Abstract:
The present disclosure relates to a removable orifice plate device which has an orifice plate having a circular portion with an aperture therein, and a graspable end portion extending therefrom. A tee body is included which has oppositely extending first and second tee runs and a tee branch. The tee runs are coupled to gas inflow and outflow pipes. The tee body has internal structure forming a slot which is aligned with an opening formed by the tee branch, and which receives the circular portion of the orifice plate. The orifice plate, when installed in the slot in the tee body, thus allows a flow of fluid only through the aperture. A removable cover encloses the orifice plate within the tee body.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 13/737,660 filed on Jan. 9, 2013, which claims the benefit of U.S. Provisional Application No. 61/586,506, filed on Jan. 13, 2012. The entire disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to devices having removable orifice plates for flow rate differential pressure determination. 
       BACKGROUND 
       [0003]    This section provides background information related to the present disclosure which is not necessarily prior art. 
         [0004]    In groundwater wells, landfill gas recovery, landfill leachate recovery wells and condensate recovery wells, hereinafter generally referred to as “landfill wells”, there is a need to monitor gas production from the well, most commonly methane gas. Landfill wells commonly produce flow rates of methane gas that are collected for off-site delivery and use. Normally, gas flow rates ranging from approximately 5 to 150 cubic feet per minute (CFM) are achieved from individual wells. Maximum gas flow rates ranging from 200 to 250 CFM are also known. Removal of methane gas is required to maintain the safety and stability of the landfill. Withdrawal of methane gas is commonly assisted using vacuum pumps located on-site at the landfill. Landfills are required to periodically measure and maintain records of methane gas produced. This can be accomplished by placing an orifice plate in the gas pipe flow stream and measuring a differential pressure across the orifice plate. The measured differential pressure together with other known or measured items such as temperature and pipe size can be used to determine the methane gas flow rate. 
         [0005]    It is known that orifice plates in many or all of the landfill well gas lines in landfill methane recovery wells are retained to control overall pressure and flow of the methane gas. If the measured differential pressure across the orifice plate exceeds a predetermined value, action may be required to 1) lower the differential pressure so that size and operation of the site vacuum pumps is not impacted, and/or 2) increase the overall flow rate to maximize the recovered volume of methane gas. Well gas flow status should be measurable without impacting the well environment. Known orifice designs provide for one or more orifice sizes in orifice plates that require a coupling to be disassembled to add or change the orifice plate. Well environments may be hazardous because of flammable gasses such as methane, or chemicals in the leachate that corrode or damage test equipment. Measurement systems that require the well to be opened to atmosphere for differential pressure measurement are therefore undesirable, particularly in wells operating under a vacuum, to prevent outside air entering the well and/or methane gas release. In addition, opening the well or disassembling components that open the well for methane gas flow measurement can by itself affect the well level, and thereby adversely impact methane recovery in methane recovery wells. 
       SUMMARY 
       [0006]    In one aspect the present disclosure relates to a removable orifice plate device. The device comprises an orifice plate having a circular portion with a precisely dimensioned aperture therein, and an end portion graspable with the fingers of one hand which extends from the circular portion. A tee body is included which has oppositely extending first and second tee runs. A tee branch extending non-parallel to the first and second tee runs. The first tee run is configured to be coupled to a gas inflow pipe, and the second tee run is configured to be coupled to a gas outflow pipe. The tee body has internal structure forming a slot. The slot is aligned with an opening formed by the tee branch and configured with a dimension for receiving the circular portion of the orifice plate. In this manner the orifice plate, when installed in the slot in the tee body, allows a flow of fluid only through the aperture. A cover is included which is adapted to be removably secured to the tee branch to enclose the orifice plate within the tee body. 
         [0007]    In another aspect the present disclosure relates to a removable orifice plate device. The device comprises an orifice plate having a circular portion with a precisely dimensioned aperture therein, and an end portion graspable with the fingers of one hand which extends from the circular portion. A tee body is included which has oppositely extending first and second tee runs, and a tee branch extending generally perpendicular to the first and second tee runs. The first tee run is configured to be coupled to a gas inflow pipe. The second tee run is configured to be coupled to a gas outflow pipe. The tee body has internal structure forming a slot aligned with the tee branch, and the slot has opposing seal members each facing the slot. The slot is further dimensioned for receiving the circular portion of the orifice plate such that the orifice plate, when installed in the slot, allows a flow flowing into the first tee run to flow only through the aperture, and subsequently into the second tee run. A cover is adapted to be removably secured to the tee branch to enclose the orifice plate within the tee body. 
         [0008]    In still another aspect the present disclosure relates to a removable orifice plate device. The device may comprise an orifice plate having a circular portion with a precisely dimensioned aperture therein, and an end portion graspable with the fingers of one hand which extends from the circular portion. The device may also comprise a tee body having oppositely extending first and second tee runs, and a tee branch extending generally perpendicular to the first and second tee runs. The first tee run is configured to be coupled to a gas inflow pipe, and the second tee run is configured to be coupled to a gas outflow pipe. The tee body has internal structure forming a slot aligned with the tee branch, and the slot has opposing seal members each facing the slot. The slot is further dimensioned for receiving the circular portion of the orifice plate such that the orifice plate, when installed in the slot, allows a flow flowing into the first tee run to flow only through the aperture, and subsequently into the second tee run. The internal structure of the tee body includes a circumferential fixed adjustment adaptor having a fixed adaptor sleeve extending through an internal area of the first tee run, and a circumferential adjustment adaptor having an adjustment adaptor sleeve extending through an internal area of the second tee run. A cover is adapted to be threadably secured to a threaded portion of the tee branch to enclose the orifice plate within the tee body. 
     
    
     
       DRAWINGS 
         [0009]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0010]      FIG. 1  is a partial cross sectional front elevational view of a well and piping assembly having a removable orifice plate device of the present disclosure; 
           [0011]      FIG. 2  is an exploded assembly view of the removable orifice plate device of  FIG. 1 ; 
           [0012]      FIG. 3  is a top plan view of the removable orifice plate device of  FIG. 1 ; 
           [0013]      FIG. 4  is a cross sectional front elevational view of the removable orifice plate device at section  4  of  FIG. 3 ; 
           [0014]      FIG. 4A  shows an orifice receiving slot offset with respect to a planar surface of a tubular shaped body of the device. 
           [0015]      FIG. 5  is a cross sectional end elevational view taken at section  5  of  FIG. 4 ; 
           [0016]      FIG. 6  is an end elevational view of a body sleeve of the removable orifice plate device of  FIG. 2 ; 
           [0017]      FIG. 7  is a cross sectional side elevational view taken at section  7  of  FIG. 6 ; 
           [0018]      FIG. 8  is a front elevational view of a transparent sleeve of the removable orifice plate device of  FIG. 2 ; 
           [0019]      FIG. 9  is a cross sectional front elevational view similar to  FIG. 4 , further showing handle nut and indicator sleeve displacement to permit removal and/or installation of an orifice plate; 
           [0020]      FIG. 10  is a front perspective view of a further embodiment of a removable orifice plate device of the present disclosure; 
           [0021]      FIG. 11  is a front perspective similar to  FIG. 10  after removal of an elastomeric cap from a tree branch; 
           [0022]      FIG. 12  is a front elevational view of the removable orifice plate device of  FIG. 11 ; 
           [0023]      FIG. 13  is a top plan view of the removable orifice plate device of  FIG. 10 ; 
           [0024]      FIG. 14  is a side elevational cross sectional view taken at section  14  of  FIG. 13 ; 
           [0025]      FIG. 15  is an exploded front elevational view of a further embodiment of a removable orifice plate device of the present disclosure; 
           [0026]      FIG. 16  is a side elevational view of the removable orifice plate device of  FIG. 15 ; and 
           [0027]      FIG. 17  is a cross sectional front elevational view taken at section  17  of  FIG. 16 . 
       
    
    
       [0028]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0029]    Example embodiments will now be described more fully with reference to the accompanying drawings. 
         [0030]    Referring to  FIG. 1 , a landfill gas recovery well system  10  includes a removable orifice plate device  12  of the present disclosure which can be either directly or indirectly connected to a well assembly  14 . Removable orifice plate device  12  is provided to permit a differential pressure measurement of a gas  16  such as methane flowing from the well assembly  14 . Well assembly  14  can include a well tube  18  commonly made of a metal, such as steel, or a plastic material, such as poly-vinyl-chloride (PVC). Well tube  18  commonly has an exposed well head portion  20  positioned above a ground surface  22  and a buried well portion  24  positioned below the ground surface  22 . Buried well portion  24  can extend from tens of feet to more than one hundred feet below ground surface  22 . 
         [0031]    A fine control valve  26  can used to isolate gas pressure in well tube  18  and can be directly or indirectly connected to removable orifice plate device  12  which is connected to a well top  28  of well tube  18 . In the exemplary embodiment shown, an inlet pipe  30  connects to well top  28 , and removable orifice plate device  12  can be directly connected to inlet pipe  30 . An orifice plate discharge pipe  31  extending from orifice plate device  12  can be connected to fine control valve  26 . Gas from a well cavity  32  of well tube  18  flows through removable orifice plate device  12  and is isolated using valve  26 . Valve  26  can also be used to throttle flow of gas  16 . Gas  16  which commonly includes a majority percentage of methane collects in and is continuously removed from well cavity  32  via valve  26  and removable orifice plate device  12 . 
         [0032]    According to several embodiments, a fluid removal tube  34 , made for example of a polymeric material such as PVC or a metal such as stainless steel, is connected to and/or extends through well top  28  and further extends downwardly for a predominant length of well tube  18  within both the exposed well head portion  20  and the buried well portion  24 . A fluid discharge pump  36  is connected at a lower end of fluid removal tube  34 . Fluid discharge pump  36  is positioned near a lower end of well tube  18  such that fluid that collects within well cavity  32  can be pumped out via fluid removal tube  34  to a fluid discharge line  38  for collection at an off-well site (not shown). 
         [0033]    Fluid discharge pump  36  is located within buried well portion  24  such that a pump inlet end  40  is positioned above a well tube lower end  41  at a distance from well tube lower end  41  that permits fluid combined with gas  16  entering through a plurality of fluid/gas inlet apertures  42  created through buried well portion  24  to reach an anticipated or normal liquid high level  43  which does not contact the pump inlet end  40 . When fluid in well cavity  32  is at or below the normal liquid high level  43 , fluid discharge pump  36  does not operate. When the fluid level within well cavity  32  rises above pump inlet end  40 , for example to a sensed liquid level  44 , fluid discharge pump  36  is energized to reduce the fluid level in well cavity  32 . It is desirable to maintain the level of fluid within well cavity  32  at or below the normal liquid high level  43  or pump inlet end  40  such that both fluid and gas  16  can enter the plurality of fluid/gas inlet apertures  42  for subsequent removal of the gas  16 , such as methane for methane recovery, from well cavity  32 . 
         [0034]    Gas  16  entering fluid/gas inlet apertures  42  rises through well cavity  32  and is discharged from well cavity  32  via inlet pipe  30  through removable orifice plate device  12  to valve  26 . A first pressure tap  46  is connected to inlet pipe  30 . A first pressure sensing line  48  is connected to both first pressure tap  46  and a differential pressure detection device  50 . A second pressure tap  52  is connected to orifice plate discharge pipe  31  leading to a vacuum pump  58  and gas storage device  60  remotely located from well assembly  14 . A second pressure sensing line  56  is connected to both second pressure tap  52  and to differential pressure detection device  50 . When gas  16  is flowing through removable orifice plate device  12 , a differential pressure created across an orifice (shown and described in reference to  FIG. 2 ) in removable orifice plate device  12  is measured by differential pressure detection device  50 . Differential pressure detection device  50  can be releasably or permanently connected across removable orifice plate device  12 . A flow rate of gas  16  through gas flow line  54  to gas storage device  60  can thereby be determined. The flow rate can be adjusted by adjusting a position of valve  26  and/or modified by changing a size of the orifice in orifice plate device  12 . 
         [0035]    Referring to  FIG. 2 , removable orifice plate device  12  includes multiple components, including a tubular shaped body  62  having an un-threaded portion  64  and a threaded portion  66 . According to several embodiments, tubular shaped body  62  can be a polymeric material such as poly-vinyl-chloride (PVC). An outer surface  68  of un-threaded portion  64  has a diameter “A”. An inner bore wall  70  defines a through bore that extends longitudinally throughout a length of body  62 . A support sleeve  72  can be made according to several embodiments from a length of schedule  80  industry standard 3 inch PVC pipe. Support sleeve  72  includes an inner bore surface  74  defining a through bore extending longitudinally throughout a length of support sleeve  72 . Inner bore surface  74  has a diameter “B” that defines a sliding fit with respect to diameter “A” of outer surface  68  of un-threaded portion  64 . An adhesive  76  applied between inner bore surface  74  and outer surface  68  fixedly connects support sleeve  72  to un-threaded portion  64 . 
         [0036]    A groove  78  is created through a portion of outer surface  68  of body  62  proximate to an inward end of support sleeve  72 . Creation of groove  78  defines a planar surface  80 . According to several embodiments, an orifice plate receiving slot  82  bisects planar surface  80  and extends approximately 50% through the diameter of un-threaded portion  64 . According to further embodiments, orifice plate receiving slot  82  can be offset with respect to a center of planar surface  80  ( FIG. 4A ), and can have a depth less than or greater than 50% of the diameter of un-threaded portion  64 . Orifice plate receiving slot  82  can therefore be positioned substantially centrally with respect to end walls  78   a,    78   b  defining extents of groove  78  that are oriented perpendicular to planar surface  80 . A width “W” of orifice plate receiving slot  82  (shown in reference to  FIG. 4 ) is selected to frictionally slidingly receive an orifice plate  84 . The frictional sliding fit of orifice plate  84  in orifice plate receiving slot  82  minimizes leak paths for gas to escape to atmosphere via orifice plate receiving slot  82  when orifice plate  84  is received therein. Orifice plate  84  includes an orifice  86  sized to reduce a velocity of gas flow through removable orifice plate device  12  and thereby create a differential pressure measurable across orifice plate  84 . A bent or formed tab  88  is created from material of orifice plate  84  that is oriented approximately perpendicular to a planar body  89  of orifice plate  84 . When orifice plate  84  is slidingly received in orifice plate receiving slot  82 , tab  88  can contact planar surface  80  on one side of orifice plate receiving slot  82  to physically and visually indicate to the user that a central axis of orifice  86  is co-axially aligned with a central longitudinal axis  90  of body  62 . 
         [0037]    To retain the orientation of orifice plate  84  in orifice plate receiving slot  82  and to further minimize gas leakage past an outer perimeter of orifice plate  84  with respect to inner bore wall  70 , first and second spacers  92 ,  94  are fixed in position using additional adhesive  76  applied at the perimeter wall of first and second spacers  92 ,  94  where they abut with inner bore wall  70 . Each of the first and second spacers  92 ,  94  include an orifice plate directed face  96 . A spacing between orifice plate directed faces  96  of first and second spacers  92 ,  94  is substantially equal to the width “W” of orifice plate receiving slot  82 , such that orifice plate  84  is also in frictional sliding contact with both faces  96  when orifice plate  84  is slidably received in orifice plate receiving slot  82 . 
         [0038]    A substantially clear or translucent, tempered glass or polymeric material indicator sleeve  98  includes an inner bore wall  100  having a diameter “D” substantially equal to diameter “B” of support sleeve  72 . Unlike support sleeve  72 , indicator sleeve  98  is not fixed to body  62 , but is permitted to slidably move in either a first longitudinal direction “E” or an opposite second longitudinal direction “F”. Indicator sleeve  98  includes a first conical end  102  and an opposite second conical end  104 . To seal against gas within body  62  escaping to atmosphere via orifice plate receiving slot  82 , indicator sleeve  98  is moved to an operating position shown in the first longitudinal direction “E” until first conical end  102  circumferentially contacts a conical engagement end  106  of support sleeve  72 . 
         [0039]    To further establish the operating position, a handle nut  108  including internal threads  110  is threadably engaged with threaded portion  66  of body  62 . Handle nut  108  is threadably displaced on threaded portion  66  in first longitudinal direction “E” until a second conical engagement end  112  of handle nut  108  circumferentially and sealingly contacts second conical end  104  of indicator sleeve  98 . With subsequent torque applied to handle nut  108 , circumferential, sealing contact is retained between first conical end  102  and conical engagement end  106 , and between second conical engagement end  112  and second conical end  104  of indicator sleeve  98  to prevent gas from escaping through orifice plate receiving slot  82  to atmosphere. According to several embodiments, the substantially clear or translucent, polymeric material used for indicator sleeve  98  provides for a visual confirmation of the presence of orifice plate  84  by visibility of tab  88 . According to further aspects, an indicator symbol  113  is provided on an outward facing side of tab  88 . Indicator symbol  113  can be a letter, a number, or other symbol indicative of one of a plurality of predetermined sizes of orifices  86  that can be provided using individual ones of a plurality of orifice plates  84 . Indicator symbol  113  can be provided on tab  88  by any of multiple methods, including but not limited to embossing, stamping, molding, etching, or engraving, or applying to a face of and adhesively connected with a backing such as tape, or by any similar method. 
         [0040]    As will be better shown in reference to  FIG. 9 , orifice plate  84  can be removed by first displacing handle nut  108  in the second longitudinal direction “F”, and then sliding indicator sleeve  98  in the second longitudinal direction “F” until first conical end  102  of indicator sleeve  98  clears groove  78 . Tab  88  is then grasped or pried away from planar surface  80  to remove orifice plate  84 . Different orifice plates  84  each having a different size (diameter) orifice  86  can be provided with removable orifice plate device  12  to provide flexibility in setting an anticipated pressure drop across orifice plate  84  given a known or anticipated gas flow rate. The same or a different orifice plate  84  (having a different diameter orifice  86 ) can then be reinserted into orifice plate receiving slot  82 , and indicator sleeve  98  and handle nut  108  re-installed as previously described. According to several embodiments, orifice plate  84  can also include an orifice  86  sized to substantially equal an inner diameter of both first and second spacers  92 ,  94 , thereby providing substantially no resistance to flow of gas through removable orifice plate device  12 . This orifice plate can also include its own unique indicator symbol  113 . 
         [0041]    Referring to  FIG. 3  and again to  FIG. 2 , a fully assembled removable orifice plate device  12  includes indicator sleeve  98  positioned between support sleeve  72  and handle nut  108 . Tab  88  is visible through indicator sleeve  98 , indicating both the presence of an orifice plate  84  in orifice plate receiving slot  82 , and via indicator symbol  113 , a size (diameter) of the orifice  86  present. If no tab  88  is visible, orifice plate  84  is not present. Indicator sleeve  98  will seal against leakage of gas via orifice plate receiving slot  82  to atmosphere even when no orifice plate  84  is present. 
         [0042]    According to several embodiments, longitudinal concave slots  114  can be provided with handle nut  108  to enhance manual or tool contact with the perimeter surface of handle nut  108  during installation or removal, and further to aid in applying torque to handle nut  108 . In lieu of concave slots  114 , similarly arranged but outwardly facing convex male ribs (not shown) can be substituted for concave slots  114 , or a combination of concave slots and convex ribs can be used. Female threads  116  created on threaded portion  66  of body  62  receive the internal threads  110  of handle nut  108 . 
         [0043]    Referring to  FIG. 4  and again to  FIGS. 1 and 2 , in the assembled, operating condition of removable orifice plate device  12 , an end face of discharge end  31  of valve  26  contacts an upstream end face  117  of first spacer  92 . An inner diameter “G” of an inner bore  118  of discharge end  31  is substantially equal to an inner diameter “H” of both first and second spacers  92 ,  94 . Similarly, an end face of gas flow line  54  contacts a downstream end face  119  of second spacer  94 . An inner diameter “J” of an inner bore  120  of gas flow line  54  is also substantially equal to inner diameter “H” of both first and second spacers  92 ,  94 . Gas flow through discharge end  31  of valve  26 , both first and second spacers  92 ,  94 , and gas flow line  54  is therefore unimpeded by changing diameters, stepped faces, or any incongruity that creates a flow restriction or pressure drop throughout the length of removable orifice plate device  12 . Substantially equal inner diameters “G”, “H” and “J” together create a smooth internal bore throughout a length of removable orifice plate device  12  to help stabilize the flow patterns both upstream and downstream of orifice plate  84 . As previously noted, the diameter of orifice  86  can be equal to diameter “H”, thereby providing no restriction to gas flow, or the diameter of orifice  86  can be smaller than diameter “H” to create a differential pressure across orifice plate  84 . 
         [0044]    As previously noted, circumferential contact between first conical end  102  of indicator sleeve  98  and conical engagement end  106  of support sleeve  72 , and between second conical end  104  of indicator sleeve  98  and second conical engagement end  112  of handle nut  108  is maintained by applying a torque to handle nut  108  in the first longitudinal direction “E”. Any gas escaping via orifice plate receiving slot  82  to groove  78  is trapped in groove  78  by indicator sleeve  98 . With continued reference to  FIGS. 1 and 4 , by closing valve  26  prior to removal of orifice plate  84 , a volume of gas released to atmosphere is minimized, and is approximately the volume of groove  78 . Air will normally be thereafter drawn into orifice plate receiving slot  82  by continued operation of the vacuum pump  58 . 
         [0045]    Referring to  FIG. 5  and again to  FIGS. 2 and 4 , each orifice plate  84  is created having a first diameter portion  122  which defines a semi-circular shape. A diameter “K” of first diameter portion  122  is substantially equal to diameter “A” of body  62  such that first diameter portion  122  defines a sliding fit with respect to an inner bore wall  126  of indicator sleeve  98  proximate to orifice plate receiving slot  82 . A linear face  124  is created by removing or forming material defining first diameter portion  122  while leaving material to also create tab  88 . In the orifice plate installed position, linear face  124  is aligned with planar surface  80  such that tab  88  can align with and/or contact planar surface  80 . Each orifice plate  84  also includes a second diameter portion  128  which defines a semi-circular shape. A radius “L” of second diameter portion  128  is substantially equal to or less than a radius defining diameter “C” of first and second spacers  92 ,  94  such that second diameter portion  128  will abut against inner bore wall  70  of body  62  when orifice plate  84  is fully installed. Opposed, stepped shoulders  130 ,  132  created by a diameter difference between the first and second diameter portions  122 ,  128  each align with and abut one of the first and second ends  133 ,  134  of orifice plate receiving slot  82  in the installed position of the orifice plate  84 . Outer surface  68  of un-threaded portion  64  of body  62  also defines a sliding fit with respect to inner bore wall  126  of indicator sleeve  98 . 
         [0046]    Referring to  FIG. 6  and again to  FIG. 2 , support sleeve  72  can be created by cutting a length of standard schedule  80  PVC pipe. Although the outer diameter of PVC pipe is normally controlled to provide for fit-up to corresponding fittings and valves, the inner diameter “B” is generally known, or can be machined to substantially match the diameter “A” of un-threaded portion  64  of body  62  so support sleeve  72  can be slid into position on body  62  and fixed thereto. 
         [0047]    Referring to  FIG. 7  and again to  FIG. 2 ,  106  of support sleeve  72  is created at an angle α with respect to the end face of support sleeve  72 . Angle α defines a complimentary angle with respect to the angle defined by first conical end  102  of indicator sleeve  98 . 
         [0048]    Referring to  FIG. 8  and again to  FIGS. 2 and 7 , each of the first and second conical ends  102 ,  104  of indicator sleeve  98  are created at an angle β with respect to an outer wall of indicator sleeve  98 . As previously noted, angle β defines a complimentary angle with respect to angle α defined by the end face of support sleeve  72 . Angle β further defines a complimentary angle with respect to the angle of second conical engagement end  112  of handle nut  108 . Although angles α and β preferably define complimentary angles with respect to each other, angle α and the angle of second conical engagement end  112  of handle nut  108  can each be less than a corresponding complimentary angle with respect to angle β to ensure a circumferential contact is maintained with respect to first and second conical ends  102 ,  104  of indicator sleeve  98  when applying torque to handle nut  108 . 
         [0049]    Referring to  FIG. 9  and again to  FIG. 2 , access to install or remove orifice plates  84  is provided by rotating handle nut  108  counterclockwise (when threads  110 ,  116  are right-hand threads) to move handle nut  108  in the second longitudinal direction “F”. Indicator sleeve  98  is then slidably displaced in the second longitudinal direction “F” until first conical end  102  of indicator sleeve  98  clears groove  78  as shown. Tab  88  can then be manually grasped or a tool such as a slot end screwdriver can be placed between tab  88  and planar surface  80  to assist with removal of orifice plate  84 . 
         [0050]    According to further aspects (not shown), groove  78  can be positioned partially or entirely in threaded portion  66 . In these aspects, indicator sleeve  98  is adapted to axially slide with respect to threads  116 . First and second conical engagement ends  106 ,  112  can be modified in these aspects to maintain sealing alignment with first and second conical ends  102 ,  104  of indicator sleeve  98 . A resilient material first seal member  136  such as an O-ring can be positioned against first conical engagement end  106  of support sleeve  72  to assist in creating a fluid seal when indicator sleeve  98  is abutted against support sleeve  72 . A similar second seal member  138  can be positioned between second conical end  104  and second conical engagement end  112  of handle nut  108 . 
         [0051]    It will be apparent that the material of un-threaded portion  64  of body  62  removed or excluded to create orifice plate receiving slot  82  weakens the body  62 , particularly with respect to longitudinal bending loads applied to body  62 . Replacement of orifice plate  84  and indicator sleeve  98 , followed by re-torquing handle nut  108 , stiffens body  62  to substantially the same or a greater stiffness than lost by creation of orifice plate receiving slot  82 . A similar body stiffness is also achieved using indicator sleeve  98 , even when orifice plate  84  is not installed. After the same or a different orifice size orifice plate  84  is replaced in orifice plate receiving slot  82 , indicator sleeve  98  is again moved in the first longitudinal direction “E” until first conical end  102  contacts conical engagement end  106  of support sleeve  72 , and handle nut  108  is rotated until second conical engagement end  112  contacts second conical end  104  of indicator sleeve  98 . A torque is then applied to handle nut  108  to provide sealing contact of indicator sleeve  98 . 
         [0052]    Referring to  FIG. 10  and again to  FIG. 1 , a removable orifice plate device  140  can be substituted for removable orifice plate device  12 . Removable orifice plate device  140  includes a tee body  142  which according to several embodiments is a polymeric tee which can be modified from a commercially available schedule  80  tee. An inlet gas flow pipe  144  is received in a first tee run  146  of tee body  142  such that gas flows through removable orifice plate device  140  in a gas flow direction “M”. An outlet gas flow pipe  148  is connected to a second tee run  150 . A tee branch  152  which is oriented orthogonally with respect to inlet and outlet gas flow pipes  144 ,  148  is normally covered using an elastomeric cap  154  which is sealed using a clamp  156  circumferentially extending about a perimeter of elastomeric cap  154  where it contacts tee branch  152 . 
         [0053]    An inlet pressure fitting  158  is threadably received through a threaded aperture  160  created in tee body  142 . Similarly, an outlet pressure fitting  162  is received through an elongated aperture  164  created in tee body  142 . The outlet pressure fitting  162  is therefore not directly connected to tee body  142  for reasons which will be described in greater detail in reference to  FIG. 14 . The inlet gas flow pipe  144  is connected to first tee run  146  using a fixed adapter  166 . The outlet gas flow pipe  148  is connected to second tee run  150  using an adjustment adapter  168 . Fixed adapter  166  and inlet gas flow pipe  144  are therefore fixed with respect to first tee run  146 . Adjustment adapter  168  and outlet gas flow pipe  148  can be displaced with respect to second tee run  150 . An adapter nut  170  is axially rotatable with respect to adjustment adapter  168 . Adapter nut  170  is threadably engaged with an acme thread  172  which is created at the free end of second tee run  150 . Axial displacement of both outlet gas flow pipe  148  and adjustment adapter  168  is therefore provided by axial rotation of adapter nut  170  with respect to acme thread  172 . 
         [0054]    Referring to  FIG. 11  and again to  FIG. 10 , with the elastomeric cap  154  removed, access is provided to remove and/or replace a removable orifice plate  174  by rotation of adapter nut  170  in a nut release direction “R”. The removable orifice plate  174  is received through a branch cavity  176  of tee branch  152 . The removable orifice plate  174  includes an orifice plate tab  178  that can be manually grasped to permit the removable orifice plate  174  to be displaced in an orifice plate installation direction “N” or oppositely in an orifice plate release direction “P”. An orifice I.D. number  180  is provided with orifice plate tab  178  such that the orifice I.D. number  180  is visible to the operator when the elastomeric cap  154  is removed. The orifice I.D. number  180  corresponds to a diameter of the orifice (shown and described with reference to  FIG. 14 ) of the removable orifice plate  174 . A differential pressure across removable orifice plate  174  can be measured by determining the pressure at inlet pressure fitting  158  and comparing this to a pressure at outlet pressure fitting  162  such that the differential pressure is indicative of a gas flow rate through removable orifice plate device  140 . The gas flow rate can also be modified by changing the removable orifice plate  174  such that a smaller or larger orifice size is provided. 
         [0055]    Referring to  FIG. 12  and again to  FIGS. 1 ,  10 , and  11 , when the elastomeric cap  154  is removed, the operator can visually identify a fixed adapter sleeve  184  of fixed adapter  166  which as shown in reference to  FIG. 12  is positioned below an orifice plate receiving slot  188 . An adjustment adapter sleeve  186  of adjustment adapter  168  is positioned above the orifice plate receiving slot  188 . To remove a removable orifice plate  174  from the orifice plate receiving slot  188 , the operator rotates adapter nut  170  in the nut release direction “R” which displaces the adjustment adapter sleeve  186  in a release direction “Q”, thereby increasing a width of orifice plate receiving slot  188  and allowing the removal of the removable orifice plate  174  (toward the viewer as shown in  FIG. 12 ). Once a new or replacement removable orifice plate  174  is once again installed in the orifice plate receiving slot  188 , the adapter nut  170  is oppositely rotated, which causes displacement of the adjustment adapter sleeve  186  in a retention direction “S” until the removable orifice plate  174  is frictionally engaged between the fixed adapter sleeve  184  and the adjustment adapter sleeve  186 . At this time, the elastomeric cap  154  can be reinstalled. In order to permit the gas flow pressure to be determined using the inlet and outlet pressure fittings  158 ,  162 , each of the inlet and outlet pressure fittings  158 ,  162  is provided with a tube fitting end  190  which is known in the industry, which provide for a friction fit of a tube (not shown) which can be led to a differential pressure detection device  50  such as shown and described with reference to  FIG. 1 . 
         [0056]    Referring to  FIG. 13  and again to  FIGS. 10-12 , each of the inlet and outlet pressure fittings  158 ,  162  are aligned with respect to a pressure fitting axial plane  192 . The pressure fitting axial plane  192  is oriented with respect to a branch axis  194  of tee branch  152  by an angle γ which according to several embodiments can range between approximately 90 degrees to approximately 270 degrees. The elastomeric cap  154  can also include a clamp channel  196  circumferentially defined with respect to elastomeric cap  154 . The clamp channel  196  is sized to receive the clamp  156 . 
         [0057]    Referring to  FIG. 14  and again to  FIGS. 10-13 , removable orifice plate device  140  can be assembled as follows without restriction to the specific order of steps identified. The fixed adapter  166  is slidably disposed within first tee run  146  until a fixed adapter shoulder  198  directly contacts a run end face  200  of first tee run  146 . The inlet gas flow pipe  144  is slidably disposed in a first receiving bore  202  of fixed adapter sleeve  184  until an inlet pipe end face  204  contacts a first receiving face  206  of fixed adapter sleeve  184 . The inlet pressure fitting  158  which is threadably received within threaded aperture  160  of tee body  142  is coaxially aligned with a clearance bore  208  created through fixed adapter  166 . The clearance bore  208  is used to align and drill a pressure bore  210  through the wall of inlet gas flow pipe  144  such that gas pressure within inlet gas flow pipe  144  can enter inlet pressure fitting  158 . An interior facing end of fixed adapter sleeve  184  receives a first seal member  212  such as an O-ring in a first seal member slot  214  which can contact and therefore seal against the removable orifice plate  174 . An orifice  216  created through removable orifice plate  174  is in coaxial alignment with each of the inlet and outlet gas flow pipes  144 ,  148  in its installed position. A diameter of orifice  216  can be varied by changing the individual removable orifice plate  174  with a different removable orifice plate  174 . 
         [0058]    A second seal member  218 , such as an O-ring, is similarly received within a second seal member slot  220  created on an interior facing end wall of adjustment adapter sleeve  186 . The second seal member  218  is oppositely directed with respect to first seal member  212  such that opposite sides of removable orifice plate  174  are directly contacted by one of the first or second seal members  212 ,  218 . Fluid in the inlet or outlet gas flow pipes  144 ,  148  is therefore not exposed via the orifice plate receiving slot  188  to the branch cavity  176  while removable orifice plate  174  is in position. The inlet gas flow pipe  144  can be fixedly engaged in the first receiving bore  202 , for example using an adhesive. Similarly, the outlet gas flow pipe  148  is slidably received in a second receiving bore  222  created in adjustment adapter sleeve  186 . The outlet gas flow pipe  148  can be fixed with respect to second receiving bore  222  also using a fixing agent such as an adhesive. The outlet gas flow pipe  148  is slidably inserted in second receiving bore  222  until an outlet pipe end face  224  of outlet gas flow pipe  148  contacts a second receiving face  226  created in adjustment adapter sleeve  186 . 
         [0059]    The adapter nut  170  is also hereinafter referred to as a “captured nut” for the following reasons. Adapter nut  170  is positioned in direct contact with an adjustment adapter shoulder  228  of adjustment adapter sleeve  186  by contact with an adapter nut shoulder  230 . The adjustment adapter  168  is then positioned as shown with respect to adapter nut  170  such that the adapter nut shoulder  230  is captured between adjustment adapter shoulder  228  and adjustment adapter  168  while still allowing adapter nut  170  to axially rotate. Adjustment adapter  168  is fixed with respect to outlet gas flow pipe  148 , for example by applying an adhesive between an adapter nut inner bore wall  232  of adjustment adapter  168  and a tubular surface  234  of outlet gas flow pipe  148 . Adjustment adapter  168  is therefore fixedly connected to outlet gas flow pipe  148  while still permitting axial rotation of adapter nut  170 . By thereafter engaging adapter nut  170  with the acme thread  172  created on second tee run  150 , a clockwise rotation of adapter nut  170  will displace the adjustment adapter sleeve  186  toward removable orifice plate  174  until sealing contact occurs using the first and second seal members  212 ,  218 . To release the sealing pressure created between first and second seal members  212 ,  218  with respect to removable orifice plate  174 , the adapter nut  170  can be rotated in a counterclockwise direction by approximately one quarter turn to allow displacement of adjustment adapter sleeve  186  away from removable orifice plate  174 , thereby permitting removal of removable orifice plate  174 . 
         [0060]    As previously noted, the elongated aperture  164  created through second tee run  150  permits axial displacement of adjustment adapter sleeve  186  without removal of outlet pressure fitting  162 . The outlet pressure fitting  162  is allowed to displace coextensively with adjustment adapter sleeve  186  by the clearance provided by elongated aperture  164 . Adjustment adapter sleeve  186  together with outlet gas flow pipe  148  can be completely removed from tee body  142  by first removing outlet pressure fitting  162 , and then rotating adapter nut  170  in a counterclockwise direction until adapter nut  170  clears the acme thread  172 . 
         [0061]    Referring to  FIG. 15  and again to  FIGS. 1 and 10 , a removable orifice plate device  240  is modified with respect to removable orifice plate devices  12  and  140 . Removable orifice plate device  240  includes an orifice plate receiver  242  which includes an orifice plate receiving slot  243  adapted to slidably receive a removable orifice plate similar to those previously described herein. The orifice plate receiver  242  is adapted to connect to an inlet gas flow pipe  244  using a connector/viewsleeve  246  and oppositely to an outlet gas flow pipe  248 . Inlet gas flow pipe  244  includes a male thread  249  at a free end thereof and further receives a seal member  250  such as an O-ring in a first seal receiving slot  252 . An inlet pressure fitting  254 , similar to the pressure fittings previously described herein, is threadably connected to inlet gas flow pipe  244  proximate to the male thread  249 . A tube fitting end  256  of inlet pressure fitting  254  can be covered using a cap  258 , made for example of a polymeric material, which acts as a protector for the tube fitting end  256  when differential pressure measurements are not required. The connector/viewsleeve  246  is threadably engaged with the male thread  249  to releasably couple connector/viewsleeve  246  to inlet gas flow pipe  244 . 
         [0062]    In addition to the connector nut  260 , which allows for manual rotation of connector/viewsleeve  246 , a viewsleeve  262  is also fixedly connected to connector nut  260 . The viewsleeve  262  can be made of a clear or semitransparent polymeric material such that when in its installed position with respect to orifice plate receiver  242 , the tab of the corresponding removable orifice plate (not visible in this view) received in orifice plate receiving slot  243  will be visible to an operator through viewsleeve  262  without disassembly of removable orifice plate device  240 . 
         [0063]    First and second viewsleeve seal members  264 ,  266 , which can be provided for example as O-rings, are used to seal the interior of viewsleeve  262  as will be better described in reference to  FIG. 17 . The first and second viewsleeve seal members  264 ,  266  therefore provide a fluid tight boundary to prevent escape of the fluid within inlet and outlet gas flow pipes  244 ,  248  during operation of removable orifice plate device  240 . 
         [0064]    Orifice plate receiver  242  further includes a male thread  268  at a first end and a receiver body  270  at an opposite or second end. The male thread  268  is threadably engaged with connector/viewsleeve  246  as will be better shown and described with reference to  FIG. 17 . An outlet pressure fitting  272  is releasably coupled to receiver body  270  and includes a tube fitting end  274  which can be covered by a cap  276 , similar to cap  258 , to protect tube fitting end  274  when differential pressure measurements are not being conducted. 
         [0065]    Outlet gas flow pipe  248  is provided with a male thread  278  at a first end thereof and can also receive a seal member  280 , such as an O-ring, in a second seal receiving slot  282 . The male thread  278  is threadably engaged within receiver body  270  and a fluid seal is provided by seal member  280 , as will be better shown and described in reference to  FIG. 17 . An extension nipple  284  can be threadably connected to outlet gas flow pipe  248  which subsequently threadably receives a pressure fitting  286 . Pressure fitting  286  can also include a tube fitting end  288  which can be normally covered and protected by a cap  290 . The pressure fitting  286  can be used for measurement of system pressure downstream of removable orifice plate device  240 . 
         [0066]    Referring to  FIG. 16  and again to  FIG. 15 , inlet gas flow pipe  244  can include an inlet pressure port  292  which receives inlet pressure fitting  254 . Receiver body  270  can similarly be provided with an outlet pressure port  294  which receives outlet pressure fitting  272 . A first port spacing “T” is provided between inlet and outlet pressure ports  292 ,  294  which is predetermined based on the fluid flow volumes and rates expected during operation of removable orifice plate device  240 . A system pressure port  296  can also be created through outlet gas flow pipe  248  which releasably receives extension nipple  284  and pressure fitting  286 . A second port spacing “U” is provided between outlet pressure port  294  and system pressure port  296  to allow the flow stream of fluids in outlet gas flow pipe  248  downstream of removable orifice plate device  240  to be unaffected by the disruption of flow created by removable orifice plate device  240 . 
         [0067]    Referring to  FIG. 17 , removable orifice plate device  240  can be assembled as follows without restriction to the specific installation step sequencing identified. The inlet gas flow pipe  244  is threadably engaged within a first threaded receiving bore  298  until inlet gas flow pipe  244  is entirely seated within orifice plate receiver  242 . Outlet gas flow pipe  248  is similarly threadably engaged within a second threaded receiving bore  300  created in receiver body  270  until outlet gas flow pipe  248  is fully seated. The viewsleeve  262  is fixedly connected to connector nut  260 , for example using an adhesive at a connector nut shoulder  302 . 
         [0068]    To releasably couple the inlet and outlet gas flow pipes  244 ,  248 , the connector nut  260  is threadably engaged with the male thread  268  of orifice plate receiver  242  and rotated in a clockwise direction. The removable orifice plate  304 , which is slidably captured within the orifice plate receiving slot  243 , is releasably captured within a circumferential wall  306  defined by viewsleeve  262 . The connector nut  260  is rotated until viewsleeve  262  contacts a receiver body shoulder  308  of receiver body  270 . The orifice plate tab  310  of removable orifice plate  304  is thereafter visible through viewsleeve  262  by an operator during use of removable orifice plate device  240 . Removable orifice plate  304  can be removed by rotation of connector nut  260  in a counterclockwise rotational direction, which pulls viewsleeve  262  away from receiver body shoulder  308  and continues until viewsleeve  262  is clear of orifice plate tab  310 , allowing the sliding removal of removable orifice plate  304 . 
         [0069]    Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
         [0070]    The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
         [0071]    When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0072]    Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
         [0073]    Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
         [0074]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.