Abstract:
Flow regulator, system and method that allow regulation of gas flow, both during a purging operation such as to purge a line of oxygen, and during a brazing operation to maintain the line free or substantially free of oxygen during the brazing operation. The system includes a gas source, such as a nitrogen tank containing a source of nitrogen, a gas regulator in fluid communication with the gas source to regulate the delivery pressure from the gas source, and a flow regulator in fluid communication with the gas source to regulate the flow of gas during the purge and brazing operations. The flow regulator provides a visual indication that gas is flowing, and a visual indication of the particular flow rate of the flowing gas.

Description:
BACKGROUND 
     In the HVAC industry, purging refrigeration lines with nitrogen to eliminate oxygen prior to and during a brazing operation during installation or maintenance reduces or eliminates the formation of deleterious oxides. For example, when brazing copper, the combination of the heat applied and oxygen in the ambient air creates a chemical reaction that forms copper oxide. The oxide can form flakes that can become lodged in the thermal expansion valve of the HVAC system and cause system failure, or can foul system filters. Flowing nitrogen during brazing eliminates the oxygen and thus the formation of the oxides. 
     In such a purging and brazing operation, it is important to have the correct amount of nitrogen flow in the system while avoiding the formation of these deleterious oxides. If too much nitrogen flows during brazing, pin holes can be created and a poor quality braze can result. If insufficient nitrogen flows during brazing, deleterious oxides can be formed. 
     Embodiments disclosed herein enable proper purging of a refrigerant system with nitrogen gas and ensure that the correct amount of nitrogen flows in the line during the brazing operation. 
     SUMMARY 
     Problems of the prior art have been overcome by the embodiments disclosed herein, which include a flow regulator, system and method that allow regulation of gas flow, both during a purging operation such as to purge a line of oxygen, and during a brazing operation to maintain the line free or substantially free of oxygen during the brazing operation. In certain embodiments, the system includes a gas source, such as a nitrogen tank containing a source of nitrogen, a gas regulator in fluid communication with the gas source to regulate the delivery pressure from the gas source, and a flow regulator in fluid communication with the gas source to regulate the flow of gas during the purge and brazing operations. In certain embodiments, the flow regulator provides a visual indication that gas is flowing, and a visual indication of the particular flow rate of the flowing gas. 
     In its method aspects, embodiments include A method of monitoring the flow of gas in a brazing operation by providing a gas source and a gas flow regulator in communication with the gas source, the gas flow regulator comprising a valve body having a gas inlet and a gas outlet spaced from the gas inlet, a regulator body in fluid communication with the valve body, the regulator body having a sight housing visible through at least one window in the regulator body, and a floating member in the sight housing. In certain embodiments, the method includes flowing gas from the gas source to the gas flow regulator, the flowing gas causing the floating member in the sight housing to float in the housing, the position of the floating member in the sight housing corresponding to a gas flow rate. Based upon the indicated gas flow rate, the flow rate of the gas can be increased or decreased (or can remain the same) accordingly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of a flow regulator in accordance with certain embodiments; 
         FIG. 2  is a cross-sectional view of a bottom cap of the flow regulator of  FIG. 1  in accordance with certain embodiments; 
         FIG. 3  is a cross-sectional view of an inlet nipple of the flow regulator of  FIG. 1  in accordance with certain embodiments; 
         FIG. 4  is a cross-sectional view of a sight tube of the flow regulator of  FIG. 1  in accordance with certain embodiments; 
         FIG. 5  is a first cross-sectional view of a top cap of the flow regulator of  FIG. 1  in accordance with certain embodiments; 
         FIG. 5A  is a second cross-sectional view of a top cap of the flow regulator of  FIG. 1  in accordance with certain embodiments; 
         FIG. 6  is a cross-sectional view of a connector of the flow regulator of  FIG. 1  in accordance with certain embodiments; 
         FIG. 7  is a cross-sectional view of a valve body of the flow regulator of  FIG. 1  in accordance with certain embodiments; 
         FIG. 8  is a cross-sectional view of a connector nut of the flow regulator of  FIG. 1  in accordance with certain embodiments; 
         FIG. 9  is an exploded view of a valve stem assembly in accordance with certain embodiments; 
         FIG. 10  is a cross-sectional view of a seat holder of the flow regulator of  FIG. 1  in accordance with certain embodiments; 
         FIG. 11  is a cross-sectional view of a safety valve relief cap of the flow regulator of  FIG. 1  in accordance with certain embodiments; 
         FIG. 12  is a cross-sectional view of a hose connector of the flow regulator of  FIG. 1  in accordance with certain embodiments; 
         FIG. 13A  is a front view of a connector of the flow regulator of  FIG. 1  in accordance with certain embodiments; 
         FIG. 13B  is a top view of the connector of  FIG. 13A ; 
         FIG. 14  is a schematic view of a system including a nitrogen source, a gas regulator, and a flow regulator in accordance with certain embodiments; and 
         FIG. 15  is a cross-sectional view, in perspective, showing the gas flow through the gas flow regulator in accordance with certain embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Turning first to  FIG. 1 , there is shown a flow regulator  100  in accordance with certain embodiments. In certain embodiments, the flow regulator  100  includes a connector nut  1 , a neoprene sleeve  2 , and an inlet nipple  3  connected to a valve body  4 . The neoprene sleeve  2  and the inlet nipple  3  fit into the connector nut  1 . The valve body  4  is affixed to body member  12  using O-rings  7  and  8 , which body member  12  houses sight housing  11  such as a tube, the sight housing  11  containing float ball  10 . Bottom cap  14  is sealed to the body member  12  using O-rings  117  and  118 . 
     As best seen in  FIG. 8 , the connector nut  1  mates to one end of inlet nipple  3 . Preferably a neoprene sleeve  2  or the like is interposed between the nipple  3  and the connector nut  1  and serves as a gasket to help effectuate a seal. The opposite end of inlet nipple  3  is threadingly coupled to the inlet  70  of the valve body  4 . The connector nut  1 , as seen in  FIG. 8 , includes an internal cavity  181  that is configured to receive in a lower portion thereof the inlet nipple  3 . The upper portion of the internal cavity  181  is internally threaded with threads  119  to mate with a member in fluid communication with a gas source. In certain embodiments, the connector nut  1  includes one or more (preferably two, spaced 180° apart) axially extending vent slots  90 . The vent slots  90  allow vapor to vent in the direction of the gas source upon disconnection of the device. 
       FIG. 3  shows an embodiment of inlet nipple  3 , one end of which has external threads  32  for mating with internal threads in inlet  70  of the valve body  4 . In certain embodiments, the inlet nipple  3  is stepped, and includes a first elongated portion  34  having a first diameter, a second portion  35  defined at annular shoulder  33  having a second diameter larger than said first diameter, and a third portion  36  defined at annular shoulder  37  having a third diameter larger than the second diameter. The third portion  36  includes a cavity  38  that may include a neoprene sleeve. Third portion  36  is configured to fit into connector nut  1 , with shoulder  37  seating against a corresponding shoulder  41  in the connector nut  1 . An axial bore  40  communicates with cavity  38  and axial bore  71  in the inlet  70  of the valve body  4  and extends through the inlet nipple  3  as shown. 
     As shown in the embodiment of  FIG. 7 , the valve body  4  includes outlet  24  having external threads  127 . In certain embodiments, the outlet  24  includes a bore  50  that is formed at a 13° angle with respect to the longitudinal centerline X. In the embodiment shown, the bore  50  extends into the valve body at distance of 0.625 inches, where it is in fluid communication with bore  52  in gas flow regulator inlet  51 . 
     In certain embodiments, the gas flow regulator inlet of valve body  4  has external threads  53 , and includes internally threaded bore  52 . The gas flow regulator inlet receives valve stem assembly  160 , shown in detail in  FIG. 9 . In certain embodiments, the valve stem assembly  160  includes valve wheel  161 , packing nut  62 , packing washer  63 , valve stem  64 , and ball  65 . One end  64   a  of the valve stem  64  is affixed to the valve wheel  161 , such as by press fitting. A portion of the valve stem  64  includes external threads  67 , which mate with the internal threads of the gas flow regulator inlet  51 . Packing nut  62  and packing washer  63  fit over the valve stem  64 . The packing nut  62  includes internal threads  66 , which mate with the external threads on the gas flow regulator inlet  51  and secure the valve stem assembly to that inlet. The end  64   b  of valve stem includes stainless steel ball member  65 , which protrudes out of the valve stem a fixed distance. Actuation of the valve wheel  161 , such as by rotation, causes rotation of the valve stem  64  and thus axial displacement of the valve stem within the bore  52  of the gas flow regulator inlet  51 . As the valve stem  64  is actuated axially deeper into the bore of the gas flow regulator inlet  51 , it proceeds deeper into the narrow bore  68  ( FIG. 7 ), eventually completely cutting off fluid communication between the bore  73  and the bore  68 , stopping gas flow. 
     Referring back to  FIG. 7 , in certain embodiments the valve body  4  includes inlet  70 . The inlet  70  includes an internally threaded bore  71  that is in fluid communication with the bore  52  of the gas flow regulator inlet  51  via internal angled bore  73 . 
     The valve body  4  is affixed to top cap  5 , best seen in  FIG. 5 . In certain embodiments, the outlet  24  of the valve body  4  is in fluid communication with the axial bore  81  of the top cap  5 . Axial bore  81  communicates with stepped radial bore  82 . In certain embodiments, stepped radial bore  82  has its largest diameter at the most radially outwardly portion of the bore, with a narrower diameter in the intermediate portion of the bore, and the narrowest diameter at the radially inwardly most portion of the bore, the latter intersecting with the axial bore  81 . This stepped radial bore  82  receives pressure relief assembly  190 . 
     In certain embodiments, the reseatable pressure relief assembly  190  includes connector  17  ( FIG. 6 ), O-ring  18 , seat holder  19  ( FIG. 10 ), biasing member  20 , and safety valve relief cap  21  ( FIG. 11 ). Connector  17  includes an externally threaded stem  91  that mates with internally threaded bore  82  of the top cap  5 . The stem  91  extends from connector body portion  83  that is internally threaded to receive external threads  191  of safety valve relief cap  21 . The safety valve relief cap  21  holds in place O-ring  18 , seat holder  19  and biasing member  20 . The biasing member  20  sits on seat holder  19 . In certain embodiments, as best seen in  FIG. 11 , the safety valve relief cap  21  includes axial slots  92 ,  93  which communicate with the interior cavity of the safety valve relief cap  21 . Preferably two diametrically opposed axial slots  92 ,  93  are present and are positioned so that when relief cap  21  is coupled to the cap  5 , at least a portion of a slot  92 ,  93  is open to ambient. The slot or slots  92 ,  93  extend radially inwardly, and allow fluid communication between radial bore  82  and the ambient. An axial bore  95  is offset from the longitudinal centerline of the top cap  5 , and communicates with the stepped radial bore  82  as shown in  FIG. 5 . This allows for escape of gas to ambient through the axial slots  92 ,  93  in the event of an over pressurization. The biasing member  20 , which in certain embodiments is a compression spring, is positioned during operation in the generally hollow interior of the relief cap  21 . The biasing member  20  seats on seat holder  19 . The seat holder  19  includes a generally cylindrical portion  19 A, preferably chamfered at its top, which has an outer diameter slightly smaller than an inner diameter of the biasing member  20 . An annular flange  19 B extends radially outwardly from the base of the portion  19 A, and preferably has a diameter substantially the same as the outer diameter of the biasing member  20 . Accordingly, the biasing member is supported on the flange  19 B, with the portion  19 A extending into the interior of the biasing member  20  when in the assembled condition. Extending axially from the flange  19 B is a tapered portion  19 C. Portion  19 C tapers radially outwardly towards its free end  19 D a distance sufficient to carry O-ring  18 . 
     If the pressure is sufficient to overcome the force of the biasing member  20 , that pressure forces the seat holder  19  radially outwardly, thereby opening the pressure relief valve and allowing fluid flow out the one or more slots  92 ,  93  to ambient. As a result, the device is protected from over-pressurization. Those skilled in the art will appreciate that the biasing member  20  is thus selected to have a spring constant such that over-pressurization is prevented. A suitable spring constant is one where a pressure of about 200-210 psi is sufficient to overcome the bias of the biasing member  20 . 
     Turning back to  FIG. 5 , top cap includes axial bore  89  that is offset from the longitudinal centerline of the top cap  5 , and communicates with radial bore  82 , which in turn is in communication with radial bore  81 . When the top cap is properly position on body member  12 , the axial bore  89  aligns with an axial bore  99  in the body member  12 , as discussed in greater detail below. 
     In certain embodiments, a second radial bore  85 , spaced 90 degrees from the stepped radial bore  82 , is provided in the top cap  5 , as seen in  FIG. 5A . The second radial bore  85  is internally threaded, and receives externally threaded hose connector  16  shown in  FIG. 12 , which in operation is an outlet and connects to the access fitting of a refrigeration system via a hose  202  or the like ( FIG. 14 ). The second radial bore  85  is in fluid communication with hollow tube  86 , which extends axially through the externally threaded outlet  87  and protrudes slightly therefrom. The protruding end of the tube  86  is notched, and has an outside diameter sufficient to receive one end of the sight housing  11  ( FIG. 4 ). The annular gap between the tube  86  and the outlet  87  is fitted with a sealing ring (not shown) against which the sight housing abuts. In certain embodiments, sight housing  11  is an elongated hollow tube, which can be made of plastic, which holds float ball  10 . The bottom of sight housing  11  mates with externally threaded notched stem  97  on bottom cap  14  ( FIG. 2 ). 
     In certain embodiments, the body member  12  ( FIGS. 13A, 13B ) includes one or more (two shown) elongated windows  60 ,  61  that provide visual access to the float ball  10  in sight housing  11 . Through the thus formed window or windows, the status of the flow of gas can be visually monitored. Indicia can be provided on the body member  12  that indicates the actual flow rate of gas based on the vertical height of the float ball  10 . In certain embodiments, the body member  12  also includes axial bore  99  offset from the longitudinal centerline of the body member  12 . The axial bore  99  extends through the length of the body member  12 , and when the body member  12  is coupled to the top cap  5  (such as via externally threaded outlet  87  that mates with internally threaded bore  110  in the body member  12 ), the axial bore  99  aligns with axial bore  89  of the top cap  5  and is in fluid communication therewith. In the assembled condition, the axial bore  99  is also in fluid communication with radial bore  96  of bottom cap  14  ( FIG. 2 ), which in turn communicates with axial bore  98  as shown. The base  111  of the body member  12  can include an annular recess  113  for receiving an O-ring or the like to seal to the bottom cap  14 . 
     In operation, the gas flow regulator  100  is placed in gas-receiving communication with a gas source  200  ( FIG. 13 ), such as a nitrogen cylinder. In certain embodiments, the gas flow regulator is placed in fluid communication with the outlet of a standard gas regulator  201  that is in fluid communication with the gas source  200 . The gas cylinder valve  203  is opened, and the delivery pressure is set to the desired pressure for purging the lines of oxygen (e.g., 60 psi), using the gas regulator  201 . The gas flow regulator  100  is then adjusted to fine tune the gas flow rate, such as to 20+ (plus) standard cubic feet per hour (SCFH), using the valve stem assembly  15 , and in particular, by rotating the wheel  161 . 
     Gas flows from the gas source  200 , through the regulator  201 , and into the inlet connector nut  1  of the gas flow regulator  100 . As seen by arrows in  FIG. 15 , from there it travels through valve body  4 , into axial bore  81  of the top cap  5 , through radial bore  82 , into axial bore  89 , axial bore  99  of the body member  12 , radial bore  96  of the bottom cap  14 , axial bore  98  of the bottom cap  14 , and then into the sight housing  11 . The flow of gas in the sight housing  11  floats the ball  10 . The height of the float ball  10  indicates to the operator the actual gas flow rate both in the regulator and to the line in communication with the outlet of the regulator, to facilitate the gas flow adjustment and to monitor the gas flow. The gas flows out of the sight housing  11 , back into top cap  5  via tube  86 , and out the device via radial bore  85 . 
     Once the lines have been purged, the gas pressure can be set to the desired pressure for brazing, such as 20 psi. To that end, the conventional regulator is adjusted to about 20 psi, and then the flow rate is fine tuned by adjusting the gas flow regulator  100 , again using valve wheel  161  of the valve stem assembly  15 , to a flow rate of 3 to 5 SCFH, for example. During brazing, the height of the float ball  10  can be monitored visually through the connector windows to ensure that the proper gas flow rate is maintained during the brazing operation. In certain embodiments, the body  12  can include visual indicia, such as markings on a label appropriately affixed to the body  12 , which correlate the height of the float ball  10  to the flow rate of gas. 
     The result is a simplified process of purging a refrigeration system with gas, such as nitrogen, and during the brazing of copper tubing, providing a protective internal cover gas.