Abstract:
A pressurized fluid filtering vessel of the type having a rigid porous container which may be a basket filled with filtering material has a barrier disposed in the outlet such that, in the event of structural failure of the container, particles of the container are prevented from entering the outlet of the pressure vessel. In one version, the barrier comprises a grid and in another version, the barrier comprises a perforated plate.

Description:
BACKGROUND 
       [0001]    The present disclosure relates to filtering fluids in a system having pressurized fluid flowing therethrough and particularly systems where the fluid is circulated in a closed system. Systems employing pressurized fluid such as hydraulic fluid or water may require filtering to remove foreign matter and debris which may accumulate in the system over time and in prolonged service. In providing filtering of such fluid systems, it has been found particularly convenient and economical to provide a pressure vessel with a removable filter element or filtering material employed in a basket which may be accessible for removal and replacement. The filtering element may have the form of a rigid porous container which may be filled with particulate filtering material or may comprise a filter bag or even a combination thereof or permanent removable straining elements such as perforated screen metal mesh or slotted wedge wire formed into a removable basket for providing the desired level of filtration. The pressure vessel is typically provided with a closure or lid which is releasable for enabling access to the interior of the vessel to permit removal and replacement of the filtering material or filter bag. 
         [0002]    Where the filtering apparatus is employed for high volume flow or in systems where relatively high fluid pressure is employed, a significant pressure differential may occur across the filtering material or bag, upon containment of a significant amount of trapped material and clogging in the filter. This pressure differential may result in forces causing catastrophic structural failure of the basket resulting in fragments and debris entering the vessel outlet and the fluid system. 
         [0003]    Where failure of the filter basket has been experienced, entry of loose metal fragments of the basket into the outlet of the vessel, and thus the fluid system, can result in significant damage to the fluid operating system and to the pumps employed for the fluid. Failures of this type can be particularly catastrophic in hydraulic fluid systems such as those employed for operating high volume flow cooling circuits in industrial plants, power generation applications and ships. 
         [0004]    Thus, it has been desired to provide a way or means of protecting a fluid filtering apparatus from discharging metal fragments or other debris into the fluid system in the event of catastrophic structural failure within the filtering apparatus. 
       SUMMARY 
       [0005]    The present disclosure describes a fluid filtering apparatus having a pressure vessel defining a fluid chamber with an inlet and outlet communicating with the chamber. Fluid filtering material is disposed with a rigid porous container or basket which is disposed in the fluid pressure chamber. The basket may contain filtering material such as granular material or may be employed in conjunction with a filter bag. A porous barrier is provided in the outlet of the pressure vessel to contain and prevent entry into the outlet of fragments of the basket in the event of catastrophic structural failure of the basket. The barrier, in one version disclosed, comprises a metal mesh or plurality of spaced rods disposed in a grid and may be attached in the vessel outlet by suitable fasteners or weldment. In another disclosed version, the barrier has the form of a perforated plate and may have a ratio of open to closed area of about 2:1. The barrier is configured to provide the desired fluid flow yet is sufficiently robust to retain any loose fragments of the basket in the event of such failure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is an elevation view of the pressure vessel employing the filter and containment member of the present disclosure; 
           [0007]      FIG. 2  is a cross-sectional view of  FIG. 1 ; 
           [0008]      FIG. 3  is a perspective view of one version of the containment barrier of the apparatus in the present disclosure; and, 
           [0009]      FIG. 4  is a view similar to  FIG. 3  of another version of the containment barrier of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    Referring to  FIGS. 1 and 2 , a pressure vessel indicated generally at  10  is illustrated as having a generally hollow cylindrical configuration with the upper end thereof open and the lower end thereof closed in a somewhat domed configuration and the vessel thus forms therein a pressure chamber  12  with lid  14  which is shown in a closed position in  FIG. 1 . 
         [0011]    The lid  14  may be secured by fasteners such as swing bolts  13  pivotally attached via a pin  15  through apertures in attachment lugs  16  disposed about the open end of the vessel  10  and engaging a lug  23  on the lid  14 . Additional lugs such as lug  19  may be provided on the open end of vessel  10  for pivotal mounting thereto of the lid by lug  21  provided on lid  14  and pivotal pin  17  if desired. 
         [0012]    The pressure vessel has an outlet boss or standoff  18  formed on the side wall thereof with an attachment flange  20  provided thereabout for connection to a fluid pressure conduit (not shown). The flange  20  has a plurality of fastener apertures  22  formed therethrough and spaced circumferentially thereabout for enabling the attachment to the fluid pressure system. The boss  18  is provided with a passage or port  24  (see  FIG. 2 ) which communicates with the interior of the pressure chamber  12  as will be hereinafter described. In the present disclosure, the port  24  is the inlet port for the pressure chamber  12 . 
         [0013]    Disposed circumferentially spaced from the boss  18  is an outlet boss  26  which has a circular attachment flange  28  provided thereon with circumferentially spaced apertures  30  provided on the flange for enabling attachment to a conduit (not shown) for supplying filtered pressurized fluid thereto. The boss  26  has provided therein an outlet passage or port  32  which communicates with the interior of the pressure chamber  12 . The diameter of the interface between the vessel shell  10  and the boss  26  is larger than that of the outlet through the flange  28 . The transition between the larger flow, inlet diameter and the smaller flow outlet diameter  32  is accomplished through a concentric or eccentric reducer  27 . 
         [0014]    Referring to  FIGS. 2 and 3 , a containment barrier indicated generally at  40  is shown in one version in the form of a mesh or grid of wire members or rods  42  welded in an open grid manner to permit flow of fluid to the outlet passages  32 . The rods or bars  42  which form the barrier  40  may be pre-formed as a welded grid and subsequently welded into the outlet passage  32 . Referring to  FIG. 3 , the containment barrier  40  is illustrated in the prefabricated form with a circumferential ring  46  provided thereon to facilitate installation within the outlet port  32 . Alternatively the rods  42  may be individually welded into the passage. 
         [0015]    Referring to  FIG. 2 , a porous rigid filtering container shown in the form of a removable basket  44  is disposed in the pressure chamber  12 ; and, the basket  44  may contain additional desired filtering material. In the present practice the basket indicated generally at  44  may be constructed of a porous permanent filtering media of coarse retention; however, alternatively, a filter bag may be employed in connection with the basket  44 . 
         [0016]    The open end of the basket is sealed about its periphery through an aperture provided in a bulkhead or interior wall  46  provided in pressure chamber  12  which isolates the basket such that only the upper end thereof communicates with inlet passage  24 ; and thus, all fluid entering the inlet port  24  flows through the filtering material associated with the basket  44  before exiting to outlet port  32 . If desired, the open end of the basket may have an outwardly extending flange  45  provided about the open end thereof for providing sealing about the aperture  47  in wall  46 . 
         [0017]    Referring to  FIG. 4 , an alternative version of the containment barrier is indicated generally at  50  and comprises a plate  52  having a plurality of spaced apertures  54  formed therethrough to permit the desired fluid flow yet prevent passage of fragmentary metal which would be deleterious to the system employing the filter. In the present practice, it has been found satisfactory to form the plate  52  as having the ratio of open area of the apertures to the closed areas of the plate in the range of no less than 2 to 1. 
         [0018]    It will be understood that in either version of the containment barrier  40  of  FIG. 3  or  50  of  FIG. 4 , the barrier must be sufficiently robust to withstand the forces of fragments of the basket in the event of catastrophic structural failure of the filter basket. In the present practice, the version  40  has the bars or rods formed of wire having a diameter of about 0.1875″ to 0.5″ (4.7 mm-12.2 mm) with an open area spacing of about one fourth (¼) to one sixth (⅙) of the inlet diameter of boss  26 . In practice this relates to spacing between 0.5″ to 3″ (12.2 mm-76 mm) between between adjacent rods. In the version  50  of  FIG. 4 , the containment barrier plate has a thickness of about 0.6 to 1.6 mm and a plurality of apertures, each having a diameter of about 4 mm with at least 50% of the surface area of the plate being open for flow. In the present practice, one version of a pressure vessel employed with either barrier  40  or  50  has an inlet diameter to boss  26  of sufficient diameter to result in an open area at the throat of the boss of at least 50% greater cross-sectional area than that of the inlet side boss  18 . This additional surface area is offset by the reduction in flowable area caused by either version  40  or version  50  of the porous barrier plates. The containment barrier of the present disclosure may be employed with filtering systems employing vessels of different dimensions than those of the illustrated versions. 
         [0019]    The exemplary embodiment has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiment be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.