meter  10  until threaded fasteners  40  are pushed to the outer limit position and meter flow passage  12  is aligned with pipe flow passage  34 . 
       FIG. 5A  is an exploded view of flexible neck  44  attached to wafer-style flow meter  10 , and  FIG. 5B  is a perspective view of flexible neck  44 . Flexible neck  44  includes rotatable segments  46 . Rotatable segments  46  include ridges  48  for sealable engagement with other rotatable segments  46  or transmitter  16 . 
     Flexible neck  44  extends from flow meter body  14  of flow meter  10 , connecting the housing of transmitter  16  to flow meter body  14 . Electrical connections between flow meter body  14  and transmitter  16  are made by wires (not shown) that extend through flexible neck  44 . Flexible neck  44  can have any number of rotatable segments  46  to achieve the desired length and flexibility. Each rotatable segment  46  has a ridge  48  at one end that connects it to other rotatable segments  46 . Rotatable segments  46  can be generally cylindrical with one side being shorter than the other. Thus, when rotatable segments  46  are twisted, flexible neck  44  can be twisted into any number of positions. In this manner, transmitter  16  can be repositioned to an optimal orientation after meter flow passage  12  has been aligned with pipe flow passages  34  via the rotation of flow meter body  14  end plates  24  having cams  26 . 
     While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.