Abstract:
An improved mechanical seal and repair method can be used with mechanical pump seal assemblies. The improved seal utilizes rotating and non-rotating sections of improved configuration, each of which can form a seal using a standard size carbon-face O-ring. The mechanical seal can be in the form of replacement parts that replace the old parts without modifications to the overall seal and assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   Priority of my U.S. Provisional Patent Application Ser. No. 60/654,217, filed 18 Feb. 2005, incorporated herein by reference, is hereby claimed. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable 
   REFERENCE TO A “MICROFICHE APPENDIX” 
   Not applicable 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to mechanical seal assemblies for pumps. More particularly, the present invention relates to an improved mechanical pump seal assembly that includes a specially configured seal cartridge enabling standard O-rings to be used instead of specially configured Teflon® seals and that can be used as a retrofit for existing mechanical seal assemblies associated with pumps such as barge pumps. 
   2. General Background of the Invention 
   An example of a mechanical seal assembly is shown in the U.S. Pat. No. 4,648,605 issued to Joseph Marsi and entitled “Mechanical Seal Assembly”. The &#39;605 patent discloses a mechanical seal assembly especially adaptable for use in the chemical industry in which a jacket that is impervious to the chemical involved surrounds a spring which urges seal faces toward one another, the spring being capable of transmitting torque and providing axial support to the jacket. 
   At the Flowserve website (www.flowserve.com), a number of pump sealing arrangements are displayed. The home page for seals is www.flowserve.com/Seals/seals.htm. One of the seals disclosed at the website is called a “UC” seal. The UC seal is designed for corrosive/non-corrosive high pressure services with a specific gravity of 0.45 or higher. The canned “UC” seal design incorporates a high pressure design feature that is similar to the Flowserve “U” seal while incorporating an encapsulated graphite gasketed silicon carbide rotating face. The UC seal&#39;s canned face design provides for low level emissions control. 
   Borg Warner sells mechanical seals for pumps such as barge pumps under its product designations U2250 and U1875. These seal designs utilize a cylindrically shaped sleeve that fits in between the pump shaft and a seal cartridge that employs a U-shaped cup seal. Over time, the sleeve can be fret damaged by the cup seal. 
   Fret damage occurs as a result of the original factory Teflon® U-cup moving up and down on the shaft sleeve. The U-cup (when in operation) is inflated by the product being pumped under pressure, thus putting pressure on the shaft sleeve. The Teflon® U-cup under such pressure will scratch the sleeve. These resulting scratches can be described as fret damage. This fret damage can cause leaking of gases to occur through the Teflon® U-cup. In addition, once the pressure is relieved, the U-cup deflates, which can allow leakage of gases through the U-cup, even if it is not fret-damaged. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention provides an improved seal arrangement for sealing a sleeve having a UC type seal such as those offered by Flowserve® or Borg Warner® model U2250 or U 1875 mechanical seals. 
   The present invention provides advantages over prior art seal arrangements. The present invention enables the reuse of fret damaged seal sleeves. The seal sleeve can be reused because the new rotating face uses a different area on the shaft seal sleeve to accomplish a seal. 
   The present invention enables the use of standard size readably available O-rings. The present invention enables the use of standard rubber or synthetic rubber O-rings throughout the seal assembly, such as O-rings made of Kalrez® brand material or generic equivalents thereof. The present invention does not require modifications to the seal sleeve or cartridge. The seal sleeve is a component part of the whole cartridge seal assembly. The present invention provides a pump seal repair kit that can be field installed. 
   The present invention includes a barge pump apparatus, comprising: 
   a) a pump housing that is configured to be mounted to a barge deck and the extend vertically below deck, the pump housing having a pump head; 
   b) a pump shaft extending vertically in the housing; 
   c) a driver that rotates the pump shaft; and 
   d) a mechanical seal that prevents leakage of the barge cargo from a tank of the barge to the surrounding atmosphere, the seal including:
         a seal flange that attaches to the pump head, the seal flange having a central flange opening receptive of the pump shaft and an annular socket surrounding the central flange opening;   a sleeve that closely fits the pump shaft, being attached to the pump shaft and rotating therewith;   an annular non-rotating seal element that seats upon the seal flange socket, the non-rotating seal element providing a carbon containing sealing face;   an annular rotating seal element that is in face-to-face contact with the carbon containing sealing face, said rotating seal element having an open center and being mounted upon the sleeve at the open center;   a spring assembly that biases the seal elements together, the spring assembly having an open center that receives the sleeve and shaft, one end of the spring assembly bearing against the sleeve, the other end of the spring assembly bearing against the rotating seal element;   a plurality of O-rings that are carried by the seal members, one O-ring attached to the non-rotating seal element and another O-ring attached to the rotating seal element. Preferably, the rotating seal member is of a metallic material. Preferably, the non-rotating seal member is of a non-metallic material. Preferably, the spring assembly and rotating seal member are interconnected.       

   Preferably, the O-rings are circular in transverse cross section; preferably, the O-rings are of uniform transverse cross section; preferably, one or more of the O-rings are of a Kalrez® brand material or generic equivalents thereof (perfluoroelastomer material). 
   Preferably, the sleeve has an annular shoulder and the spring assembly bears against the annular shoulder of the sleeve. Preferably, the sleeve has multiple sections of varying outer diameter. Preferably, one of the O-rings contacts the pump shaft. Preferably, one of the O-rings contacts the seal flange. 
   The present invention also includes a barge pump seal apparatus for sealing leakage around the pump shaft of a barge pump having a pump housing that is configured to be mounted to a barge deck and the extend vertically below deck, the pump housing having a pump head and a driver that rotates the pump shaft, said seal apparatus comprising: 
   a) a seal flange that attaches to the pump head, the seal flange having a central flange opening receptive of the pump shaft and an annular socket surrounding the central flange opening; 
   b) a sleeve that closely fits the pump shaft, being attached to the pump shaft and rotating therewith; 
   c) an annular non-rotating seal element that seats upon the seal flange socket, the non-rotating seal element providing a carbon containing sealing face; 
   d) an annular rotating seal element that is in face-to-face contact with the carbon containing sealing face, said rotating seal element having an open center and being mounted upon the sleeve at the open center; 
   e) a spring assembly that biases the seal elements together, the spring assembly having an open center that receives the sleeve and shaft, one end of the spring assembly bearing against the sleeve, the other end of the spring assembly bearing against the rotating seal element; and 
   f) a plurality of O-rings that are carried by the seal members, one O-ring attached to the non-rotating seal element and another O-ring attached to the rotating seal element. Preferably, the rotating seal member is of a metallic material. Preferably, the non-rotating seal member is of a non-metallic material. Preferably, the spring assembly and rotating seal member are interconnected. 
   Preferably, the O-rings are circular in transverse cross section; preferably, the O-rings are of uniform transverse cross section; preferably, one or more of the O-rings are of a Kalrez® brand material or generic equivalents thereof. 
   Preferably, the sleeve has an annular shoulder and the spring assembly bears against the annular shoulder of the sleeve. Preferably, the sleeve has multiple sections of varying outer diameter. 
   The present invention also includes a pump seal apparatus for sealing leakage around the pump shaft of a pump having a pump housing and a driver that rotates the pump shaft relative to the housing, said seal apparatus comprising: 
   a) a seal flange that attaches to the pump housing, the seal flange having a central flange opening receptive of the pump shaft and an annular socket surrounding the central flange opening; 
   b) a sleeve that closely fits the pump shaft and being attached to the pump shaft and rotating therewith; 
   c) an annular non-rotating seal element that seats upon the seal flange socket and connects to the seal flange, the non-rotating seal element providing a carbon containing sealing face; 
   d) an annular rotating seal element that is in face-to-face sealing contact with the carbon-containing sealing face, said rotating seal element having an open center and being mounted upon the sleeve at the open center, the contact defining a gas seal that prevents leakage of gas molecules, the sealing face and the rotating seal element each having a flatness of not more than two light bands (but preferably not more than one light band); 
   e) a spring assembly that biases the seal elements together, the spring assembly having an open center that receives the sleeve and shaft, one end of the spring assembly bearing against the sleeve, the other end of the spring assembly bearing against the rotating seal element; and 
   f) a plurality of O-rings that are carried by the seal members, one O-ring attached to the non-rotating seal element and another O-ring attached to the rotating seal element. Preferably, non-rotating seal element is of a seal-grade silicon carbide. Preferably, the non-rotating seal element is of a seal-grade carbon material. Preferably, the non-rotating seal member is of a non-metallic material. Preferably, the rotating seal element is of a stainless steel material. Preferably, there is a spring that urges the seal elements together. Preferably, one or more of the O-rings are of a Kalrez® brand material or generic equivalents thereof. Preferably, the sleeve has an annular shoulder that transfers load between the sleeve and the spring. Preferably, the spring rotates with the sleeve. 
   The present invention also includes a mechanical pump seal assembly for sealing a rotatable pump shaft, a sleeve that is fitted to the shaft for rotation therewith, and a stationary housing containing a chemically active fluid, comprising: 
   a) a stationary seal ring section connected to said sleeve; 
   b) a rotatable ring section connected to said sleeve; 
   c) seal faces on said seal rings opposed to one another; 
   d) wherein each ring section has an annular groove; 
   e) an O-ring that occupies each annular groove; 
   f) wherein one of the O-rings engages the sleeve and the other O-ring engages the stationary housing. Preferably, the stationary seal ring is of metallic material. Preferably, the rotatable ring section is of a silicon carbide material. Preferably, the rotatable ring section is of a carbon material. Preferably, the O-ring is a carbon-face O-ring. Preferably, n the stationary ring section is of a stainless steel material. Preferably, the silicon carbide is a seal-grade silicon carbide. Preferably, the carbon material is a seal-grade carbon. 
   The present invention also includes a method of sealing a rotatable shaft mechanical seal with a assembly, wherein the seal assembly includes a sleeve that is fitted to the shaft and a stationary housing containing a chemically active fluid, comprising: 
   a) providing a stationary seal ring section connected to said sleeve; 
   b) providing a rotatable ring section connected to said sleeve; 
   c) providing seal faces on said seal rings opposed to one another; 
   d) wherein in step “c” each ring section has an annular groove; 
   e) placing an O-ring in each annular groove; 
   f) wherein one of the O-rings engages the sleeve and the other O-ring engages the stationary housing. Preferably, the stationary seal ring is of metallic metal. Preferably, the rotatable ring section is of a silicon carbide material. Preferably, the rotatable ring section is of a carbon material. Preferably, the O-ring is a carbon-face 0-ring. Preferably, the stationary ring section is of a stainless steel material. Preferably, the silicon carbide is a seal-grade silicon carbide. Preferably, the carbon material is a seal-grade carbon. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein: 
       FIG. 1  is an elevation view of the preferred embodiment of the apparatus of the present invention; 
       FIG. 2  is a partial sectional, elevation view of the preferred embodiment of the apparatus of the present invention; 
       FIG. 3  is a sectional view of the preferred embodiment of the apparatus of the present invention illustrating the mechanical seal; 
       FIG. 4  is a partial perspective exploded view of an alternative embodiment of the apparatus of the present invention; 
       FIG. 5  is a partial perspective view of the preferred embodiment of the apparatus of the present invention; 
       FIG. 6  is an exploded, sectional elevational view of the preferred embodiment of the apparatus of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows the preferred embodiment of the apparatus of the present invention, designated generally by the numeral  10 . Pump apparatus  10  provides a pump housing  11  that includes a pump head  12 . The pump apparatus  10  can be for example be a barge pump, such barge pumps being commercially available (see www.Flowserve.com). Such barge pumps have been sold for years under the trademark Byron Jackson®. 
   In  FIG. 1 , pump housing  11  is shown being attached to barge deck  13 . Lower end portion  14  of pump housing  11  extends below deck into a compartment  17  that contains a fluid to be pumped. 
   The present invention also discloses an improved mechanical pump seal  16  for sealing rotary pump shaft  15  as it extends downwardly in pump housing  11 . The overall configuration of pump housing  11  and shaft  15  as well as any selective shaft driver  18  (e.g. diesel engine and transmission) is known in the art. While the cargo is contained in the below deck compartment  17  that is positioned below deck  13 , the mechanical seal  16  would typically be positioned above deck  13  as shown in  FIG. 1 . 
   Mechanical seal  16  is shown more particularly in  FIGS. 2-6 . The mechanical seal  16  includes the number of different parts that are interconnected as shown in  FIGS. 2 ,  3 ,  4  and  6 . Mechanical seal  16  includes seal flange  19  which is a non-rotating part. Non-rotating seal element  44  nests in seal flange  19  as shown in  FIG. 3  and is thus a non-rotating part. Rotating seal element  43  is urged into face-to-face sealing engagement with non-rotating seal element  44  by spring cage assembly  22 . Compression of the coil spring  23  of cage assembly  22  is realized by providing a larger diameter section  32  on sleeve  21  which is attached to and rotates with pump shaft  15 . In addition, a drive collar  49  is attached to pump shaft  15  opposite spring cage assembly  22  and rotates with pump shaft  15 . This arrangement can be seen in  FIGS. 2 ,  4 ,  5  and  6 . 
   Seal flange  19  is attached to pump head  12  with bolted connections  20 . The pump head  12  can be drilled and tapped for bolts that secure the seal flange  19  to the pump head  12 . The seal flange  19  can be provided with a register that centers it appropriately on the pump head  12 . 
   The spring cage assembly  22  carries a coil spring  23  in between parts  37  and  24 . The part  24  is a ring that has one or more lugs  25  that are circumferentially spaced such as for example 90 degrees apart or 180 degrees apart. These lugs  25  fit into slots  26  on the larger diameter section  32  of sleeve  21 . Ring  24  has a larger diameter section  27  and a smaller diameter section  28  as shown in  FIG. 3 . An annular shoulder  29  is provided at the interface between the larger and smaller diameter sections  27 ,  28  as shown in  FIG. 3 . This annular shoulder  29  rests upon an annular shoulder  34  of sleeve  21  that is in between the larger diameter section  32  and an intermediate diameter section  31 . Another annular shoulder  31  is provided on sleeve  21  in between the intermediate diameter section  31  and the smaller diameter section  30 . 
   A plurality of openings  35  are provided in the smaller diameter section  30  of sleeve  21 . These openings  35  are preferably circumferentially spaced such as for example about 90 degrees apart. Each opening  35  is receptive of a bolt  50  of driver  49 . 
   Ring  24  provides an open center  36  so that it fits over the smaller and intermediate sections  30 ,  31  of sleeve  21 , enabling the annular shoulder  29  of the ring  24  to sit upon the annular shoulder  34  of sleeve  32  as shown in  FIG. 3 . 
   The spring cage assembly  22  includes cage  37 , coil spring  23 , and ring  24 . The coil spring  23  fits over the intermediate diameter section  31  of sleeve  21  and is contained within cage  37  (see  FIG. 3 ). Cage  37  provides a plurality of longitudinal slots  38 . Cage  37  also provides an annular shoulder  39 . Rotating seal element  33  interlocks with cage  37 , the lugs  42  on rotating seal element  43  registering in the slots  38  of cage  37  as shown in  FIG. 3 . The cage  37  thus provides a larger diameter section  40  that contains coil spring  23  and a smaller diameter section  41  that connects with rotating seal element  43 . This interconnection can be seen in  FIG. 3 . 
   A pair of O-rings  45 ,  46  are provided, one being carried by the rotating seal element  43  and another being carried by the non-rotating seal element  44 . The rotating seal element  43  has an annular recess  51  or groove that is receptive of O-ring  45  as shown in  FIGS. 3 and 6 . The O-ring  46  fits an annular recess  52  on non-rotating seal element  44  as shown in  FIGS. 3 and 6 . Locking pin  47  on non-rotating seal element  44  nests in a recess  48  of seal flange  19  as shown in  FIGS. 3 and 6 . 
   In order to assemble the various components of mechanical seal  16 , the sleeve  21  is first fitted with spring cage assembly  22  by placing it over the sleeve  21 , lowering it until ring  24  rests upon larger diameter section  32  and lugs  25  engage slots  26 . The rotating seal element  43  is then placed over the upper end portion of sleeve  21  and lowered until it registers upon spring cage assembly  22  wherein lugs  42  interlock with longitudinal slots  38 . Before placing the rotating seal element in position, it is fitted with O-ring  45  as indicated schematically by arrows  53  in  FIG. 6 . The non-rotating seal element  44  is also fitted with O-ring  46  as indicated by arrows  54  in  FIG. 6 . The non-rotating seal element is then placed over the sleeve  21  until sealing face  55  rests upon sealing face  56  of rotating seal element  43 . The non-rotating seal element  44  is preferably of a carbide material. The rotating seal element  43  can be of stainless steel, silicon carbide, tungsten carbide, ceramic, bronze, or other material as may be appropriate for the type of material being pumped, so that the faces  55 ,  56  form a seal that when placed under compression are urged together by spring  23 . This allows sealing even of gases of very small molecular diameter (unlike in the prior art where the Teflon® U-seals, once deflated, will allow gases to leak). The O-ring  45  forms a seal with the outer surface of sleeve  21  as indicated in  FIG. 3 . The O-ring  46  forms a seal with seal flange  19  as indicated in  FIG. 3 . The load is transferred from pump shaft  15  to sleeve  21  using drive ring  49  and bolts  50  that extend through the drive ring  49  and through openings  35  of sleeve  21 , then connecting to pump shaft  15 . 
   The following is a list of parts and materials suitable for use in the present invention. 
   
     
       
             
           
             
             
             
           
         
             
                 
             
             
               PARTS LIST 
             
           
        
         
             
                 
               Part Number 
               Description 
             
             
                 
                 
             
             
                 
               10 
               pump apparatus 
             
             
                 
               11 
               pump housing 
             
             
                 
               12 
               pump head 
             
             
                 
               13 
               barge deck 
             
             
                 
               14 
               lower end portion 
             
             
                 
               15 
               pump shaft 
             
             
                 
               16 
               mechanical seal 
             
             
                 
               17 
               below deck compartment 
             
             
                 
               18 
               driver 
             
             
                 
               19 
               seal flange 
             
             
                 
               20 
               bolted connection 
             
             
                 
               21 
               sleeve 
             
             
                 
               22 
               spring cage assembly 
             
             
                 
               23 
               coil spring 
             
             
                 
               24 
               ring 
             
             
                 
               25 
               lug 
             
             
                 
               26 
               slot 
             
             
                 
               27 
               larger diameter section 
             
             
                 
               28 
               smaller diameter section 
             
             
                 
               29 
               annular shoulder 
             
             
                 
               30 
               smaller diameter section 
             
             
                 
               31 
               intermediate diameter section 
             
             
                 
               32 
               larger diameter section 
             
             
                 
               33 
               annular shoulder 
             
             
                 
               34 
               annular shoulder 
             
             
                 
               35 
               opening 
             
             
                 
               36 
               open center 
             
             
                 
               37 
               cage 
             
             
                 
               38 
               longitudinal slot 
             
             
                 
               39 
               annular shoulder 
             
             
                 
               40 
               larger diameter section 
             
             
                 
               41 
               smaller diameter section 
             
             
                 
               42 
               lug 
             
             
                 
               43 
               rotating seal element 
             
             
                 
               44 
               non-rotating seal element 
             
             
                 
               45 
               O-ring 
             
             
                 
               46 
               O-ring 
             
             
                 
               47 
               locking pin 
             
             
                 
               48 
               recess 
             
             
                 
               49 
               drive collar 
             
             
                 
               50 
               bolt 
             
             
                 
               51 
               recess 
             
             
                 
               52 
               recess 
             
             
                 
               53 
               arrow 
             
             
                 
               54 
               arrow 
             
             
                 
               55 
               sealing face 
             
             
                 
               56 
               sealing face 
             
             
                 
                 
             
           
        
       
     
   
   All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. 
   The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.