Abstract:
The present invention relates to a high capacity gas filter system. The metal filter of the system includes a visible indicator which indicates when the filter is spent. The indicator is preferably a non-reactive glass tube with indicator material therein. The glass tube can be protected to maintain gas flow integrity in case the glass tube breaks. The filter is attachable to or removable from its connecting base using a cooperating threaded knob and threaded bolt such that the filter is pulled tightly onto the base and forced off of the base depending on how the knob is rotated.

Description:
[0001]    This application claims the benefit of U.S. provisional patent application Ser. No. 60/795,142, filed Apr. 26, 2006, for a high capacity gas filter with indicator, incorporated herein by reference. 
     
     BACKGROUND OF THE INVENTION 
       [0002]    (a) Field of the Invention 
         [0003]    The present invention relates to a high capacity gas filter system, the filter having a visible indicator showing when the filter is spent. 
         [0004]    (b) Description of the Prior Art 
         [0005]    In previously known large capacity filters, the filter is generally made of metal and the filter does not include any indicator as part of the filter to know when the filter is spent. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention relates to a gas filter system which includes a filter and the connecting base to which it is attached. 
         [0007]    More particularly, the present invention comprises a high capacity gas filter system having a filter which has a metal filter housing having a cap end and an opposed end. The filter housing has a filter inlet and a filter outlet which are in sequential flow communication via a large adsorbent bed portion, a smaller adsorbent bed portion, and a smaller transparent portion, the smaller transparent portion having an indicator portion which extends externally from and then back into the metal filter housing. The filter inlet and filter outlet are preferably toward the opposed end, the large adsorbent bed portion extends preferably from the filter inlet to the cap end and the smaller adsorbent bed portion preferably extends from a location near the cap end toward the opposed end. 
         [0008]    In this high capacity gas filter system, no gas can enter or exit from the filter other than through the filter inlet or filter outlet. The large adsorbent bed preferably contains at least one of an oxygen adsorbent, a molecular sieve, and an activated charcoal, the smaller adsorbent bed portion preferably includes at least one of the activated charcoal and the oxygen adsorbent, and the smaller transparent portion preferably includes at least one of an oxygen indicator and a moisture indicator as well as oxygen adsorbent, the indicators being downstream of the large and smaller adsorbent bed portions. These indicators preferably change color upon contact with appropriate amounts of oxygen or moisture, as appropriate, to indicate when the adsorbents in the filter are no longer able to adsorb oxygen or moisture, so that the filter can be timely replaced when spent. 
         [0009]    It is preferable that the transparent portion include an inner sleeve at least partially surrounded by an outer sleeve, the inner sleeve and outer sleeve each being sealed circumferentially at one end against the smaller adsorbent bed portion and at their other end against the metal filter housing. It is also preferable that inner sleeve is a glass inner sleeve and the outer sleeve is a plastic outer sleeve and where additional seals are provided between the transparent portion and the metal filter housing. If there is any gap between the inner sleeve and outer sleeve, it is preferably less than 2 mm. 
         [0010]    In the preferred embodiment the metal filter housing comprises a filter body, a relatively large metal portion, and a cap, said relatively large metal portion has internal threaded ends, the filter body has an externally threaded end which is threaded to one end of the relatively large metal portion, the cap has an external threaded portion which is threaded into the other end of the relatively large metal portion, these threaded connections having at least one sealing part therebetween to create gas tight threaded connections. The filter body includes the filter inlet and filter outlet, and the indicator portion extends externally from and then back into the filter body. 
         [0011]    Further, the high capacity gas filter system preferably includes a connecting base having an inlet and an outlet and a threaded member extending therefrom, the metal filter housing has a threaded knob retained at least partways therein, the threaded knob having a threaded receptacle therein, the inlet being engageable with the filter inlet, the outlet being engageable with the filter outlet, the threaded member being engageable with the threaded knob&#39;s threaded receptacle, where tightening the threaded knob threads the threaded member into the threaded receptacle and engages the inlet and the filter inlet and engages the outlet and the filter outlet to create gas tight connections, and where loosening the threaded knob threads the threaded member out of the threaded receptacle and forces apart the inlet and the filter inlet and forces apart the outlet and the filter outlet. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    A better understanding of the present invention will be had upon reference to the following description in conjunction with the accompanying drawings, wherein: 
           [0013]      FIG. 1  shows a perspective view of the filter cartridge of the present invention and its connecting base; 
           [0014]      FIG. 2  shows a front perspective view of the filter cartridge of the present invention connected to its connecting base; 
           [0015]      FIG. 3  shows a side perspective view of the filter cartridge of the present invention connected to its connecting base, the view being rotated 90° from the view of  FIG. 2 ; 
           [0016]      FIG. 4  shows a top perspective view of the filter cartridge of the present invention connected to its connecting base, this top view being a top down view of the cartridge and base of  FIG. 2 ; 
           [0017]      FIG. 5  shows a cross-section portion along the lines  5 - 5  of  FIG. 2  demonstrating the connectivity of the filter cartridge and its connecting base; 
           [0018]      FIG. 6  shows a cross-section of the filter cartridge along the lines  6 - 6  of  FIG. 3  showing the gas flow in the filter cartridge through adsorbents; 
           [0019]      FIG. 7  shows an expanded cross-section view of the lower right portion of the filter cartridge of  FIG. 6 ; and, 
           [0020]      FIG. 8  shows a cross-section view of the top portion of the filter cartridge and its cap. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    A filter cartridge system for filtering non-reactive or inert gases such as helium, argon and nitrogen, as well as more reactive gases such as hydrogen. In  FIGS. 1-8 , the following drawing legend is used:  1 —bracket;  2 —connecting base or manifold;  3 —gas flow in;  4 —inlet;  5 —gas flow out;  6 —outlet;  7 —threaded hex headed bolt;  8 —guide pin;  10 —filter cartridge;  11 —filter body;  12 —relatively large metal portion;  13 —filter inlet;  14 —large adsorbent bed;  16 —smaller bed;  17 —filter body opening;  18 —smaller transparent portion;  19 —filter outlet;  20 —oxygen indicator;  21 —moisture indicator;  22 —arrows;  24 —glass inner sleeve;  26 —plastic outer sleeve;  28 —sealing parts—compression O ring;  29 —sealing parts—gland O ring;  30 —gap;  31 —metal tube;  32 —threaded return tube fitting;  33 —screen;  34 —cap;  35 —bore;  36 —weld at outlet;  37 —threaded portion;  38 —threaded portion;  40 —threaded knob;  41 —threaded receptacle;  42 —guide pin notch;  43 —retaining ring;  44 —circumferential groove;  45 —oxygen adsorbent;  46 —molecular sieve; and  47 —activated charcoal. 
         [0022]    With reference to  FIGS. 1-8 , the filter cartridge  10  and its connecting base  2  have the characteristics explained hereinafter. Together, they form the filter system of the present invention. 
         [0023]    The cartridge  10  is constructed from a metal filter body  11  having a relatively large metal portion  12  threadably attached thereto at threads  37 . A double gas seal is formed by compression o ring  28  and gland o ring  29  between the outside of filter body  11  and inside of metal portion  12  (see  FIG. 6 ). The cartridge  10  contains adsorbents for purification. Downstream, in the gas flow, there is a smaller transparent portion  18  which contains adsorbents which change color in the present of impurities in the gas stream. The large metal portion  12  is positioned at the inlet side of the filter cartridge  10 , and the transparent portion  18  is positioned at the exit side of the filter cartridge. 
         [0024]    In  FIG. 1 , the cartridge  10  is shown separated from its connecting base  2  which can be connected to the gas lines at gas flow in  3  and gas flow out  5 . For gas flow from the connecting base  2  in and out of the filter  10 , there is an inlet  4  and an outlet  6 . Connecting base also has a threaded hex headed bolt  7  and a guide pin  8 , both of which are received by filter  10 , hex headed bolt  7  by threaded knob  40  and guide pin  8  by guide pin notch  42 . 
         [0025]    With specific reference to  FIGS. 2-5 , the filter  10  is shown attached to connecting base  2 . A bracket  1  is attached to connecting base  2 . Having an “L” shape,  FIGS. 2 ,  3 , and  5  show that the bracket  1  can be screwed or attached to a surface to retain the connecting base  2  as desired. 
         [0026]    With specific reference to  FIG. 5 , the connectivity of filter  10 &#39;s filter body  11  to the connecting base  2  is shown. Threaded knob  40  has a threaded receptacle portion  41  which will mate with threaded hex headed bolt  7  of the connecting base  2 . Turning the knob  40  one way, typically clockwise, secures the cartridge  10  to the manifold  2  and turning the knob  40  the other way, typically counter-clockwise, forces the cartridge  10  off the manifold or connecting base  2 . This has the benefit that the mechanical advantage of the threaded knob can be used to help move the cartridge  10  past sealing parts between the manifold  2  and the cartridge  10  that provide considerable resistance to cartridge  10  removal. Knob  40  has a circumferential groove  44  toward its end with the threaded receptacle  41 . A retaining ring  43  is received therein. As is seen in  FIG. 5 , this ring  43  and groove  44  retain the knob  40  at least partways within filter body  11  so that turning the knob  40  in the proper direction, typically counter-clockwise) actually forces the connecting base  2  and the filter  10  to separate because the ring  43  and groove  44  will not let the knob  40  come further out of the filter body  11 . 
         [0027]    The inlet  4  and outlet  6  components are typical and, from left to right, include a check valve spool, check valve spring, face seal o ring seal, check valve o ring seal, gland o ring seal, check valve cap, retaining ring, seal cup, check valve needle, and frit. This allows for inlet  4  to connect to filter inlet  13  and filter outlet  19  to connect to outlet  6  so that no gas is able to leak from these filter  10 /connecting base  2  connections. 
         [0028]      FIG. 6  shows the gas flow direction and  FIGS. 6 and 7  show the preferred adsorbent configuration, and the filter component connectivity. The gas path in the metal portions  11  and  12  is so arranged that the gas flows in through filter inlet  13  (which mates with base inlet  4 ) and then through a large adsorbent bed  14  of relatively large cross-section and then through a smaller bed  16  of relatively small cross section prior to passing through the transparent portion  18  to exit the filter  10  through filter outlet  19  (which mates with base outlet  6 ). 
         [0029]    The large adsorbent bed  14  can contain activated charcoal  47  portions to remove hydrocarbons and a molecular sieve  46  to remove water. Further bed  14  can optionally include a high-capacity Cu, Ni, or Mn based oxygen adsorbent  45 . The bed of smaller cross section  16  allows the optimal use of a special adsorbent, of which the performance must be maximized for adsorbtion capacity and efficiency. For example, it could contain a Cu, Ni, or Mn based oxygen adsorbent. The arrows  22  show the direction of gas flow. 
         [0030]    As shown in this preferred embodiment, bed  14  contains oxygen adsorbent  45  between the filter inlet  13  and the location where molecular sieve  46  starts. The molecular sieve is at about the filter middle portion. Above the molecular sieve  46  in bed  14  is activated charcoal  47 , which preferably extends slightly into smaller bed  16 . 
         [0031]    Smaller bed  16  is formed by metal tube  31  which then connects to a threaded return tube fitting  32 . Threaded return tube fitting  32  will interface the transparent inner sleeve  24  and transparent outer sleeve  26 , as is explained hereinafter. Below the activated charcoal  47  in smaller bed  16  is oxygen adsorbent  45 , which preferably extends the rest of the way through metal tube  31 , through return tube fitting  32 , and into the top portion of inner sleeve  24 , which is the start of the transparent portion  18 . Inner sleeve  24  will also preferably contain oxygen adsorbent  45  in the area below the indicator portions. At the bottom of inner sleeve  24 , there is a screen  33  of preferably about 100 mesh which confines the adsorbent material but allows gas flow. Instead of screen  33 , a porous metal frit or glass wool could be employed to confine the adsorbent material. 
         [0032]    Filter body  11  is made such that there is an opening  17  which permits the transparent portion  18  to be visible. In the visible portion, the transparent portion  18  contains color changing indicator adsorbent material, preferably an oxygen indicator  20  and a moisture indicator  21 . These indicators allow one to see when filter  10  is no longer able to remove oxygen and water from the gas stream and needs replacement. 
         [0033]      FIG. 6  shows how filter outlet  19  is formed. A bore is drilled from the outside of the filter body  11  to connect below the location of screen  33  so that there will be gas connectivity. The bore opening at the outside of filter body  11  is then closed by weld  36 . 
         [0034]    With continued reference to  FIG. 6  and specifically  FIG. 7 , the transparent portion  18  of the cartridge may consist of two sleeves  24 ,  26 , the inner sleeve  24  of glass and the outer sleeve  26  of a plastic material, for example. Where the inner sleeve  24  is of glass, compression o rings  28  at each end or sleeve  24  protect the ends of sleeve  24  from chipping during assembly. Multiple sealing parts can be inserted between the inner sleeve  24  and the metal filter housing and between the outer sleeve  26  and the metal filter housing, so that if the inner sleeve  24  is broken or if any one of the sealing parts fails, the gas being purified still can not leak from the filter  10 . Multiple seals may also be placed between the manifold and cartridge units and all joints in the filter cartridge. The presence of at least double seals at all joints amounts to a double-fault protection system and renders the filter system more suitable for handling hydrogen and other reactive gases. 
         [0035]    As shown in  FIG. 7 , compression o rings are at the top and bottom of glass inner sleeve  24  and also at the top and bottom of plastic outer sleeve  26 . A pair of gland o rings  29  are also toward the top and bottom of plastic outer sleeve  26 . 
         [0036]    If the transparent portion  18  of the cartridge  10  consists of two sleeves  24 ,  26  as shown, the gap  30  between the inner  24  and outer sleeve  26  is preferably less than 2 mm in order to prevent the accumulation of reactive gas between the inner  24  and outer sleeve  26  in the event that the inner sleeve  24  is broken or if a sealing part  28 ,  29  fails. 
         [0037]    If the transparent portion  18  of the cartridge  10  consists of two sleeves  24 ,  26 , the compression of one or more of the sealing parts  28 ,  29  can be effected by a force directed through the outer sleeve  26  in the axial direction. This can allow the assembly of the transparent portion  18  of the filter cartridge  10  from a single end. As is seen in  FIG. 7 , it is the threading of threaded return tube fitting  32  into filter body  11  that exerts this force. This threading allows the transparent portion  18  of the filter  10  to be assembled from the top side of the cartridge  10 , and additionally connects the optimized portion of the filter bed directly to the indicating  18  and exit portion of the filter. 
         [0038]      FIG. 8  shows how the cap  34 , also seen in  FIGS. 1 and 6 , is threadably received by the threaded top end of metal portion  12 . These threads are shown at  38 . The top of cap  34  contains a pair of bores  35  therein for insertion and removal of cap  34 . A double gas seal is formed by compression o ring  28  and gland o ring  29  between the cap  34  and inside of metal portion  12 . 
         [0039]    The foregoing detailed description is given primarily for clearness of understanding and no unnecessary limitations are to be understood therefrom for modifications can be made by those skilled in the art upon reading this disclosure and may be made without departing from the spirit of the invention and scope of the appended claims.