Patent Publication Number: US-2015086401-A1

Title: Retrofit of a reciprocating compressor with a concentric valve and a valve clamp having an inlet port in a top cover of the clamp

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     None 
     BACKGROUND OF THE INVENTION 
     Industrial compressors include three basic types: reciprocating, rotary screw, and rotary centrifugal. A reciprocating compressor is a positive displacement machine wherein a piston travels inside a cylinder wherein the piston intakes compressible fluid into the cylinder on a down stroke and exhausts compressible fluid by compressing the compressible fluid on the upstroke. The intake compressible fluid travels through a valve that prevents intake compressible fluid to escape through the inlet on the up stroke. The exhausted compressible fluid travels through a valve that prevents the exhausted compressible fluid from coming back into the cylinder on the down stroke. Thus, multiple reciprocations of the piston causes a volume of compressible fluid to be exhausted into a fixed volume holding tank thereby increasing the pressure inside the holding tank on every reciprocation. The piston continues its reciprocation until a desired pressure is reached in the holding tank. As the compressible fluid inside the holding tank is exhausted out of the holding tank, the piston is then reciprocated as needed to maintain a desired operating pressure. 
     Essential components for any reciprocating compressor are the valve that allows compressible fluid to flow into the cylinder on the down stroke and the valve that allows compressible fluid to exhaust out of the cylinder during the upstroke. The valves experience millions of cycles during their operating life and when a valve fails or begins to cease to operate effectively, the efficiency and effectiveness of the compressor significantly deteriorates.  FIG. 1  illustrates a very common configuration of a first stage of a reciprocating compressor assembly  200 . The assembly comprises a piston cylinder  202  having an inner diameter D 1  coupled to a valve head  204  with a seal  206  there between. The valve head  204  can also be called a cylinder head. Valve head  204  is a divided chamber head having an intake orifice  208  that allows compressible fluid to be drawn into an intake chamber  210 . One or Two intake valve assemblies  212  are seated within intake chamber  210  and configured to allow compressible fluid to enter the cylinder  202  during the piston&#39;s down stroke. For convenience only one of the two intake valve assemblies is shown. Each valve assembly includes a body  250 . The body is cylindrical and can be called a valve clamp or holder. The cylindrical body  250  carries a circular one way intake valve  253 . The valve carries one or more valve plates (not shown) which move from an open to a closed position. Each valve assembly  212  is a one way, modular, self-contained valve assembly. Valve head  204  further comprises at least one or two exhaust valve assemblies  214  configured to allow compressible fluid to flow out of cylinder  202  during the piston&#39;s up stroke into exhaust chamber  216  and subsequently out exhaust orifice  218 . For convenience only one of the valve assemblies  214  is shown. Each valve assembly includes a body  254 . The body is cylindrical and can be called a valve clamp or holder. The cylindrical body carries a circular one way exhaust valve  257 . The valve carries one or more valve plates (not shown) which move from an open to a closed position. The valve assembly is a modular, one way, self-contained valve assembly. Each body  250 ,  254  would also include a cap or closure (not shown) opposite its valve. Each intake valve assembly  212  is coupled to the valve head  204  and in fluid connection with the intake chamber  210 . Each valve assembly  212  extends through respective openings  210 ′ and  210 ″ of chamber  210 . The openings lead into the interior of chamber  210 . Each intake valve assembly  212  extends into chamber  210 . Each exhaust valve assembly  214  is coupled to the valve head  204  and in fluid connection with the exhaust chamber  216 . Each valve assembly  214  extends through openings  216 ′ and  216 ″ of chamber  216 . The openings lead into an interior of chamber  216 . Each valve assembly  214  extends into chamber  216 . Chamber and openings  210 ,  210 ′,  210 ″ are separate, isolated and sealed off from chamber  216  and openings  216 ′,  216 ″. Valve assemblies  212  and  214  are coupled to valve head  204  with threading  220  as shown or can be externally bolted (not shown). Valve head  204  is coupled to piston cylinder  202  from above using a plurality of head fasteners  222  inserted through head apertures  227  and through cylinder apertures  224  in the cylinder flange  226  as illustrated. The valve head  204  carries a quad valve arrangement. The prior art also includes dual one way valve arrangements. In this case there is only one intake  212  and one exhaust  214  valve. The valve head is configured accordingly. As an alternative to the above it is be possible that the head and cylinder is integrated as one piece with no gasket between. 
     Many of these multiple valve compressors have been in operation and either in part or fully the valves have reached the end of their functional life. Partially functioning valves are difficult to recognize, and can significantly affect the overall compressor performance as well as contribute to subsequent subsystem damage. In addition, many of these cases the individual valves have, over the years, become very difficult to remove individually as the connections become fused, or the fasteners corrode to a point that it is extremely difficult to remove the individual valve that is not operating correctly. Further, if one valve is not functioning correctly, it becomes a decision whether to replace the non-functioning valve or all the other valves at the same time. Either option results in increased maintenance costs because replacing the valve before the end of its functional life is wasteful, but paying for maintenance personnel to return to the pump to replace the valve also involves an increase in maintenance costs. Moreover, as the relative labor to material cost differential has changed, the industry maintenance standard has become to remove the entire valve head and valves and replace it with a new or rebuilt valve head including new valves already installed into the head. This method, while more cost effective than trying to replace one or both valves individually, still generates considerable waste and consumes unnecessary maintenance cost resources. 
     The vast majority of these compressors have a substantial remaining functional life. 
     SUMMARY OF THE INVENTION 
     A method for retrofitting a reciprocating compressor embodies the invention. The method includes selecting for removal from a piston cylinder a first valve head. The first valve head is configured to house at least a one way intake valve assembly in an intake chamber of said head and at least a one way exhaust valve assembly in an exhaust chamber of said head. The intake and exhaust chambers sealed off from each other. The first valve head is removed from the piston cylinder. A second valve head is selected. A bottom of the second valve head is removably coupled to the piston cylinder. A concentric two-way valve is seated within the second valve head. The concentric valve is secured within the second valve head with a valve clamp having a top cover. An intake opening of an intake port tis positioned over an intake portion of said concentric valve. The intake opening is positioned at the top of the second valve head. Positioning the intake port, including its intake opening, includes arranging the top cover having the intake opening over the concentric valve, over the intake portion of the concentric valve, and at the top of the second valve head. 
     An assembly of a compressor that is retrofitted includes an existing piston cylinder, a valve head including an exhaust orifice removably coupled to the piston cylinder, a concentric two-way valve carried within the valve head, and a valve clamp having an intake port with an intake opening in a top cover of the valve clamp. The valve clamp removably coupled to the valve head to secure the valve within the valve head. 
     The valve clamp extends into a central hollow of the valve head and contacts and secures the concentric valve within the valve head. The valve clamp includes an annular first wall having an inner face and an outer face, the inner face of annular first wall may define an intake chamber. The valve clamp may also include an annular second wall outside the first wall, wherein the second wall has an inner face and an outer face. The inner face of the second wall and the outer face of the first wall may define an exhaust chamber. 
     The two-way valve may include a spring-loaded plunger to hold open an intake portion of the two-way valve, and facilitate the unloading of the compressor cylinder by allowing intake compressible fluid to escape during the piston up stroke. The valve clamp may also include a plunger housing. The plunger housing may be supported with a plurality of support arms. The plurality of support arms may divide the intake port into a plurality intake ports wherein the intake port is in fluid connection with the intake chamber of the valve clamp. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The accompanying drawings form a part of the specification and are to be read in conjunction therewith, in which like reference numerals are employed to indicate like or similar parts in the various views, and wherein: 
         FIG. 1  is a perspective view of a prior art embodiment of a quad valve head; 
         FIG. 2   a  is a perspective exploded view of one embodiment of a valve retrofit assembly in accordance with the teachings of the present invention; 
         FIG. 2   b  is a perspective exploded view of the valve retrofit assembly shown in  FIG. 2   a  except  FIG. 2   b  includes a filter adaptor not shown in  FIG. 2   a ; and 
         FIG. 3  is a cross-section of the embodiment of the valve retrofit assembly of  FIG. 2   a  taken along the line  3 - 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description of the invention references the accompanying drawing figures that illustrate specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The present invention is defined by the appended claims and the description is, therefore, not to be taken in a limiting sense and shall not limit the scope of equivalents to which such claims are entitled. 
       FIG. 2  provides an example of a concentric valve head assembly  10  to retrofit with the existing reciprocating compressor piston cylinder  202  shown in  FIG. 1 . Concentric valve head assembly  10  includes a valve head  12 ; a concentric valve  14  housed within valve head  12 ; and a valve clamp  16  that secures concentric valve  14  within valve head  12 . The assembly also includes seals  18  for preventing intake compressible fluid and exhaust compressible fluid from escaping their designated flow paths. 
     Valve head  12  can also be called cylinder head  12 . As shown in  FIG. 2 , valve head  12  includes a top  20 , a bottom  22 , a sidewall  24 , a top flange  26 , an exhaust orifice  28  and a hollow  30 . The hollow  30  is delimited in the radial direction by inner surface  34  of side wall  24 . Accordingly, sidewall  24  in part defines a substantially hollow valve head  12 . 
     Sidewall  24  has an outer face  32  and an inner face  34  formed by inner surface. The sidewall  24  has an axial length defined by top  20  and bottom  22  of valve head  12 . The axial length is measured along the axis of the valve head  12 . The axis extends from the top  20  to the bottom  22  and through hollow  30 . Further, outer face  32  is an outer surface. The outer face of sidewall  24  may include annular ribs  36  around its circumference and may also include vertical ribs (not shown) spanning substantially from bottom  22  to top  20  and radially distributed around the circumference of outer face  32 . The pattern of annular ribs  36  and vertical ribs, if any, may serve in part to increase the stiffness of sidewall  24 . They may also provide for heat exchange with ambient air by increasing the exposed surface area of the valve head. Sidewall  24  may, alternatively, have a substantially smooth outer face and substantially uniform thickness (not shown). The exhaust orifice  28  opens and extends through side wall  24 . 
       FIG. 2  further shows top flange  26  of valve head  12  extending around the circumference of top  20  of sidewall  24 . Flange  26  may also be called an end wall of head  12 . Top flange  26  includes a plurality of continuous head coupling apertures  40  that extend continuously and substantially vertical through top  20  and bottom  22  of sidewall  24 . Head coupling apertures  40  may be distributed around the circumference of top flange  26  in a known pattern that matches the pattern of cylinder apertures  224  of existing reciprocating compressor assembly  200  shown in  FIG. 1 . Concentric valve head assembly  10  may be removably coupled to cylinder  202  of existing compressor assembly  200  with head fasteners  42  that extend through head coupling apertures  40  and into or through cylinder apertures  224 . Head fasteners  42  are configured to removably couple valve head  12  to cylinder  202  of  FIG. 1 . Fasteners  42  and fasteners throughout this disclosure may include bolts, screws, clamps, or any other fastening method now known or hereafter developed to result to removably couple two elements. Another embodiment of the present invention could include valve head  12  being permanently coupled to a cylinder through a permanent coupling method including welds or single casting. In this case the single piece casting would replace a separately cast existing head, cylinder and a mating gasket. The existing head and cylinder to be replaced would have the same type of one way modular valves as discussed herein. 
     Valve head  12  may be configured and proportioned to be used with existing piston cylinders  202  of varying manufactures and diameters D 1  as shown in  FIG. 1 . Top flange  26  and the pattern and location of head coupling apertures  40  thereon may be configured to match the pattern of apertures  224  on an existing piston cylinder  202  of various manufacturers now known or hereafter developed. In this manner, a user may select a valve head  12  configured to be used with the piston cylinder  202  of a certain manufacturer having a certain size. 
     As further shown in  FIG. 2 , concentric valve  14  is a single modular element that performs dual functions and replaces the necessity of two or multiple one way valves. Concentric valve  14  is divided into at least two operable portions including an intake portion  46  and an exhaust portion  48 . One embodiment of concentric valve  14  has a circular shape and includes intake portion  46  including and surrounding the center of concentric valve  14  and exhaust portion  48  occupying the outer ring of concentric valve  14  as best shown in  FIG. 3 . One embodiment of the present invention may include intake portion  46  and exhaust portion  48  having substantially identical areas for allowing the intake and exhaust flow to be substantially equal. 
     As shown in  FIG. 3 , concentric valve  14  includes two circular plates combined in one element. Valve  14  provides valved flow of fluid in at least two substantially opposing directions. A first plate  81  is at a top  98  of valve  14 . A second plate  85  is at a bottom  96  of valve  14 . The two plates  81  and  85  are circular and can be called circular discs. The construction of concentric valves is known in the art and any such construction now known or hereafter developed may be incorporated into valve head assembly  10  of the present invention. Concentric valve  14  may also include a push rod assembly which includes a spring loaded plunger  50  whose main function is to move fingers  52  down thus holding the intake portion of valve  14  and thus stopping the compression process. Air flows into intake portion  46  and back out without compression. The push valve assembly is also known as a suction valve un-loader. An un-loader supply port  88 ′ is in fluid connection with plunger  50 . The supply port extends completely through rib  88  extending across opening  59 ′ of port  59 . The port  88 ′ also extends through radially opposite sides of ring  61 . A first end of rib  88  terminates at a first side of the of the ring  61  through which port  88 ′ extends. An opposite second end of rib  88  terminates at a second side of ring  61  radially opposite the first side of the ring. The port  88 ′ extends through the second side of ring  61 . When the supply port  88 ′ is pressurized the plunger  50  is activated and the fingers  52  are pushed down. The compressor operates off-load. When the supply port  88 ′ de-pressurized the compressor operates under load. 
       FIG. 2 , further shows valve clamp  16  including a top cover  54  that includes coupling tabs  56 . A recessed portion  57  may be present between each tab  56 . Each tab  56  may include an aperture  58  therethrough. This configuration ensures that tabs  56  fit in-between head fasteners  42  when fasteners  42  are in an installed position in apertures  40  and the head  12  is coupled to cylinder  202 . Each tab may also include lift-off apertures  89 . The apertures receive threaded bolts to help valve clamp  16  lift off head  12 . Valve clamp  16  includes an intake port  59  having an opening  59 ′ which opens through a top of valve clamp  16 . The intake port  59  has a recessed pocket  59 ″axially between opening  59 ′ and a top surface of arms  86 . The intake port  59  is in fluid connection with intake portion  48  of valve  14 . The intake port  59  and opening  59 ′ are in a central region of the top cover. The intake opening  59 ′, recessed pocket  59 ″ and central region are bounded by a raised ring portion  61  of top cover  54  of valve clamp  16 . Intake opening  59 ′ opens through raised ring portion  61 . The intake port  59  may alternatively be called an intake orifice. 
     Now turning to  FIG. 3 , valve clamp  16  further includes a first wall  60  extending away from a bottom surface  63  of top cover  54 . The first wall is annular. First wall  60  includes an inner face  62  and an outer face  64 , the inner face  62  and outer face  64  define a wall thickness in the radial direction. First wall  60  also includes a seal protrusion  66  extending from and formed at a free end of first wall  60 , wherein the seal protrusion  66  may have a lesser wall thickness than defined by inner face  62  and outer face  64 . Seal protrusion  66  is configured to be received into a groove  68  in top  98  of concentric valve  14 . The protrusion  66  and groove are annular. An O-ring seal  18  may be seated on the outer radial face of protrusion  66  to create a seal between first wall  60  and concentric valve  14  as shown. 
     Also shown in  FIG. 3 , valve clamp  16  includes an annular second wall  70  radially outward of first wall  60  and extending away from bottom surface  63  of top cover  54 . First wall  60  and second wall  70  may be substantially concentric. First wall  60  and second wall  70  may be substantially tubular. Second wall  70  has an inner face  72  and an outer face  74 . Second wall  70  may include one or more apertures  76 ′ through both inner and outer faces  72  and  74 . Some of the exhaust may flow out of exhaust portion  48 , through second wall  70  by way of the apertures  76 ′. From the apertures  76 ′ the fluid flows into a portion of the hollow  30 , a gap  92 , between the outer face  74  and the inner surface  34  of head  12  and from the gap passage in hollow  30  into and out exhaust orifice  28 . The second wall  70  also has an aperture  76 ″ adjacent and overlapping the exhaust orifice  28 . The adjacent and overlapping nature allows some of the exhaust fluid to flow into and out orifice  28  without traversing as much of the hollow  30  as exhaust fluid passing through aperture  76 ′. As further shown, outer face  64  of first wall and inner face  72  of second wall  70  define a space which may be an exhaust chamber  79  that is in fluid connection with exhaust portion  48  of two-way concentric valve  14 . Most of the fluid that enters exhaust chamber  79  traverses the chamber  79  until it reaches aperture  76 ″. It exits chamber  79  through aperture  76 ″ and out orifice  28 . Notably air that passes through apertures  76 ′ into gap portion of hollow  30  contacts inner surface  34  of head  24  and is cooled due to heat exchange. 
     As further shown in  FIG. 3 , inner face  62  of first wall  60  defines an intake chamber  78 . Valve clamp  16  includes a plunger housing  80  that comprises a body  82  and a plunger nest  84  configured to receive plunger  50  as shown. An O-ring  18  radially about a top of the plunger  50  seals the plunger  50  to a wall delimiting. Plunger housing  80  may be supported proximate the center of raised ring  61  of top cover  54  with a plurality of support arms  86 . Support arms  86  may be disposed radially outward from plunger housing  80  and rib  88 . Rib  88  spans across raised ring  61  and divides inlet opening  59 ′. The rib  88  increases the rigidity of plunger housing  80 , and as stated facilitates the ducting of the pressurized air necessary to activate the plunger  50 . As shown in  FIG. 2 , support arms  86  are in a “cross” orientation and, therefore, divide intake port  59  into four defined inlet ports  90   a - d  which form inlet port  59 . Inlet port  59  is in fluid connection with intake chamber  78 . The chamber  78  is in fluid connection with intake portion  46 . The fluid connections place intake portion  46  in fluid connection with the exterior environment or other intake channel. For instance in the shown embodiment the intake port  59  is in fluid connection with a port formed in and extending through a tube  300 . The tube  300 , at a first end  301 , is coupled to the ring  61 . The coupling places intake port  59  in fluid connection with the port formed in tube  300 . The tube  300  at a second end  302  is coupled to a filter (not shown). The tube orients and fluidly connects a filter to head  12  in a place near where it would be connected to head  204  and inlet  208 . The second end  302  has the same connection configuration as the connection configuration around inlet  208 . There may be any number of arms  86  disposed in any pattern which define any number of inlet ports  90  as sufficient to provide the necessary intake port area to provide the desired intake fluid flow. 
     When exhaust portion  48  of valve  14  is open, exhaust chamber  79  is in fluid connection with the piston chamber of cylinder  202  allowing the exhaust to flow into exhaust chamber  79  and through apertures  76 ′,  76 ″. From apertures  76 ′ the exhaust fluid flows into gap portion  92  of hollow  30 . From the gap portion  92 , the exhaust fluid flows into and out of orifice  28 . From the aperture  76 ″ the exhaust fluid flows into orifice  28 . Thus exhaust portion  48  is in fluid connection with exhaust chamber  79 ; exhaust chamber  79  is in fluid connection apertures  76 ′,  76 ″; the aperture  76 ′, are in fluid connection with gap portion  92 , gap portion  92  is in fluid connection with orifice  28 . Aperture  76 ″ is in fluid connection with orifice  28  and also gap portion  92 . The first wall  60  isolates the intake port  59 , intake chamber  78  and intake portion  46 , from the exhaust portion  48 , the exhaust chamber  79 , the exhaust orifice  28 , and the gap portion  92  in a manner to substantially prevent exhaust fluid passing out of the exhaust portion from leaking into the intake chamber and to substantially prevent fluid in the exhaust chamber  79 , exhaust orifice  28 , gap portion  92 , and hollow  30  from leaking into the intake chamber and being drawn into the intake portion  46 . The first wall  60  fluidly separates the intake portion  46  from the exhaust portion  48 . It separates the exhaust fluid from the intake fluid. It diverts the flow to the exhaust orifice from the intake chamber. Wall  60  is a flow diverter. 
     Now turning to  FIG. 3 , assembled valve head assembly  10  of the present invention is illustrated in cross section. As shown, inner face  34  of sidewall  24  is positioned at a radius R 1  from the center of valve head  12  and defines a single axially extending hollow passageway  30  therethrough and outer face  32  is located at a radius R 2  from the center of valve head  12  wherein the difference between R 2  and R 1  substantially defines the thickness of sidewall  24  in the radial direction. The gap portion  92  extends circumferentially around the axis of head  12 . This gap portion  92  has at least a portion at an axial height measured from the bottom  22  of the valve head  12  which is the same as the axial height of a least a portion of the orifice  28 . Opposing ends of gap portion  92  terminate at orifice  28 . Further, inner face  34  of sidewall  24  includes a valve seat  94  that concentric valve  14  bears upon within valve head  12 . 
     As further shown in  FIG. 3 , a portion of the circular valve plate at the bottom  96  of concentric valve  14  is seated on valve seat  94  and valve clamp  16  is inserted within the hollow passageway  30  defined by inner face  34  of valve head  12  such that second wall  70  of valve clamp  16  bear against top  98  of concentric valve  14 . Valve clamp  16 , and more particularly second wall  70 , contacts and secures valve  14  within valve head  12  against valve seat  94 . The second wall primarily serves to clamp and secure the valve  16  in sealing engagement with head  12 . The valve  16  is sealed to the head  12  with the aid of O-ring  18  coupled around the perimeter of valve  16  and situated between valve  16  and inner face  34  of head  12 . Concentric valve  14  may also be nested against inner face  34  of sidewall  24  by any other means known in the art including the outside of concentric valve being angled upward and outward and being wedged into a portion of inner face  34  similarly configured to receive concentric valve  14 . 
     To secure concentric valve  14  within valve head  12  with valve clamp  16 , a plurality of clamp fasteners  100  are inserted through apertures  58  of top cover  54  of valve clamp  16  and into clamp apertures  44  of top flange  26  and operated to removably couple valve clamp  16  to valve head  12 . One or more seals or O-rings  18  may be positioned on outside face  74  of second wall  70  of valve clamp  16  just under top cover  54  as shown in  FIG. 3 . One of the apertures  44 ′ has a position radially offset from the other apertures  44 . The clamp has one aperture  58 ′ also radially offset to match the radial offset of aperture  44 ′. Having the radial offset apertures ensures that the clamp  16  is coupled to the head  12  to orient the valve clamp aperture  76 ″ with orifice  28  in an overlapping alignment. 
     Valve head assembly  10  of the present invention is used to retro-fit existing piston cylinders  202  of a reciprocating compressor assembly  200  shown in  FIG. 1  by replacing a valve head  204  with valve head assembly  10  that incorporates a concentric valve  14 . Replacing valve head  204  with valve head assembly  10  results in more efficient operation of the reciprocating compressor and substantially reduces maintenance costs with respect to replacing warn out valves. To affect replacement, a user will first remove the existing valve head  204  from piston cylinder  202 . The valves  214  and  212  can be removed with the head. The head is removed by releasing a plurality of fasteners  222  coupling the head  204  to the cylinder  202 . Seal  206  is removed and cylinder flange  226  of piston cylinder  202 . The flange  226  is cleaned and prepared to receive valve head  12  of valve assembly  10 . A replacement seal, sealant, or combination thereof may be placed between valve head  12  and cylinder flange  226  to provide an air-tight seal. The replacement concentric valve head is designed to provide equivalent flow capability as to the existing head which utilizes 2 intake valves and 2 exhausts valves. Although  FIG. 1  shows a quad valve, it is within the scope of the invention to replace a dual valve head. In this case the valve head replaced only carries one intake valve  212  and one exhaust valve  214 . Valve head  12  is removably coupled to piston cylinder  202 . More particularly valve head  12  is placed in sealing engagement with cylinder flange  226  and aligned such that head coupling apertures  40  are aligned with apertures  224  in cylinder flange  226 . Head fasteners  42  are inserted into and extended through head coupling apertures  40  and are extended through or received by apertures  224  through flange  226 . Fasteners  42  are tightened to securely and removably couple valve head  12  to piston cylinder  202 . 
     Concentric valve  14  is placed into hollow  30  of valve head  12 . A portion of the circular plate of the bottom  96  of concentric valve  14  is rested upon valve seat  94  as shown in  FIG. 3 . Intake port  59  is arranged over concentric valve  14 . The intake port is arranged over the intake portion  46  of the concentric valve. The intake port  59  is arranged at the top  20  of the head. The intake opening  59 ′ is arranged in the same manner as the intake port  59 . Arranging the intake opening  59 ′ as described above includes arranging the intake port opening  59 ′ in the top cover  54  over the concentric valve, over the intake portion  46 , and at the top of the head. Arranging the intake port  59  as described above includes arranging the intake port  59  formed in the valve clamp  16  over the concentric valve  14 , over the intake portion  46 , and at the top  20  of the head. Valve clamp  16  is inserted into hollow  30  of valve head  12 . First wall  60  is arranged to be in sealing engagement with concentric valve  14 . The seal protrusion  66  is received into groove  68  at the top  98  of concentric valve  14 . The second wall  70  bears on top  98  of concentric valve  14 . When seal protrusion  66  is received into groove  68 , upon valve clamp  16  being secured to valve head  12 , the intake chamber  78  is effectively sealed from the exhaust passageway  79  and second wall  70  bears against and seats concentric valve  14  within valve head  12  as shown in  FIG. 3 . Valve clamp  16  is removably coupled to valve head  12 . More particularly, valve clamp  16  is positioned such that apertures  58  align with clamp apertures  44  on top flange  26 . Fasteners  100  are inserted through apertures  58  and are received into clamp apertures  44  to couple valve clamp  16  to valve head  12 . The fasteners are tightened to removably secure the clamp  16  to the head. Then, any existing intake pipes, such as 300, may be coupled to ring  61  or ring may be coupled directly to a filter. Exhaust pipes may be coupled to valve head  12  and the reciprocating compressor is ready for operation. 
     In operation, the piston in piston cylinder  202  is stroked and repeatedly translated upward and downward within piston cylinder  202 . On the downs stroke, compressible fluid is drawn in through intake port  59  through opening  59 ′. Fluid passes form intake  59  into intake chamber  78 . In the present valve head assembly  10 , the placement of the intake port  59  varies from configurations in the prior art. Typically, as shown in  FIG. 1 , intake orifice  208  is located on the side of a valve head. However, the present valve head assembly  10  re-positions the intake port  59  at the top of the head. The port  59  has its opening at the top and centrally located in the valve clamp. It is at and in the valve top cover. The opening  59 ′ and port  59  is over the intake portion  46 . The positioning results in benefits over a known configuration of a removable valve head having a two way concentric valve. The known head (side entry head) has both the intake and exhaust orifices/outlets located in the sidewall of the valve head. The details are shown in U.S. Patent Publication No. 2013/0121860. 
     In the present disclosure, because the intake ports are directly above the intake chamber  78  and intake portion  46  of concentric valve  14 , the incoming air does not have to make any turns or be directed toward the intake portion  46  of concentric valve  14 . Repositioning the intake ports  90  to the top of the present valve head assembly  10  allows the axial height of the valve head  12  to be reduced as compared to the side entry head. The axial height reduction reduces the amount of material saving on material costs. The reduced height also makes the compressor more compact which may be desirable to a person of skill in the art because in many applications, the compressors are located in tight spaces and the reduced height makes it easier maintain or repair the present valve head assembly  10 . 
     Other benefits measured through operational testing indicates that having the intake ports  90  directly above the intake chamber  78  and valve  14  reduces the temperature of the air flow within the valve clamp  16  by an average of 11.8 degrees Fahrenheit as compared to the side entry head. The temperature was measured at test location  102  just above the intake portion  46  of concentric valve  14 . The reduced air temperature may provide for more air to be present in a given volume which may thereby increases the volume of flow for identical piston sizes and piston revolutions per minute. For example, in one embodiment of the present valve head assembly  10 , compared to the side entry head design, the flow volume increased from 148.0 inlet cubic feet per minute (“icfm”) to 172.0 icfm. This results in a sixteen percent (16%) increase in the volume of air flowing through the intake over having the intake orifice in the side of the valve head when the pistons are driven at the same piston velocity such as rpm. 
     The temperature and pressure measurements are made during a continually running condition wherein the compressor was driven at a specific speed and allowed to run continually at a specific discharge pressure. The inlet temperature measurement and flow measurement are taken simultaneously. The inlet temperature was measured using a thermocouple and electronic measurement equipment. The flow measurement is done similarly, but by measuring the pressure loss across an orifice at the package discharge. The pressure loss is used in a calculation that allows for other variables including ambient inlet temperature, barometric pressure, and relative humidity. The present valve head assembly  10  performs best when retrofit in single stage compressor or, when compressors with multiple heads and multiple stages are present, the present valve head assembly  10  performs best when retrofit at the low-pressure heads of the first stage. The high-pressure heads perform better when retrofit with the retro-fit the side entry head assembly described in U.S. Patent Publication No. 2013/0121860. Although, it is within the scope of the present invention for the present valve head assembly  10  to be used to retro-fit any compressor head. 
     Now further describing the operation of the present valve head assembly  10 , after air is drawn into the intake chamber  78 , intake portion  46  of concentric valve  14  opens to allow intake compressible fluid to be drawn into cylinder  202  as indicated in  FIG. 3  by arrow  104 . Upon the up-stroke of the piston  228  within cylinder  202 , compressible fluid in cylinder  202  is compressed upward. Intake portion  46  of concentric valve  14  closes and exhaust portion  48  of concentric valve  14  opens allowing compressible fluid to be forced out of cylinder  202 . The exhaust fluid flows through concentric valve  14  into exhaust chamber  79  between first wall  60  and second wall  70 , through apertures  76 ′,  76 ″ in second wall  70 , and some of the exhaust fluid flows into gap portion  92 . The exhaust fluid then flows out exhaust orifice  28  as indicated in  FIG. 3  by arrow  106 . The piston of the reciprocating compressor  200  cycles repeatedly until one or both of concentric valve portions  46  and/or  48  wears out. 
     In the event one or both concentric valve portions  46  and/or  48  wear out, a user will remove valve clamp  16  by releasing or removing fasteners  100  and pulling valve clamp  16  upward and out of hollow valve head  12 . The user may then remove concentric valve  14  by pulling it upward off of seat  94  and remove it from valve head  12 . The user may then insert a new or rebuilt concentric valve  14  such that new or rebuilt concentric valve  14  seats on valve seat  94  and the user may then re-insert valve clamp  16  into hollow  30  of valve head  12  and couple top cover  54  to valve head  12  as described above. 
     The retro-fit of an existing reciprocating compressor with the valve head assembly  10  of the present invention as described above substantially reduces the time and materials required to maintain the reciprocating compressors and increases the efficiency of the existing compressors by allowing the valve to be immediately proximate the piston of the reciprocating compressor. 
     From the foregoing it will be seen that this invention is one well adapted to attain all ends and objects hereinabove set forth together with the other advantages which are obvious and which are inherent to the structure. 
     It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. 
     Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense.