Abstract:
When a fluid passes through a conventional elbow or valve in a piping system, turbulence is created in the fluid flow. The fluid may not stabilize and return to a laminar flow until 40-50 pipe diameters downstream. Turbulence in a piping system can cause a variety of problems such as noise, vibration, and/or erosion. Turbulence also creates a pressure drop which is undesirable. The flow diffuser of the present invention may be configured as a 90° elbow for use in a piping system to reduce turbulence and pressure drops as the fluid passes through the improved elbow. The elbow of the present invention included an elongate tapered discharge nozzle. The elbow can restore substantially laminar flow in a space of about four pipe diameters.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates a flow diffuser with an elongate discharge nozzle which can be used as a 90° elbow in piping systems. In an alternative embodiment, the flow diffuser can be used in conjunction with a fire hydrant. The present flow diffuser facilitates better measurement because it promotes laminar flow. 
     2. Description of the Prior Art 
     In piping systems, orderly or streamlined flow is desirable. When a fluid passes through a conventional valve or a 90° turn at a conventional elbow, the fluid flow becomes disorderly or turbulent. This turbulent fluid does not return to a streamlined or laminar flow for at least 40-50 pipe diameters downstream of an elbow. (Assuming that the downstream piping is axially aligned with the outlet of the valve or elbow and has the same inside diameter.) 
     Turbulence can be caused by a number of factors including, but not limited to, boundary layer separation, sometimes referred to as flow separation, vortices, pressure waves, and/or cavitation. Turbulence in pipe systems often causes noise, vibration, erosion and/or stress cracking. Reduction of turbulence is desirable in valves, at elbows, in piping systems generally, upstream of gas or liquid measurement and downstream of compressor stations. 
     Turbulence also causes a drop in fluid pressure. Each time a fluid flows through a valve or an elbow, there is an incremental drop in fluid pressure between the inlet and the outlet. In transmission pipelines, pressure drops are undesirable. If the fluid pressure drops low enough, additional pumping stations may be required. In any event, adding pressure to the fluid in the pipeline increases transportation costs. Because the elbow of the present invention reduces turbulence, it has less of a pressure drop when compared with conventional 90° elbows. 
     Elbow induced turbulence has been recognized and addressed by a number of prior art designs including the vanes of U.S. Pat. No. 5,197,509 and U.S. Pat. No. 5,323,661 which are located upstream from an elbow. These vanes impart rotation to the fluid as it passes through the elbow to reduce downstream turbulence. Others have considered the deleterious effects of elbow induced turbulence and have included rotation vanes both upstream and downstream of an elbow as described in U.S. Pat. No. 5,529,084. These inventions seek to create non-turbulent or laminar flow after fluid passes through a conventional elbow. 
     The use of curved vanes to influence fluid flow for various reasons is not a new concept. In U.S. Pat. No. 1,570,907, a plurality of vanes were used in a locomotive to separate water from steam. 
     In some piping systems, granular or particulate material will quickly wear out a conventional elbow. One way to address this problem is by increasing the radius of curvature of the elbow to about 10 pipe diameters. However, this is not entirely an acceptable solution, especially in areas where space is at a premium. There have been many attempts to solve this erosion problem, including the use of inserts in the elbow, the insert being a disposable item intended to be replaced when it wears out. Examples of this type of replaceable insert in an elbow can be found in the following U.S. Pat. Nos. 1,357,259; 2,911,235; 3,942,684; and 5,590,916. 
     Other proposed solutions to this erosion problem include a circular pocket off the elbow. This pocket accumulates a certain quantity of the particulate material which serves as a pad to absorb the blow of the subsequent material to reduce the erosive effects thereof as shown in U.S. Pat. Nos. 4,387,914 and 5,060,984. 
     Conventional valves are also known to create turbulence and a pressure drop between the inlet and the outlet. Robert H. Welker, the inventor herein and the inventor of U.S. Pat. No. 5,730,416, has developed various approaches to deal with valve induced turbulence. In another patent, U.S. Pat. No. 5,769,388, Mr. Welker has developed a plurality of vanes and passageways in the valve to reduce turbulence. The apparatus shown in U.S. Pat. No. 5,769,388 has certain shortcomings because of the short discharge nozzle which tapered at an included angle of approximately 12°. There is still a need to reduce turbulence in elbows, in valves and in piping systems in general. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention can be used as a 90° elbow in piping systems to reduce turbulence and promote laminar flow. It can also be used in conjunction with a fire hydrant. The elbow is connected to an inlet conduit and an outlet conduit. The elbow includes three primary components: a flow conditioner, a transition zone, and an elongate tapered discharge nozzle. The discharge nozzle should have a taper with an included angle of about 5°-7.5° measured from the circular outlet of the tapered discharge nozzle. If the discharge nozzle tapers at a 7° included angle, it will have a length of about four times the diameter of the inlet conduit. 
     The flow conditioner includes a plurality of vanes defining a plurality of passageways to guide the fluid flow from the inlet into the transition zone. The purpose of the guide vanes is to reduce turbulence and promote a streamlined and/or laminar flow as the fluid turns a 90° corner. The flow conditioner can be fabricated as a replaceable part to facilitate maintenance of the elbow. In an alternative embodiment, the individual vanes can be replaceable to facilitate maintenance and prolong the life of the valve. The transition zone includes a curved outer wall extending from the side wall of the flow conditioner, the transition zone being in fluid communication with the tapered discharge nozzle. 
     The elbow can be used in piping systems with liquids, gases, and steam, as well as two-phase flow, three-phase flow, and dry particulate and granules. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the above-identified features and advantages of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiment thereof which is illustrated in the appended drawings. 
     It is noted, however, that the appended drawings illustrate only a typical embodiment of this invention and is therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. Reference the appended drawings, wherein: 
     FIG. 1 is a section view of the elbow with the flow conditioner and cap in exploded view. 
     FIG. 2 is a section view of the elbow of FIG. 1 with the flow conditioner and cap fully assembled. 
     FIG. 3 is a section view of the elbow along the line  3 — 3  of FIG.  1 . 
     FIG. 4 is an enlarged partial section view of flow conditioner, vanes and passageways of FIG.  3 . 
     FIG. 5 is an enlargement of the inlet, and flow conditioner along the line  5 — 5  of FIG.  1 . 
     FIG. 6 is a section view of the rectangular inlet of the discharge passageway in the discharge nozzle at the line  6 — 6  of FIG.  1 . 
     FIG. 7 is a section view of the polygonal interior surface of the discharge passageway in the discharge nozzle at the line  7 — 7  of FIG.  1 . 
     FIG. 8 is a section view of the polygonal interior surface of the discharge passageway in the discharge nozzle at the line  8 — 8  of FIG.  1 . 
     FIG. 9 is a section view of the circular outlet of the discharge passageway in the discharge nozzle at the line  9 — 9  of FIG.  1 . 
     FIG. 10 is a partial section view of an alternative embodiment of the elbow with replaceable vanes and side wall. 
     FIG. 11 is a section view of a vane attached with screws to the body along the line  11 — 11  of FIG.  10 . 
     FIG. 12 is a section view of the cap, a screw and removable cylindrical tip. 
     FIG. 13 is a section view of an alternative embodiment of the elbow that can be used in conjunction with a fire hydrant. 
     FIG. 14 is a bottom perspective view of the flow conditioner of FIGS. 1-5. 
     FIG. 15 is a bottom perspective view of the flow conditioner of FIGS. 10 and 11. 
     FIG. 16 is a bottom perspective view of the flow condition of FIG.  13 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1, a flow diffuser is generally identified by the numeral  10  and is shown in exploded view. The top of the flow diffuser  10  is generally identified by the arrow  11  and the bottom is generally identified by its numeral  13 . The flow diffuser is configured as a 90° elbow  10  to be used in a piping system, not shown. The flow diffuser  10  has a body  12  which defines an inlet  14  and an outlet  16 . An inlet conduit, not shown in the drawing, has a flange that aligns and mechanically connects by a bolt circle to the inlet flange  18  of the elbow  10 . The inlet flange  18  has a plurality of bolt holes, for example at  20  and  22  which receive the bolts for securing the inlet conduit flange to the inlet flange  18  of the elbow  10 . An outlet conduit, not shown in the drawing, has a flange which aligns and is connected to the outlet flange  24  of the elbow  10  by a bolt circle. The outlet flange  24  of the flow diffuser  10  has a plurality of bolt holes, for example at  26  and  28  which align with the bolt holes in the outlet conduit flange. The alignment and connection of the inlet conduit flange and the outlet conduit flange to the flanges  18  and  24  of the elbow  10  in a piping system is well known to those skilled in the art. 
     To reduce turbulence, the inside diameter of the inlet  14  should be about the same as the inside diameter of the inlet conduit. To reduce turbulence, the inside diameter of the outlet  16  should be about the same as the inside diameter of the inlet conduit. To reduce turbulence, the inside diameter of the outlet conduit should also be about the same as the inside diameter of the inlet conduit. 
     In FIG. 1 bolt holes  20 ,  22 ,  26  and  28  are shown at a 12 o&#39;clock and 6 o&#39;clock position merely for illustrative purposes. One skilled in the art will recognize that the actual locations of these bolt holes are out of hand about 16° from the position shown in these drawings for a 4 inch flange. 
     As indicated by the arrow in FIG. 1, fluid flows into the inlet  14 , past the throat  29 , through the flow conditioner  30 , into the transition zone  32 , through the discharge passageway  33  of the elongate tapered discharge nozzle  34 , through the outlet  16 , and finally into the outlet conduit, not shown in the drawing. The present invention can be used with liquids, such as water, gasoline, diesel and other hydrocarbons. It can also be used with gases, including natural gas and/or other hydrocarbons. It can be used for two-phase flow, such as a cold slurry or natural gas with entrained liquids. It can also be used with three-phase flow, such as oil, water and gas. It can be used with steam and it can be used with dry particulate or granules. For purposes of this application, all of the foregoing will simply be referred to as fluid. 
     The elbow  10  includes a removable cap  36 . The cap  36  can be threadably attached to the body  12 , it can be welded to the body  12 , or attached by other means well known in the art. From an operational perspective, the elbow includes three primary components: a flow conditioner  30 , a transition zone  32 , and a discharge passageway  33  in the elongate tapered discharge nozzle  34 . As a matter of manufacturing convenience, the flow conditioner  30  can be manufactured as a separate part that is inserted into receptacle  38  in the body  12  by removing the cap  36 . Once the removable flow conditioner  30  is inserted into the receptacle  38  of the body  12 , the cap  36  is replaced and secured. In some conditions, the flow conditioner may experience more wear than other components in the elbow  10 . To facilitate maintenance and prolong the life of the elbow  10 , the flow conditioner is replaceable. 
     When fluid passes through a conventional 90° elbow in a piping system, turbulence is generated because of the 90° turn. Conventional wisdom indicates that laminar flow does not return to the fluid stream after it passes through a 90° elbow until as much as 40 to 50 pipe diameters past the elbow (assuming an axially aligned straight discharge pipe having the same inside diameter as the elbow). For example, with a conventional 2 inch elbow and 2 inch piping system, laminar flow may not return until as much as 80 inches to 100 inches downstream of the elbow. It is desirable for many reasons to restore laminar flow as quickly as possible after a fluid passes through a 90° elbow. A length of 40 or 50 pipe diameters is simply impractical in many real world applications. 
     The present invention restores substantially laminar flow to a fluid stream after it passes through the 90° turn within about 4 pipe diameters after the transition zone  32 . Reducing the distance necessary to achieve substantially laminar flow from 40 or 50 pipe diameters to about 4 pipe diameters is an advantage in a number of situations, especially in close quarters, such as offshore drilling or production platforms. In addition, the elbow  10  is able to restore laminar flow after the fluid passes through this 90° turn with reduced noise and vibration when compared with a conventional elbow. Reduction in noise and vibration is accomplished because of the reduced turbulence in the elbow  10  when compared with prior art elbows. 
     To function properly, the flow conditioner  30  must be aligned properly in the receptacle  38 . To ensure proper alignment, an aligning pin  56  is mounted in the body  12  and the pin  56  protruded into the receptacle  38 . An aperture is formed in the flow conditioner  30  and is shaped to receive the pin  56 . When the removable flow conditioner  30  is inserted in receptacle  38 , proper alignment is assured because the pin  56  must register with the hole for the flow conditioner  30  to sit flat in the receptacle  38 . Other aligning means may also be used which are well known to those skilled in the art. For example, a slot could be formed in the flow conditioner  30  which registers with a lug extending from the body  12  into the receptacle  38 . In the alternative, aligning key ways could be formed in the body  12  and the flow conditioner  30  to receive a key to ensure proper alignment. 
     FIG. 2 is a section view of the elbow  10  of FIG. 1, with the cap  36  and flow diffuser  30  assembled for operation. The flow conditioner  30  has a top  40  and a bottom  42 . The guide vanes  50   a-q  are positioned between the top  40  and the bottom  42  of flow conditioner  30 . The flow conditioner  30  also includes a side wall  44  which extends from the top surface  40  to the bottom surface  42 . The side wall  44 , the top  4  and the bottom  42  contain the fluid flow in the flow conditioner  30 . The flow conditioner  30  includes an outlet port identified generally by the dotted curved line  46  better seen in FIG.  3 . The outlet port  46  is defined by the side wall  44 , the top surface  40  and the bottom surface  42  of the flow conditioner  30 . 
     The inlet  14  feeds the fluid into an inlet zone  48  better seen in FIG. 3. A generally conical protrusion  54  extends from the top  36  into the inlet zone  48 . The area of the inlet zone  48  is reduced by the area of the generally conical protrusion  54 ; however, in the preferred embodiment, the inlet zone  48  has an area at least twice the cross-sectional area of the inlet  14 . 
     FIG. 3 is a section view of the elbow  10  along the line  3 — 3  of FIG. 1 except the conical protrusion  54  is not shown. In other words, FIG. 3 is a section view of the elbow  10  viewed from the top  11 . A positioning pin  56  is mounted in the body  12  and extends into the receptacle  38 . The pin  56  aligns with a hole in the flow conditioner  30  to properly position the flow conditioner  30  in the receptacle  38 . An aligning pin  56  also prevents the flow conditioner  30  from moving during operation of the apparatus and aligns the vanes for proper operation of the elbow. Vanes  50   a-p  define a plurality of curvilinear passageways  52   a-q . In the preferred embodiment, 16 passageways are shown; however, a larger number or a smaller number of passageways can be used depending on the fluid matrix, pressure, pipe size and other operational parameters. The side wall  44  of the flow conditioner  30  together with the top  40  and the bottom  42  direct fluid flow as it exits the passageways  52   a-q . The guide vanes have a generally heart-shaped outline. Each passageway  52  has a beginning  58  and an ending  60 . The beginning  58  in fluid communication with the inlet zone  48  and the ending  60  is in fluid communication with the transition zone  32 . In the preferred embodiment, the area of each beginning  58  has a cross-sectional area that is about twice as large as the cross-sectional area of the end  60 . The width of each passageway  52  at the beginning  58  is preferably equal to the circumference of the inlet zone  48  divided by the number of passageways  52 . The area of the beginning  58  and the end  60  at the width of each passageway  52  may be adjusted depending on the fluid matrix, pressure, pipe size and other operational parameters. 
     The taper of the discharge nozzle  34  is important to reduce turbulence of the fluid as it passes from the transition zone  32  towards the outlet conduit. Applicant prefers a taper with an included angle of about 5°-7.5°. The included angle of taper will determine the length of the discharge nozzle  34  as shown in the table below. 
     
       
         
               
             
               
               
               
               
             
           
               
                   
               
               
                 Discharge Nozzle Lengths 
               
             
          
           
               
                   
                 Diameter of 
                   
                   
               
               
                   
                 Inlet Conduit 
                 7° Included Angle 
                 5° Included Angle 
               
               
                   
                   
               
               
                   
                 1″ 
                 App. 4.1″ 
                 App. 6.53″ 
               
               
                   
                 2″ 
                 App. 8.2″ 
                 App. 13.05″ 
               
               
                   
                 4″ 
                 App. 16.4″ 
                 App. 26.11″ 
               
               
                   
                 6″ 
                 App. 24.5″ 
                 App. 39.16″ 
               
               
                   
                 8″ 
                 App. 32.7″ 
                 App. 52.22″ 
               
               
                   
                 12″ 
                 App. 49.1″ 
                 App 78.33″ 
               
               
                   
                   
               
             
          
         
       
     
     As indicated in this table, a discharge nozzle  34  tapered at a 7° included angle will have a length approximately 4 times the diameter of the inlet conduit. A discharge nozzle tapered at a 5° included angle will be longer and have a length approximately 6½ times the diameter of the inlet conduit. 
     As shown in FIG. 3, the interior surface  66  of the discharge nozzle  34  has a taper of 3.5° on all surfaces as measured from lines extended parallel to the outlet conduit. The tapered discharge nozzle  34  extends from the line  6 — 6  to the line  9 — 9 . The parallel lines in the drawing extend parallel to the walls of the outlet  16 . The outlet  16  has parallel sides aligned with the outlet conduit to reduce turbulence. 
     In FIG. 4, an enlarged section view of the flow conditioner  30  similar to the view in FIG. 3 without the conical protrusion  54 . Fluid flows from the inlet  14  into the inlet zone  48  which has a larger area than the cross-sectional area of the inlet  14 . The fluid encounters the conical protrusion  54 , the guide vanes  50   a-p  and the beginning  58  of each curvilinear passageway  52   a-q  as shown by the flow arrows. The fluid then passes through the passageways  52   a-q  and moves into the transition zone generally identified by the numeral  32 . The transition zone  32  is defined by an upper portion  70  and a lower portion  72  of the body  12  and a curved outer wall  74 , which is likewise a portion of the body  12 . In the preferred embodiment, the curved outer wall  74  has a radius about 2½ times the diameter of the inlet  14 . The transition zone  32  is in fluid communication with the outlet opening  46  of the flow conditioner  30 , and the elongate tapered discharge nozzle  34 . The diameter of the flow conditioner from point R to point S in the preferred embodiment is approximately  3  times the diameter of the inlet  14 . 
     FIG. 5 is an enlarged section view of the flow conditioner  30  along the line  5 — 5  of FIG.  1 . The flow conditioner  30 , the top  36  and the surrounding body portions  12  are shown in greater detail. The conical protrusion  54  extends into the inlet zone  48 . The conical protrusion  54  has a symmetric concave surface  80 . In the preferred embodiment, the radius of the concave surface  80  is about equal to the radius of the inlet  14 . However, other radiuses are suitable and, in fact, the protrusion  54  can be shaped as a pure cone instead of a generally concave surface. A streamlined shoulder  82  completely surrounds the throat  29 . The radius of the streamlined shoulder is about ⅛ the diameter of the inlet  14 . The ramp  84  extends from this radius as a tangent taken on a 90° angle. 
     FIG. 6 is a section view of the discharge nozzle  34  along the line  6 — 6  of FIG.  1 . The interior surface  86  of the discharge nozzle  34  defines a discharge passageway  33  with a generally rectangular shaped inlet  88 . In the preferred embodiment, the height of the rectangular shaped inlet  88  is about ½ the diameter of the inlet  14  and the width of the rectangular inlet  88  is about 1.5 times the diameter of the inlet  14 . However, other dimensional configurations for this rectangle fall within the scope of this invention and may be adjusted, depending upon the fluid matrix, pressure, pipe size, and other operational parameters. 
     FIG. 7 is a section view of the discharge nozzle  34  along the line  7 — 7  of FIG.  1 . The interior surface  86  begins to change shape from the generally rectangular inlet  88  to a polygon as shown in the drawing. Other polygonal shapes fall within the scope of this invention, provided that the interior surface  86  maintains a taper with an included angle of about 5°-7.5°. 
     FIG. 8 is a section view of the discharge nozzle  34  along the line  8 — 8  of FIG.  1 . The interior surface  86  is polygonal. Other polygonal shapes fall within the course of this invention, provided that they are tapered as discussed above. 
     FIG. 9 is a section view along the line  9 — 9  of FIG. 1 showing the discharge nozzle  34  as it converges to a circular outlet  90 . The diameter of the circular outlet  90  is approximately equal to the diameter of the inlet  14 . The inlet conduit and the outlet conduit should be approximately equal in diameter and cross-sectional area to reduce turbulence. The cross-sectional area of the discharge passageway  33  as it extends from line  6 — 6  to line  9 — 9  should be approximately the same. The rectangular shaped discharge passageway  88  should have approximately the same cross-sectional area as the circular outlet  90 . The length of the discharge nozzle  34  from the line  6 — 6  to the line  9 — 9  for a 7° included angle is about 4 times the diameter of the inlet  14 . The length of the discharge nozzle  34  from the line  6 — 6  to the line  9 — 9  with a 5° included angle is about 6½ times the diameter of the inlet  14 . FIG. 10 the elbow  10  is viewed from the bottom  13 . 
     FIG. 10 is a partial section view of an alternative embodiment of the flow conditioner generally identified by the numeral  100 . In this alternative embodiment, each vane  50   a - 50   p  is replaceable. In this alternative embodiment, the side wall  102  is also replaceable. In this embodiment, the top of the flow conditioner  100  is formed from a flat plate  101 . The bottom  106  of this flow conditioner is formed by the receptacle  38 . In other words, this flow conditioner  100  does not have the same top  40  and the bottom  42  as the flow conditioner  30 . These differences are necessitated primarily by the different fluid matrices and other operational parameters that may vary from application to application and different manufacturing preferences. 
     In some situations with uniform wear characteristics, it will be easier and cheaper to replace the unitized flow conditioner  30  of FIG.  1 . The unitized flow conditioner  30  also isolates and protects the body  12 , the cap  36  and the receptacle  38  from the erosive effects of the fluid which may in some situations prolong the life of the elbow. In other situations, it may be easier and cheaper to replace only a few selected vanes of the alternative embodiment shown in FIG.  10 . The apparatus of FIG. 10 allows the fluid to come into contact with the plate  101  and the bottom  106  of the receptacle  38 . In some applications, this is desirable and in others it may be undesirable. If wear and erosion on the body becomes severe, the unitized flow conditioner  30  of FIG. 1 is preferable. If wear on the vanes is more severe, then the flow conditioner  100  of FIG. 10 may be a better choice. 
     The vane  50   a  is secured by a first bolt  108  and a second bolt  110  to the plate  101 . Likewise, vane  50   b  is secured by a first bolt  112  and a second bolt  114  to the plate  101 . Each of the other vanes  50   c - 50   p  are likewise each attached by two bolts to the plate  101 . 
     FIG. 11 is a cross-section view along line  11 — 11  of FIG. 10. A portion of the vane  50   a  is shown in section view along with bolts  108  and  110 . These bolts threadably engage the plate  101 . The plate  101  abuts the cap  36  on the topside of the elbow  10  and protects the cap  36  from fluid flow. The bottom edge of the vane  50   a  about the bottom  106  of the receptacle  38 . 
     FIG. 12 is a cross-section view of the top  36  and a removable conical tip  114 . A bolt  116  passes through a hole in the top and is sealed by washer  118 . The bolt  116  threadably engages the removable conical tip  114 . The removable conical tip  114  can be used in conjunction with the flow diffuser  100  shown in FIG.  10 . This allows selective removal and replacement of wear parts, i.e. the conical tip  114 , the vanes  50   a - 50   p  and the side wall  102 . In certain situations, the ability to selectively remove and replace worn parts may have advantages over removal and replacement of the integral flow conditioner  30  of FIG.  1 . 
     Repair kits for the flow conditioner shown in FIGS. 10,  11  and  12  would include replaceable vanes  50   a-p , screws, the replaceable side wall  102  and replaceable conical tip  114 . 
     FIG. 13 shows a cross-section view of another alternative embodiment of the diffuser that may be used on a fire hydrant. In this embodiment, the elbow generally identified with the numeral  120  can rotate to facilitate connection of a fire hose to the fire hydrant. The hose and hydrant are not shown in this drawing. Also another embodiment of the flow conditioner  122  is shown. 
     The fire hydrant is designed with a special outlet  124 . A yoke assembly is generally identified by the numeral  125 . The outlet  124  forms a circumferential channel  126  that receives one side of a circular yoke  128 . The body  12  likewise forms a circumferential channel  130  that receives the other side  132  of the yoke  128 . The yoke is secured by cross bolts  134 ,  136 ,  138  and  140 . The yoke  128  is sealed in a circular channel  126  by an o-ring  142  and in channel  130  by an o-ring  144 . This yoke  128  thus allows the elbow  120  to rotate about the fire hydrant outlet  124  to make hose attachment easier. The outlet  124  is further sealed against the body  12  by an o-ring  146  positioned in o-ring groove  148 . The yoke assembly  125  includes the yoke  128 , the cross bolts  134 ,  136 ,  138  and  140 , and the o-ring seals  142 ,  144  and  148 . 
     In this alternative embodiment, the flow conditioner  122  has a flat top plate  150  that is connected to the vanes  50   a - 50   p . The bottom of the flow conditioner  122  is formed by the bottom  106  of the receptacle  38 . In other words, the fluid comes in contact with the bottom  106  of the receptacle  38 . In this embodiment, the conical tip  114  is also removably attached to the cap  36  by bolt  116  as shown in FIG.  12 . This allows replacement of the tip  114  without having to replace the entire flow conditioner  112 . Threads  152  are formed on the end of the discharge nozzle  34  to threadably engage the coupling on the end of a fire hose, not shown. The flow conditioner  122  with slight modifications to the body  12  can be used in lieu of the flow conditioner  30  in FIG. 1 or in lieu of the flow conditioner  100  of FIG.  10 . 
     Again, this embodiment of the flow conditioner  122  may have advantages in certain applications over the embodiment shown in FIG. 10 or the embodiment of FIG.  1 , depending on where erosion and wear is most pronounced. The embodiment of FIG. 13 may also be easier to manufacture than the embodiment in FIG.  1 . However, the embodiment of FIG. 13 allows the fluid to contact the body  12  at the bottom  106  of the receptacle  38 . This may or may not be a disadvantage based on the application. At present, Applicant believes that the flow conditioner  122  of FIG. 13 is the best mode because it isolates fluid flow from contact with the cap  36  and presently is the easiest to manufacture. 
     It may be that wear is not a problem and manufacturing convenience is the primary issue. Regardless of how it is configured, the flow conditioner includes at a minimum, a top, a bottom, a side wall, and a plurality of vanes. In the best mode is also includes a generally conical tip which may or may not be removable. 
     While the foregoing is directed to the preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims which follow. 
     FIG. 14 is a bottom perspective view of the flow conditioner  30  of FIGS. 1-5. The top surface  40  is flat. The bottom surface  42  is curvilinear. The sidewall  44  connects the top surface  40  and the bottom surface  42 . The outlet port  46  is defined by the sidewall  44 ; the top surface  40  and the bottom surface  42  of the flow conditioner  30 . The circular inlet zone is generally identified by the numeral  48 . 
     FIG. 15 is a bottom perspective view of the flow conditioner  100  of FIGS. 10 and 11. This second embodiment has removable vanes that attach to a flat top plate  101  via a plurality of screws. The bottoms of the vanes are curvilinear. 
     FIG. 16 is a bottom perspective view of the flow conditioner  122  in FIG.  13 . This third embodiment has a flat top plate and the vanes are rigidly attached thereto. The bottoms of the vanes are curvilinear. 
     It should be understood that the three embodiments of the flow conditioner  30  of FIG. 14,  100  of FIG. 14 and 122 of FIG. 16 may be used in the elbow  10  or on the fire hydrant of FIG. 13, depending on the application. All three have flat tops and curvilinear bottoms. 
     At present, Applicant believes that the third embodiment of FIG. 16 is the best mode and recommends it for both the elbow  10  of FIG.  1  and the fire hydrant of FIG.  13 .