Abstract:
A burst disk assembly is configured for use in a pressurized gas system for venting pressurized gas from the system in the event that the gas exceeds a predetermined pressure. A plug has a tapered cylindrical shape with a minimum cross-section that is less than a body plug region open cross-section of the assembly, and a maximum cross-section that is greater than the body plug region open cross-section. The plug defines, at an end adjacent the minimum cross-section, a disk face. A frangible disk is positioned in the plug region and is sandwiched between the plug disk face and a body radial wall of the assembly.

Description:
BACKGROUND OF THE INVENTION 
   The present invention is directed to a novel burst disk. More particularly, the present invention is directed to a novel burst disk assembly that seals and secures the disk in a pressure retaining component. 
   Paint ball events provide the participant with an adventure in military strategy and the feel of the fear and exhilaration of battle and have become very popular. Generally participants are equipped with a gas projectile gun or rifle (which can launch a projectile without seriously harming the victim) and protective gear and are divided into two or more combat groups each with the goal of surviving the others. In a typical paintball event, participants fire projectiles, or paintballs, at one another and, when struck, are “painted” by the paint ball. The objective of such an event is to be the last person that has not been “painted” or hit with a projectile. 
   Typically, the projectiles used in these events are propelled using a compressed gas to avoid the potential dangers of explosives such as gun powder. Compressed gas is provided or supplied from a high-pressure source carried by the participant in a gas bottle. Although high-pressure gas is needed at the gun firing mechanism to propel the paint balls, typically the pressure in these bottles is greater than the pressure needed to safely propel the projectile within the parameters of the game. As such, it is necessary to regulate the pressure of the compressed gas provided to the gun firing mechanism to allow projectiles to be launched at a safer velocity and prevent damage to the gun. Typically, a regulator is provided, mounted to the gun or the compressed gas bottle. 
   Typically, pressure regulators are provided with gas at a high pressure and regulate the gas, emitting the gas at a lower pressure for use by the gun. Even though these devices are generally fairly rugged items, they do have their limitations. That is, there may be an upper pressure limit at the inlet or high pressure side and a set outlet or low pressure side. 
   In order to prevent overpressurizing the regulator or overpressurizing the downstream components (e.g., the paint ball gun), sacrificial elements are used to provide a vent path from the high or low pressurized region to an area of lower pressure, typically to the atmosphere. One type of sacrificial element is a burst disk. A burst disk is an element that is positioned within the pressurized region that has a failure pressure that is less than a maximum pressure for the system, but greater than a system operating pressure. Thus, if for some reason the pressure in the system exceeds the operating pressure, rather than reaching system “failure” pressure, the burst disk will fracture venting pressure from the system. The burst disk is thus a safeguard for the system components. 
   There are, however, no burst disk assemblies that permit readily and positively installing the assembly within a pressure regulator. Accordingly, there exists a need for a low cost, readily installable burst disk assembly that positively secures the disk within the assembly or housing. Desirably, such an assembly is configured such that the disk is more tightly held or secured to the regulator body as the assembly is secured to the regulator body. 
   BRIEF SUMMARY OF THE INVENTION 
   A burst disk assembly is configured for use in a pressurized gas system for venting pressurized gas from the system in the event that the gas exceeds a predetermined pressure. The present burst disk assembly positively secures the disk within the assembly such that the disk is more tightly held to the system component to which it is installed as the assembly is secured to the component. 
   The assembly includes a body having a plug region, a transition region adjacent and contiguous with the plug region and a venting region adjacent and contiguous with the intermediate region. The plug region defines an end rim and has an open cross-section. The transition region has an open cross-section that is less than the open cross-section of the plug region. The plug region and the transition region define a radial wall therebetween having a flat face. The venting region has an open cross-section that is less than the open cross-section of the intermediate region. In a present embodiment, the open regions are all coaxial and each region has a constant cross-section. The regions thus appear “stepped”. 
   Alternately, the plug region and the intermediate region are coaxial (appear stepped) and the venting region is transverse to the plug region and the intermediate region. 
   A plug is fitted into the plug region of the body. The plug has a tapered cylindrical shape having a minimum cross-section that is less than the body plug region open cross-section and a maximum cross-section that is greater than the body plug region open cross-section. The plug defines a through bore having a diameter that is less than the open cross-section of the intermediate region. The plug defines, at an end adjacent the minimum cross-section, a disk face. 
   A frangible disk is positioned in the plug region and is sandwiched between the plug disk face and the body radial wall. 
   In a present assembly, the body plug region has a depth defined between the end rim and the radial wall and the plug has a length that is greater than the depth of the body plug region. The plug has a bearing face opposite the disk face, which bearing face has an arcuate profile. 
   To secure the assembly to a pressure retaining component (e.g., a pressure regulator), the burst disk assembly includes a thread formed on an outer surface of the body. 
   The tapered cylindrical shape of the plug defines an angle of taper of about 1 degree to about 5 degrees. Preferably, the angle of taper is about 2 degrees. 
   These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The benefits and advantages of the present invention will become more readily apparent to those of ordinary skill in the relevant art after reviewing the following detailed description and accompanying drawings, wherein: 
       FIG. 1  is an exploded view of a burst disk assembly embodying the principles of the present invention; 
       FIG. 2  is a cross-sectional view of the burst disk assembly of the  FIG. 1  shown in an assembled state; 
       FIG. 3  is a cross-sectional view of the assembly body; 
       FIG. 4  is a cross-sectional view of the plug; and 
       FIG. 4   b  is a cross-sectional view of an alternate embodiment of the burst disk assembly showing a transverse venting region. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiment illustrated. 
   It should be further understood that the title of this section of this specification, namely, “Detailed Description Of The Invention”, relates to a requirement of the United States Patent Office, and does not imply, nor should be inferred to limit the subject matter disclosed herein. 
   Referring to the figures and briefly to  FIG. 1  there is shown a burst disk assembly  10  embodying the principles of the present invention. The assembly  10  includes a body  12 , a frangible disk  14  and a plug  16 . The body  12  is formed with a fastening element, such as the exemplary thread  18  formed in the body  12 . The thread  18  permits threadedly engaging the body  12  with, for example, a regulator, such as that disclosed in Carroll et al., U.S. Pat. No. 6,170,519, or other pressure retaining component. In this manner, the gas pressure is applied in the direction indicated by the arrow at  20 . 
   The body  12  includes three distinct regions each having a predetermined diameter. A first region is the plug region  22 . The plug  16  (which will be described in more detail below) is positioned in this region. The inner circular wall  24  of this region  22  is formed as a straight cylinder. That is, the cross-section or diameter d 22  remains constant along the length l 22  of this region  22 . A second region is an intermediate region  26  that also has a constant cross-section or diameter d 26  that is smaller than the diameter d 22  of the plug region  22 . The third region is a venting region  28  that likewise has a constant cross-section or diameter d 28 , which diameter is less than the intermediate region diameter d 26 . 
   As can be seen from the figures, the regions  22 ,  26 ,  28  are formed coaxial with one another, all lying along a common or central axis A 10  of the assembly  10 . The regions  22 ,  26 ,  28  thus appear to be “stepped”. 
   A first radial wall  30  separates the plug region  22  from the intermediate region  26 , and a second radial wall  32  separates the intermediate region  26  from the venting region  28 . The first radial wall  30  is straight, that is perpendicular to the inner wall  24  of the plug region  22  and the inner wall  34  of the intermediate region  26 . The first and second radial walls  30 ,  32  essentially define the stepped profile of the body  12 . 
   The burst disk  14  is positioned in the plug region  22  against the first radial wall  30 . The burst disk  14  is a relatively thin breakable or frangible element that is sized according to the desired “burst” pressure. Those skilled in the art will recognize that the pressure at which the disk  14  ruptures is a function of the disk  14  material, the thickness t 14  of the disk  14  and the diameter d 26  of the intermediate region  26 . 
   The plug  16  is fitted into the plug region  22  to secure the disk  14  within the body  12 . The plug  16  is tapered such that it forms a snug fit within the plug region  22 . The plug  16  has an inner disk facing face or disk face  36  and an outer bearing face  38 . When in use, the bearing face  38  is positioned within and binds against an inner wall of the pressure retaining component (not shown). A minimum diameter portion of the plug d 36 , at the disk face  36 , has a diameter that is smaller than the diameter d 22  of the plug region  22 . Further, the disk face  36  is flat across the cross-section or smallest diameter. Preferably, the plug  16  is longer than the plug region  22  and, as such, when the assembly  10  is assembled, the plug  16  extends beyond an end  40  of the body  12 . 
   In a present embodiment, the plug bearing face  38  has a diameter d 38  that is larger than the plug region diameter d 22  and has a slightly arcuate or cured profile, as indicated at  42 . This facilitates seating the plug  16  in the pressure retaining component (e.g., the regulator) and also provides a larger area against which pressure is applied on the plug  16  (from the pressurized region), to further enhance seating of the plug  16  in the plug region  22 . 
   The  16  plug has a through-bore indicated at  44  having a diameter d 44  that has a constant cross-section that is smaller than the intermediate region cross-section or diameter d 26 . In this manner, the plug  16  snuggly fits within the body  12  and abuts the disk  14 . When the plug  16  is in position in the plug region  22 , the plug through bore  44  is coaxial with the plug region  22 , the intermediate region  26  and the venting region  28 , lying along the assembly axis A 10 . 
   In a present assembly, the plug region diameter d 22  is about 0.275 inches and the plug region length l 22  is about 0.140 inches; the intermediate region diameter d 26  is about 0.152 inches and the intermediate region length l 26  is about 0.210 inches; and the venting region diameter d 28  is about 0.060 inches and the venting region length l 28  is about 0.160 inches. The plug  16  has a maximum length l 16  of about 0.157 inches, a minimum diameter d 36  (at the disk face  36 ) of about 0.268 inches and a maximum diameter d 38  (at the binding face  38 ) of about 0.280 inches. The plug through-bore diameter d 44  is about 0.125 inches and the binding face  38  has a radius of curvature (as indicated at  42 ) of about 0.650 inches. The taper along each side of the plug can be formed at a variety of angles α, such as between about 1.0 degrees and about 5.0 degrees and is preferably formed at an angle α of about 2.2 degrees. In a present assembly, the body  12  and plug  16  are formed from brass. 
   As set forth above, the disk  14  is formed from a material, and has a thickness t 14  that varies depending upon the desired burst pressure. In a present assembly, the disk  14  is formed from copper and has a thickness t 14  of about 6/1000 of an inch (6 mils) for a pressure rating of about 3000 psi and a thickness of about 8 mils for a pressure rating of about 4500 psi. The disk  14  is held in place by the plug  16  compressing the disk  14  as the assembly  10  is fastened (e.g., threaded) to the body of the pressure retaining component. 
   An alternate embodiment of the burst disk assembly  110  is shown in  FIG. 4   b.  In this embodiment, the venting region  128  is transverse to the central axis A 110  of the assembly  110 . The total cross-sectional (flow) area of the transverse venting region  128  is less than the cross-sectional (flow) area of the intermediate region  126 . 
   All patents referred to herein, are hereby incorporated herein by reference, whether or not specifically done so within the text of this disclosure. 
   In the present disclosure, the words “a” or “an” are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular. 
   From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the present invention. It is to be understood that no limitation with respect to the specific embodiments illustrated is intended or should be inferred. The disclosure is intended to cover by the appended claims all such modifications as fall within the scope of the claims.