Patent Publication Number: US-11654382-B2

Title: Overpressure leak detection lug

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of and claims priority to U.S. Non-Provisional patent application Ser. No. 16/263,723 filed on Jan. 31, 2019, which is a divisional patent application of and claim priority to U.S. Non-Provisional patent application Ser. No. 15/144,656, now U.S. Pat. No. 10,226,722, filed on May 2, 2016, which claims priority to Provisional Patent Application Ser. No. 62/158,474, filed May 7, 2015, the entire contents of each of the foregoing are incorporated herein by reference. 
    
    
     BACKGROUND 
     Existing water filter cartridges have an elongated housing for filter media with a neck that fits into a manifold in the appliance. The neck of the filter cartridge or the top part of the filter cartridge typically has a bayonet mount with inclined (cam) ends that rotatably engage a mating flange in the manifold so that rotating the filter cartridge locks the cartridge into position during use. When the manifold allows pressurized water to flow into and through the filter cartridge the water exerts an axial force on the cartridge that wants to push the filter cartridge out of the manifold. The bayonet mount resists this ejection pressure and prevents the water pressure in the manifold from pushing the filter cartridge out of the manifold. 
     Sometimes the filter cartridge splits open because the line pressure in the manifold is at too high of a pressure or because repeated pressure variations (water hammer) gradually weaken the filter cartridge housing, causing it to break. High line pressures arise because the municipal water line often carries water at pressures of 60-120 psi, with a home pressure regulator typically being located between the municipal water line and the home in which the appliance is located for a more typical line pressure of about 60-80 psi. These home pressure regulators typically regulate the pressure in residential water lines to about 60 psi, but the selected pressure is adjustable. These home pressure regulators wear and may cause excessive line pressure damaging to appliance water filters, and sufficiently damaging that the housings on appliance water filters may rupture or leak. 
     Moreover, even at 60 psi, valves associated with various residential and office items that use water, such as sprinklers, toilets, washers, faucets, showers, bathtubs, water heaters and outdoor hose bibs may have valves configured to operate various different pressures so that the opening and especially the closing of these valves causes a sudden back pressure in the residential water line, resulting in water hammer. The pressures from water hammer can be very high, and can occur with high frequency. Water hammer may occur with sufficient frequency and magnitude that the water filter cartridges rupture or that the home pressure regulator is damaged and allows increased line pressure to the home. 
     When a water filter cartridge ruptures or leaks, water can flood the surrounding area, causing damage to the affected area commensurate with the volume and duration of the leak and the location of the lead. The result can be very large damage claims by the homeowner. Since there is currently no reliable way to show the rupture of a water filter cartridge was caused by too much line pressure from the appliance&#39;s manifold, the cartridge manufacturer may sometimes be held liable for the water damage when the failure was not caused by the filter cartridge. To help avoid such ruptures, leaks and water damage, filter cartridges are tested to at 300 psi and sometimes up to 500 psi, even though the cartridge is rated at 60 psi for operational uses. Typically, the rated operating pressure is qualification tested to three times that rated pressure. But despite this overpressure testing, cartridge failures still occur. There is thus a need to help determine whether the failure of a water filter arises from overpressure in the water supplied to the filter. There is a further need to help determine whether the failure of a water filter arises from water hammer. There is a further need to help determine whether the failure of a water filter is due to a defect in the filter or something outside the filter. There is a still further need to help determine the source of filter cartridge failures while still allowing the cartridge to be tested using pressures greater than the represented operating pressure at which the filter cartridge is advertised and sold. 
     BRIEF SUMMARY 
     An improved filter cartridge has an outwardly extending connector such as a bayonet mount, which has a first permanently deformable portion sized and configured to permanently deform above a rated operating pressure of the filter cartridge. A second stop portion is located adjacent the first stop portion and is sized and configured to maintain a watertight seal at the higher test pressure of 300-500 psi when the first permanently deformable portion deforms. If a water leak occurs and the first deformable portion is permanently deformed the deformation indicates that the cartridge met its specified pressure rating and the failure arose from applying a pressure that exceeded the rated pressure, the manifold pressure—so the cartridge manufacturer is not at fault for the leak. The second stop limits the deformation and axial movement of the cartridge when overpressure occurs so that the cartridge can pass the qualification test pressure of 300-500 psi without leaking. The second stop may be sufficiently strong by itself to limit axial movement and leakage or the combination of the second stop with a permanently deformed first stop may be sufficiently strong to limit axial movement and leakage. The filter cartridges may move axially without moving the cartridge seals out of sealing contact with the manifold surface and the total movement of the filter cartridge is thus less than needed to move the filter cartridge seals out of contact with the manifold and allow fluid leakage. 
     The first and second stop portions of the connecting mount may be spaced apart a short distance of about 0.03 inches (about 7-8 mm) with the bottom stop portion that abuts the manifold during use to resist expulsion from the manifold having a thickness of about 0.09 inches (about 2.3 mm) when the lugs are made of polypropylene. Thus, the slot separating the first and second lower and upper to form a slot about 0.03 inches (about 7-8 mm) wide along the longitudinal axis of the filter and manifold to show permanently deformation and movement of the first stop with the second stop configured to maintain a water tight seal on the cartridge during high pressure testing. Alternatively, a connecting mount with a single stop may be provided with a non-linear stiffness such that the stiffness increases with the deformation of the mount and with the bottom of the bayonet mount showing permanently deformation above the rated pressure. The connecting mounts are preferably a bayonet mount. The permanently deformation indicator is especially useful for water filters, but the design and invention are not so limited and may apply to other filters. 
     There is thus advantageously provided a filter cartridge for an appliance having a manifold into which the filter cartridge is inserted during use where the manifold has a flange that is configured to rotatably engage a bayonet mounting lug on the cartridge to hold the filter cartridge in the manifold during use. The filter cartridge further has a distal end and a longitudinal axis. The filter cartridge is advantageously designed for a nominal line pressure of X psi. The filter cartridge includes a filter cap connected to a filter housing and enclosing a filter media to form a filter cartridge. The filter cap has an inlet and outlet both of which cooperate with the housing to pass unfiltered water from the inlet through the filter media and to the outlet. The filter cartridge has a rated line pressure Y that is greater than X psi. 
     The filter cartridge also has at least two outwardly extending mounting lugs each configured to mate with a different flange of the manifold to hold the filter in the manifold during use. Each lug has a deformable portion and an aligned stop portion that are axially aligned. Each stop portion is separated from the axially aligned deformable portion by an axial distance d. The deformable portion is below the stop portion during use and is located to contact the flange of the manifold during use. The deformable portion is configured to permanently deform above the rated pressure Y and below a qualification pressure Z that is at least twice the pressure X. 
     In further variations, at least a portion of the deformable stop permanently deforms at a pressure between about 100 psi and about 200 psi in the filter. The deformable stop may permanently deform at a pressure between about 100 psi and about 300 psi in the filter. The distance d is preferably less than about 0.08, and more preferably about 0.030 inches when the deformable stop is made of polyethylene. The stop portion and the deformable portion may extend circumferentially the same distance. The stop portion and deformable portion are advantageously made of polyethylene. The qualification pressure Z is preferably less than 10 times the line pressure X pressure and advantageously less than five times the line pressure X pressure. Ideally, the advertised maximum operating pressure Y is above the expected line pressure X and the qualification test pressure Z is two or three times the rated operating pressure Y, and more preferably about three times the rated operating pressure Y. The stop portion may include a plurality of stop segments, each spaced a distance d from an axially aligned deformable portion. 
     In further variations the deformable portion may have a curved bottom surface. Advantageously, the deformable and stop portions each have a leading end and at least one of those leading ends is inclined in a direction to help the deformable section mate with the flange during use. Moreover, the deformable portion may connect to the filter cap at a radial distance that is greater than where the stop portion connects to the filter cap. Preferably, the distance between the deformable and stop portions is between about 0.02 and 0.04 inches, especially when the parts are made of polyethylene. More preferably the distance between the deformable and stop portions is between about 0.025 and 0.035 inches, with a preferred distance of 0.030 inches, especially when the parts are made of polyethylene. 
     There is also provided a filter cap for a water filter for an appliance having a manifold into which the filter cap is inserted during use. The manifold has a plurality of flanges each configured to rotatably engage a different bayonet mounting lug on the filter to hold the filter in the manifold during use. The filter cap may have a distal end and a longitudinal axis. The water filter is designed for a nominal line pressure of X psi. The filter cap includes at least one outwardly extending mounting lug configured to mate with one of the flanges of the manifold during use. The at least one mounting lug has a deformable portion and a stop portion separated by axial distance d. The deformable portion is axially aligned with but below the stop portion during use. The deformable portion is configured to permanently deform above a rated pressure Y of the filter cartridge to which the filter cap is fastened during use. The rated pressure Y is greater than line pressure X and below a qualification pressure Z, with the qualification pressure Z being at least about twice the pressure X and preferably two or three times the rated pressure Y, and less preferably Z is two or three times the expected line pressure X. 
     The filter cap may have the same variations as described above for the filter cartridge, especially wherein the distance between the deformable and stop portions is between about 0.02 and 0.04 inches, and more preferably about 0.025 and 0.035 inches and even more preferably about 0.03 inches—especially when the portions are made of polyethylene. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages of the filter cartridge permanently deformation indicator will become more apparent in light of the following discussion and drawings, in which like numbers refer to like parts throughout, and in which: 
         FIG.  1    is a front plan view of a first filter cap with first mounting lugs suitable for use with a filter cartridge with the back view being a mirror image thereof; 
         FIG.  2    is a perspective view of the filter cap of  FIG.  1    rotated about 90 degrees; 
         FIG.  3    is a view of the mounting lugs of  FIG.  1   ; 
         FIG.  4    is a sectional view of a filter cartridge having the filter cap of  FIG.  1    mounted thereon and inserted into a manifold or head; 
         FIG.  5    is a front plan view of a filter housing with a second embodiment of permanently deformable mounting lugs suitable for use with a filter cartridge with the back view being a mirror image thereof; 
         FIG.  6    is right side view of the filter housing of  FIG.  5   ; 
         FIG.  7    is a perspective view of the filter housing of  FIG.  5    rotated about 90 degrees; 
         FIG.  8    is a top perspective view of the filter housing of  FIG.  5   ; 
         FIG.  9    is a front plan view of a still further embodiment of a filter cap with mounting lugs, with the back plan view being a mirror image thereof; 
         FIG.  10    is an upper perspective view of the filter cap and mounting lugs of  FIG.  9   ; 
         FIG.  11    is an upper perspective view of the filter cap and mounting lugs of  FIG.  9    rotated about 90 degrees from the view of  FIG.  9   ; 
         FIG.  12    is a plan view of the mounting lugs of  FIG.  9   ; 
         FIG.  13    is a plan front view of yet another embodiment of a filter cap with mounting lugs having a thin profile on the lugs, with the opposing back view being a mirror image thereof; 
         FIG.  14    is an upper perspective view of the filter cap of  FIG.  13    showing a leak indicator slot; 
         FIG.  15    is a plan view of the mounting lugs of  FIG.  13   ; 
         FIG.  16    is a front plan view of another embodiment of a filter cap having mounting lugs where the mounting lugs form keys, with the opposing back view being a mirror image of the front view; 
         FIG.  17    is an upper perspective view of the filter cap of  FIG.  16    rotated about 90 degrees; and 
         FIG.  18    is plan view of the mounting lugs of  FIG.  16   ; 
         FIG.  19    is a front plan view of a further embodiment with a radially offset first mounting portion, with the opposing back view being a mirror image thereof; 
         FIG.  20    is an upper perspective view of the mounting lug embodiment of  FIG.  19    rotated about 90 degrees; 
         FIG.  21    is a plan view of the mounting lugs of  FIG.  19   ; 
         FIG.  22    is a sectional view of the filter cap of  FIG.  19    inserted into a manifold; 
         FIG.  23    is a sectional view of the filter cap of  FIG.  5    in a manifold; 
         FIG.  24    is a front plan view of a filter cartridge housing  FIG.  9    with a different lug arrangement, with the opposing back view being a mirror image thereof; 
         FIG.  25    is a top plan view of the filter cartridge housing of  FIG.  9   ; 
         FIG.  26    is a sectional view of the filter cartridge housing of  FIG.  9    taken along section  26 - 26  of  FIG.  25   ; and 
         FIG.  27    is a perspective view of the filter cartridge housing of  FIG.  24   . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS.  1 - 4   , a filter cartridge  10  has a filter cartridge cap  12  (also referred to as the filter cap  12 ) fastened to one end, with the filter cap  12  configured to fit into and be releasably retained in a fluid head or manifold  14  of an appliance (not shown). The filter cartridge  10  is inserted into the manifold  14  along a longitudinal axis  16 , with the cartridge  10  being held in the manifold  14  by sets of mounting lugs  20  each having a first permanently deformable portion  22   a  (also referred to as the first lug portion  22   a  or the first portion  22   a  or the deformable portion  22   a ) and a second stop portion  22   b  (also referred to as the second lug portion  22   b  or the second portion  22   b  or stop portion  22   b ) with first permanently deformable portion  22   a  having a leading end  24   a  and a trailing end  24   b  and the second stop portion  22   b  having a leading end  26   a  and a trailing end  26   b . The first and second portions  22   a ,  22   b  are separated an axial distance d, preferably separated by a straight channel forming a gap of about 0.03 inches. The lugs  20  are preferably located on and extend from the outer surface of the filter cap  12  but could be on the body of the cartridge  10 . In the depicted embodiments the lug portions  22   a ,  22   b  are located on and extend from the outer, cylindrical surface of an outer neck  23 . There are preferably at least two sets of mounting lugs  20  advantageously equally spaced around the circumference or periphery of the filter cap  12 . From two to four lugs are typically equally spaced around the periphery of a filter cap  12  or the filter cartridge  10 , with at least two diametrically opposed lugs being common and with more being used as the size of the filter increases or as the expulsion force from the manifold  14  increases. 
     As used herein, the relative terms above, below, top and bottom are with respect to the longitudinal axis  16  which extends through the parts when assembled. The relative terms inner, outer, inward, outward are the respective directions or positions relative to the longitudinal axis  16  of the parts when assembled. The manifold  14  and the filter cartridge  10  have the same longitudinal axis  16  when separated as when assembled. 
     Before going into details on the first and second portions  22   a ,  22   b , the basic structure in which those stop portions are used is first described as shown in  FIG.  4   . The filter cartridge  10  has a filter media or element  28  shown as a tubular, cylindrical filter, typically of carbon. The filter media  28  has a filter end piece  30  that forces water radially through the cylindrical wall of the filter media  28 . The filter end piece  30  is shown with a tubular neck  32  surrounding in fluid communication with a central, cylindrical cavity of the filter media  28  through a fines filter  34 . A filter housing  36  encloses the filter media  28  with a space between the filter media  28  and housing  36  for water to flow. The housing  36  is shown as cylindrical, and has a closed end (not shown). A fluid flow path is formed through the outside of the filter end piece  30  but inside the filter cartridge cap  12 , around the outside of the filter media  28 , through the media  28  and into the central cavity of the media and then out the neck  32  of the filter end piece  30 . The flow path could be in the opposite direction. The filter cap  12  is fastened to one end of the housing  36  by various means, with the use of adhesives, melting by friction welding, sonic welding or spin welding being commonly used. 
     The head or manifold  14  is configured to receive the filter cap  12  and hold it in place while water flows through the manifold  14  and the filter cartridge  10  to filter the water. In the depicted embodiment the flow path is through a first manifold opening  40  and various internal passages  42  (some of which may be partially formed in cooperation with the filter cap  12 ) to the space between the inside of the cartridge filter cap  12  and the outside of the neck  32 . The manifold  14  has a protruding male nozzle  44  configured to fit into the neck  32  of the filter cartridge  10 , with O-ring seals  47  (such as ring seals  47  depicted in  FIGS.  23  and  23   ) located in the grooves or glands  46  to form the fluid flow paths into and out of the filter cartridge  10 . A second manifold opening  50  is in fluid communication with an internal passage  48  that extends through the manifold  14  and the nozzle  44  to form a fluid path for water flowing out of the filter cartridge  10  through the neck  32 . The direction of the fluid flow through the manifold  14  and the filter cartridge  10  may be reversed. 
     The manifold  14  has a flange  52  located below a space configured to receive each of the lugs  20  during use. The lugs  20  form a bayonet mount to releasably connect the filter cartridge  10  to the manifold  14  so the basic construction of the broadly described parts may be known, but not the details of the lugs  20  described herein. The manifold  14  has an internal passage (not shown) allowing the lugs  20  to be inserted into the manifold  14  along axis  16 , with rotation of the filter cartridge  10  and the lugs  20  about the axis  16  to engaging the lower, first lug portion  22   a  with the top of the mating flange  52  that extends inward and surrounds a recess configured to receive at least a portion of the filter cap  12 . Typically, there are as many flanges  52  as there are first portions  22   a  of the lugs  20 . The flanges  52  are typically in the same plane orthogonal to the axis  16 , and may be formed as a single flange with recesses cut out or cast or molded to allow passage of the lugs  20  through the recesses passage. The flanges  52  are typically formed in a skirt  54  of the manifold  14  and extend radially inward, although the flanges  52  may have a portion that is slightly inclined along a length of the axis  16  to resemble a screw thread and facilitate rotation and axial movement of the cartridge  10 . 
     Referring to  FIGS.  1 - 4   , the lugs  20  in this embodiment are in a plane generally orthogonal to the axis  16  so the lugs  20  are horizontal when the axis  16  is vertical. The leading ends  24   a ,  26   a  of the lug portions  22   a ,  22   b  may be inclined to form cam surfaces that make it easier to rotate the first lug portion  22   a  onto the top of the mating flange  52 . In use, the filter cartridge  10  is inserted into the manifold  14  with the lugs aligned with axial paths through the manifold  14 . When the lugs  20  are above or slightly above the top of the flanges  52 , the cartridge  10  is then rotated to engage the lugs  20  with the flanges  52 . The cartridge  10  is rotated (usually clockwise) to engage the first lug portion  22   a  with the top of the mating flange  52  and to align the fluid passages in the manifold  14  with the passages through the filter cartridge  10  so unfiltered water from the manifold  14  may enter the filter cartridge  10 , pass through the filter media  28 , and return to the manifold  14  for use by the appliance to which the manifold  14  is connected. 
     The fluid passages are aligned because the appliance is preferably a household appliance such as a refrigerator, water dispenser, soda machine or other device using filtered water. But the manifold  14  could be on any system and the filter cartridge  10  is not limited to filtering water. When the filter media  28  in the filter cartridge  10  is depleted the cartridge  10  is rotated the opposite direction (usually counterclockwise) than when it was installed to align the lugs  22  with gaps in the flanges  52  to permit passage of the lugs  20  through those gaps and removal of the filter cartridge  10  from the manifold  14 . 
     The lugs  22  and the flanges  52  are aligned to keep the filter cartridge  10  retained in the manifold  14  during use. The first lug portion  22   a  has a lower surface that contacts the mating flange  52  and an upper surface that is spaced apart from the bottom surface of the second lug portion  22   b . In some manifolds  14  the lugs  20  fit into an annular space with the top of the lug adjacent the top of the annular space as shown in  FIG.  4   , in order to restrain movement of the cartridge  10  in both directions along the axis  16 . 
     The first portion  22   a  has a length and thickness and material selected so that it does not permanently deform in the direction of axis  16  at a predetermined pressure preferably corresponding to an advertised rated line pressure, typically about 60 psi to about 100 psi for residential and commercial water filters, but permanently deforms at a pressure slightly above those rated pressures. Random filters are tested to a higher qualification testing pressure which permanently deforms the first portion  22   a , as discussed later. The rated pressure rating is preferably the pressure for which the cartridge is rated for actual use. If the rated pressure for the filter cartridge  10  is 60 psi then the first portion  22   a  is configured to permanently deform at above 60 psi and preferably within about 10% to about 30% of that rated pressure. If the filter cartridge  10  is rated for 100 psi, the first portion  22   a  is configured to permanently deform at above 100 psi, and preferably within about 10% to about 30% of that rated pressure. 
     For the configuration of  FIGS.  1 - 4   , a first portion  22   a  made of polypropylene and having an axial thickness of about 0.09 inches (about 2.3 mm) and a circumferential length of about 0.5-0.8 inches is believed suitable for a pressure rating of 60 psi for a filter cartridge  10  used with a residential refrigerator. The first portion  22   a  is advantageously thick enough that allows the water filter cartridge  10  to be pressure tested to the rated line pressure for quality assurance without permanent deformation, and to be tested to higher quality control pressures causing permanent deformation, with cartridges showing visual axial permanent deformation of the first portion  22   a  during such higher pressure testing for quality control purposes. 
     The first lug portion  22   a  is separated from the second lug portion  22   b  an axial distance d sufficient so that at least some of the first portion  22   a  can be visually observed to have permanent axial deformation (along axis  16 ). As the first lug portion  22   a  continues to be permanently deformed axially it will contact the second portion  22   b  which will provided increased resistance to axial movement of the first lug portion  22   a.    
     The deformable portion  22   a  permanently deforms in shear at the juncture of the portion  22   a  with the neck  32 . It is the shear stress for permanent deformation and the corresponding physical deformation to achieve that permanent shear stress that are the guiding parameters for configuring the deformable portion  22   a  relative to the pressure at which the deformation occurs. The deformable portion  22   a  usually connects to a cylindrical part of the filter cap  12 , but some filter caps have oval nozzle portions so the deformable portion  22   a  and stop portion  22   b  could connect to non-circular sections of the filter cap  12 . The deformable portion  22   a  advantageously extends a uniform distance from the neck  23  so as to have a circular periphery. The distance between the first and second lug portions  22   a ,  22   b  is advantageously selected so the first portion  22   a  does not shear completely off and separate from the filter cap  12  or the housing  36  to which it is attached. The added resistance of the second lug portion  22   b , or if complete shear occurs, the sole resistance of the second lug portion  22   b , stops further movement of the first lug portion  22   a . An axial separation of about 0.03 inches (about 7.6 mm) between the top of the first lug portion  22   a  and the bottom of the second lug portion  22   b  is believed suitable for the described embodiment. Smaller axial separations of about 0.05 to 0.015 is believed suitable but make it difficult to injection mold, and while the separation could be cut using lasers, water pressure, or bladed instruments or saws, that requires an extra manufacturing step that increases costs. The smaller axial separations also make it harder to visually ascertain permanent deformation. Larger axial separations of about 0.035 to 0.045 or even larger are believed suitable but the ring seals  47  between the filter cap  12  and manifold  14  may leak and the large deformation may completely shear off the first portion  22   a , which may be permissible in some situations where the sheared portion remains interposed between the flange  52  and the second portion  22   b , but is not desirable. These deformations are for water filter cartridges  10  with lugs  20  made of various plastics and other applications may alter the dimensions and spacing between the first and second portions  22   a ,  22   b.    
     The distance separating the lug portions  22   a ,  22   b  is selected to allow visual confirmation that the first portion  22   a  has permanently deformed, and it is also preferably selected so that the ring seals  47  between the neck  23  and the manifold  14  do not leak. Referring to  FIGS.  22 - 23   , the ring seals  47  permit about 0.01 to about 0.04 inches of axial movement before leakage is believed to start under normal line pressure, and preferably permit about 0.03 inches of such motion and more preferably permit about 0.030 inches of motion. The motion will vary with the particular cartridge and manifold design. The permitted axial movement before one of the seals disengages from the mating surface sufficient to allow leakage will vary. The permitted axial motion is discussed above, with the preferred movement of about 0.03 inches (about 2.3 mm) being preferred for water filter cartridges for household appliances. 
     As the circumferential length of the lug portions  22   a ,  22   b  vary the resistance to axial deformation increases. As the thickness in the axial direction increases, the lug portions  22   a ,  22   b  increase in resistance to axial deformation. As the thickness in the axial direction decreases, the lug portions  22   a ,  22   b  decrease in resistance to axial deformation. The greater the axial distance between the lug portions  22   a ,  22   b , the more deformation needed before the first portion  22   a  abuts the second portion  22   b  and the resistance to axial movement increases. Thus, the resistance to permanent axial deformation will vary in ways that may be determined using strength of materials information and deformation information suitable for the particular configurations and material used. 
     The second lug portions  22   b  are configured so that the axial movement of the filter cartridge  10  stops when the first portion  22   a  abuts against the second portion  22   b , preferably along a substantial portion (over half) of the length of the first and second portions  22   a ,  22   b , and preferably over the entire length of the first portion  22   a . Advantageously, the first portion  22   a  is configured so that it permanently deforms uniformly along the circumferential length of the first portion and in the axial direction. When the first portion  22   a  moves along the axis  16  and abuts against the second portion  22   b  the resistance to axial motion is then provided by both the lug portions  22   a ,  22   b  so the resistance increases. 
     The deformed first portion  22   a  and the second portion  22   b  combine to provide the resistance needed to meet the qualification testing pressure. Typically, a random quantity of filter cartridges  10  are selected and pressurized to a much higher pressure to qualify the design and provide assurance it will readily survive the rated pressure. A qualification test pressure of about 300 psi to about 500 psi for residential or commercial water filter cartridges is believed suitable, with discrete test pressures of about 350 psi, 400 psi and 450 psi also believed suitable for configuring the first lug portion  22   a , and with lower test pressures of about 200 psi and about 250 psi also believed suitable, as well as higher pressures of about 550 psi, about 600 psi, about 650 psi and about 750 psi. 
     For the configuration of  FIGS.  1 - 4   , the first portion  22   a  made of polypropylene and having an axial thickness of about 0.09 inches (about 2.3 mm) and a circumferential length of about 0.5 inches is believed suitable for a ratted pressure of 60 psi. The second portion  22   b  of polypropylene and having an axial thickness of about 0.1 inches or more and a circumferential length of about 0.5 is believed suitable for a qualification pressure of about 300 psi. The portions  22   a ,  22   b  may extend about 0.2 to about 0.2 inches radially. The circumferential length of the portions  22   a ,  22   b  is preferably the same in this embodiment and in the other embodiments. 
     The first and second lug portions  22   a ,  22   b  allow the filter cartridge  10  to undergo and pass a high pressure qualification of the cartridge. The deformation of the first portion  22   a  allows permanent deformation to occur if the actual water pressure in the filter cartridge  10  exceeds the rated pressure, given as 60 psi in the example. The axial distance separating the first and second lug portions  22   a ,  22   b  allows visual confirmation of permanent deformation and excessive line pressure, while also preventing the cartridge  10  from moving axially far enough to leak. In the event the cartridge does leak, the permanent deformation of first lug portion  22   a  confirms that the line pressure exceeded the rated pressure for the cartridge sufficiently to permanently deform the first portion  22   a . The permanently deformed first portion  22   a  thus provided objective evidence that the filter cartridge met its pressure rating. Thus, in use, if the rated pressure is exceeded the deformable portion  22   a  permanently deforms against the second, stop portion  22   b  which advantageously prevents leakage but shows the rated pressure is exceeded. If a leak occurs, the permanent deformation of the first portion  22   a  shows that the rated pressure of the cartridge  10  was exceeded. 
     Not previously described are recesses  60  in the base of the filter cap  12 . The recesses  60  extend circumferentially around a periphery of the base of the filter cap  12  and mate with and receive corresponding projections on the manifold to limit rotation of the filter cap  12  relative to the manifold. The configuration and location of the recess  60  vary, and may be omitted, depending on the design of the filter cartridge  10  and the manifold  14 . 
     Referring to  FIGS.  5 - 8   , a further embodiment is shown for the lugs  20 . The filter cap  12  has two lugs  20  on diametrically opposing sides of the filter cap  12 . The filter cap  12  has a base with a circumferentially inclined slope forming a ledge at the end of the inclined recesses  60  that is configured to receive mating portions of the manifold  14  during use, with the ledge abutting part of the manifold to limit rotation. The filter cap  12  has grooves or glands  46  to receive the ring seals  47  such as O-rings and openings to provide flow paths for water to pass from the manifold  14  to the filter cartridge  10  during use. 
     The first portion  22   a  of the lugs  20  is as generally described earlier but the first portion  22   a  is inclined relative to the axis  16  and has a uniform axial thickness with leading and trailing ends  24   a ,  24   b  parallel to the axis  16 . The incline of the lower, first portion  22   a  helps engage the flange  52  in the manifold  14 . 
     The second lug portion  22   a  has a leading end  26   a  extending axially and a trailing end  26   b  extending axially and parallel to the leading end  26   a . A horizontal member  62  in the plane orthogonal to axis  16  joins the axially extending ends  26   a ,  26   b . The ends  26   a ,  26   b  may be viewed as depending from the upper lug portion or second portion  22   b , or the portion  62  may be viewed as extending between adjacent sides of the vertical ends  26   a ,  26   b . The leading end  26   a  is shorter in axial length than the trailing end  26   b . The distance between the upper side of the first portion  22   a  and the lower side of ends  26   a ,  26   b  is the same, and is advantageously about 0.03 inches (about (about 7-8 mm). The first and second portions  22   a ,  22   b  are separated an axial distance d, preferably by a straight channel forming a gap of about 0.03 inches at the closest parts, here the ends  26   a ,  26   b  and the corresponding adjacent ends  24   a ,  24   b.    
     While the figures show two vertical ends  26   a ,  26   b , additional vertical portions could be used between the ends  26   a ,  26   b . If the ends  26   a ,  26   b  are thin then more vertical segments depending from the horizontal member  62  may be provided to increase the axial resistance to motion as desired. The configuration of the first portion  22   a  of this embodiment is as described above. The axially depending ends  26   a ,  26   b  stop axial movement of the first portion  22   a , but at two separated locations (ends) of the first portion  22   a . Other than the configuration, the design considerations for the first and second portions  22   a ,  22   b  are as described regarding  FIGS.  1 - 4   . 
     Thus, in use, if the rated pressure is exceeded the deformable portion  22   a  permanently deforms against the second portion  22   b  which advantageously prevents leakage but shows the rated pressure is exceeded. If a leak occurs, the permanent deformation of the first portion  22   a  shows that the rated pressure of the cartridge  10  was exceeded. 
     Alternatively described, the stop portion  22   b  is located above the first portion  22   a  and extends around a circumference of the filter cap  12  corresponding to the circumference of the first portion  22   a . Two or more stop portions depend from or extend from the bottom of the horizontal member  62 , with two of the stop portions preferably located at the leading and trailing ends  26   a ,  26   b  of the second portion  22   b . If more than two stop portions are used them may be located between the depending end stop portions  26   a ,  26   b.    
     In use, the first portion  22   a  permanently deforms against the second portion  22   b  which advantageously prevents further movement of portion  22   a  and prevents movement of the ring seals  47  as would cause leakage but which permanent deformation shows the rated pressure is exceeded. If a leak occurs, the permanent deformation of the first portion  22   a  shows that the rated pressure of the cartridge was exceeded. 
     Advantageously, the first portion  22   a  has a circumferential length of about 0.5 inches, an axial length of about 0.5 to about 0.8 inches, and is made of polypropylene. The lug portions  22   a ,  22   b  are advantageously injection molded with the filter cap  12 , although the gap separating the closest parts of the first and second portions  22   a ,  22   b  could be cut or formed after the lugs  20  are formed—as discussed herein. 
     Referring to  FIGS.  9 - 12   , a still further embodiment is shown for the lugs  20 . The filter cap  12  has two lugs  20  on diametrically opposing sides of the filter cap  12 . The filter cap  12  has a base with an alignment projection  62  instead of a recess  60  ( FIG.  5   ) with the horizontal member  62  abutting a stop in the manifold  14  to position the filter cap  12  relative to the manifold  14  during use. 
     The mounting lug  20  has the first portion  22   a  having a curved lower side forming a portion of a semi-circle. The second portion  22   b  has a rectangular shape with curved ends continuing the semi-circular shape of the first portion  22   b . The upper corners of the second portion  22   b  may be rounded. The first and second portions  22   a ,  22   b  are separated an axial distance d, preferably by a straight channel forming a gap of about 0.03 inches. In use, the curved ends of the first and second portions  22   a ,  22   b  allow the lower first portion  22   a  to ramp onto the mating flange  52  in the manifold  14  during use. The curved end on second portion  22   b  helps guide the lug  20  onto the mating flange  52 . 
     In use, if the rated pressure is exceeded the deformable portion  22   a  permanently deforms against the stop portion  22   b  which advantageously prevents leakage but shows the rated pressure is exceeded. If a leak occurs, the permanent deformation of the first portion  22   a  shows that the rated pressure of the cartridge  10  was exceeded. 
     For a rated pressure of 60 psi, when made of polyethylene the mounting lugs  20  advantageously have the first portion  22   a  with a circumferential length of about 0.65 inches and preferably 0.650 inches, and extend radially outward about 0.1 inches and preferably about 0.106 inches. The preferred first portion  22   a  has an axial thickness of about 0.09 inches and preferably 0.090 inches, with the gap or distance d being 0.03 inches and preferably 0.030 inches. The deforming pressure is the axial pressure in the filter cartridge reacted  10  by the mounting lugs  20  and the flange  52 . The second portion  22   b  is advantageously configured to have a stiffness and shear deformation in the axial direction of about half that of the first portion  22   a  and preferably the same as that of the first portion  22   a  and more preferably at least twice that of the first portion  22   a.    
     As better seen in  FIGS.  9 - 11   , the first and second portions  22   a ,  22   b  may have an alignment projections  64  on them. While the alignment projections  64  may increase the size of the parts to which they are affixed, they do not alter the permanent deformation of the deformable portion  22   a  unless the projection  64  extends to the juncture of the first portion  22   a  with the filter cap  12 . 
     This still further embodiment is configured to function as described herein. In use, if the rated pressure is exceeded the first, deformable first portion  22   a  permanently deforms against the second portion  22   b  which advantageously prevents leakage but shows the rated pressure is exceeded. 
     Referring to  FIGS.  13 - 15   , in some instances there is not a lot of axial distance to accommodate the lugs  20  and thus, the stop portion  20   b  may be thinner axially than the first permanently deformable portion  20   a , yet the stop portion  20   b  still resists further movement of the deformable portion  22   a . Further, in these embodiments the lugs  20  are shown on a filter cap  12  having a leak indicator slot  66 , as generally disclosed in U.S. Pat. No. 8,216,463, the complete contents of which are incorporated herein by reference. 
     The first portion  22   a  extends in a plane orthogonal to the axis  16 . The first and second portions  22   a ,  22   b  are separated an axial distance d, preferably by a straight channel forming a gap of about 0.03 inches at the closest parts, here the top of the first portion  22   a  and the bottom of the second portion  22   b . The distance between the top surface of the second portion  22   b  and the bottom surface of the first portion  22   a  is about 5/16 inch, or about 0.313 inches (about 9 mm) when the parts are made of polyethylene. 
     In use, the curved end  24   a  of the first portion  22   a  allows the first portion  22   a  to ramp onto the mating flange  52  in manifold  14  during use. The curved end on second portion  22   b  helps guide the lug  20  onto the mating flange  52  to position the cartridge  10  in the manifold  14  for use. If the rated pressure of the cartridge  10  is exceeded the first, deformable portion  22   a  permanently deforms against the second portion  22   b  which advantageously prevents leakage but shows the rated pressure is exceeded. If a leak occurs, the permanent deformation of the first portion  22   a  shows that the rated pressure of the cartridge was exceeded. In the depicted embodiment the stop portion  22   b  has a smaller axial thickness than the permanently deformable portion  22   a  and the result is that if the pressure on the filter cartridge  10  is greatly exceeded, then the deformable first portion  22   a  may permanently deform and it is possible that the stop portion  22   b  may be insufficient to maintain the positon of the cartridge  10  in the manifold  14  to prevent leakage. 
     Referring to  FIGS.  16 - 18   , an embodiment is shown using a variation of keyed mounting lugs as generally disclosed in U.S. Pat. No. 7,763,170, the complete contents of which are incorporated herein by reference. The first portion  22   a  extends radially away from the axis  16  and neck  32  as do the three segments  68   a ,  68   b ,  68   c  cooperating to collectively form the second portion  22   b . The second portion  22   b  is segmented into three, equally spaced segments  68   a ,  68   b ,  68   c  that extend over the same arc and same circumferential distance as first portion  22   a . The first portion  22   a  is depicted as in a horizontal plane, orthogonal to the axis  16  with the first and second portions  22   a ,  22   b  ( 68   a ,  68   b ,  68   c ) separated an axial distance d, preferably by a straight channel forming a gap of about 0.03 inches at the closest parts, here the top of the first portion  22   a  and the bottom of the three segments  68   a ,  68   b ,  68   c  forming the second portion  22   b.  But the first portion  22   a  could be a curved member with the bottoms of segments  68   a ,  68   b ,  68   c  located so they are an equal distance from the closest part of the deformable portion  22   a . In the depicted embodiment the segments  68   a ,  68   b ,  68   c  are trapezoidal in shape and extend radially outward from the outer neck  23 . 
     The segments  68   a ,  68   b ,  68   c  are each generally trapezoidal in shape, each with axially aligned leading edges  26   a  and inclined trailing edges  26   b . But leading segment  68   a  is larger than intermediate or middle segment  68   b  which is larger than trailing segment  68   c , with the largest portion  68   a  preferably forming the leading end  26   a  of the second portion  22   b.    
     For a rated pressure of 60 psi, when made of polyethylene the mounting lugs  20  advantageously have a first portion  22   a  with a circumferential length of about 0.65 inches and preferably 0.650 inches, and extend radially outward about 0.1 inches and preferably about 0.106 inches. The preferred first portion  22   a  has an axial thickness of about 0.09 inches and preferably 0.090 inches, with the gap or distance d being 0.03 inches and preferably 0.030 inches. This configuration is believed to not begin to yield until an axial pressure of 370 psi is applied to the filter cartridge  10 . The deforming pressure is the axial pressure in the filter cartridge reacted by the mounting lugs  22  (segments  68   a ,  68   b ,  68   c  and lug  22   a ) and flange  52 . 
     For a rated pressure of 60 psi, when made of polyethylene the mounting lugs  20  advantageously have the first portion  22   a  with a circumferential length of about 0.78 inches and extend radially outward about 0.08 inches and preferably about 0.078 inches. The preferred first portion  22   a  has an axial thickness of about 0.27 inches and preferably 0.266 inches, with the gap or distance d being about 0.03 inches and preferably 0.030 inches. The second portion  22   b  and its segments  68   a ,  68   b ,  68   c  are as follows. The largest segment  68   a  has a circumferential width of about 0.19 inches and preferably about 0.193 inches, with the inclined face at an angle of about 36° relative to the axis  16 . The first segment  68   a  preferably extends radially outward the same distance as the first portion  22   a , a distance of about 0.08 inches and preferably about 0.078 inches. The second (middle) segment  68   b  has an axial thickness of about 0.09 inches (preferably 0.090 inches), a circumferential width of about 0.16 inches, extends radially outward a distance of about 0.08 inches (preferably 0.078 inches) and has its depicted inclined end inclined at an angle of about 36° relative to axis  16 . The smallest segment  68   c  has an axial thickness of about 0.06 inches (preferably 0.62 inches), a circumferential width of about 0.09 inches (preferably 0.090 inches), extends radially outward a distance of about 0.08 inches (preferably about 0.078 inches) and has its depicted inclined end inclined at an angle of about 36° relative to axis  16 . The end  24   a , and trailing end  26   b  and the inclined surfaces  26   c ,  26   d  on the segments  68   a ,  68   b ,  68   c , respectively, are all preferably inclined at the same angle, about 36°, relative to axis  16  in this embodiment. This configuration is believed to have a 0.030 inch deformation at an axial pressure of 282 psi applied to the filter cartridge  10  when there are two lugs  20  and their portions  22   a ,  22   b  are made of polyethylene. The deforming pressure is the axial pressure in the filter cartridge  10  reacted by the mounting lugs  22  (segments  68   a ,  68   b ,  68   c  and first portion  22   a ) and flange  52 . 
     In use, the inclined end  24   a  of the first portion  22   a  allows the lower first portion  22   a  to ramp onto the mating flange  52  in the manifold  14  during use. The segments  68   a - 68   c  forming the second portion  22   b  act as keys to fit within mating portions (not shown) of the manifold  14  position the cartridge  10  and the filter cap  12  in the manifold  14  for use. If the rated pressure of the cartridge  10  is exceeded the deformable first portion  22   a  permanently deforms against the second portion  22   b  ( 68   a ,  68   b ,  68   c ) stop further deformation and which advantageously prevent sufficient motion of the filter cartridge  10  to prevent leakage. If a leak occurs, the permanent deformation of the first portion  22   a  shows that the rated pressure of the cartridge  10  was exceeded. 
     The shape of the specific segments  68   a ,  68   b ,  68   c  are shown as trapezoidal with the trailing ends  26   b  being generally parallel but the shape may vary and be other than a trapezoid, and may be take the form of axial segments with rectangular shapes (as in  FIGS.  5 - 8   ). Likewise, the number and spacing of the segments  68   a ,  68   b ,  68   c  may vary in order to act as “keys” to mate with corresponding located locks or recesses in the manifold  14  as described in U.S. Pat. Nos. 7,135,113 and 6,458,260. 
     The permanent deformation may extend along the entire length of the first portion  22   a  or may be initially localized and spread along a greater length as the pressure increases. The amount of deformation will also vary with the amount by which the actually applied pressure exceeds the rated pressure, and with the particular design of the portions  22   a ,  22   b . For example, in the embodiment of  FIGS.  16 - 18    which has a deformable first portion  22   a  with a (preferably) tapered leading end  24   a  and uniform axial thickness along its circumferential width, the permanent deformation typically begins at the leading end  24   a , in part because the mating of the manifold flanges and deformable portion  22   a  makes the leading end a primary contact point with slightly larger forces than at the trailing end  24   b . As operating pressure is applied to the filter  10  the force on the mounting lugs  20  and deformable first portions  22   a  increases. When the applied pressure exceeds exerts a force on the deformable portions  22   a  that exceeds the yield strength of those deformable portions then they permanently deform, typically at the leading end  24   a . As more pressure is applied and the rated pressure is further exceeded the permanent deformation extends further toward the trailing end  24   b . For small excess pressures and smaller permanent deformations, the deformable portion  22   a  may or may not abut the second portion  22   b , but measuring the gap between the first and second portions  22   a ,  22   b  or measuring the deformation of the first portion  22   a  may show the permanent deformation and confirm excess pressure was applied. For larger excess pressures and deformations the leading end  24   a  of the deformable portion  22   a  will abut the stop portion  22   b  and may remain in contact after the excess pressure is released. The larger the excess pressure the more the deformation extends along the length of the deformable portion  22   a . For large excess pressures the permanent deformation may extend along the entire length and if the excess pressure is increased enough even the stop portions  22   b  may deform and ultimately shear off. But whether the permanent deformation begins at one end and progresses along the length of the deformable portion  22   a  depends on the design of the mating parts as that affects how the lugs  20  react the pressure pushing the filter cartridge  10  out of the manifold  14 . 
     Preferably, the permanent deformation extends along less than a substantial part of (50% or less) of the circumferential length of the deformable portion  22   a , and less preferably the permanent deformation extends more a than substantial part (over 50%) of the circumferential length of the deformable portion  22   a . Advantageously the gap between the first and second portions  22   a ,  22   b  is constant and measured before shipment of the filters  10  in order to provide an visual reference for determining permanent deformation. 
     By way of specific examples, for the deformable portion  22   a  in  FIGS.  16 - 18   , each of two deformable portions  22   a  may have an axial thickness of about 0.07 inches (preferably 0.069 inches), a circumferential length of about 0.76 inches (preferably 0.758 inches end-to-tip), and extend radially outward from the neck a distance of about 0.08 inches (preferably 0.078 inches) when made of polypropylene, with the gap between portions  22   a ,  22   b  being 0.030 inches. That is, the top surface of radially and horizontally extending deformable portion  22   a  is 0.030 inches from the bottom surfaces of stop portions  22   b . An applied pressure of 382 psi (191 psi on each of two lugs  20  and deformable portions  22   a ) results in a permanent deformation of 0.030 inches. 
     Referring to  FIGS.  19 - 21   , another embodiment is shown with the lower, first deformable portion  22   a  being radially offset from the  16  axis relative to the second portion  22   b  in that the ends of the portions  22   a ,  22   b  are not radially aligned with the first portion  22   a  extending over a circumferential arc that is rotationally shifted or rotated relative to the circumferential arc of the second portion  22   b . As best seen in  FIG.  21   , the first deformable portion  22   a  is shifted to the left while the second stop portion  22   b  is shifted to the right. The ends of the first and second portions  22   a ,  22   b  are thus not in the same radial plane through axis  16 , but are radially offset. Advantageously, the leading edge of the second portion  22   b  is offset to the right as shown in the orientation of  FIG.  21   , which corresponds to a counter-clockwise direction when viewed along axis  16  extending through the filter cartridge neck. The leading edge is the edge of the portion  22   a ,  22   b  located in the direction of rotation for connecting the filter  10  to the manifold  14 , and the trailing end is the opposite end which is located in the direction of rotation for removing the filter cartridge  10  from the manifold  14 . Advantageously, the trailing edge of the first portion  22   a  is offset to the left as shown in the orientation of  FIG.  21   , which corresponds to a clockwise direction when viewed along axis  16  extending through the filter cartridge neck. Advantageously the stop portion  22   b  has a leading edge that is located circumferentially ahead of a leading end of the deformable portion  22   a  in the direction of rotation during installation, and that is also ahead of the trailing end of the deformable portion  22   a . The deformable portion  22   a  has a trailing end that is located circumferentially behind the trailing edge of the stop portion  22   b.    
     In the depicted embodiment the first and second portions  22   a ,  22   b  each extend from the filter cap  12  except in this configuration the portions  22   a ,  22   b  do not extend from the same surface. Instead, the first portion  22   a  extends outward from a boss  70  on a neck  72  of the filter cap  12  while the second portion  22   b  extends from the neck  72 . The boss  70  places the juncture of the first, deformable portion  22   a  and the boss  70  further outward from the axis  16  than the juncture of the second, stop portion  22   b  with the neck  72 . The boss  70  positions the base of the first portion  22   a  radially outward from the base of the second portion  22   b . The boss  70  positions the base of the first portion  22   a  radially outward about 0.02 to about 0.05 inches or less. The radial offset helps the filter cap  12  fit into the manifold  14 . The boss  70  results in the deformable portion connecting to the filter cap at a radial distance that is greater than where the stop portion connects to the filter cap. 
     Referring to  FIG.  22   , the manifold  14  may comprise a mounting bracket  80  which has the manifold flange  52  formed thereon to engage the locking, bayonet lugs  20  with the bottom of the first deformable portion  22   a  abutting the top of the flange  52 . The flange  52  forms part of a cylindrical recess or socket in the bracket  80  within which the manifold  14  sits. The depicted manifold  14  has a housing  81  that surrounds a barrel valve  82  with a ring seal  84  between the outside of barrel valve  82  and the inside of a manifold housing  81 . The barrel valve  82  has a cylindrical tube  86  that extends downward along axis  16 , with the neck  32  of the filter cap  12  fitting inside the tube  86  to form a fluid path in fluid communication with an opening  20 ′ of the barrel valve  82  which is in fluid communication with and preferably aligned with the opening  20 ′ of the barrel valve housing  81  and manifold  14 . The outside of the cylindrical tube  86  forms a fluid path in fluid with the outside of the filter media ( FIG.  4   ). 
     The second portion  22   b  is advantageously configured to have a stiffness and shear deformation in the axial direction of about half that of the first portion  22   a  and preferably the same as that of the first portion  22   a  and more preferably at least twice that of the first portion  22   b . For a rated pressure of 60 psi, when made of polyethylene the mounting lugs  20  advantageously have a first portion  22   a  with a circumferential length of about 0.65 inches and preferably 0.650 inches, and extend radially outward about 0.1 inches and preferably about 0.106 inches. The preferred first portion  22   a  has an axial thickness of about 0.09 inches and preferably 0.090 inches, with the gap or distance d being 0.03 inches and preferably 0.030 inches. The deforming pressure is the axial pressure in the filter cartridge  10  reacted by the mounting lugs  20  and flange  52 . 
     In use, the inclined end  24   a  of the first portion  22   a  allows the lower portion  22   a  to ramp onto the mating flange  52  in the manifold  14  during use. The segments  68   a - 68   c  forming the second portion  22   b  act as keys to fit within mating portions (not shown) of the manifold  14  position the cartridge  10  and filter cap  12  in the manifold  14  for use. If the rated pressure of the cartridge is exceeded the first, deformable portion  22   a  permanently deforms against the second, stop portion  22   b  ( 68   a ,  68   b ,  68   c ) stop further deformation and which advantageously prevent sufficient motion of the filter cartridge to prevent leakage. If a leak occurs, the permanent deformation of the first portion  22   a  shows that the rated pressure of the cartridge was exceeded. 
     Referring to  FIG.  23   , the filter cap  12  of  FIGS.  1 - 5    is inserted into the manifold  14  having a stepped configuration with an outer manifold housing  90  having a smaller, cylindrical diameter upper portion  90   a  and a lower, larger diameter, cylindrical portion  90   b . The larger diameter portion  90   b  fits into a recess or socket in a manifold bracket  92  shown as a cylindrical tube with a mounting flange (not shown). The manifold bracket  92  has an inward extending flange forming the manifold flange  52  that form the bottom of the recess or socket within which the lower portion  90   b  of the manifold housing is located. The manifold flange is configured to engage the locking, bayonet lugs  20  with the bottom of the first deformable portion  22   a  abutting an annular recess  96  in the top of the flange  52 . The flange  52  forms part of a cylindrical recess or socket in the bracket  80  within which the manifold  14  sits during use. The depicted manifold with upper and lower portions  90   a ,  90   b  forms a stepped, cylindrical housing that surrounds a stepped, barrel valve  94  having an upper, cylindrical portion  94   a  and a lower, larger diameter stepped portion  94   b  that fits inside manifold portion  90   a ,  90   b . The ring seal  84  is located between the outside of barrel valve  82  and the inside of the manifold housing  81 . The distal end of the filter cap  12  extends into the inside of the smaller diameter portion  94   a  of the barrel valve with seals  47  sealing on at two spaced-apart locations to define the two flow paths into and out of the filter cap  12  and the filter cartridge  10 . A fluid path through the neck  32  of the filter cap  12  forms one fluid path and flow around the outside of the neck  32  but below the distal ring seal  46  forms the second fluid path to the barrel valve. The barrel valve  82  places these two fluid paths in fluid communication with corresponding flow paths in the manifold  14  as is known in the art and not described in detail herein. 
     Referring to  FIGS.  24 - 26   , a still further embodiment is shown for the lugs  20  which are a variation of the lugs  20  of  FIGS.  9 - 11   . The filter cap  12  has two lugs  20  on diametrically opposing sides of the filter cap  12 . The filter cap  12  has a base with an alignment projection  62  instead of a recess  60  ( FIG.  5   ) with the projection  62  abutting a stop in the manifold to position the filter cap  12  relative to the manifold  14  during use. The filter cap  12  is integrally molded as part of the filter housing  36  in this configuration. An interior portion of the filter cap  12  will extend from the inside of the filter body to form the remainder of the filter cap  12  during use. 
     The mounting lug  20  has a first portion  22   a  having a curved lower side forming a portion of a semi-circle and an upper portion that is flat in preferably in a plane orthogonal to the axis  16 . The semicircular first portion  22   a  has a central protrusion  98  on its outward face shaped like a rectangle with the rectangular protrusion angled inward toward the axis  16  so the top portion of the protrusion  98  is further from the axis  16  than is the bottom portion. The rectangular shaped protrusion leaves a generally triangular shape on each end as seen in the front view of  FIG.  24   . The part of first portion  22   a  that permanently deforms is adjacent the juncture with the cylindrical neck of the filter cap  12 . 
     As best seen in  FIG.  27   , the second portion  22   b  has three axial slots separating the second portion  22   b  into four projections  100   a ,  100   b ,  100   c ,  100   d , with the two end projections  100   a ,  100   d  having rounded outer edges and an inner straight, axial side, and the middle two projections  100   b ,  100   c  having two axial sides and extending further radially outward than the outer sides. The end two projections forming second portions  22   b  with the curved outer sides are axially aligned with and block the view of the outer ends of the first portion  22   a  when viewed from the top as in  FIG.  25   . As best seen in the top view of  FIG.  25    and the perspective view of  FIG.  27   , the recesses or axial slots separating the middle projections  100   b ,  100   c  advantageously but optionally do not extend to the surface of the cylindrical neck  23  so there is a circumferential shear area at the neck  23  having a circumferential length (or width) of about 0.5 inches and about 0.1 inches axial length. The axial shear resistance of the second portion  22   b  is thus much larger than the projections  100   a - 100   d.    
     As best seen in  FIG.  27   , the outward facing surface of the middle projections  100   b ,  100   c  may be inclined toward the axis  16  so the top portion of these two projections are further from the axis  16  than is the bottom portion. These inclined portions on upper portions  100   b ,  100   c  and on the lower projection  98  show that the outward facing surfaces of the portions  22   a ,  22   b  can have various shapes to actuate various mechanisms in the mating manifolds  14 . 
     The first and second portions  22   a ,  22   b  are separated an axial distance d, preferably by a straight channel forming a gap of about 0.04 to 0.05 inches, and preferably about 0.04 to 0.045, and more preferably about 0.046 inches. The curvature of the bottom of the first portion  22   a  is about 0.5 inches and more preferably about 0.53 inches, with the leading and trailing ends  26   a ,  26   b  of the outer projections  100   a ,  100   d  having the same curvature and same center of curvature as the first portion  22   a . The greatest axial length or thickness of the lower portion is about 0.08 inches and preferably about 0.075 inches. The projections  100   b ,  100   c  have a circumferential length or width of about 0.3 inches and an axial length or height of about 0.1 inches and preferably about 0.12 inches. 
     In use, if the rated pressure is exceeded the first, deformable portion  22   a  permanently deforms against the second, stop portion  22   b  which advantageously prevents leakage but shows the rated pressure is exceeded. If a leak occurs, the permanent deformation of the first portion  22   a  shows that the rated pressure of the cartridge was exceeded. 
     The permanent deforming pressure is the axial pressure in the filter cartridge reacted by the mounting lugs  22  and the flange  52  and for the above described embodiment of  FIGS.  24 - 27   , is believed to occur at about 370 psi or 400 psi when made of polyethylene The rated pressure for this cartridge would normally be 100 psi or 120 psi, which represents the maximum operating pressure, and the qualification pressure is typically three times the rated pressure or 300 psi and 360 psi, respectively. These pressures are for a normal system line pressure of 60-80 psi. In this example the specific dimensions given do not permanently deform between the rated and qualification pressures. 
     As better seen in  FIGS.  9 - 11   , the lug portions  22   a ,  22   b  may have alignment projections  64  on them. While the alignment projections  64  may increase the size of the parts to which they are affixed, they do not alter the permanent deformation of the first, deformable portion  22   a  unless the projection extends to the juncture of the portion  22   a  with the filter cap  12 . 
     This still further embodiment is configured to function as described herein. In use, if the rated pressure is exceeded the first, deformable portion  22   a  permanently deforms against the second, stop portion  22   b  which advantageously prevents leakage but shows the rated pressure is exceeded. 
     The depicted filter  10  and filter cartridge cap  12  are aligned along longitudinal axis  16 , but need not be so aligned as cartridges exist with the connecting filter cartridge cap  12  at right angles to the axis of the body of the filter cartridge. The portions  22   a ,  22   b  are equally applicable to this cartridge configuration with deformation occurring along that portion of the longitudinal axis  16  extending through the filter cartridge cap  12 , which is at right angles to the axis of the filter housing  36 . 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. 
     The above description is given by way of example, and not limitation. Further, the various features of this invention can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the invention is not to be limited by the illustrated embodiments.