Abstract:
The present invention relates to centrifugal pumps, and more specifically to a centrifugal pump device with a governor actuated cartridge seal and a method of attaching a centrifugal pump device with a governor actuated cartridge seal. The centrifugal pump comprises a sealing system that prevents undesirable fluid leaking or air ingestion when in operation while allowing ease of installation and maintenance. The governor actuated cartridge seal automatically increases sealing capabilities by urging a movable seal as a function of impeller or engine drive shaft rotational speed. The governors actuate radially so as to present a minimal profile and therefore not introduce a safety hazard. Scalable weights attached to the governors allow predictable calibration and initialization of the pump under varying hydraulic pressures and rotational speeds.

Description:
FIELD OF THE INVENTION 
       [0001]    The disclosure relates to pump seals, and more specifically to governor actuated seals for use with centrifugal pumps, and a method of and apparatus for adjusting cartridge seals to pumps. 
       BACKGROUND OF THE INVENTION 
       [0002]    Centrifugal pumps transport fluid by converting input rotational energy to hydrodynamic energy. The energy conversion is provided by an impeller driven by an engine. Fluid enters the impeller inlet along an axis parallel to the pump&#39;s drive shaft. The disc-like impeller reduces liquid pressure at the eye which draws in more fluid and centrifugally accelerates the fluid into a radial pump outlet. Centrifugal pumps are commonly used to transport fluids containing solid particles, referred to as “slurries.” Because of the naturally high dynamic loading and hydraulic pressures inherent in centrifugal pumps, and attendant maintenance and installation requirements, a variety of seals are employed. The variety of seals attempt to balance the need to prevent undesirable fluid leaking or air ingestion during pumping operations while allowing ease of installation and maintenance. Ideally, the configuration of seals allows predictable containment and control of the fluid within the pump under varying hydraulic pressures and rotational speeds. In addressing the above engineering and operational requirements, centrifugal pumps may include a dynamically-actuated seal to automatically engage or increase sealing capabilities as a function of impeller or drive shaft rotational speed. It is desirable that any dynamically-actuated pump sealing elements require minimal lengthening of the drive shaft and are easily and predictably installed. 
         [0003]    One example of a centrifugal pump fitted with a dynamically-actuated seal is disclosed in U.S. Pat. No. 5,667,356 to Whittier et al (“Whittier”), incorporated herein by reference in its entirety. The centrifugal pump incorporates a ball bearing assembly as a force-responsive governor to control opening and closing of a fluid path leading from an expeller region into a seal. The seals are composed of hard, low-friction sealing materials for handling acids and of resilient materials for handling slurries owing to the solids content in the slurries. The force-responsive governor of Whittier is limited in its operational range once installed due to the self-confined design that requires disassembly to adjust the number of governor balls. Also, Whittier&#39;s seals do not lend to predictable containment and control of the fluid of the pump due to lack of adjustment for compounded tolerances. 
         [0004]    Another example of a centrifugal pump fitted with a dynamically-actuated seal is disclosed in U.K. Patent Application No. GB 2,078,877 to Waters (“Waters”), incorporated herein by reference in its entirety. The centrifugal pump of Waters has a drive shaft rotating a pumping impeller and an axially adjacent impeller providing a dynamic seal for a pump chamber. A partition separates the dynamic seal from a static seal comprising a carbon ring on a carrier on the shaft spring pressed against a stationary ring secured to the partition. As illustrated in FIG. 1 of Waters, the carrier is axially moved by centrifugally acting arms ( 58 ) to withdraw the sealing ring when a predetermined shaft speed is exceeded. The force-responsive seal of Waters, as provided by the centrifugally acting arms, present an unnecessarily large footprint due to an extended axial length of the shaft to accommodate the axially aligned arms. Lengthening a drive shaft is more costly, creates a heavier shaft requiring more robust bearings adding further expense, and increases vibration and noise. In addition, the orientation of the arms parallel to the shaft create a hazard for operators working in the vicinity of the arms during operation. A hand, arm or tool placed in the path of the rotating arms would likely be damaged and could also cause damage to the pump. Furthermore, Waters&#39; seals do not provide predictable calibration and initialization of the pump under varying hydraulic pressures and rotational speeds. 
         [0005]    A further issue with cartridge seals generally is the use of removable pre-load tabs.  FIG. 1  is an illustration of one example of pre-load tabs applied to a cartridge seal. As shown, the tabs secure the shaft sleeve to the cartridge housing and apply a pre-load to the seal. Once the cartridge seal is installed, the tabs must be removed for the pump to operate as the shaft sleeve must be free to rotate with the pump shaft. However, the tabs must be reinstalled for maintenance and adjustment of the cartridge seal. Therefore, the tabs must be saved and stored in a known and reliable location for use during future maintenance. As can be appreciated, the tabs are often misplaced, lost or even thrown away. 
         [0006]    There is a need for a pump fitted with a sealing system that prevents undesirable fluid leaking or air ingestion. There is a need to provide a centrifugal pump with a dynamically-actuated seal that automatically increases sealing capabilities as a function of impeller or engine drive shaft rotational speed. There is a further need to provide a dynamically actuated seal in a manner that reduces overall seal axial length and that presents a minimal profile when actuated. In addition, there is also a need for a cartridge sealing system for use with pumps that provides ease of installation and maintenance, as wells as predictable containment and control of the fluid within the pump under varying hydraulic pressures and rotational speeds. There is a need for a system and method to apply a preload to a cartridge seal without removable tabs. The present invention meets these needs by providing both an improved governor actuated seal and a cartridge seal that provides a method of and apparatus for attaching a cartridge seal to a pump. 
       SUMMARY OF THE INVENTION 
       [0007]    In one embodiment, the cartridge seal comprises a cylindrical shaft sleeve, a plurality of governors positioned on the exterior of the proximal end of the cylindrical shaft sleeve, and at least one movable seal positioned radially outwardly of the shaft sleeve and axially movable relative to the shaft sleeve by operation of the governors. A housing surrounds the at least one movable seal to form a cartridge. The cylindrical shaft sleeve is adapted to interconnect the cartridge seal to a drive shaft and receive a fluid pressure at the distal end. The governors are configured to extend outwardly with drive shaft rotation. Preferably, the governors extend outwardly within the same plane, where the plane is defined perpendicular to the axis of the shaft. The movable seal has a proximal end which engages with a respective actuator of each governor. The at least one movable seal is positioned distally of each respective governor and is positioned outwardly of the cylindrical shaft sleeve. When the drive shaft is at rest, the at least one movable seal is at a first position and provides a fluid seal with respect to the fluid pressure. When the drive shaft is at a rotational speed, the governors extend radially outwardly to displace the at least one movable seal to a second position distal to the first position to provide an increased fluid seal. 
         [0008]    In another aspect of one embodiment, the seal housing is provided in the form of a cartridge that is connected to the drive shaft of a pump by a plurality of set screws. The housing comprises a cylindrical collar surrounding a majority of the cylindrical shaft sleeve and movable seal. Cutouts are formed in the cylindrical shaft sleeve at spaced locations around the circumference to receive the set screws to secure the cylindrical shaft sleeve to the drive shaft. A similar number of spaced apertures are formed in the movable seal and align with the cutouts in the cylindrical shaft sleeve when the two components are properly mated. The collar comprises a radially inward facing channel or groove covering at least a majority of the installed set screws and permits the set screws to rotate with the drive shaft without interference from the collar and without exposure to an operator, thereby also providing a safety feature. The collar does not completely encircle the cylindrical shaft sleeve and movable seal, but comprises an open portion to allow access to the set screws. The set screws replace conventional lock tabs used to apply a preload to a cartridge seal, but which are often lost or misplaced when needed for subsequent maintenance because they must be removed during operation of the pump. Accordingly, a method of and apparatus for attaching the cartridge seal to a pump is also disclosed. The method comprises the steps of: providing a cartridge seal, axially aligning and fitting the cartridge seal with a drive shaft of a pump, securing a mounting plate of the cartridge seal to the pump, accessing individual set screws through the open portion of a collar formed in the housing of the cartridge seal, and advancing the individual set screws to engage the drive shaft and secure the cartridge seal to the drive shaft. 
         [0009]    In yet another aspect of one embodiment, each governor has an arcuately-shaped length extending along a circumference of the cylindrical shaft sleeve and a height extending radially from the cylindrical shaft sleeve upon a threshold RPM being achieved. Optionally, each governor may be provided with a plurality of score lines to facilitate cutting the governor and removing a portion of the length of the governor to alter the weight and performance of each governor. Data may be provided that quantifies the operational performance of the pump and seal based upon removing weight from the governors is defined by each score line. In this way, the performance of the cartridge seal may be more closely set to meet actual operating conditions. 
         [0010]    The phrase “device” and/or “apparatus” is used herein to indicate embodiments of the invention device. The phrase “automatic” refers to a device&#39;s ability to automatically adjust and/or adapt itself to maintain and/or monitor a specified condition or state. The phrase “removably attached” and/or “detachable” is used herein to indicate an attachment of any sort that is releasable. The phrase “fluid” and/or “fluids” means liquids as well as mixtures thereof and mixtures of such with solids. The phrase “slurry” means a fluid containing solid particles. The phrases “radially outward” and “radially inward” mean relative to the axis of the drive shaft. As used herein, the terms “proximal” and “distal” are axial terms, and the terms “inner” and “outer” are radial terms. Proximal and distal refer respectively to relative right and left sides of the cartridge seal. Similarly, references inner and outer refer respectively to radial positions relatively closer and further to the axial centerline. 
         [0011]    One of ordinary skill in the art will appreciate that embodiments of the present disclosure may be constructed of materials known to provide, or predictably manufactured to provide the various aspects of the present disclosure. These materials may include, for example, stainless steel, titanium alloy, aluminum alloy, chromium alloy, and other metals or metal alloys. The sealing elements could be semi-rigid or rigid. 
         [0012]    This Summary of the Invention is neither intended nor should it be construed as being representative of the full extent and scope of the present disclosure. The present disclosure is set forth in various levels of detail in the Summary of the Invention as well as in the attached drawings and the Detailed Description, and no limitation as to the scope of the present disclosure is intended by either the inclusion or non-inclusion of elements, components, etc. in this Summary of the Invention. Additional aspects of the present disclosure will become more readily apparent from the Detailed Description, particularly when taken together with the drawings. 
         [0013]    The above-described benefits, embodiments, and/or characterizations are not necessarily complete or exhaustive, and in particular, as to the patentable subject matter disclosed herein. Other benefits, embodiments, and/or characterizations of the present disclosure are possible utilizing, alone or in combination, as set forth above and/or described in the accompanying figures and/or in the description herein below. However, the Detailed Description of the Invention, the drawing figures, and the exemplary claim set forth herein, taken in conjunction with this Summary of the Invention, define the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the disclosure and together with the general description of the disclosure given above and the detailed description of the drawings given below, serve to explain the principles of the disclosures. 
           [0015]    It should be understood that the drawings are not necessarily to scale. In certain instances, details that are not necessary for an understanding of the disclosure or that render other details difficult to perceive may have been omitted. It should be understood, of course, that the disclosure is not necessarily limited to the particular embodiments illustrated herein. 
           [0016]      FIG. 1  is a perspective view of a prior art cartridge seal, illustrating the use of pre-load tabs; 
           [0017]      FIG. 2  is a top plan view of a centrifugal pump cartridge seal (shown in solid lines) as a component of a centrifugal pump and bearing assembly (shown in dashed lines) according to one embodiment of the device; 
           [0018]      FIG. 3  is a cross-sectional left-side elevation view of the centrifugal pump cartridge seal (shown in solid lines) of  FIG. 2  as a component of a centrifugal pump and bearing assembly (shown in dashed lines); 
           [0019]      FIG. 4  is a perspective view of the proximal end of the centrifugal pump cartridge seal device of  FIG. 2 ; 
           [0020]      FIG. 5A  is a cross-sectional elevation view of the centrifugal pump cartridge seal of  FIG. 4  in a first state, taken along line  5 - 5  of  FIG. 4 ; 
           [0021]      FIG. 5B  is an elevation view of the distal end of the centrifugal pump cartridge seal device of  FIG. 5A ; 
           [0022]      FIG. 5C  is a cross-sectional elevation view of the centrifugal pump cartridge seal device of  FIG. 4  in a second state, taken along line  5 - 5  of  FIG. 4 ; 
           [0023]      FIG. 5D  is an elevation view of the distal end of the centrifugal pump cartridge seal device of  FIG. 5C ; 
           [0024]      FIG. 6  is a cross-sectional perspective view of the centrifugal pump cartridge seal device of  FIG. 4 ; 
           [0025]      FIG. 7  is a cross-sectional elevation view of the cartridge seal with the mounting plate and closing plate removed for illustrative purposes; 
           [0026]      FIG. 8  is an exploded perspective view of the centrifugal pump cartridge seal device of  FIG. 4 ; 
           [0027]      FIG. 9  is a flow-chart of a method of attaching a cartridge seal of one embodiment of the present invention to a centrifugal pump. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    The following description will typically be with reference to specific structural embodiments and methods. It is to be understood that there is no intention to limit the invention to the specifically disclosed embodiments and methods but that the invention may be practiced using other features, elements, methods and embodiments. Preferred embodiments are described to illustrate the present invention, not to limit its scope, which is defined by the claims. Those of ordinary skill in the art will recognize a variety of equivalent variations on the description that follows. Like elements in various embodiments are commonly referred to with like reference numerals. 
         [0029]    With reference to  FIGS. 2 and 3 , one embodiment of a cartridge seal  100  as a component of a centrifugal pump  10  is shown. The drive shaft  20  of the centrifugal pump  10  forms an axial centerline. Generally, slurry input  30  enters the distal or wet end of the pump  10  and flows axially toward pump impeller  40  and exits at slurry output  50 . Drive shaft  20 , supported by bearing assembly  60 , powers pump impeller  40 . When pump impeller  40  is rotating, a suction is created which urges slurry into input  30  and provides a fluid pressure onto cartridge seal  100 . When pump impeller  40  is not rotating and pump  10  is still in fluid communication with slurry at input  30 , a fluid (static) pressure is imparted to the cartridge seal  100 . 
         [0030]      FIG. 4  provides a perspective view of the proximal end of one embodiment of the cartridge seal  100 . Mounting plate or stuffing box  200  attaches to the pump housing  70  by bolts inserted through apertures  205 . Closing plate or cover  210  is affixed to the mounting plate  200  by mounting bolts  215 . A collar  220  extends outwardly from the closing plate  210  and circumferentially surrounds the drive shaft  20 . Shaft sleeve  300  fits circumferentially around drive shaft  20  and inside the collar  220 . As illustrated, two governors  305  are pivotally mounted on pivot pins  310  at the distal end  315  of the shaft sleeve  300 . Each governor  305  is secured to pivot pin  310  by a cotter key  320 . The governors  305  are configured to extend radially outwardly by rotation of the drive shaft  20 . The pivot pins  310  are oriented such that the governors extend radially outwardly in a plane perpendicular to the longitudinal axis of the shaft  20 . Preferably, the governors are oriented to extend and retract in a common plane that is perpendicular to the axis of the drive shaft  20 , but the pivot pins  310  could be offset relative to the axis of the drive shaft such that the governors extend in different but substantially parallel planes. When the drive shaft  20  and shaft sleeve  300  are not rotating, each of the governors  305  are in a first or unextended state, as depicted in  FIG. 4 . In contrast, when the drive shaft  20  and shaft sleeve  300  are rotating at or above a threshold RPM (revolutions per minute), each of the governors  305  rotate about a respective pivot pin  310  and extend radially outwardly to a second or extended state. With increased drive shaft RPM above the threshold RPM, each of the governors  305  may rotate further about respective pivot pin  310 . The threshold RPM is selectable and the weight, size and shape of the governors is also selectable. For example, one means for adjusting the threshold RPM at which the governors move to a second or extended state is to vary the weight and/or shape of the governors. As also shown in  FIG. 4 , the governors  305  may optionally be provided with pre-defined score lines  325  to facilitate removal of a portion of the governor, thereby reducing its length and weight and altering its response to the RPM of the drive shaft. The governor weights  305  may be readily accessible and adjustable by removal of the pivot pin cotter keys  320 . Once removed, the size, shape and/or weight of a governor  305  may be adjusted by cutting and removing weight from the governor, for example, along the scoring lines  325 . It should be appreciated that the governors  305  may be removed without disassembly of the pump  10 . Thus, the sealing performance of the cartridge sealing device  100  may be adjusted in the field to achieve selected centrifugal pump performance or drive shaft  20  power requirements. 
         [0031]    Further details of one embodiment of the centrifugal pump cartridge seal  100  are provided in  FIGS. 5A-D ,  6  and  7 . Generally, the cartridge seal  100  prevents fluid entering centrifugal pump  10  at slurry input  30  (see  FIGS. 2 and 3 ) from migrating past the impeller  40  and around drive shaft  20  toward the pump motor. As previously noted, shaft sleeve  300  is positioned on drive shaft and is secured to the drive shaft  20  such that it rotates in unison with the drive shaft  20 . A movable sleeve seal  400  is positioned around shaft sleeve  300  and moves axially relative to the shaft sleeve  300  and drive shaft  20 . The proximal end  405  of the movable seal  400  includes a plurality of cutouts  410  equally spaced about the circumference of the movable seal  400 . As better seen in  FIG. 7 , the shaft sleeve  300  comprises a plurality of apertures  330  which, when aligned with the cutouts  410 , permit the shaft sleeve  300  to be secured to the drive shaft  20  by set screws  415 , and also secure the movable seal  400  to rotate with the shaft sleeve  300 . 
         [0032]    With reference to  FIGS. 5A ,  5 C and  7 , the distal end  420  of movable sleeve seal  400  is spaced from the shaft sleeve  300  forming a gap  425  between the outer surface of the shaft sleeve  300  and the inner surface of the distal end  420  of the movable sleeve seal  400 . In the illustrated embodiment, the gap  425  has two sections of differing heights. The proximal end  430  of the gap  425  extends from a shoulder  435  formed by the movable seal  400 . A pair of axially aligned O-rings  440  and  445  are positioned in the proximal portion  430  of the gap  425  and are separated by a separation ring  450 . The O-rings  440  and  445  provide a seal between the inner surface of the movable sleeve seal  400  and the outer surface of the shaft sleeve  300 . The separation ring  450  maintains the axial spacing and alignment of the O-rings  440  and  445 . The distal end  455  of the gap  425  has a greater height than the proximal end  430  of the gap  425 . A channel sleeve  460  is positioned in the distal portion  455  of the gap  425 . The channel sleeve  460  fits snugly on the outer surface of the distal end of the shaft sleeve  300  and is provided with a circumferential groove  465  on its outer surface. An O-ring  470  fits in the groove  465  and forms a seal between the channel sleeve  460  and the inner surface of the movable sleeve seal  400 . The channel sleeve  460 , O-rings  440  and  445 , and separation ring  450  are held in axial alignment along the distal end of the shaft sleeve  300  by snap ring  475 , which is friction fit in a groove  480  formed in the shaft sleeve  300 . 
         [0033]    A radially outwardly facing channel  485  is formed on the outer surface of the distal end  420  of the movable sleeve seal  400 . The channel forms a first sealing surface  490 , a second sealing surface  495  spaced apart from the first sealing surface  490  and a third sealing surface  500  interconnecting the first and second sealing surfaces. As shown in  FIGS. 5A and 5C , the channel  485  receives the inner portion of a stationary disk seal  510 . The stationary disk seal  510  comprises a distal surface  515 , a proximal surface  520 , an outer surface  525  and an inner surface  530 . The stationary disk seal  510  is positioned such that the distal surface  515  and outer surface  525  abut a shoulder  225  formed in the mounting plate  200  and creates a fluid seal at that location. The radially-inner portion of stationary disk seal  510 , comprising the inner surface  530  and portions of the distal surface  515  and proximal surface  520 , is positioned to engage the first, second and third sealing surfaces  490 ,  495  and  500  of the movable sleeve seal  400 . More specifically, distal surface  515  engages the first sealing surface  490  and third sealing surface  500  of the movable sleeve seal when the pump is static or operating below the predetermined threshold RPM, and engages a second sealing surface  495  and third sealing surface  500  when the governors  305  are in a second (extended) state. In one embodiment, the stationary disk seal  510  may be a rubber seal, and may be manufactured using a lathe. 
         [0034]      FIGS. 5A-B  and  7  depict the cartridge seal  100  in a first state with governors  305  not extended, and in a second state with governors  305  extended in  FIGS. 5C-D . The first state occurs when the drive shaft is not rotating or rotating at an RPM below the activation threshold RPM discussed herein. The second state occurs when the drive shaft is operating at an RPM above the threshold RPM. Governors  305  enable a tighter or increased seal for the centrifugal pump by displacing the movable seal  400  toward the pump wet end, i.e. distally to the left in  FIGS. 5A-D ,  6  and  7 . One end of each governor  305  is configured with an actuating surface  340  which is in contact with a camming surface  550  on the movable sleeve seal  400 . As drive shaft RPM increases, centrifugal forces cause governors  305  to radially extend such that actuating surface  340  distally displaces movable sleeve seal  400  toward the pump wet end, by way of the movable sleeve seal camming surface  550 . The movement of the movable sleeve seal  400  forward the distal end of the seal  100  increases the sealing capabilities of the cartridge seal  100  in several ways. When displaced axially toward the wet end, the second sealing surface  495  engages the proximal end  520  of stationary disk seal  510 , thereby creating a new seal. The sealing pressure increases with increased RPM. If fluid escapes, a secondary path is provided to allow exiting of the slurry by way of leak elbow  230 . In addition, a flexible V-ring  555  is positioned between a proximal face  520  of the disk seal  510  and the closing plate  210 . The V-ring  555  is a pressurized lip seal and functions as a secondary seal. The profile or shape of the camming surfaces and/or actuating surfaces may be varied to alter movement of the movable seal  400 . 
         [0035]    The operation of the movable sleeve seal as displaced by the governors  305  is apparent by a comparison of  FIGS. 5A-B  with  FIGS. 5C-D . It should be appreciated that these figures are for illustrative purposes and the relative position of the component structures of the pump can and will vary depending upon actual implementation. In  FIG. 5D , the centrifugal pump is operating at sufficient RPM so as to exceed the threshold RPM required to extend the governors  305  relative to shaft sleeve  300 . In contrast, in  FIG. 5B  the centrifugal pump is either not operating or operating at insufficient RPM so as to extend the governors  305  relative to shaft sleeve  300 . In  FIG. 5C , the companion figure to  FIG. 5D  in which the governors  305  are extended, the actuating surface  340  of the governor  305  has displaced movable sleeve seal  400 , by way of the camming surface  550 , toward the pump wet end resulting in contact (and thus a seal) between the second sealing surface  495  and stationary disk seal proximal surface  520  and third sealing surface  500  and the inner surface  530  of the disk seal  510 . The axial movement of the moveable sleeve seal  400  is limited by the proximal interior corner  560  of sleeve seal against snap ring  475  via channel sleeve  460 . This limits the axial force generated by the governor  305  to prevent deteriorative thermal stress on the stationary sleeve  520 . In contrast, in  FIG. 5A , the companion figure to  FIG. 5B  in which the governors  305  are not extended, the actuating surface  340  has not displaced movable sleeve seal  400  toward the pump wet end, and thus there is no contact between the second sealing surface  495  and stationary disk seal proximal surface  520 . However, a seal does exist between the first sealing surface  490  and the distal surface  515  of the disk seal  510  and the third sealing surface  500  and the inner surface  530  of the disk seal  510 . Thus, the movable sleeve seal  400  provides dual seal capability; it provides a seal when the pump is at rest or at slower speed and provides a dynamic seal when the pump is at higher speed. 
         [0036]    In addition, when displaced axially toward the wet end, the distal O-ring  440  and proximal spring O-ring  445  function as a compression spring in addition to a seal. With increased drive shaft  20  rotational speed, the distal O-ring  440  and proximal O-ring  445  are compressed between the channel sleeve  460  and the shoulder  435 . When the drive shaft  20  slows such that the governors  305  are no longer applying a force on the movable sleeve seal  400  or are applying a reduced force, the distal O-ring  440  and proximal O-ring  445  expand, providing a return force on the movable sleeve  400  in the proximal direction, thereby assisting movement of the movable sleeve seal  400  to its static or first position. The separation ring  450 , together with the shape of the proximal section  430  of the gap  425 , maintain the linear position of the distal spring O-ring  440  relative to the proximal spring O-ring  445  such that they behave consistently and remain in the same position during repeated compression cycles. If these O-rings were able to reorient relative to each other, inconsistent compression could result. In one embodiment, the separation ring  450  is made of hard rubber and provides approximately 80 to 100 pounds per square inch of force. The use of the O-rings  440  and  445  is preferable over conventional coil springs because the gap may collect fluid slurry, potentially compromising the long term viability of a conventional spring. Additionally, a conventional spring would require a greater axial length than the O-rings, thereby increasing the axial length of the cartridge seal and the footprint of the overall pump. Similarly, O-rings are preferred over Bellville disc springs given the reduced axial length provided by O-rings. 
         [0037]    The shape and radially-extending configuration of the governors  305  provide a number of advantages over existing governors used in centrifugal pump applications. Existing governors extend axially, such as the Waters device discussed above. Such axially-extending governor arms require more axial space than radially-extending governors, and may present a lengthy pinch-point along the drive shaft axis. In addition, they require a longer drive shaft  20  which increases the length and footprint of the pump  10  and bearing assembly  60 . In contrast, the radially-extending governors  305  disclosed here require less axial space and thus a shorter drive shaft, which yields several benefits. A shorter drive shaft is less costly and lighter, produces less vibration and noise, and can operate more efficiently for a given RPM or fluid viscosity. Further, a shorter and thus relatively more rigid drive shaft will reduce seal wear and friction, thereby extending the operational life of the pump and extending maintenance intervals. In addition, the radially-extending governors  305  disclosed may be more aerodynamic than conventional axially-extending governors, thereby providing energy savings in operating the drive shaft  20 . Further still, radially extending governors are safer in operation compared to governors of the type used in Waters. An object inadvertently placed in the path of the governors  305  will cause deflection of the governors about pivot points  260 . The governors disclosed in Waters will not deflect and will likely break and/or be damaged and/or cause damage to the pump. 
         [0038]    The governors  305  of  FIGS. 3-7  have a height extending radially from the cylindrical shaft sleeve and a length extending along a circumference of the cylindrical shaft sleeve, wherein the length is generally of an arcuate shape. In some embodiments, other shapes are provided, e.g. a generally arcuate shape on the upper surface and most of the lower surface, yet a reduced profile away from the rotation pin point. Such a shape would allow increased rotation of a governor in that any lower surface contact of the governor with the shaft sleeve  300  would be prevented. 
         [0039]    As shown in  FIGS. 5A-D ,  6  and  7 , centrifugal pump cartridge seal  100  is secured to drive shaft  20  (not shown) through a plurality of set screws  415 . Each set screw  415  fits through a cutout  410  in the movable shaft seal  400  and into a corresponding set screw aperture  330  in the shaft sleeve  300 . As a result, the set screws  415  secure the shaft sleeve  300  to the drive shaft  20  and simultaneously accommodate axial movement of the movable sleeve seal  400 . The collar  220  extends to cover the set screws  415  and includes a groove  240  to accommodate the heads of the set screws  415  as they rotate with the drive shaft  20 . The collar  220  includes an open portion  250  to access the set screws for purpose of installation and subsequent adjustment and maintenance. The method of attaching the cartridge seal  100  to the drive shaft  20  is superior to the use of conventional lock tabs shown in  FIG. 1 . Lock tabs provide a pre-load to the seal necessary for installation purposes, but which must be removed for operation of the pump. Failure to remove the lock tabs can damage the seal and/or the pump if the pump is operated with the lock tabs in place. When maintenance or adjustment of the pump and/or seal is subsequently required, the lock tabs must be located and reinstalled. Because of their small size, the lock tabs are easily misplaced, resulting in frustration and unnecessary pump down-time. If the lock tabs cannot be located, servicing of the pump and/or seal is inhibited. In contrast, with the structure of embodiment of the present invention, the set screws may apply a preload to the cartridge seal, but also remain in place throughout operation of the pump. The access opening  250  allows an operator access to the set screws  415 . The set screws may be accessed and tightened or loosened and the drive shaft  20  and shaft sleeve  300  rotated without the need for conventional lock tabs. This structure and equivalents of it, may be applied to any cartridge seal for a variety of pumps, not just centrifugal pumps. This means and configuration of securing the centrifugal pump cartridge seal  100  to the drive shaft  20  of a centrifugal pump  10  enables an easy and predicable method of installing and maintaining the centrifugal pump cartridge seal  100 , as described below with reference to  FIG. 9 . 
         [0040]      FIG. 9  is a flow-chart of a method of attaching the centrifugal pump cartridge seal device  100  of  FIG. 2  to a centrifugal pump without the use of lock tabs. The method  900  of attaching the cartridge seal to a centrifugal pump begins with step  910 . At step  920 , a cartridge seal  100 , as described above, is provided in a pre-assembled state. At step  930 , the cartridge seal  100  is axially aligned with and fitted to the drive shaft  20 . That is, the shaft sleeve  300  is axially aligned with and slid over the drive shaft  20 . Next, the apertures  330  of the shaft sleeve  300  and the cutouts  410  of the movable seal  400  are aligned and axially positioned with respect to the drive shaft such that set screws  415  may engage the drive shaft  20  at user-desired locations. At step  940 , the mounting plate  200  of the centrifugal pump cartridge seal device  100  is secured to the pump housing  70  by mounting bolts positioned through apertures  205 . At step  950 , the set screws  415  are advanced through the cutouts  410  and into a corresponding shaft sleeve set screw aperture  330  to secure the cartridge seal device  100  to the drive shaft  20 . The method ends at step  960 . This method  900  provides an easy and predicable method of installing and maintaining the centrifugal pump cartridge seal device  100  without the use of lock tabs. The set screws  415  may be accessed and adjusted, and the drive shaft  20  and/or shaft sleeve  300  rotated, without the need for problematic lock tabs of conventional devices. The method may be reversed to remove the centrifugal pump cartridge seal device  100  from the centrifugal pump  10 . 
         [0041]      FIG. 8  is an exploded perspective view of the centrifugal pump cartridge seal device  100 . Mounting plate O-ring  260  attaches distally to mounting plate  200 . In series, from the distal-most element to the most proximal, the following elements are assembled to fit within and/or engage the mounting plate  200 : stationary seal  510 , snap ring  475 , channel sleeve  460  with channel sleeve O-ring  470 , the series of distal O-ring  440 , separation ring  450  and proximal O-ring  445  fitted at proximal end of movable sleeve seal  400 , and V-ring  555  also fitted at proximal end of movable sleeve seal  400 . Moveable sleeve seal cutouts  410  are depicted at the proximal end  405  of movable sleeve seal  400 . The movable sleeve seal cutouts  410  allow set screws  415  to secure movable seal  400  relative to shaft sleeve  300  and drive shaft  20 . Closing plate  210  attaches to mounting plate  200  by mounting screws  215 . A leak elbow  230  fits to closing plate  200  to direct any errant fluid that may leak through the centrifugal pump cartridge seal device  100 . Shaft seal  350  attaches to the inner radial surface of shaft sleeve  300  to seal shaft sleeve  300  to the drive shaft  20  (not shown). Finally, each of two governors  305  attach to shaft sleeve  300  by way of pivot pin  310  and pivot pin cotter key  320 . 
         [0042]    In one embodiment of the invention, the device is fitted with one or more active and/or passive sensors for qualitative and/or quantitative sensing of mechanical, electrical, physical, and/or chemical quantities, to detect, for example, position of the governors and/or the movable seals. Such sensors can be selected in particular from the group of temperature sensors, motion sensors, elongation sensors, rotation speed sensors, proximity sensors, flow sensors, vibration sensors, pressure sensors, conductivity sensors, acoustic pressure sensors, “lab on a chip” sensors, force sensors, acceleration sensors, tilt sensors, pH sensors, moisture sensors, magnetic field sensors, RFID sensors, magnetic field sensors, Hall sensors, biochips, odor sensors, and/or MEMS sensors. In one embodiment, the sensors are conveyed as control signals to a control unit. 
         [0043]    While various embodiment of the present disclosure have been described in detail, it is apparent that modifications and alterations of those embodiments will occur to those skilled in the art. For example, more than two governors may be utilized to move the movable seal  400  and the slopes of the actuating and camming surfaces may be configured to achieve dynamic sealing as each individual scenario demands. It is to be expressly understood that such modifications and alterations are within the scope and spirit of the present disclosure, as set forth in the following claims. 
         [0044]    The foregoing discussion of the disclosure has been presented for purposes of illustration and description. The foregoing is not intended to limit the disclosure to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the disclosure are grouped together in one or more embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed disclosure requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate preferred embodiment of the disclosure. 
         [0045]    Moreover, though the present disclosure has included description of one or more embodiments and certain variations and modifications, other variations and modifications are within the scope of the disclosure, e.g., as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights which include alternative embodiments to the extent permitted, including alternate, interchangeable and/or equivalent structures, functions, ranges or steps to those claimed, whether or not such alternate, interchangeable and/or equivalent structures, functions, ranges or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter.