Patent Publication Number: US-2023158349-A1

Title: Hermetically sealed portable fire extinguisher with pressure indicator

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. patent application Ser. No. 16/109,055, filed Aug. 22, 2018, which is a divisional of U.S. patent application Ser. No. 15/074,234, filed Mar. 18, 2016, which claims the benefit of priority to U.S. Provisional Patent Application No. 62/139,855 filed Mar. 30, 2015, all of which are incorporated by reference herein in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The subject invention is directed to portable fire extinguishers, and more particularly, to a portable fire extinguisher having a discharge valve with a flexible hermetic seal, along with a visual pressure indicator. 
     2. Description of Related Art 
     Discharge valves used on stored pressure portable fire extinguishers have a pressure indicator to monitor interior pressure during storage, and a stem to control the flow of a pressurized fire extinguishing agent during discharge. The pressure indicator is periodically inspected to ensure that the fire extinguisher is fully pressurized and ready for use in the event of a fire. Bourdon tube type pressure indicators have been utilized in fire extinguishers for decades, as disclosed for example in U.S. Pat. No. 3,815,421. 
     Bourdon tube type pressure indicators are expensive to fabricate and provide potential leak points within the discharge valve. These potential leak points exist at the connection between the bourdon tube and the valve body, as well as in the tube itself, which can develop cracks resulting from the flattening, coiling and welding processes used during manufacture. 
     It would be beneficial therefore, to provide a portable fire extinguisher with a pressure indicator that is less expensive and less susceptible to leaks than typical bourdon tube type pressure indicators to monitor pressure within the fire extinguisher during storage. It would also be beneficial to eliminate the potential leak point at the piston that controls flow during activation. During storage the piston is in a closed position to retain pressure. Imperfections or contamination at its sealing surfaces can result in leakage. 
     SUMMARY OF THE INVENTION 
     The subject invention is directed to a new and useful stored pressure portable fire extinguisher that includes a cylinder for storing a pressurized fire extinguishing agent, a novel pressure indicator mechanism that overcomes the disadvantages that have been associated with prior art bourdon tube type pressure indicators typically employed in portable fire extinguishers, and a novel sealing method that reduces leakage typically associated with piston type valves. 
     The cylinder includes a neck portion that defines an outlet. A flexible hermetic seal is supported across the outlet of the cylinder. The flexible hermetic seal is adapted and configured to transition between three different conditions. The first condition is an unexpanded condition that corresponds to an unpressurized cylinder. The second condition is an expanded condition that corresponds to a pressurized cylinder. The third condition is a bursted condition that corresponds to an opened cylinder. 
     In accordance with a preferred embodiment of the subject invention, the fire extinguisher includes a valve assembly that is threadably associated with the neck portion of the cylinder and it secures the hermetic seal in place across the outlet of the cylinder. The valve assembly includes a valve housing having an interior cavity with an exit port and a piston. The piston has an elongated stem and a lower body portion. A sealing ring is positioned within an annular groove surrounding the lower body portion of the piston for sealing against an interior surface of the valve housing. This controls the egress of pressurized fire extinguishing agent from the exit port of the valve housing during use. 
     A siphon tube extends downwardly into the cylinder from the neck portion thereof for delivering pressurized fire extinguishing agent to the outlet of the cylinder. An upper portion of the siphon tube defines a recess for accommodating an outer rim portion of the flexible hermetic seal, such that the rim is secured between an interior wall of the valve housing and the upper portion of the siphon tube. 
     The piston of the valve assembly is mounted for movement within the interior cavity of the valve housing between three different positions. The first position is a seated position that corresponds to an unpressurized cylinder, in which the lower body portion of the piston is in contact with the flexible seal while the seal is in an unexpanded condition. The second position is a lifted position that corresponds to a pressurized cylinder, in which the lower body portion of the piston remains in contact with the flexible seal while the seal is in an expanded condition. The third position is an activated position that corresponds to an opened cylinder outlet, in which the lower body portion of the piston is displaced from and out of contact with the flexible seal, allowing the seal to burst and open the outlet of the cylinder. 
     A pressure indicator beam extends perpendicularly outward from the stem of the piston, through a window in a side wall of the valve assembly to provide a visual indication of a pressure level within the cylinder. A coiled spring is positioned around an upper portion of the stem between the pressure indicator beam and a top wall of the valve housing. The force of the coiled biasing spring opposes the expansion of the hermetic seal, indicating the amount of pressurization in the cylinder. 
     A release pin is operatively associated with the valve assembly and it is mounted for movement between a locked condition in which the piston is maintained in the pressurized position and an unlocked condition in which the piston is free to move to the activated position. The release pin includes axially spaced apart upper and lower parallel retention arms that intersect the stem of the piston. The upper arm is positioned to retain the pressure indicator beam when the piston is in the pressurized position, and the lower arm is positioned to retain a coiled compression spring in a compressed condition. 
     A coiled compression spring is positioned around an upper portion of the stem of the piston between the pressure indicator beam and a bottom wall of the valve housing. The valve assembly further includes a lever arm adapted and configured to move the piston within the valve assembly against the bias of the coiled compression spring to permit pressurized fire extinguishing agent to be selectively released through the exit port of the valve assembly. 
     In accordance with another preferred embodiment of the subject invention, the valve assembly includes a valve housing having an interior cavity with an exit port and a piston having an elongated stem, a lower body portion and a sharpened projection depending downwardly from the lower body portion. In this embodiment of the invention, the piston is mounted for movement within the interior cavity of the valve housing between two positions. The first position is a seated position in which the lower body portion of the piston is biased against an interior wall of the valve housing by a coiled retention spring and the sharpened projection is spaced from the flexible hermetic seal. The second position is an activated position in which the lower body portion of the piston compresses the coiled retention spring and the sharpened projection pierces the flexible hermetic seal, causing the seal to burst and open the outlet of the cylinder. 
     A pressure indicator beam extends upwardly from a lower end of the coiled spring, through a window in a side wall of the valve assembly to provide a visual indication of a pressure level within the cylinder. The valve assembly further includes a lever arm adapted and configured to move the piston within the valve assembly against the bias of the coiled retention spring, to initially pierce the flexible hermetic seal and subsequently permit pressurized fire extinguishing agent to be selectively released through the exit port of the valve assembly. 
     The subject invention is further directed to a new and useful method of filling a portable fire extinguisher with a pressurized fire extinguishing agent. The method includes the steps of providing a cylinder having threaded neck portion defining an opening; providing a valve housing having a threaded interior cavity defining an injection port; threadably engaging the valve housing onto the neck portion of the cylinder in such a manner so that the injection port remains in fluid communication with the opening of the cylinder; injecting a pressurized fire extinguishing agent or propellant gas into the opening of the cylinder through the injection port; and then threadably securing the valve housing onto the neck portion of the cylinder in such a manner so that the injection port is blocked by the neck portion of the cylinder. 
     Preferably, the method further includes the step of positioning a separate sealing member around the valve housing and the neck portion when the valve housing is threadably engaged to the neck portion and the injection port is in fluid communication with the opening of the cylinder. This sealing member is removed prior to threadably securing the valve housing to the neck portion after it has been filled with a fire extinguishing agent or propellant gas. 
     These and other features of the subject invention and the manner in which it is manufactured and employed will become more readily apparent to those having ordinary skill in the art from the following enabling description of the preferred embodiments of the subject invention taken in conjunction with the several drawings described below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that those skilled in the art to which the subject invention appertains will readily understand how to make and use the hermetically sealed portable fire extinguisher of the subject invention without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to certain figures, wherein: 
         FIG.  1    is a perspective view of a hermetically sealed portable fire extinguisher constructed in accordance with one embodiment of the subject invention; 
         FIG.  2    is a side elevational view of the portable fire extinguisher of  FIG.  1   , in cross-section, illustrating the flexible hermetic seal in an unexpanded condition corresponding to an unpressurized cylinder, with the pressure indicator in an empty position; 
         FIG.  3    is a side elevational view of the portable fire extinguisher of  FIG.  1   , in cross-section, illustrating the flexible hermetic seal in an expanded condition corresponding to a pressurized cylinder, with the pressure indicator in a full position; 
         FIG.  4    is a side elevational view of the portable fire extinguisher of  FIG.  1   , in cross-section, illustrating the flexible hermetic seal in a bursted condition corresponding to an open cylinder ready for discharge; 
         FIG.  5    is a side elevational view of the portable fire extinguisher of  FIG.  1   , in cross-section, illustrating the lever in a depressed condition to unseal the piston body and discharge the cylinder; 
         FIG.  6    is a perspective view of a hermetically sealed portable fire extinguisher constructed in accordance with another embodiment of the subject invention; 
         FIG.  7    is a side elevational view of the portable fire extinguisher of  FIG.  6   , in cross-section, illustrating the flexible hermetic seal in an unexpanded condition corresponding to an unpressurized cylinder with the pressure indicator in an empty position; 
         FIG.  8    is a side elevational view of the portable fire extinguisher of  FIG.  6   , in cross-section, illustrating the flexible hermetic seal in an expanded condition corresponding to a pressurized cylinder, with the pressure indicator in a full position; 
         FIG.  9    is a side elevational view of the portable fire extinguisher of  FIG.  6   , in cross-section, illustrating the flexible hermetic seal being pierced to open the cylinder so it is ready for discharge; 
         FIG.  10    is a side elevational view of the portable fire extinguisher of  FIG.  6   , in cross-section, illustrating the lever in a depressed condition to unseal the piston body and discharge the cylinder; 
         FIG.  11    is a localized side elevational view of the neck portion of the cylinder of the potable fire extinguisher of  FIG.  1   , in cross-section; 
         FIG.  12    is a side elevational view of the valve assembly of the portable fire extinguisher of  FIG.  1   , in cross-section, separate and apart from the neck portion of the cylinder shown in  FIG.  11   ; 
         FIG.  13    is a side elevational view of the portable fire extinguisher of  FIG.  1   , in cross-section, with the valve assembly of  FIG.  12    partially threaded onto the cylinder neck portion of  FIG.  11    prior to filling the cylinder with a pressurized fire extinguishing agent; 
         FIG.  14    is a side elevational view of the portable fire extinguisher of  FIG.  1   , in cross-section, with an exterior seal associated with the partially threaded valve assembly, when the cylinder is being filled with a pressurized fire extinguishing agent or propellant gas; and 
         FIG.  15    is a side elevational view of the portable fire extinguisher of  FIG.  1   , in cross-section, with the valve assembly completely threaded on to the neck potion of the cylinder. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings, wherein like reference numerals identify similar structural features or aspects of the subject invention, there is illustrated in  FIG.  1    a portable fire extinguisher constructed in accordance with a preferred embodiment of the subject invention and designated generally by reference numeral  10 . Fire extinguisher  10  includes a cylinder  12  for storing a pressurized fire extinguishing agent and a valve assembly  14  for manually discharging the agent from the cylinder  12  during use. The agent may be a gaseous agent, dry powdered chemical agent or a fluid media depending upon the intended use of the fire extinguisher. 
     Referring to  FIG.  2   , the cylinder  12  of fire extinguisher  10  includes a neck portion  16  that defines an outlet  18  for the cylinder  12 . The neck portion  16  has a threaded outer surface. An alternate embodiment could utilize an inner threaded surface for the neck portion  16 . A flexible hermetic seal  20  is supported across the outlet  18  of the cylinder  12 . The flexible hermetic seal  20  is adapted and configured to transition between three different conditions. The first condition is an unexpanded condition that corresponds to an unpressurized cylinder. The second condition is an expanded condition that corresponds to a pressurized cylinder. The third condition is a bursted condition that corresponds to an opened cylinder. 
     The valve assembly  14  is threadably associated with the neck portion  16  of the cylinder  12  and it secures the hermetic seal  20  in place across the outlet  18  of the cylinder  12 . The valve assembly  14  includes a valve housing  22  having an interior cavity  24  with a threaded inner surface for cooperating with the threaded outer surface of the neck portion  16  of the cylinder  12 . An alternate embodiment could utilize an outer threaded surface for the valve housing  22  for cooperating with a threaded inner surface of the neck portion  16  of the cylinder  12 . The valve housing  22  has an exit port  26  and a piston  28 . The piston  28  has an elongated stem  30  and a lower body portion  32 . A sealing ring  34  is positioned within an annular groove  36  surrounding the lower body portion  32  of the piston  28  for sealing against an interior surface  38  of the valve housing  22  to control the egress of pressurized fire extinguishing agent from the exit port  26  of the valve housing  22  during use. 
     A siphon tube  40  extends downwardly into the cylinder  12  from the neck portion  16  for delivering pressurized fire extinguishing agent to the outlet  18  of the cylinder  12 . An upper portion  42  of the siphon tube  40  defines an annular recess  44  for accommodating an outer rim portion  25  of the flexible hermetic seal  20 , such that the rim  25  is secured between an interior wall of the valve housing  22  and the upper portion  42  of the siphon tube  40 . Alternate embodiments could have an annular recess created between the cylinder  12 , neck portion, and the valve housing  22  defining an annular recess for accommodating the outer rim portion  25  of the flexible hermetic seal  20 . 
     The piston  28  of the valve assembly  14  is mounted for movement within the interior cavity  24  of the valve housing  22  between three different operational positions. The first positon is a seated position shown in  FIG.  2    that corresponds to an unpressurized cylinder. In this first position, the lower body portion  32  of the piston  28  is in contact with the flexible seal  20  while the seal is in an unexpanded condition. The second position is a lifted position shown in  FIG.  3    that corresponds to a pressurized cylinder. In this second position, the lower body portion  32  of the piston  28  remains in contact with the flexible seal  20  while the seal is in an expanded condition. The third position is an activated position shown in  FIG.  4    that corresponds to an opened cylinder outlet  18 . In this third position, the lower body portion  32  of the piston  28  is displaced from and out of contact with the flexible seal  20 , allowing the seal  20  to burst and open the outlet of the cylinder. 
     With continuing reference to  FIG.  2   , a pressure indicator beam  46  extends perpendicularly outward from the stem  30  of the piston  28 , through a window  48  in a side wall of the valve assembly housing  22  to provide a visual indication of a pressure level within the cylinder  12  (e.g., empty or full). By way of example,  FIG.  1    shows the indicator beam  46  in a full position within window  48  of valve assembly  14 . 
     A release pin  50  with a latch tab  55  is operatively associated with the valve assembly  14  and is mounted for movement between a locked condition ( FIG.  3   ) in which the piston  28  is maintained in the pressurized position and an unlocked condition ( FIG.  4   ) in which the piston  28  is free to move to the activated position. The release pin  50  includes axially spaced apart upper and lower parallel retention arms  52  and  54  intersecting the stem  30  of the piston  28 . The upper arm  52  is positioned to retain the pressure indicator beam  46  when the piston  28  is in the pressurized position of  FIG.  3   , and the lower arm  54  is positioned to retain a coiled compression spring  56  in a compressed condition. Coiled compression spring  56  is positioned around an upper portion of stem  30  of piston  28  between the lower retention arm  54  of release pin  50  and a bottom wall  61  of the valve assembly housing  22 . 
     A coiled biasing spring  58  is positioned around an upper portion of the stem  30  of the piston  28  between the pressure indicator beam  46  and a top wall  60  of the valve assembly housing  22 . The valve assembly  14  further includes a lever arm  62  adapted and configured to move the piston  28  within the valve assembly  14  against the bias of the coiled compression spring  56  to permit pressurized fire extinguishing agent to be selectively released through the exit port  26  of the valve assembly  14 , as shown in  FIG.  5   . A fixed handle  64  is also provided for cooperative use with lever arm  62 . 
     Referring to  FIG.  6   , there is illustrated another portable fire extinguisher constructed in accordance with a preferred embodiment of the subject invention and designated generally by reference numeral  100 . As illustrated in  FIG.  7   , fire extinguisher  100  includes a cylinder  112  and a valve assembly  114 . The cylinder  112  has a threaded neck portion  116  with an opening  118 . A flexible hermetic seal  120  extends across the opening  118  of the neck portion  116  of cylinder  112 . A siphon tube  140  extends from the opening  118  through the neck portion  116  and into the cylinder  112  for delivering fire extinguishing agent from the cylinder to the valve assembly  114 . The siphon tube  140  includes an upper portion  142  with an annular seat  144  for accommodating the outer rim  125  of hermetic seal  120 . An alternate embodiment could provide an annular seat  144  between the lower portion of valve housing  122  and the upper neck portion  116  of cylinder  112 . 
     Valve assembly  114  includes a valve housing  122  having an interior cavity  124  with an exit port  126 . The valve assembly  114  further includes a piston  128  having an elongated stem  130 , a lower body portion  132  and a sharpened projection  135  depending downwardly from the lower body portion  132 . The piston  128  is mounted for movement within the interior cavity  124  of the valve housing  122  between two positions. The first position is a seated position shown in  FIG.  8   . In this position, the lower body portion  132  of the piston  128  is biased against an interior wall of the valve housing  122  by a coiled retention spring  156  and the sharpened projection  135  is spaced from the flexible hermetic seal  120 . The second position is an activated position shown in  FIG.  9   . In this position, the lower body portion  132  of the piston  128  compresses the coiled retention spring  156  and the sharpened projection  135  pierces the flexible hermetic seal  120 , causing the seal  120  to burst and open the outlet  118  of the cylinder  120 . 
     A pressure indicator beam  146  extends upwardly from a lower end of the coiled retention spring  125 , through a window  148  formed in a side wall of the valve assembly  114  to provide a visual indication of a pressure level within the cylinder  112 . By way of example, in  FIG.  6   , the pressure indicator  146  is shown in a full position in window  148 . The valve assembly  114  further includes a lever arm  162  adapted and configured to move the piston  128  within the valve assembly  114  against the bias of the coiled retention spring  156  to initially pierce the flexible hermetic seal  120  as shown in  FIG.  9   , and subsequently permit pressurized fire extinguishing agent to be selectively released through the exit port  126  of the valve assembly  114 , as shown in  FIG.  10   . The lever arm  162  cooperates with a fixed handle  164 . A removable lock ring  150  maintains lever arm  162  and handle  164  in a locked condition for storage. The lock  150  can be readily removed by a user to actuate the lever arm  162 . 
     The subject invention is further directed to a new and useful method of filling a portable fire extinguisher with a pressurized fire extinguishing agent or propellant gas, such as, for example, the fire extinguisher of  FIGS.  1  through  5   . The filling method includes the initial steps of providing a cylinder  12  having threaded neck portion  16  defining an opening  18 , as shown in  FIG.  11   , and providing a valve housing  22  having a threaded interior cavity defining an injection port  75 , as shown in  FIG.  12   . 
     The method further includes the step of threadably engaging the valve housing  22  onto the neck portion  16  of the cylinder in such a manner so that injection port  75  remains in fluid communication with the opening of the cylinder  12 , as shown in  FIG.  13   . Next, a pressurized fire extinguishing agent or propellant gas is injected into the injection port  75 , through the opening  18  of the cylinder  12 , and down into the cylinder through the siphon tube  40 , as shown in  FIG.  14   . Then, the valve housing  22  is threadably secured onto the neck portion  16  of the cylinder  12  in such a manner so that the injection port  75  is blocked by the neck portion  16  of the cylinder  12 , as shown in  FIG.  15   . 
     Preferably, the method further includes the step of positioning a separate sealing member  80  around the valve housing  22  and the neck portion  16  when the valve housing  22  is threadably engaged to the neck portion  16  and the injection port  75  is in fluid communication with the opening  18  of the cylinder  12 , as shown in  FIG.  14   . This sealing member  80  is removed prior to threadably securing the valve housing  22  to the neck portion  16  after it has been filled with a fire extinguishing agent and propellant gas. 
     While the subject invention has been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that various changes and/or modifications may be made thereto without departing from the spirit and scope of the subject invention as defined by the appended claims.