Abstract:
The compressor head, internal and/or external discriminator, and manifold design in general utilize ball valves on the suction and discharge of a cylinder head in the recovery of refrigerant liquid and/or vapor. The device facilitates the flashing of liquid refrigerant pumped to the compressor which, in turn, assists to cool the compressor head. The flashing of liquid refrigerant to vapor also deters liquid transfer into the compressor enhancing performance thereof. The vapor passages within the discriminator, cylinder head and/or manifold are sized for receipt of spring actuated ball&#39;s to open and/or close the vapor passages during suction and/or discharge of refrigerant vapor or liquid by the compressor.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims benefit of and priority to U.S. Provisional Patent Application Ser. No. 60/366,208, filed Mar. 21, 2002, the entire contents of which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     Refrigerant recovery devices are used in the repair of refrigeration equipment to reclaim/recover refrigerant vapor and/or liquid.  
         [0003]     Generally, devices utilized to recover refrigerant vapor and/or liquid include compressors having cylinders, compressor heads, pistons and valves. In the past it was common to use a triangular shaped poppet valve as a portion of the compressor head used to recover refrigerant vapor during repair of a refrigeration system. The problem with the use of poppet valves is the exposure of the valve to liquids. A poppet valve exposed to liquid will frequently be pulled into the suction chamber by a piston during the piston down stroke. When the piston proceeds to the upstroke, the piston may crush the poppet valve against the cylinder head destroying the compressor. Alternatively, compressors as known may utilize reed valves. The problem with reed valves is the failure to provide acceptable performance following exposure to liquids which will blow and destroy the reed valve causing compressor failure.  
         [0004]     In the past, discriminators have been used to differentiate between liquid and gas refrigerants during the refrigerant recovery process. The known discriminators were generally electronic devices which attempted to separate liquid from vapor by sensing the pressure of the liquid or vapor and then redirecting the liquid or vapor through the use of solenoid valves to open or close ports of the inlet into the compressor. Electronic discriminators are frequently very costly and oversized reducing utility in practical applications. In the past, another method utilized to separate liquid from vapor occurred by employing a cycling solenoid. The compressor was generally protected in this embodiment, however, the flow of liquid and/or vapor through the compressor was not maximized.  
         [0005]     Manifolds are normally an integral portion of a compressor utilized to recover refrigerant vapors and/or liquids. The manifolds as known generally utilize extremely complicated circuitry and normally employ the use of three valves. A need exists to reduce the complication of circuitry used within manifolds and to reduce the complexity, number, and to improve the types of valves utilized within a manifold which is a portion of a device used for the recovery of refrigeration vapor and/or liquids from a refrigeration system.  
       GENERAL DESCRIPTION OF THE INVENTION  
       [0006]     The compressor head, internal and/or external discriminator, and manifold design in general utilize ball valves on the suction and discharge of a cylinder head in the recovery of refrigerant liquid and/or gasses. The device facilitates the flashing of liquid refrigerant pumped to the compressor which, in turn, assists to cool the compressor head. The flashing of liquid refrigerant to vapor also deters liquid transfer into the compressor enhancing performance thereof. The vapor passages within the discriminator, cylinder head and/or manifold are sized for receipt of spring actuated ball&#39;s to open and/or close the vapor passages during suction and/or discharge of refrigerant vapor or liquid by the compressor.  
         [0007]     A principal advantage of the present invention is the provision of a compressor formed of relatively simple and inexpensive design and construction which fulfills the intended purpose of recovering refrigerant vapor and/or liquid without risk of damage to refrigeration equipment and/or injury to individuals.  
         [0008]     Another principal advantage of the present invention is the provision of a discriminator formed of relatively simple and inexpensive design, construction, and operation which fulfills the intended purpose of recovering refrigeration vapor and/or liquid without risk of damage to refrigeration equipment and/or injury to individuals.  
         [0009]     Still another principal advantage of the present invention is the provision of a compressor head formed of relatively simple and inexpensive design, construction, and operation which fulfills the intended purpose of recovering refrigeration vapor and/or liquid without risk of damage to refrigeration equipment and/or injury to individuals.  
         [0010]     Still another principal advantage of the present invention is the provision of a manifold formed of relatively simple and inexpensive design, construction, and operation which fulfills the intended purpose of recovering refrigeration vapor and/or liquid without risk of damage to refrigeration equipment and/or injury to individuals.  
         [0011]     Still another principal advantage of the present invention is to prevent a valve from being drawn into the suction chamber of a compressor when exposed to liquid to prevent crushing of the valve against the cylinder head and damage to the compressor.  
         [0012]     Still another principal advantage of the present invention is to provide at least one, and preferably two, ball valves within the cylinder head for communication with the suction chamber and discharge chamber of the compressor.  
         [0013]     Still another principal advantage of the present invention is the provision of a discriminator which flashes liquid refrigerant to vapor during the recovery of refrigerant for minimization and/or elimination of refrigeration liquid entry into the compressor.  
         [0014]     Still another principal advantage of the present invention is the provision of a discriminator which flashes liquid refrigerant to vapor reducing the temperature of the cylinder head during operation of the compressor.  
         [0015]     Still another principal advantage of the present invention is the provision of a ball valve in the suction chamber is a cylinder head which enables the discharge valve to be fully open, while preventing the suction valve from being drawn into the compressor.  
         [0016]     Still another principal advantage of the present invention is the provision of a compressor head which does not heat incoming vapor by exposing the incoming vapor to vapor to be discharged, which in turn, reduces the heat of the compressor.  
         [0017]     Still another principal advantage of the present invention is the provision of a compressor head which eliminates stress points of known valves, such as poppet valves, thereby extending the useful life of the valves and the compressor head.  
         [0018]     Still another principal advantage of the present invention is the provision of a compressor head which is flexible and which may be easily and efficiently maintained by convenient replacement of balls functioning within the intake and discharge valves eliminating the necessity of replacement and discard of an entire compressor head.  
         [0019]     Still another principal advantage of the present invention is the provision of a discriminator which automatically and mechanically distinguishes recovered refrigeration liquid from gas or vapor permitting the compressor to safely function.  
         [0020]     Still another principal advantage of the present invention is the provision of a discriminator which minimizes the volume of flow of liquid enabling the flashing of the liquid to a vapor during refrigerant recovery efforts.  
         [0021]     Still another principal advantage of the present invention is the provision of a discriminator which includes a ball valve where the ball of the ball valve is buoyant with respect to liquid refrigerant.  
         [0022]     Still another principal advantage of the present invention is the provision of a discriminator which includes a ball valve where the ball drops and does not float when recovered refrigerant is in the vapor phase.  
         [0023]     Still another principal advantage of the present invention is the provision of a discriminator which includes a ball valve which assists in metering the volume of liquid refrigerant to be exposed to the compressor during refrigerant recovery procedures.  
         [0024]     Still another principal advantage of the present invention is the provision of a discriminator which includes a ball valve which, in turn, floats when exposed to liquid refrigerant shutting off the intake and/or inlet passage of the compressor during refrigerant recovery efforts.  
         [0025]     Still another principal advantage of the present invention is the provision of a discriminator which includes a ball valve where the ball includes rivulets permitting a minimum volume of a refrigerant liquid to bypass the valve for flashing into vapor and for passage to the compressor during use of the refrigerant recovery apparatus.  
         [0026]     Still another principal advantage of the present invention is the provision of a discriminator which includes a ball valve where minimal amounts of liquid refrigerant are forced around the ball, bypassing the valve, where the liquid is exposed to negative pressure on the opposite side of the ball valve causing the flashing of the liquid refrigerant into vapor while simultaneously cooling the compressor head.  
         [0027]     Still another principal advantage of the present invention is the provision of a manifold which enables simpler valves to be utilized within the intake and discharge ports.  
         [0028]     Still another principal advantage of the present invention is a manifold which redirects flow of recovered refrigerant into desired circuitry so that the recovery and/or purpose of a refrigerant recovery system may be accomplished.  
         [0029]     Still another principal advantage of the present invention is the provision of a manifold which assists in the discrimination between recovered liquid and/or vapor refrigerant for control of the flow of the liquid and/or vapor refrigerant to maximize operation and useful life of a compressor.  
         [0030]     Still another principal advantage of the present invention is the provision of a manifold which may include a third valve utilized to purge a refrigeration system under maintenance and repair.  
         [0031]     Still another principal advantage of the present invention is the provision of a manifold which does require a control device on the suction side enabling continued operation of the compressor during the presence of liquid refrigerant.  
         [0032]     Still another principal advantage of the present invention is the provision of a manifold which simplifies the refrigerant recovery circuitry by the presentation of all desired valves, gauges, inlets, and outlet ports proximate to the same phase.  
         [0033]     Still another principal advantage of the present invention is the provision of a manifold which permits convenient mounting of safety devices within minimal tubing and fixtures utilized during the refrigerant recovery procedures. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)  
       [0034]      FIG. 1  is an isometric view of the refrigerant recovery system;  
         [0035]      FIG. 2  is a detail isometric view of the manifold;  
         [0036]      FIG. 3  is a detail cross-sectional side view of the discriminator;  
         [0037]      FIG. 4  is an alternative detail cross-sectional side view of the discriminator;  
         [0038]      FIG. 5  is a detail cross-sectional side view of a fitting;  
         [0039]      FIG. 6  is an alternative detailed cross-sectional side view of a fitting;  
         [0040]      FIG. 7  is an alternative detailed cross-sectional side view of an external discriminator;  
         [0041]      FIG. 8  is an isometric view of a cylinder head;  
         [0042]      FIG. 9  is an alternative isometric view of a cylinder head;  
         [0043]      FIG. 9A  is a detail cross-sectional side view of a cylinder head taken along the line  9 - 9  of  FIG. 9 ;  
         [0044]      FIG. 10  is a cross-sectional side view of a cylinder head taken along the line of  10 - 10  of  FIG. 8 ;  
         [0045]      FIG. 11  is a detail view of the manifold;  
         [0046]      FIG. 12  is a three dimensional view showing the improved vacuum sensor mounted on a circuit board;  
         [0047]      FIG. 13  is a two dimensional schematic showing the improved vacuum sensor mounted on a circuit board; and  
         [0048]      FIG. 14  is a circuit schematic of the improved vacuum sensor. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0049]     In general, the compressor head, internal/external discriminator, manifold refrigerant recovery system is indicated by the numeral  10 . The compressor head, internal/external discriminator, manifold refrigerant recovery system  10  initiates with a refrigeration system  12  which is in need of servicing. Frequently, during servicing of a refrigeration system  12 , liquid and vapor refrigerant is recovered and is not discarded into the environment.  
         [0050]     Conventional compressors  14  may be utilized during the refrigerant recovery process, where the conventional compressors  14  include motors, rotors, and/or stators as known. Generally, the compressor  14  functions to withdraw lubricating and cooling emulsions from a system  12  subject to repair for ultimate transfer into a temporary storage tank  16 .  
         [0051]     In general, a refrigeration system contains liquid oil which may be used for lubrication and rust prevention for internal parts of the refrigerant circulation system. In general, liquid refrigerant  104  is vaporized in an evaporator which permits the absorption of heat from a surrounding environment. Oil within a refrigeration system may be maintained in a liquid state as a result of a higher evaporation point. Oil and liquid refrigerant may flow together with vapor refrigerant within a closed refrigeration system. The existence of oil/liquid refrigerant within a compressor cylinder may cause severe damage to a piston and/or to the inner wall of the compressor cylinder or valve plate. Further, liquid oil and/or liquid refrigerant may deter the compression of vapor refrigerant thereby decreasing the efficiency of the compressor  14 .  
         [0052]     Referring to  FIG. 1 , the refrigeration system subject to servicing  12  is generally in vapor and fluid flow communication with a manifold  18  through the use of a first conduit or hose  20 . The refrigeration system  12  may include a first outlet  22  and the manifold  18  may include a first inlet  24 . The first outlet  22  and the first inlet  24  may further include fittings to facilitate coupling of the first conduit or hose  20 .  
         [0053]     In general, the manifold  18  includes vapor and/or liquid circuits which define passages for vapor and/or liquid flow through the manifold  18  to the second outlet  28 . A discriminator  30  is preferably positioned in fluid and vapor flow communication with the second outlet  28  of the manifold  18 . In an alternative embodiment, the manifold  18  may be replaced with an external discriminator  30  as described herein.  
         [0054]     An internal discriminator  30  is preferably positioned to the interior of the manifold  18  proximate to the second outlet  28 . The discriminator  30  preferably functions to eliminate the transfer of liquid to a compressor. The discriminator  30  also preferably functions to flash the liquid refrigerant from a liquid phase to a vapor phase prior to introduction into the compressor  14 .  
         [0055]     A second conduit or hose  32  is preferably in communication with the discriminator  30  providing a vapor passageway to the cylinder head inlet  34 . The cylinder head inlet  34  is preferably in vapor passage communication with the cylinder head  36  which in turn includes vapor passages which are in communication with the piston cylinder and piston. The cylinder head  36  preferably includes a first ball valve  38  which is proximate to the cylinder head inlet  34  and a second ball valve  40  which is proximate to the cylinder head outlet  42 .  
         [0056]     Refrigerant in the vapor phase passes through the compressor  14 , cylinder head  36 , and cylinder as known where the piston down stroke creates suction for drawing of vapor into the cylinder head  36  and into the cylinder where the piston up stroke discharges refrigerant vapor through the cylinder head outlet  42  into a conduit or hose  43  for return to manifold  18 . Vapor refrigerant is then transferred to condenser  218  by a conduit/hose  43 . The condenser  218  is connected to the condenser return port  210  of the manifold  18  by another conduit or hose  43 . Recovered refrigerant then exits the manifold  18  for passage through a third conduit or hose  44  for transfer into a temporary storage tank  16 .  
         [0057]     The temporary storage tank  16  may include an inlet valve  46  which may be a one way check valve or any other type of valve for passage of refrigerant into the temporary storage tank  16 .  
         [0058]     As may be seen in  FIG. 2  and  FIG. 11 , the manifold  18  is generally rectangular block shaped. Internal to the manifold  18  is the vapor/liquid circuit  194  defining liquid and vapor flow passages which terminate proximate to the second outlet  28 . A first fitting  48  may be threadably coupled within the first inlet  24  for releasable affixation to the first conduit or hose  20  as secured to the refrigeration system  12  subject to service. The discriminator  30  may be included internally within the manifold  18  proximate to the second outlet  28 . A second fitting  50  may be threadably coupled to the second outlet  28 . The second conduit or hose  32  may be releasably coupled to the second fitting  50  to provide a vapor passage to the cylinder head inlet  34 .  
         [0059]     The manifold  18  preferably functions to separate drawn liquid and/or vapor refrigerant from the refrigeration system  12  as passing to the compressor/cylinder. The manifold  18  further functions to prevent passage of liquid refrigerant to the compressor/cylinder thereby minimizing risk of damage to the compressor  14  during refrigerant recovery efforts.  
         [0060]     The first inlet  24  may include a first set of receiving threads  52  which are adapted to receivably engage a second set of penetrating threads  54  of the first fitting  48 . The fitting  48  may include a third set of penetrating threads  56  which are adapted for coupling to a receiving set of threads integral to a fitting within a distal end of the first conduit or hose  20 .  
         [0061]     The second outlet  28  also preferably has a fourth set of receiving threads which are adapted to receivably engage a fifth set of penetrating threads of the second fitting  50 .  
         [0062]     The manifold  18  includes a cavity  62  which is positioned below and in communication with the second outlet  28 . The cavity  62  is the location of the termination of the closed vapor/liquid refrigeration circuit/passages  194  of the manifold  18 .  
         [0063]     The discriminator  30  is positioned in vapor/fluid flow communication with the vapor/liquid circuit passages  194 , cavity  62 , and second outlet  28  of the manifold  18 . The discriminator  30  includes a retainer  64  which is generally cylindrical shaped having a base  66 . The retainer  64  has a lateral passage identified by arrow  68  which is defined by substantially aligned opposing openings  70 . The retainer  64  also preferably includes an open top  72 . Below the lateral passage  68  is a liquid accumulation region  74 . A ball  76  is positioned internal to the retainer  64 . ( FIGS. 3 and 4 .) The retainer  64  is preferably affixed, secured, and/or integral to the bottom  78  of second fitting  50 . The fifth set of penetrating threads  60  are located proximate to the bottom  78  of fitting  50 .  
         [0064]     Fitting  50  includes a grasping region  80  which is used for tightening relative to manifold  18 . Immediately below the grasping region  80  is preferably located an O-ring  82 . The O-ring  82  is preferably positioned between the bottom surface of the grasping region  80  and the top surface of the manifold  18  to provide for a sealing engagement between the second fitting  50  and the second outlet  28  of the manifold  18 .  
         [0065]     The fitting  50  preferably includes an upper section  84  which includes a sixth set of penetrating threads  86 .  
         [0066]     Within the interior of the second fitting  50  is preferably a vapor passage in general identified by the numeral  88 . The vapor passage  88  preferably includes a first region  90  which is positioned proximate to the exit port for the fitting  50 . A second region  92  is positioned below the first region  90  and includes opposing spring ledges  94 . Generally, the second region  92  is larger in size or diameter than the first region  90 . A spring  96  is located within the second region  92 . The spring  96  is prohibited from positioning within the first region  90 , and exit from the second fitting  50 , by engagement to the spring ledges  94 . The second region  92  terminates at a first seat  98  which is positioned proximate to the open top  72  of the retainer  64 . The spring  96  extends from the opposing spring ledges  94  downwardly through the second region  92  and through the open top  72  of the retainer  64  into the liquid accumulation area  74  for engagement to the ball  76 .  
         [0067]     The ball  76  is generally spherical and formed of any type of plastic or other material which is buoyant and/or floats and is further inert upon exposure to liquid refrigerant. One example of a material used for the ball  76  is PDFE plastic or an equivalent material thereof.  
         [0068]      FIG. 3  shows the relative positioning of the ball  76  as proximate to the base  66  within the interior of the retainer  64 . In this position the spring  96  is fully expanded where the compressor  14  is drawing vapor refrigerant through the manifold  18  from the refrigeration system  12  being serviced. Arrow  100  identifies the vapor flow through the lateral passages  68  upwardly past the spring  96 , second region  92  and into the first region  90  for exit from the second fitting  50  and into the second conduit/hose  32 .  
         [0069]     The O-ring  82  functions to provide a vapor seal with the exterior surface of the manifold  18  proximate to the second outlet  28 .  
         [0070]     The first seat  98  preferably includes an arcuate wall  102  which is adapted for contact with the exterior surface of the ball  76  when the compressor  14  is drawing liquid refrigerant within the liquid accumulation region  74 . The positioning of the ball  76  upwardly in contact with the arcuate wall  102  preferably closes access to the second region  92  preventing passage of liquid refrigerant out of the second fitting  50  and manifold  18  during recovery of vapor refrigerant.  
         [0071]      FIG. 4  shows the liquid accumulation region  74  holding liquid refrigerant  104 . The level of the liquid refrigerant  104  has preferably elevated to the level of the lateral passage  68  of the retainer  64 . The closed vapor/liquid circuit  26  of the manifold  18  causes the liquid refrigerant  104  to accumulate within region  74  to elevate ball  76  to compress spring  96  for positioning of ball  76  within the first seat  98  to close vapor passage  88  preventing the suction of liquid refrigerant  104  from the discriminator  30  through the second conduit or hose  32  and into the cylinder head  36 . The integrity of the compressor  14  and cylinder head  36  is thereby maintained by the prevention of exposure to liquid refrigerant  104 .  
         [0072]     The buoyancy of the ball  76  upon the liquid refrigerant  104  is preferably of sufficient strength to compress spring  96  within the second region  92  and against the opposing spring ledges  94 . The lowering of the level of liquid refrigerant  104  within the accumulation region  74  permits the spring  96  to expand for lowering of the ball  76  toward the base  66  of the retainer  64 . The separation of the ball  76  from the first seat  98  permits vapor refrigerant passage into the second region  92  and out of the first region  90  for transfer to the cylinder head  36  by way of the second conduit or hose  32 .  
         [0073]      FIG. 5  is a detail view of the second fitting  50  showing the arcuate wall  102  of the first seat  98 . The arcuate wall  102  is preferably adapted for sealing engagement with the exterior of the ball  76  at such times as the accumulation region  74  is filled with liquid refrigerant  104 .  
         [0074]     The spring  96  and ball  76  thereby function to restrict the passage of liquid refrigerant  104  through the second fitting  50  during the recovery of refrigerant from a refrigeration system  12 .  
         [0075]     Referring to  FIG. 6 , the first seat  98  preferably includes a plurality of rivulets/striations  106  which create minute flow passages between the open top  72  of the retainer  64  and the second region  92  of the vapor passage  88 . During positioning of the ball  76  within the first seat  98 , the rivulets/striations  106  establish minute fluid flow passages into the second region  92  of the vapor passage  88 . During positioning of the ball  76  within the first seat  98 , high pressure is established within the retainer  64  and low pressure exists within the second region  92  and first region  90  of the vapor passage  88 . As the compressor  14  continues to draw vapor, a partial vacuum is created within the first region  90  and second region  92 . The creation of minute fluid passages through the rivulets/striations  106  enables a small amount of liquid refrigerant  104  to bypass the ball  76  as positioned within the first seat  98 . The passage of liquid refrigerant from a high pressure side within the retainer  64  to the low pressure as existing between the first region  90  and second region  92  causes the liquid refrigerant to expand and to flash to vapor.  
         [0076]     Generally, liquid refrigerant  104  is incompressible. In compressing any gas a large amount of heat is generated. Heat is generally detrimental to pistons, cylinder heads  36  and valves and seals within the cylinder head  36 . The flashing of liquid refrigerant to vapor instantly cools the cylinder head  36 , lowering the overall temperature of the system which extends the life of the compressor  14 .  
         [0077]     Generally, the rivulets/striations  106  are positioned between the top portion of the first seat  98  and the bottom portion of the second region  92  of the vapor passage  88 .  
         [0078]     An alternative embodiment of the discriminator is depicted in  FIG. 7 . The discriminator  30  of  FIG. 7  is generally referred to as an external discriminator which is substantially tubular in shape. The external discriminator  30  may be secured, attached, and/or connected by the first conduit or hose  20  to a refrigeration system  12  being serviced. The inlet  108  is required to be in sealing vapor and fluid flow communication with the first conduit or hose  20 . The external discriminator  30  as depicted in  FIG. 7  is generally used in substitution and/or in replacement of the manifold  18 .  
         [0079]     The inlet  108  may be either externally and/or internally threaded for coupling to the first conduit or hose  20 , alternatively, the inlet  108  may be integral to and/or press fit with respect to the first conduit or hose  20 .  
         [0080]     The first inlet  108  preferably includes a first inlet chamber  110  which is of smaller size and/or diameter than the central chamber  112 . A second seat  114  preferably is located between the first inlet chamber  110  and the central chamber  112 . The second seat  114  preferably prevents the forcing of the ball  76  downwardly into the first inlet chamber  110  and/or first conduit or hose  20  thereby blocking fluid and/or vapor flow communication from the refrigeration system  12 .  
         [0081]     The central chamber  112  is generally defined by one or more exterior walls  116 . Preferably the exterior wall  116  is cylindrical in shape and is formed of one piece construction. Alternatively, the exterior walls  116  may be formed in any desired configuration provided that the essential functions, features, and attributes described herein are not sacrificed.  
         [0082]     The external discriminator preferably includes an upper portion  118  having an open top  120 . The interior of the upper portion  118  may include a seventh set of internal receiving threads  122  which are preferably adapted for mating engagement with a fifth set of penetrating threads  60  of second fitting  50 .  
         [0083]     The features of the second fitting  50  namely the vapor passage  88 , first region  90 , second region  92 , opposing spring ledges  94 , spring  96 , and/or first seat  98 , in addition to the grasping region  80  are preferably identical between the external and internal discriminator  30 .  
         [0084]     The spring  96  is preferably located within the central chamber  112  of the external discriminator  30  and the central region  92  of the second fitting  50 . The spring  96  preferably traverses the first seat  98  and is engaged to the ball  76 . The ball  76  within the external discriminator  30  preferably functions as a fluid flow meter/restrictor in an identical manner as described with respect to the internal discriminator  30 .  
         [0085]     An O-ring  82  is preferably in sealing engagement between the open top  120  and the bottom portion of the grasping region  80  of the second fitting  50 .  
         [0086]     The spring  96  preferably does not manipulate the ball  76  downwardly to the second seat  114 . Therefore, the suction of the compressor to draw vapor elevates the ball  76  from the second seat  114  upwardly to establish a vapor passage indicated in general by arrow  124 . Preferably the ball  76  does not have sufficient mass to block the inlet  108  during the suction down stroke of the cylinder within the compressor  14 . Preferably the ball  76  is sufficiently light weight to upwardly disengage from the inlet  108  and second seat  114  during suction for engagement to the spring  96 . In the event that fluid/liquid refrigerant is drawn into the external discriminator  30 , the ball  76  will float as earlier described and compress spring  96  against opposing spring ledges  94  of second region  92  within second fitting  50  as earlier described. At such time as the external discriminator is filled with liquid refrigerant, the ball  76  will elevate to sealing engagement with the first seat  98 . A very small amount of fluid will be permitted to pass the ball  76  as positioned within the first seat  98  by way of the rivulets/striations  106  which preferably flash liquid refrigerant to vapor within the second region  92 .  
         [0087]     The inherent buoyancy of the ball  76  elevates the ball  76  towards the first seat  98  compressing spring  96  during the presence of fluid within the central chamber  112 . The ball  76  is positioned within the first seat  98  upon filling of the central chamber  112  with liquid refrigerant. The first seat  98  also includes rivulets/striations  106  as earlier described to permit flashing of liquid refrigerant as passing from the high pressure central chamber  112  to the low pressure second region  92  past the ball  76  and first seat  98  as earlier described.  
         [0088]     The external discriminator  30  may be used to replace or as a supplement to the manifold  18  as earlier described. Alternatively, a manifold  18  without an internal discriminator  30  may be used in conjunction with an external discriminator  30  to reduce and preferably eliminate the suction of liquid refrigerant into the compressor  14 .  
         [0089]      FIGS. 8, 9 , and  9 A, depict the cylinder head  36 . Generally, the cylinder head  36  is substantially rectangular and includes an inlet  34  and an outlet  42 . A plurality of affixation apertures  126  traverse the cylinder head  36  and are used to releasably secure the cylinder head  36  to the compressor  14 .  
         [0090]     The base or bottom  128  of the cylinder head  36  is depicted in  FIG. 9 . An inlet orifice  130  and an outlet orifice  132  traverse the base  128  of the cylinder head  36  and are in vapor flow, and to a minimum extent, fluid flow relationship with the inlet  34  and the outlet  42  respectively. A gasket  134  as is known in the art is preferably positioned between the cylinder head  36  and the cylinder of the compressor  14 .  
         [0091]      FIG. 9A  depicts, in cross-section, the internal suction passage from the inlet orifice  130  to the inlet  34 . The suction passage  136  preferably includes an angle of approximately 90° between the inlet  34  relative to the inlet orifice  130 . The discharge passage  138  is substantially aligned between the outlet orifice  132  and the outlet  42 .  
         [0092]      FIG. 10  depicts in cross-section the cylinder head  36  and the first ball valve  38  and the second ball valve  40 . The first ball valve  38  is preferably proximate to the suction inlet  34  and the second ball valve  40  is preferably proximate to the discharge outlet  42 . A third fitting  140  is preferably disposed within the inlet  34  and a fourth fitting  142  is preferably disposed within the outlet  42 .  
         [0093]     In more detail, the suction side of the cylinder head  36  includes a fitting receiving chamber  144  having an eighth set of receiving threads  146 . Interior to the fitting receiving chamber  144  is preferably a first transition chamber  148 . The suction passage  136  is preferably in vapor/liquid communication with the first transition chamber  148  to permit vapor passage there through. A third seat  150  preferably defines the inner section between the first transition chamber  148  and the suction passage  136 . A second spring  152  is positioned in transverse relationship to the suction passage  136  for engagement to the ball  76 . The second spring  152  manipulates the ball  76  horizontally toward the fourth seat  166  of the third fitting  140 .  
         [0094]     The third fitting  140  preferably includes a ninth set of penetrating threads  154  on the exterior surface of the distal end  156 , a grasping central region  158 , and a tenth set of penetrating threads  160  on the proximate end  162  as adapted to mate with the second conduit/hose  32 . A first bore passage  164  is preferably centrally located through the third fitting  140  traversing the proximate and distal ends  156 ,  162  respectively. The first bore passage  164  includes a fourth seat  166  as positioned between the third fitting  140  and the fitting receiving chamber  144 . The fourth seat  166  is preferably adapted to receive the ball  76  to close the first bore passage  164  and the inlet  34  during the up stroke of the cylinder and the discharge of vapor from the outlet  42 . During the down stroke of the cylinder, the ball  76  is preferably drawn to compress the second spring  152  toward the interior of the inlet  34  disengaging the ball  76  from the fourth seat  166 . A vapor passage identified by arrow  168  through the first bore passage  164 , past the ball  76  through the first transition chamber  148 , past the second spring  152 , through the suction passage  136  and into the cylinder is thereby provided.  
         [0095]     In more detail, the discharge side of the cylinder head  36  includes a fitting receiving chamber  170  having an eleventh set of receiving threads  172 . Interior to the fitting receiving chamber  170  is a first transition chamber  174 . The discharge passage  138  is preferably in vapor/liquid communication with the first transition chamber  174  to permit vapor passage there through. A fifth seat  176  preferably defines the area between the first transition chamber  174  and the discharge passage  138 . A third spring  178  is positioned in normal relationship to the discharge passage  138  for engagement to a ball  76 . The third spring  178  manipulates the ball  76  vertically toward the first seat  98  of the fourth fitting  142 .  
         [0096]     The fourth fitting  142  preferably includes a twelfth set of penetrating threads  180  on the exterior surface of the distal end  182 , a grasping central region  184 , and a thirteenth set of penetrating threads  186  on the proximate end  188 . A second bore passage  190  is preferably centrally located through the fourth fitting  142  traversing the proximate and distal ends  188 ,  182  respectively. The second bore passage  190  includes the first seat  98  as positioned proximate to the distal end  182 . The fifth seat  176  is adapted to receive the ball  76  to close the second bore passage  190  at the outlet orifice  132  during the down stroke of the cylinder and the suction of vapor from the inlet  34 . During the up stroke of the cylinder, the ball  76  is preferably elevated to compress the third spring  178  toward the exterior and outlet  42 , disengaging the ball  76  from the fifth seat  176 . A vapor passage depicted by arrow  192  occurs past the fifth seat  176 , ball  76 , third spring  178 , first transition chamber  174 , fitting receiving chamber  170 , and second bore passage  190  for exit from the outlet  42 . The vapor discharge in general is depicted by arrow  192 .  
         [0097]     Referring to  FIG. 11 , the manifold  18  is shown in detail. The manifold  18  includes a first inlet or suction port  24  and a second outlet  28  for communication to the compressor  14 . A first manifold passage  194  provides vapor/fluid passage from the system  12  through the manifold  18  to the compressor  14 . A suction valve  196  may be in communication with the first manifold passage  194  between the first inlet  24  and the second outlet  28 . The discriminator  30  may also be in communication with the first manifold passage  194  between the first inlet  24  and the second outlet  28 . The first manifold passage  194  may also include a port  198  adapted to receive a low pressure gauge. The low pressure gauge may be in electric communication with an electric cutoff which, in turn, severs power to the compressor  14  at such time as the pressure within the manifold  18  drops below a preset level. Generally, the preset low pressure level is determined in conformance with the environmental protection agency requirements for automatically terminating operations of the refrigerant recovery system  10 .  
         [0098]     During the refrigerant recovery mode the suction valve  196  is open permitting vapor and/or liquid refrigerant to flow from the first inlet  24  through the discriminator  30  for exit from the second outlet  28  and to the compressor  14 . Recovered refrigerant may be exit the compressor  14  for reentry into the manifold  18  at port  202 . Port  202  defines the entry into the second manifold passage  200 .  
         [0099]     The second manifold passage  200  includes a discharge/purge port  204  and a pressure relief port  206  which is preferably in communication with a pressure relief valve. The second manifold passage  200  is also in communication with a condenser access port  208  and a condenser return port  210 . The second manifold passage  200  further includes a high pressure gauge port  212  preferably including a high pressure gauge and a high pressure switch port  214  which includes a high pressure switch. The high pressure switch is preferably in electric communication with an electrical cutoff for termination of electrical power to the compressor  14  upon detection of a high pressure condition.  
         [0100]     A discharge valve  216  is preferably in communication with a second manifold passage  200 . The suction valve  196  and the discharge valve  216  are preferably Parker Valves. The use of the suction valve  196  and discharge valve  216  in conjunction with the manifold  18  preferably eliminate the need for a third valve and/or a control device on the suction side. In addition, suction valve  196  and discharge valve  216  may be located on the same face of the manifold  18 . The manifold  18  further includes safety devices and facilitates the use of minimal tubing and fixtures to provide a simplified manifold  18 . During the refrigerant recovery mode the vapor refrigerant entering the manifold  18  at port  202  is directed through the opening of discharge valve  216  to the condenser  218 . High pressure vapor refrigerant returns to liquid refrigerant  104  in the condenser  218 . The recovered refrigerant  104  then enters the manifold  18  at the condenser reentry port  210  for exit through the discharge/purge port  204 . The discharge/purge port  204  is in communication with the third conduit/hose  44  for passage and transfer of recovered refrigerant to storage tank  16 .  
         [0101]     It is well known in the art to measure the thermal conductivity of ambient surrounding air to determine the level of vacuum. Applicant&#39;s have invented an improved vacuum sensor which utilizes low cost dual transistor IC&#39;s mounted on a circuit board to make the required thermal conductivity measurements. By mounting the transistors on a circuit board, the sensors can be assembled using automated circuit board assembly processes, resulting in a decrease in the cost of manufacturing the improved vacuum sensor.  
         [0102]      FIG. 12  is a three dimensional view showing the improved vacuum sensor mounted on a circuit board.  
         [0103]      FIG. 13  is a two dimensional schematic showing the improved vacuum sensor mounted on a circuit board.  
         [0104]      FIG. 14  is a circuit schematic of the improved vacuum sensor.  
         [0105]     Referring now to  FIGS. 12 and 13 , the circuit board is shown at  310 , with a thin layer of electrically insulating thermally conductive material  312  mounted on top of the circuit board  310 , and a metal well  314  mounted on top of the electrically insulating thermally conductive material  312 .  FIG. 12  shows in more detail the two areas  312  of electrically insulating thermally conductive material  312  with the two leg portions of metal well  314  mounted on top of material  312 .  
         [0106]     A first dual transistor IC (U 2 ), shown at reference numeral  316 , is used to generate a fixed amount of heat and to measure the corresponding temperature rise due to that heat. IC  316  is connected by four copper traces to four large copper areas  320 ,  322 ,  324  and  326 . The copper areas  320 ,  322 ,  324  and  326  provide a thermal interface for the metal well  314 . IC  316  is placed in metal well  314  and mounted in such a way as to minimize thermal mass and minimize thermal loss through the electrical connections. Thermal mass is minimized by using 0.031″ thick circuit board material, by removing circuit board material around the IC&#39;s (the white areas in  FIG. 13 ), by using ½ ounce copper foil, and by using 0.008″ wide traces to make electrical connections to the IC  316 . Thin narrow copper traces are also used to connect IC  316  to copper areas  320 ,  322 ,  324  and  326 , which also reduce the thermal loss through the electrical connections.  
         [0107]     A second dual transistor IC (U 1 ), shown at reference numeral  318 , is used to measure the ambient temperature of the metal well  314 . The second IC  318  is mounted in such a way as to maximize the thermal conductivity between IC  318  and the metal well  314 . Thermal conductivity is maximized by connecting the IC with two very short copper traces to two of the large copper areas  322  and  326  which make thermal contact with the metal well  314 . This is done to get the most accurate ambient reading possible.  
         [0108]     Each of the dual transistor IC&#39;s ( 316  and  318 ) used in this embodiment of the inventive vacuum sensor are On Semiconductor&#39;s MBT3904DW1T1, which is a dual NPN transistor in a six-leaded SOT-363 surface mount package. Any commercially available dual transistor could be utilized in the inventive vacuum sensor, if desired.  
         [0109]     Referring now to  FIG. 14 , a circuit schematic of an embodiment of the inventive vacuum sensor circuit is shown. IC  316  is comprised of two transistors  330  and  332 . Transistor  330  of IC  316  is used to generate heat. A regulated DC supply voltage (Vcc) is provided at the collector (pin  3 ) of the heating transistor  330 . The emitter (pin  4 ) of the heating transistor  330  is connected to ground  334  through a current sensing resistor (R 3 )  336 .  
         [0110]     An operational amplifier circuit is used to maintain a fixed voltage and current at the heater transistor  330 . This results in a very efficient constant heat source. The operational amplifier (U 3 :A)  338  compares the voltage at the sensing resistor (R 3 )  336  with a reference voltage (Vref), which is pin  5  of operational amplifier (U 3 :B)  340  and changes the current at the base (pin  5 ) of the heating transistor  330  in order to keep the sensed current constant. The power dissipated in the heating transistor  330  is then (Vcc−Vref)*(Vref/R 3 ).  
         [0111]     The other transistor  332  in this IC  316  is wired as a diode (base and collector connected, pins  2  and  6 ) and is used to measure the temperature of IC  316 . Because the two transistors  330  and  332  are in the same IC  316 , the heat transfer between the two transistors  330  and  332  is very good.  
         [0112]     IC  318  is used to measure the ambient temperature of the metal well  314  and is comprised of two transistors  342  and  344 . Transistor  342  in this IC  318  is wired as a diode (base and collector connected, pins  5  and  3 ), and used to measure the ambient temperature. The other transistor  344  in this IC  318  is not used in this embodiment.  
         [0113]     The sensor board  310  is mounted in contact with the metal well  314  with a thin layer of electrically insulating thermally conductive material  312  between the sensor board  310  and the metal  314 .  
         [0114]     The external connections to the sensor board consist of a regulated DC voltage (Vcc)(pin  8  of Op Amp  338 ), a ground return path  334 , and a connection to each of the temperature measuring diodes  332  and  342 . A fixed current is passed through the two diodes. This fixed current results in a forward voltage at each diode  332  and  342  that changes with temperature. The difference between the two forward voltages (heat sensor and ambient sensor) are compared and converted into a vacuum reading.  
         [0115]     While this invention may be embodied in many different forms, there are described in detail herein specific preferred embodiments of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated.  
         [0116]     For the purposes of this disclosure, like reference numerals in the figures shall refer to like features unless otherwise indicated.  
         [0117]     The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to”. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims.  
         [0118]     Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim  1  should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below (e.g. claim  3  may be taken as alternatively dependent from claim  2 ; claim  4  may be taken as alternatively dependent on claim  2 , or on claim  3 ; claim  6  may be taken as alternatively dependent from claim  5 ; etc.).  
         [0119]     This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.