for purposes of description herein , the terms “ upper ”, “ lower ”, “ right ”, “ left ”, “ rear ”, “ front ”, “ vertical ”, “ horizontal ” and derivatives thereof shall relate to the invention as oriented in fig2 . however , it is to be understood that the invention may assume various alternative orientations and step sequences , unless it is expressly specified to the contrary . it is also to be understood that the specific devices and processes illustrated in the attached drawings , and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims . hence , specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting , unless the claims expressly state otherwise . turning to the drawings , fig2 to 4 show a flow meter 30 , which is one of the preferred embodiments of the present invention , and illustrates its various components . a preferred embodiment of flow meter 30 , as shown in fig2 , comprises a housing 31 which receives therein an inner member 80 . inner member 80 has a central bore 82 through which a fluid flows in a direction indicated by arrow “ a ”. although the fluid in fig2 is shown as flowing in direction “ a ”, this is for illustration purposes only , and those skilled in the art will recognize that the various possible embodiments permit accurate metering of fluid flowing in either direction through flow meter 30 . flow meter 30 can be installed in either a ‘ forward ’ or ‘ reverse ’ orientation with no effect on the accuracy or operation of the flow meter . a flow restrictor 97 is formed internally within the inner wall of inner member 80 and forms part of a metering structure . first and second port connections 47 and 49 respectively are equidistantly spaced from flow restrictor 97 . first port connection 47 is positioned upstream from flow restrictor 97 and second port connection 49 is positioned downstream from flow restrictor 97 . as illustrated in fig2 , housing 31 generally comprises a tubular body 32 having a flange 33 at a first end 34 thereof and a second flange 35 at a second end 37 . first and second flanges 33 and 35 have a plurality of attach holes 36 to affix flow meter 30 within a pipeline . second end 37 is configured in a manner to mate with a tube or a pipe in a fluid transmission system ( not shown ), and can take on a variety of configurations dependent on the requirements of the fluid transmission system . housing 31 has an internal bore 42 extending longitudinally therethrough and has a central longitudinal axis 44 . peripheral lip 43 extends radially into internal bore 42 at second end 37 to define a bore opening at second end 37 that is smaller in diameter than bore 42 . peripheral lip 43 has an internal chamfer 39 which substantially faces inwardly from the opening to internal bore 42 at second end 37 . first end 34 of housing 31 has a circular recess 38 machined therein and further includes at least two alignment pins 40 embedded within flange 33 and extending into recess 38 . alignment pins 40 are precision located in a predefined pattern for engagement and positioning of a first end of inner member 80 as further described below . flow meter 30 has a vertical center line generally shown by dashed line 45 . first and second port connections 47 and 49 respectively are positioned equidistant from centerline 45 . port connections 47 and 49 , in the preferred embodiment , are connections that are commercially available and well known in the art . port connections 47 and 49 are affixed to tubular body 32 by welding to a top portion thereof . each of port connections 47 and 49 has a vertical bore 51 extending therethrough and are in fluidic communication with internal bore 42 . an upper portion 52 of central bore 51 in port connections 47 and 49 are internally threaded while a lower portion 53 is a smooth non - threaded bore and generally of smaller diameter than upper portion 52 . each of port connections 47 and 49 receive therein a hollow core bolt 55 . referring also to fig3 , each hollow core bolt 55 has an upper threaded shank portion 59 and a lower non - threaded shank portion 61 . each bolt 55 is threaded into each of port connections 47 and 49 ( shown in fig2 ) to a desired depth wherein lower non - threaded shank portion 61 extends into internal bore 42 ( shown in fig2 ) in a sealing manner with inner member 80 as further described below . bolts 55 are retained in their vertical position within port connections 47 and 49 by lock nuts 56 ( shown in fig2 ) engaging a portion of upper threaded shank 59 and bearing against a top of port connections 47 and 49 . bolts 55 also have a head 58 ( shown in fig2 ) which extends above lock nuts 56 . a central bore 57 extends the length of bolt 55 to provide fluid communication with housing internal bore 42 . head 58 further includes a threaded bore 60 for receiving a pressure gauge or a pressure transmission tube for connection to a pressure gauge . smooth non - threaded shank portion 61 of bolt 55 includes a groove 62 therearound . groove 62 retains a first o - ring 66 to create a pressure seal between lower smooth portion 53 of central bore 51 ( shown in fig2 ) in port connections 47 and 49 and lower unthreaded shank 61 of bolt 55 . bottom 63 of bolt 55 defines a second circular groove 64 therein which retains a second o - ring 68 for sealing engagement with inner member 80 as further described below . fig4 illustrates inner member 80 which generally comprises inner cylindrical tube 81 having a flange 86 at a first end 85 . flange 86 is generally circular in configuration and is sized to be received within circular recess 38 at first end 34 of housing 31 ( as shown in fig2 ). flange 86 includes alignment pin holes 88 therein in a precision pattern coincident with the pattern of alignment pins 40 in recess 38 of housing 31 ( as shown in fig2 ). inner cylindrical tube 81 has an inner wall 83 which defines an internal bore 82 extending longitudinally therethrough . bore 82 has a central longitudinal axis illustrated by dash line 84 . as illustrated in fig4 a , inner cylindrical tube 81 has a pressure equalization hole 90 extending therethrough permitting fluidic communication between internal bore 82 and an exterior of inner cylindrical tube 81 . inner member 80 has a second end 92 which has an external chamfer 94 at second end 37 of housing 31 ( as shown in fig2 ). chamfer 94 is angularly oriented substantially equal to internal chamfer 39 ( as shown in fig2 ) for engagement therewith . inner member 80 has a vertical center line shown by dash line 96 . vertical center line 96 of inner member 80 and vertical center line 45 of housing 31 are substantially coincident when inner member 80 is received into housing 31 . a flow restrictor 97 is integrally formed within the inner wall 83 of cylindrical tube 81 . in the preferred embodiment , flow restrictor 97 is a 360 degree torus wedge 98 having opposing first and second wedge member 100 and 102 respectively . wedge member 100 and 102 have substantially a full internal v - shaped circumference and are adjoined at circular vertex 406 to form flow constrictor member 99 . wedge member 100 and 102 each are respectively defined by circular base ( 400 , 401 ) and adjoining circular vertex ( 406 ). both base 400 and 401 have a diameter coincident to the diameter of inner cylindrical tube 81 . along the circumference of base 400 and 401 , internal wall 83 uniformly inclines inwardly and converges into the circumference of vertex 406 to form constrictor member 99 . the inclined v - shaped inner wall of wedge member 100 and 102 reduces the area available to flow through constrictor member 99 , but the inclined v - shaped inner wall also channels the incoming and outgoing flow through constrictor member 99 . the diameter of circular vertex 406 is smaller than diameter of base 400 and 401 , thereby restricting the fluid flow through internal bore 82 . however , in the preferred embodiment , the diameter of circular vertex 406 can be any diameter necessary to create the differential used for measurement . constrictor member 99 is formed within inner wall 83 of cylindrical tube 81 such that the central radius of constrictor member 99 is substantially perpendicular to both longitudinal axis 84 and the diameter of constrictor member 99 is coincident with vertical axis 96 . torus wedge 98 is retained to housing 31 by fastener 104 thereby rendering torus wedge 98 removable and readily replaceable with a torus wedge of different dimensions or configuration . the angular inclined depth between adjoining wedge members 100 and 102 as taken along vertical center line 96 perpendicular to axis 84 ranges between 45 and 90 degrees . those knowledgeable in the art will also realize that opposing wedges 100 and 102 can also be utilized to provide the desired flow restriction with substantially the same results as a single wedge as disclosed in the prior art . each combined wedge 98 ( wedge members 100 and 102 ) and tube 81 can be precalibrated for use in any housing 31 without requiring recalibration of the tube - wedge combination . however , those skilled in the art will also recognize that the replacement of a wedge 98 in a specific tube 81 will require recalibration of the wedge - tube combination . cylindrical tube 81 further includes circular recesses 105 at a top portion thereof . recesses 105 are equally spaced about center line 96 and upon receipt of inner member 80 within housing 31 are in vertical registration with central bores 51 of port connections 47 and 49 ( as shown in fig2 ). recesses 105 have a circular land 108 and a pressure port 106 extending through land 108 to internal bore 82 . fig5 illustrates another aspect of the present invention wherein the torus wedge is incorporated into outer member 380 . outer member 380 which generally comprises inner cylindrical tube 381 having a flange 333 at a first end 334 thereof and a second flange 335 at a second end 337 . first and second flanges 333 and 335 have a plurality of attach holes 336 to affix outer member 380 within a pipeline . inner cylindrical tube 381 has an inner wall 383 which defines an internal bore 382 extending longitudinally therethrough . bore 382 has a central longitudinal axis illustrated by dash line 384 . outer member 380 has a vertical center line shown by dash line 396 . a flow restrictor 97 ′ is integrally formed within the inner wall 383 of cylindrical tube 381 . in the preferred embodiment , flow restrictor 97 ′ is a 360 degree torus wedge 98 ′ having opposing first and second wedge member 100 ′ and 102 ′ respectively . wedge member 100 ′ and 102 ′ have substantially a full internal v - shaped circumference and are adjoined at circular vertex 406 ′ to form flow constrictor member 99 ′. wedge member 100 ′ and 102 ′ each are respectively defined by circular base ( 400 ′, 401 ′) and adjoining circular vertex ( 406 ′). both base 400 ′ and 401 ′ have a diameter coincident to the diameter of inner cylindrical tube 381 . along the circumference of base 400 ′ and 401 ′, internal wall 383 uniformly inclines inwardly and converges into the circumference of vertex 406 ′ to form constrictor member 99 ′. the inclined v - shaped inner wall of wedge member 100 ′ and 102 ′ reduces the area available to flow through constrictor member 99 ′, but the inclined v - shaped inner wall also channels the incoming and outgoing flow through constrictor member 99 ′. the diameter of circular vertex 406 ′ is smaller than the diameter of base 400 ′ and 401 ′, thereby restricting the fluid flow through internal bore 382 . constrictor member 99 ′ is formed within inner wall 383 of cylindrical tube 381 such that the central radius of constrictor member 99 ′ is substantially perpendicular to both longitudinal axis 384 and the diameter of constrictor member 99 ′ is coincident with vertical axis 396 . the angular inclined depth between adjoining wedge members 100 ′ and 102 ′ as taken along vertical center line 396 perpendicular to axis 384 ranges between 45 and 90 degrees . those knowledgeable in the art will also realize that opposing wedges 100 ′ and 102 ′ can also be utilized to provide the desired flow restriction with substantially the same results as a single wedge as disclosed in the prior art . in use , each combined wedge 98 ′ and cylindrical tube 381 must be pre - calibrated . in use , referring to fig .&# 39 ; s 1 - 4 , a housing 31 is selected for insertion in a fluid line to measure the fluid flow therethrough . an inner member 80 comprising a specific 360 degree wedge 98 and tube 81 configuration is selected based upon the type of fluid to be measured and the flow rate to be measured thereby . inner member 80 is telescopically inserted into first end 34 of housing 31 and aligned so that alignment pins 40 in circular recess 38 are received in alignment pin holes 88 of flange 86 ( as shown in fig4 ). engagement of pins 40 in holes 88 substantially centers first end 85 with respect to bore 42 ( as shown in fig2 ). upon full insertion chamfer 94 at second end 92 of inner member 80 is received by internal chamfer 39 of housing 31 . the tapered surfaces of chamfers 39 and 94 interact such to center the second end 92 of inner cylindrical tube 81 within internal bore 82 of housing 31 . flange 86 of inner member 80 is sealed against circular recess 38 and inner cylindrical tube 81 is centered along its length within internal bore 42 of housing 31 . since , the outer diameter of inner cylindrical tube 81 is smaller than bore 42 , a space 110 ( as shown in fig3 ) is defined by the outer diameter of tube 81 and inner bore 42 of housing 31 ( as shown in fig2 ). space 110 is sealed from internal bore 82 of inner member 80 except for pressure equalization hole 90 ( fig4 a ) which permits the fluid pressure within space 110 to be equalized with the pressure of the fluid flowing through internal bore 82 . however , because space 110 is otherwise sealed from internal bore 82 , there is no fluid flow therethrough . after inner member 80 is received and centered within internal bore 42 , hollow core bolts 55 are inserted in first and second port connections 47 and 49 . bolts 55 are threaded down until first o - ring 66 ( as shown in fig3 ) seals the upper portion of bore 51 from the fluid pressure in space 110 . further , bottom 63 of bolt 55 bears against circular land 108 of inner cylindrical tube 81 such that second o - ring 68 seals space 110 from internal bore 82 . lock nuts 56 are used to secure bolts 55 within port connections 47 and 49 to maintain the pressure seals created by o - rings 66 and 68 . pressure gauges or fluid pressure transmission lines ( not shown ) can be coupled with threaded bore 60 in head 58 of bolt 55 such that when a fluid flows through bore 82 , the pressure differential between pressure port 106 at port connection 47 upstream from the flow restrictor 97 can be compared with the pressure at pressure port 106 of port connection 49 downstream from flow restrictor 97 in a manner well known in the art to determine the fluid flow rate therethrough . the preferred embodiment permits the measurement of fluid flow in a bi - directional manner with out loss of metering accuracy in either direction . those skilled in the art will recognize that different flow restrictor sizes , shapes and configurations can be utilized to optimize the fluid flow metering performance of meter 30 , and that different quantities of pressure sensing ports can also be utilized as alternate embodiments . further , in addition to the foregoing description , those skilled in the art will readily appreciate that other modifications may be made to the invention without departing from the concepts disclosed herein . such modifications are to be considered as included in the following claims , unless these claims expressly state otherwise .