Abstract:
A seal cartridge and a rotating nozzle assembly utilizing the seal cartridge are disclosed. The main seal member in the nozzle assembly is mounted as part of the seal cartridge. The seal cartridge is also easily removable from the rotating nozzle assembly without requiring the separate removal of the main seal member from the seal cartridge. This configuration allows a user to quickly install a new or rebuilt seal during an operation while minimizing or eliminating the necessity to manipulate small parts in the field.

Description:
TECHNICAL FIELD 
       [0001]    This application relates to seal cartridges for use in ultra high pressure rotating nozzles. Related methods are also disclosed. 
       BACKGROUND 
       [0002]    In high-pressure water blasting operations, it is often desirable to rotate a nozzle head to increase surface coverage, and thus productivity. However, sealing between the stationary and rotating components of the water blasting system must be addressed. The high-pressure environment and relative motion between components accelerate wear on the sealing components. For this reason, the sealing components must be changed regularly. The length of time required for this maintenance reduces the productivity of the water blasting system. Multiple solutions have been developed to address this sealing problem. 
         [0003]    In one solution, in which seal members are not used, the stationary and rotating components are separated by a very small space, for example less than a thousandth of an inch. The working fluid is allowed to escape through this space. Since there is no contact between the components, friction is minimized. In this solution, the power used to pressurize the fluid which escapes is wasted as it does not flow through the nozzle. At ultra-high pressures, near 40,000 PSI, this can be as much as 30% of the power used in the system. 
         [0004]    In another solution, sealing is accomplished using a plastic seal member bearing against a metal mandrel. The pressure of the working fluid forces the plastic seal member against the mandrel, preventing the working fluid from escaping. The plastic seal member is typically supported by a metal backup bushing. While this seal design is quite popular, the maintenance of this design is complicated and time consuming. This seal design uses a number of small parts which are removed and replaced separately. Removing and installing these small parts increases the time required to service the assembly, decreasing overall water blasting system productivity. Further, as such parts are often changed in the field, there is an inherent risk that some of the parts may be mishandled and either damaged or lost. Improvements are desired. 
       SUMMARY 
       [0005]    A seal cartridge and an ultra high pressure rotating nozzle assembly incorporating the seal cartridge are disclosed. The main seal member in the nozzle assembly is mounted as part of the seal cartridge. The seal cartridge is also easily removable from the rotating nozzle assembly without requiring the separate removal of the main seal member, or its associated backup bushing. This configuration allows a user to quickly install a new or rebuilt seal during an operation while minimizing or eliminating the necessity to manipulate smaller individual parts in the field. 
         [0006]    In one embodiment, the seal cartridge includes a mandrel having an exterior surface and an internal fluid path in which the mandrel has an upstream end with a first cross-sectional diameter and a downstream end with a second cross-sectional diameter that is smaller than the first cross-sectional diameter. Also included is a retaining member that is disposed about the mandrel and is constructed and arranged to connect the seal cartridge to the rotating nozzle assembly. The seal cartridge also includes a main seal member and a backup bushing, both of which are disposed about a portion of the exterior surface of the mandrel. The main seal member is in direct contact with the mandrel while there is a small clearance gap between the backup and the mandrel. The seal cartridge can also include an upstream seal member and a downstream seal member oriented to create a seal about the exterior surface of the seal cartridge. In addition to, or instead of, the upstream seal member, the downstream end of the mandrel can have a straight tapered shape or a radiused shape for forming a seal against a tapered or radiused seal surface of the nozzle shaft. The main seal member can be shaped to have a downstream surface that slopes towards the exterior surface of the mandrel in a direction towards the downstream end of the mandrel. In such a case, the backup bushing can also have a sloped upstream surface that is in at least partial contact with the downstream surface of the main seal member. The seal cartridge can also have a retainer, such as a retaining ring, constructed and arranged to hold the main seal, backup bushing and retaining member onto the mandrel. Further, the mandrel of the seal cartridge can be directly coupled to a rotating shaft within the rotating nozzle assembly by an engagement mechanism. 
         [0007]    Also, the seal cartridge can be assembled by (a) installing a retaining member onto a mandrel that has an upstream end and a downstream end wherein the mandrel defines an internal fluid path; (b) installing a backup bushing onto the mandrel from the upstream end of the mandrel such that the backup bushing and retaining member can be brought into contact with each other; and (c) installing a main seal member directly onto the mandrel from the upstream end of the mandrel such that the main seal member and the backup bushing can be brought into contact with each other. In another step, a retainer can be installed directly onto the mandrel from the upstream end of the mandrel so as to secure the main seal member and backup bushing onto the mandrel. However, the friction between the seal member and the mandrel, in certain embodiments, can also provide the necessary resistance to hold the main seal member, the backup bushing and the retaining member onto the mandrel. Other possible steps in the assembly process are installing an upstream seal member and installing a downstream seal member onto the seal cartridge so as to create a seal about the exterior surface of the seal cartridge. 
         [0008]    A rotating nozzle assembly is also disclosed that includes the above described seal cartridge, and can also include a seal cartridge housing directly connected to the seal cartridge via the retaining member of the seal cartridge, a nozzle housing directly connected to the seal cartridge housing, a nozzle shaft directly coupled to the mandrel of the seal cartridge, and a rotating nozzle head directly coupled to the nozzle shaft. The rotating nozzle assembly can be serviced by installing a fully assembled seal cartridge into the rotating nozzle assembly, by securing the fully assembled seal cartridge to the seal cartridge housing, and by securing the seal cartridge housing to the housing of the rotating nozzle assembly. Once the seal cartridge is spent, the fully assembled seal cartridge from the rotating nozzle assembly can be removed and replaced with a new seal cartridge. By use of the term “fully assembled”, it is meant to indicate that the seal cartridge remains intact during the installation and removal process such that the subcomponents of the seal cartridge are not further separated from the mandrel at any point during the process. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view of a first embodiment of a seal cartridge. 
           [0010]      FIG. 2  is a perspective, cut-away view of a rotating nozzle assembly within which the seal cartridge of  FIG. 1  is installed. 
           [0011]      FIG. 3  is a combined cross-sectional, side view of the seal cartridge of  FIG. 1 . 
           [0012]      FIG. 4  is an upstream end view of the seal cartridge of  FIG. 1 . 
           [0013]      FIG. 5  is a combined cross-sectional, side view of the nozzle assembly of  FIG. 2  within which the seal cartridge of  FIG. 1  is installed. 
           [0014]      FIG. 6  is an upstream end view of the nozzle assembly of  FIG. 2  within which the seal cartridge of  FIG. 1  is installed. 
           [0015]      FIG. 7  is a combined cross-sectional, side view of a first embodiment of a mandrel suitable for use in the seal cartridge of  FIG. 1 . 
           [0016]      FIG. 8  is a combined cross-sectional, side view of a second embodiment of a mandrel suitable for use in the seal cartridge of  FIG. 1 . 
           [0017]      FIG. 9  is a combined cross-sectional, side view of a third embodiment of a mandrel suitable for use in the seal cartridge of  FIG. 1 . 
           [0018]      FIG. 10  is a close-up view of the mandrel of  FIG. 8  disposed against the sealing surface of a rotating nozzle shaft. 
           [0019]      FIG. 11  is a close-up view of the mandrel of  FIG. 7  disposed against the sealing surface of a rotating nozzle shaft. 
           [0020]      FIG. 12  is a perspective view of the seal cartridge of  FIG. 1  and a portion of the rotating nozzle assembly of  FIG. 2 . 
           [0021]      FIG. 13  is a combined cross-sectional, side view of a backup bushing. 
           [0022]      FIG. 14  is a perspective view of the backup bushing of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    This disclosure relates to seal cartridges for use in ultra high pressure rotating nozzles.  FIG. 1  represents one embodiment of an uninstalled seal cartridge  100  that can be installed within a rotating nozzle assembly  200 .  FIG. 2  shows the seal cartridge  100 , as installed in the rotating nozzle assembly  200 .  FIGS. 3-4  show additional views of seal cartridge before or after installation into the rotating nozzle assembly  200 .  FIGS. 5-6  show additional views of the rotating nozzle assembly  200  with the seal cartridge  100  installed therein. The following paragraphs describe the various components and functions of both the seal cartridge  100  and the nozzle assembly  200 . 
         [0024]    In the embodiment shown, seal cartridge  100  includes a mandrel  102 . Mandrel  102  is a rotating component for providing an interior flow path through which pressurized fluid can flow, for providing a positive pressure bias when pressurized fluid (not shown) is flowing through the mandrel, and for providing a sealing surface to prevent pressurized fluid from escaping the nozzle assembly  200  in which the seal cartridge is installed. By the use of the term “positive pressure bias” it is meant that the mandrel is configured such that the pressurized fluid exerts a net pressure or force on the mandrel in the same direction as the pressurized fluid is flowing. As can be best seen at  FIGS. 3-4 , the mandrel  102  defines an exterior surface against which main seal member  104 , discussed later, can form a seal. 
         [0025]    Mandrel  102  also defines an interior flow path  102   b  through which the pressurized fluid can flow. As shown at  FIG. 3 , the pressurized fluid flows in a first direction  120  from an upstream end  102   d  to a downstream end  102   f . By use of the term “upstream end” it is meant to identify the end of the mandrel nearest to which pressurized fluid flows into the internal flow path  102   b . By the use of the term “downstream end”, it is meant to identify the end of the mandrel nearest to which pressurized fluid flows out of the internal flow path  102   b . The upstream end  102   d  has a cross-sectional diameter  102   c  while the downstream end  102   f  has a cross-sectional diameter  102   e  that is less than the cross-sectional diameter  102   c . This difference in diameters results in the upstream end  102   d  of the mandrel  102  having a greater cross-sectional surface area than the downstream end  102   f . As such, when the mandrel  102  is exposed to the pressurized fluid, the fluid exerts a first pressure  122  on the upstream end  102   d  and a second pressure  124  on the downstream end  102   f . Because the cross-sectional area of the upstream end  102   d  is greater than the cross-sectional area of the downstream end  102   f , the pressurized fluid will create a net force on the mandrel in the direction of pressurized fluid flow  120 . Thus, a positive pressure bias is created on the mandrel by the pressurized fluid. This pressure bias is further enhanced by the frictional forces between the pressurized fluid and the internal flow path  102   b  of the mandrel  102  that creates a pressure drop between the upstream and downstream ends. The benefit of the positive pressure bias is that the seal cartridge  100  will be inherently maintained in its desired position within nozzle assembly  200  when pressurized fluid is flowing, thereby eliminating the need to further secure the seal cartridge  100  to the nozzle assembly  200  by mechanical or other means. 
         [0026]    Another feature of mandrel  102  relates to the various shapes front end  102   f  can be formed to include. These various shapes are for enabling a metal-to-metal seal to form between the front end  102   f  of the mandrel  102  and a sealing surface  202   d  on the nozzle shaft  202 . This type of seal can be used instead of or in conjunction with the seal formed by the downstream seal  114 . Many types of shapes are suitable for the purpose of forming a metal-to-metal seal. For example, front end  102   f  can be formed with a straight tapered shape having an angle α relative to the flow direction  120 , as best seen at  FIG. 7 . In the particular embodiment shown, α is about 29.0 to 29.5 degrees. Instead of having a straight tapered shape, front end  102   f  can have a curved or radiused shape defined by radius ‘r’, as best seen at  FIGS. 8 and 9 . In the particular embodiment shown, radius ‘r’ is a constant radius of about 0.058 inches. In a further variation, the interior flow path  102   b  at front end  102   f  can be tapered outward at an angle β, as can be most easily seen at  FIG. 9 . This outward taper can help to provide additional sealing force. With respect to the shaft  202 , the sealing surface  202   c  can have either a straight tapered shape, as shown in  FIG. 10 , or a curved or radiused shape, as shown in  FIG. 11 . In the particular embodiment shown in  FIG. 10 , the taper θ is about 30.0 to 30.5 degrees with respect to the direction of flow  120 . In the particular embodiment shown in  FIG. 11 , the radius R is about 0.075 inches. 
         [0027]    In operation, the positive pressure bias force causes the front end  112   f  of the mandrel  102  to be forced against the sealing surface  202   d  of the shaft  202 . The resulting contact area between the front end  112   f  and  202   d  is designed to be relatively small such that the positive pressure bias force creates a suitably high pressure for creating the seal. The size of the contact area can be controlled by several methods. One example, is by using a straight tapered front end  112   f  that has a slightly smaller angle α than a straight taper angle θ on the sealing surface  202   d . This difference in angles allows for only the tip of front end  112   f  to come into contact with the sealing surface  202   d , thereby creating a sufficiently small contact area. Alternatively, the contact area can be minimized by using a radiused front end  112   f  against either a tapered sealing surface  202   c  (shown in  FIG. 10 ) or a radiused sealing surface  202   d  (shown in  FIG. 11 ). This approach allows for only a portion of the radiused front end  112   f  to come into contact with the sealing surface. The particular arrangement of a radiused front end  112   f  and a straight tapered sealing surface  202   d  is shown in  FIG. 10 . For this particular embodiment, the radius of the mandrel  102  initially contacts the angled surface  202   d  of the shaft  202  in a circle line of contact. The deformation of the material of both the mandrel  102  and the shaft  202  will produce a small surface area of contact. Yet another approach to minimizing the contact area is by using a straight tapered front end  112   f  against a radiused sealing surface  202   d . This particular arrangement is shown in  FIG. 11 . Where a radius is used for the front end  112   f  or the sealing surface  202   d , it is expected that less material wear will result, as compared to a configuration of a tapered front end  112   f  against a tapered sealing surface  202   d  where grooving may occur. Many other combinations of dimensions and shapes for the front end  112   f  and the sealing surface  202   d  can be utilized to enable a metal-to-metal seal, so long as the resulting contact area is small enough to allow the positive pressure bias force to create enough pressure to form a seal. 
         [0028]    Other aspects of mandrel  102  are a first enlarged portion  102   g  and a second enlarged portion  102   h . The first enlarged portion  102   g  enables machining of the mandrel  102  to be performed more easily and also serves as a surface to engage the retaining member  108 , when removing the seal cartridge  100  from the nozzle  200 . The second enlarged portion  102   h  is for providing a mounting surface for engagement mechanism  116 . The engagement mechanism  116  and the retaining member  108  are discussed in more detail below. In the particular embodiment shown, both the first and second enlarged portions  102   g ,  102   h  have a diameter that is greater than that of cross-sectional diameters  102   c  and  102   e . Additionally, second enlarged portion  102   h  has a diameter that is larger than that of first enlarged portion  102   g . It should be noted, that mandrel  102  does not need to be machined to have first and second enlarged portions  102   g ,  102   h  and that, if absent, engagement mechanism  116  could be installed on a non-enlarged portion of mandrel  102  and would perform the same removal function as portion  102   g.    
         [0029]    In the particular embodiment shown at  FIGS. 3-4 , the internal fluid path  102   b  of mandrel  102  is 0.94 inches, the upstream diameter  102   c  is 0.181 inches, and the downstream diameter  102   e  is 0.175 inches. Also, as shown, mandrel  102  is manufactured from 17-4 precipitation hardening stainless steel. However, one skilled in the art will appreciate that other materials and dimensions are possible without departing from the concepts presented herein. 
         [0030]    Another aspect of seal cartridge  100  is the seal assembly which is comprised of a main seal member  104  and a backup bushing  106 . The seal assembly is for preventing pressurized fluid from leaking past the exterior surface  102   a  of the mandrel  102  such that all of the pressurized fluid is directed through the interior flow path  102   b  and to the nozzle assembly  200 . The seal assembly can be constructed in many variations without departing from this concept. As shown, the main seal member  104  and the backup bushing  106 , are disposed about the exterior surface  102   a  of the mandrel  102  with the main seal member  104  being in direct contact with the mandrel  102 . 
         [0031]    As best viewed at  FIG. 3 , main seal member  104  is shown as defining a downstream surface  104   a , an upstream surface  104   b  and an interior sealing surface  104   c . The interior sealing surface  104   c  is shown in the form of a bore and is the surface that effectuates a seal against mandrel  102  thereby preventing pressurized fluid from leaking out of nozzle assembly  200 . The upstream surface  104   b  of the main seal member  104  is exposed to the pressurized fluid and is thus forced in the direction of fluid flow  120 . The downstream surface  104   a  of the main seal member  104  is sloped towards the mandrel  102  in the direction of fluid flow  120 . Main seal member  104  also has a recess  104   d  for accepting an upstream seal member  112  that provides for a seal between the exterior of the main seal member  104  and the interior of the rotating nozzle assembly. Thus, the pressurized fluid cannot leak around the exterior surface of the assembled seal cartridge  100  at the upstream end of the mandrel  102 . In the particular embodiment shown, seal  112  is an o-ring, but may be any other suitable seal type known in the art configured to perform this function. By use of the term “upstream seal member”, it is meant to identify that the seal member is located nearer the upstream end of the mandrel than it is to the downstream end of the mandrel. Further, a retainer  110  is provided to hold the main seal member  104  and the backup bushing  106  onto mandrel  102  during removal from nozzle  200 . In the particular embodiment shown, retainer  110  is a retaining ring and main seal member  104  is an elastomeric component, but can be made of other suitable materials known in the art. 
         [0032]    As shown, backup bushing  106  has an upstream surface  106   a  and a downstream surface  106   b . The backup bushing  106  also has a bore  106   c  through which one end of the mandrel passes. The upstream surface  106   a  of backup bushing  106  is sloped such that at least a portion of the upstream surface  106   a  can be brought into contact with the sloped downstream surface  104   a  of the seal member  104 . As pressurized fluid forces seal member  104  in the direction of fluid flow (towards the backup bushing  106 ), the sloped surfaces  104   a ,  106   b  engage to force the interior seal surface  104   c  against the exterior surface  102   a  of mandrel  102 . Thus, through the use of the pressure of the working fluid itself, the seal assembly is able to apply additional sealing force against the mandrel  102 . The bore  106   c  of the backup bushing  106  has a very small clearance, for example less than two thousandths of an inch around the mandrel  102 . This small clearance prevents the seal member  104  from extruding past the backup bushing  106  under the action of the pressurized fluid. In the particular embodiment shown, backup bushing  106  is 9C bronze. However, the backup bushing  106  can be made of other materials suitable for accomplishing the above stated functions of the backup bushing  106 . 
         [0033]    The backup bushing  106  can also be provided with a counter bore  106   d , as shown in  FIGS. 8-9 . During operation of the nozzle  200 , portions of the main seal member  104  can deteriorate and separate from the main seal member  104 . Some of this material can become lodged between the exterior surface  102   a  of the mandrel  102  and the bore  106   c  of the backup bushing. Once this occurs, rotational friction can increase to a point where nozzle  200  fails to rotate reliably. Adding the counter bore  106   d  has the effect of shortening the length of the surface associated with bore  106   c , and thereby reducing the area upon which the trapped seal material from seal member  104  can rub. 
         [0034]    Yet another aspect of the seal cartridge  100 , is the retaining member  108 . Retaining member  108  is for installing and removing the seal cartridge  100  to and from the rotating nozzle assembly  200 . Retaining member  108  also performs the function of keeping the main seal member  104  and the backup bushing  106  in place in seal cartridge housing  212  until it is necessary to rebuild the seal cartridge  100 . In the embodiment shown, mandrel  102  passes through retaining member  108  such that the downstream surface  106   b  of the backup bushing  106  rests against the retaining member  108 . This arrangement allows for the backup bushing  106  to remain in position against the pressure from the main seal member  104  when the main seal member  104  is exposed to pressurized fluid. Retaining member  108  also has a connection point  108   b  for securing the seal cartridge  100  to the rotating nozzle assembly  100 . In the particular embodiment shown, the connection point  108   b  includes helical threads designed to engage a complementary set of threads at connection point  212   d  on the rotating nozzle assembly  200 . Other types of mechanical connections known in the art are suitable as well. Retaining member  108  also includes a head  108   a  such that an operator can use a tool to install and remove the seal cartridge  100  into and out of the seal cartridge housing  212  of the rotating nozzle assembly  200 . In the embodiment shown, head  108   a  is a hex head configured for use with a wrench. However, other configurations of head  108   a  known in the art are possible. 
         [0035]    A further aspect of seal cartridge  100  is engagement mechanism  116 . Engagement mechanism  116  is for engaging the mandrel  102  of the seal cartridge  100  to the rotating shaft  202  of the nozzle assembly  200  such that the rotating shaft  202  can impart a rotational force onto mandrel  102 . As shown, engagement mechanism  116  includes two pins inserted into the second enlarged portion  102   h  of the mandrel  102 . Once the pins of the engagement mechanism  116  have been installed and the seal cartridge fully inserted into the nozzle assembly  200 , the mandrel  102  and shaft  202  are engaged such that they will rotate together. The engagement action between the engagement mechanism  116  pins and the shaft  202  is best viewed at  FIG. 7 , where it can be seen that the pins of the engagement mechanism  116  engage tabs  202   c  of the shaft  202  to cause a rotation of the mandrel  102 . Additionally, the friction generated from the positive pressure bias caused by the pressurized fluid will also act to engage the shaft  202  and the mandrel  102 . One having skill in the art will appreciate that engagement mechanism  116  can include other means for rotationally engaging mandrel  102  and shaft  202  other than using pins and tabs without departing from the concepts presented herein. For example, polygonal mating surfaces, splines, or friction alone could be used to couple the spinning shaft  202  and the mandrel  102 . 
         [0036]    Yet another aspect of the disclosure is downstream seal member  114 . The downstream seal member  114  is for providing a water tight seal between mandrel  102  and shaft  202  such that water does not unintentionally leak out of nozzle assembly  200 . With downstream seal member  114  installed, the pressurized fluid cannot leak around the exterior surface of the assembled seal cartridge  100  at the downstream end of the mandrel  102 . In the particular embodiment shown, downstream seal member  114  is mounted within a recess in shaft  202  and comes into contact with mandrel  102  as the seal cartridge is inserted into shaft  202 . Many types of seal members are useful for this purpose. By use of the term “downstream seal member”, it is meant to identify that the seal member is located nearer the downstream end of the mandrel than it is to the upstream end of the mandrel. In the particular embodiment shown, seal  114  is an o-ring type of seal member. However, any other type of seal member known in the art configured to perform this function may be used. 
         [0037]    The above described components can be assembled to form the seal cartridge  100 , as follows. First, mandrel  102  is passed through retaining member  108  from the downstream end  102   a  of the mandrel  102  until there is sufficient clearance on mandrel  102  for installing the backup bushing  106 , main seal member  104  and retainer  110 . In some cases, this can be when retaining member  108  is pressed against either of the first or second enlarged portions  102   g ,  102   h  of the mandrel  102 . Where the first and second enlarged portions  102   g ,  102   h  are not present on mandrel  102 , retaining member  108  may be inserted onto mandrel  102  until it comes into contact with engagement mechanism  116 . Second, the backup bushing is mounted onto the mandrel  102  until it abuts the retaining member  108 . The main seal member  104  is then mounted onto mandrel  102  until its sloped downstream surface  104   a  comes into contact with the sloped upstream surface  106   a  of backup bushing  106 . Subsequently, retainer  110  is installed onto mandrel  102  to prevent the main seal member  104 , backup bushing  106  and retaining member  108  from becoming removed from the mandrel  102 . Seal member  112  can be installed onto the main seal member  104  at any time during the assembly process. The engagement mechanism can also be installed at any time in the process, but are preferably installed as a first step when access to mandrel  102  is easier. The disassembly of the seal cartridge  100  is the reverse. Once fully assembled, the seal cartridge  100  is ready for installation into the nozzle assembly  200 . It should be appreciated that seal cartridge  100  can be configured such that the individual components of seal cartridge  100  can be installed or removed in a different order than described here. 
         [0038]    It should also be appreciated that the assembly and disassembly of seal cartridge  100  does not need to occur in the field, and that multiple seal cartridges can be assembled or rebuilt in a setting conducive to the handling of small parts. This allows an operator in the field to easily remove a failed seal cartridge  100  from nozzle assembly  200  and to quickly install a second seal cartridge  100 . Thus, the nozzle assembly  200  can be rapidly placed back into service. This is in contrast to many prior art nozzle assemblies that require the complete disassembly and replacement of the failed sealing parts in the field in order to return a nozzle assembly to service. 
         [0039]    Referring to  FIGS. 2 and 5 , a nozzle assembly  200  is shown into which a seal cartridge  100  is inserted. As discussed previously, nozzle assembly  200  includes a rotating nozzle shaft  202 . Similarly to mandrel  102 , rotating nozzle shaft  202  defines an interior flow path  202   b  through which pressurized fluid can flow. Once nozzle shaft  202  and mandrel  102  are coupled and sealed together via engagement mechanism  116  and seal  114 , respectively, interior flow paths  102   b  and  202   b  from a continuous channel through which pressurized fluid can flow from a pressurized fluid source to the nozzle head  206 . Nozzle head  206  is discussed in the following paragraph. Rotating nozzle shaft  202  also has an exterior surface  202   a.    
         [0040]    As can be best seen at  FIG. 5 , nozzle assembly  200  also includes nozzle head  206 . Nozzle head  206  is for discharging pressurized fluid such that it can be delivered to the surface to be treated. As shown, nozzle head  206  is coupled to rotating shaft  202  via a threaded connection wherein a metal cone and a metal seat are used. Other methods of connection may be used as well. Additionally, the metal cone and metal seat can be replaced by an elastomeric seal member. Nozzle head  206  and rotating shaft  202  can also be formed as an integral component. 
         [0041]    Nozzle head  206  is also shown as including a plurality of interior flow paths  206   a , each of which leads to discharge nozzle receptacles  206   b . Nozzle receptacles  206   b  are adapted to receive a replaceable orifice to create the desired spray output from the nozzle assembly  200 . In the particular embodiment shown, nozzle receptacles  206   b  are angled with respect to the direction of fluid flow  120  such that the discharged pressurized fluid will cause the nozzle head  206 , the rotating shaft  202  and the mandrel  102  to rotate. This rotational force causes the nozzle assembly  200  to deliver the pressurized fluid in a circular pattern to the surface to be treated which enhances the blasting or cleaning effect of the nozzle assembly  200 . Nozzle head  206  is also shown as having a protective cover  206   d  that has openings  206   e  corresponding to discharge nozzle receptacles  206   b.    
         [0042]    The nozzle shaft  202  can also be caused to rotate through the use of an additional power source, such as an air, hydraulic, or electric motor. In such an application, it would not be necessary for nozzle receptacles  206   b  to be angled, or to rely upon a specific water pressure to obtain a particular rotational speed. However, the rotational speed of shaft  202  can be controlled even without an additional power source through the use of a braking device  210 , as shown at  FIGS. 2 and 5 . In the particular embodiment shown in the figures, braking device  210  is a magnetic eddy current type brake assembly. However, other braking devices can be utilized, such as centrifugal style brake shoes. 
         [0043]    As can be seen at  FIGS. 2 and 5 , the rotating nozzle shaft  202  is mounted partially within a nozzle casing  204 , and is supported by a plurality of bearing assemblies  208   a,b . The bearing assemblies  208   a,b  are for allowing the rotating nozzle shaft  202  to rotate within nozzle casing  204  without undue frictional forces caused by the rotation of the shaft  202  and the thrust caused by the discharged pressurized fluid. Many types of bearing assemblies  208   a,b  are possible. In the particular embodiment shown, bearing assembly  208   a  is a pair of angular contact ball bearings that are not sealed while bearing assembly  208   b  is a sealed single radial ball bearing. However, other types of bearing surfaces known in the art and configured for this purpose, such as bushings, can be used. 
         [0044]    Nozzle casing  204  also includes a main housing  204   a  and a pilot bearing housing  204   b  that are removably connected to each other. The pilot bearing housing  204   a  secures bearing assembly  208   b , and other internal components of nozzle assembly  200  near the point where mandrel  102  and shaft  202  are engaged via engagement mechanism  116 . The main housing  204   a  secures bearing assembly  208   a , and the internal components of nozzle assembly  200  downstream of the pilot bearing housing. At pilot bearing housing  204   b , a connection point  204   c  is provided for connecting the nozzle casing  204  to a corresponding connection point  212   c  on the seal cartridge housing  212 . In the particular embodiment shown, the connection point  204   c  includes helical threads designed to engage a complementary set of threads at connection point  212   c  on the seal cartridge housing  212 . Other types of mechanical connections known in the art are suitable as well. 
         [0045]    As identified above, another aspect of nozzle assembly  200  is seal cartridge housing  212 . Seal cartridge housing  212  is for mounting and retaining seal cartridge  100  on the nozzle assembly  200 . Many configurations of seal cartridge housing  212  are possible without departing from the concepts presented herein. As previously discussed, seal cartridge housing  212  has a connection point  212   c  for connecting the seal cartridge housing  212  to the pilot bearing housing  204   b  of nozzle housing  204  and another connection point  212   d  for connecting the seal cartridge housing  212  to the seal cartridge  100 . As shown, seal cartridge  212  also has an interior fluid path  212   a  that is in fluid communication with the interior fluid path  102   a  of the seal cartridge  100 . The interior fluid path  212   a  of the seal cartridge housing  212  can also be placed in fluid communication with a pressurized fluid source and can be coupled to the pressurized fluid source via connection point  212   e . In the particular embodiment shown, connection point  212   e  includes helical threads. However, other connection methods known in the art can be used. Seal cartridge housing  212  is also shown as defining an interior surface against which seal member  112  of seal cartridge  100  forms a watertight seal to prevent pressurized fluid from leaking out of the nozzle assembly  200 . 
         [0046]    In accordance with the above description, the seal cartridge  100  is installed into the nozzle assembly  200 , as follows. First, seal cartridge  100  is connected to the seal cartridge housing  212  via connection points  108   b  and  212   d . In the embodiment shown, this step is accomplished by threading the seal cartridge  100  and the seal cartridge housing  212  together. Subsequently, the seal cartridge housing is connected to the housing  204  of the nozzle assembly via connection points  204   c  and  212   c . In the embodiment shown, this step is accomplished by threading the seal cartridge housing  212  and the nozzle housing  204  together. As this step is performed, the mandrel  102  is drawn into the shaft  202 , such that the mandrel  102  and the nozzle assembly rotating shaft  202  become rotatably engaged together via engagement mechanism  116  and tabs  202   c . Removal of the seal cartridge  100  from the nozzle assembly is the reverse of the above described steps. It should also be noted that the nozzle assembly  200  can be configured differently such that the seal cartridge  100  can be installed before the step of connecting the seal cartridge  100  to the seal cartridge housing  212 . 
         [0047]    The above are example principles. Many embodiments can be made.