Abstract:
Apparatus and methods for temporarily sealing a pipe including apparatus and methods for creating a temporary airtight seal at the open end of a pipe in a plumbing or refrigeration system. One such apparatus includes a body, grommet, washer, and a nut. Multiple airtight seals are created including a first primary seal between an exterior of the pipe and the grommet and a secondary seal between the open end of the pipe and the washer. The grommet does not require teeth and the apparatus does not require adhesive, sealant, or any other type of similar materials. Use of the apparatus and methods greatly minimizes and/or eliminates the potential for marring or otherwise distorting the open end of the pipe, thereby facilitating reuse of same.

Description:
BACKGROUND OF THE INVENTION 
     Embodiments of the present invention generally relate to apparatus and methods for temporarily sealing a pipe. More specifically, the present invention relates to apparatus and methods for creating a temporary airtight seal at the open end of a pipe in a plumbing or refrigeration system. 
     Refrigeration systems are typically comprised of an evaporator that vaporizes liquid refrigerant to cool the surrounding environment; a compressor that highly pressurizes the recently evaporated refrigerant; and a condenser that returns the refrigerant to a liquid state. Each of these components is typically connected by pipes or other fluid conduits. The entire system is airtight (i.e., no air from the outside environment can enter the system). Refrigeration systems must be airtight so that: pressure is maintained in the various pipe lines; no refrigerant leaks out of the refrigeration system; and no air or other contaminants from the surrounding environment enters the pipes. 
     Refrigerants utilized in refrigeration systems are typically liquid compounds with appropriate thermodynamic properties to undergo a phase change from liquid to gas in order to cool the surrounding environment. As refrigerant evaporates, it absorbs heat energy from the environment thereby decreasing the temperature of the environment. Many compounds are known in the art that possess the thermodynamic properties appropriate for use in a refrigeration system. One such compound is chlorodifluoromethane, which is also known as HFCF-22 or R-22. However, this compound and other similar compounds are believed to have negative environmental effects such as ozone depletion. Therefore, use of chlorodifluoromethane and other compounds with similar environmental consequences is being reduced or eliminated, and alternative compounds that do not effect the same environmental consequences are being utilized. One such new replacement refrigerant is R410A, which is also known as AZ-20 or Puron, and it is a mixture of compounds including the synthetic oil polyoester. The chemical nature of this mixture causes the refrigerant to be highly hygroscopic. That is, R410A refrigerant strongly attracts and absorbs water molecules from the surrounding environment. 
     As refrigerants that are believed to have negative environmental consequences are no longer being manufactured and will eventually become unavailable for purchase or use, existing refrigeration systems incorporating these outdated refrigerants will eventually require an upgrade to accommodate the newer refrigerants. That is, to repair a refrigeration system that incorporates an unavailable refrigerant, it may be necessary to replace the existing condenser with a new condenser compatible with currently available refrigerants. This process involves cutting the existing pipe lines; removing the old condenser; and installing a new condenser and evaporator that utilize the new refrigerant. 
     Cutting pipes may also be required if pipes and fluid conduits become damaged or corroded. For example, a pipe may become corroded over time due to surrounding environmental conditions. Additionally, existing plumbing lines are sometimes accessed in order to add new fluid lines for system additions. Regardless of the reason, pipes and other fluid conduits are typically serviced by removing a portion of the conduit (e.g., the portion of the conduit that is damaged) and replacing it with a new piece of conduit. 
     In a refrigeration system, the open end of the pipe that has been cut must be sealed quickly in order to prevent air and water contamination and to quickly recreate the airtight system. This is even more critical with newer hygroscopic refrigerants, which are more susceptible to contamination due to their strong attraction of water from the surrounding environment. That is, if a hygroscopic refrigerant such as R410A is utilized in the refrigeration system, water moisture in air that enters a refrigeration system is quickly absorbed by the refrigerant oil, thereby causing contamination. When the system is reassembled, the lines and/or existing components which contain the hygroscopic polyoester oil must now be thoroughly cleaned through a process known in the art as nitrogen purging and triple evacuating, a very time consuming effort. Such contamination effects other negative consequences including, but not limited to: reduced cooling performance; malfunction of the evaporator; increased compressor noise; and/or compressor failure. 
     In non-hygroscopic systems, any contamination due to the entry of air into the refrigeration system may be remedied by vacuum purging the air prior to use of the system. However, since a hygroscopic refrigerant is contaminated by both water and air, it generally must be discarded and replaced by new refrigerant as water cannot be removed as easily as air. Therefore, sealing the open end of a cut pipe in a relatively short time frame is even more critical for hygroscopic systems to prevent the time and cost associated with refrigerant replacement. 
     One method commonly known in the art for temporarily sealing the open end of a pipe is to pinch it closed and then braze the edges together. That is, the metal walls of the pipe are compressed until the opening created by the cut is closed. An airtight seal is then created by joining the edges of the metal walls via heating of a filler metal alloy to a temperature at which the filler metal alloy melts and flows between the pinched edges of the fluid conduit as is commonly known in the art. Such a method effectively creates an airtight seal at the open end of the cut pipe. However, as is commonly known in the art, this method can take a relatively long period of time to implement and results in formation of oxidation residue on the interior surface of the fluid conduit. Additionally, upon connection of the sealed fluid conduit with other components, the portion of the fluid conduit affected by the airtight seal (i.e., the portion of the fluid conduit that is pinched closed and brazed to create an airtight seal) must be removed prior to connection of other components. The removal process is time consuming and can result in excessive refrigerant contamination. 
     Another way to create a temporary air-tight seal on the open end of a pipe is to couple an apparatus to the outer diameter of the pipe that grips the outer surface of the pipe via a plurality of teeth. That is, such a method grips the outer surface of the pipe with the teeth of the apparatus with sufficient strength to maintain an elevated internal pressure in the pipe and an air-tight seal between the interior of the pipe and the surrounding environment. As the internal pressure of the pipe is increased, the force with which the teeth grip the outer surface of the pipe increases. While providing an air-tight seal for the open end of a pipe, the teeth may also scar or mar the outer surface of the pipe, thereby necessitating removal of the pipe end to maintain the integrity of the piping and/or refrigeration system. 
     Also known in the art, a temporary air-tight seal may be created on the open end of a pipe via coupling of an apparatus to the open end of a pipe and then securing the apparatus via adhesion of the apparatus to the outer surface of the pipe. That is, an adhesive is applied to the one or more of the internal surfaces of the apparatus such that the surfaces will contact and adhere to the outer surface of the pipe upon installation of the apparatus. While providing an air-tight seal for the open end of a pipe, use of an adhesive prevents easy and/or rapid removal of such an apparatus from the open end of a pipe. It can also necessitate removal of the pipe end to maintain the integrity of the piping and/or refrigeration system. 
     BRIEF SUMMARY OF THE INVENTION 
     Briefly stated, in one aspect of the present invention, an apparatus for creating a seal on the end of an open pipe is provided. The apparatus includes: a body, the body including a threaded end, the threaded end surrounding a grommet cavity, the grommet cavity located external to and adjacent a recess; a grommet, the grommet shaped substantially identical to a shape of the grommet cavity, the grommet seated in the grommet cavity; a washer seated upon a floor of the substantially cylindrical recess; and a nut, the nut including a cavity, the cavity inversely threaded to mate with the threaded end, the nut threaded to the threaded end. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description of preferred embodiments of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings: 
         FIG. 1  is a an exploded perspective view of a cap assembly prior to attachment to a pipe in accordance with one embodiment of the present invention; 
         FIG. 2  is a perspective view of the assembled cap assembly of  FIG. 1  fitted to the end of the pipe; 
         FIG. 3  is a side elevational view of the cap assembly of  FIG. 2  fitted to the end of the pipe; 
         FIG. 4  is a top view of the cap assembly of  FIG. 2 ; 
         FIG. 5  is a cross-sectional view of the cap assembly of  FIGS. 1-4  taken along lines  5 - 5  of  FIG. 4 ; 
         FIG. 6  is a top view of the washer of the cap assembly of  FIGS. 1-5 ; 
         FIG. 7  is a side elevational view of the grommet of the cap assembly of  FIGS. 1-5 ; 
         FIG. 8  is a bottom view of the body of the cap assembly of  FIGS. 1-5 ; and 
         FIG. 9  is a flowchart of the steps of a method for using a cap assembly in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Certain terminology may be used in the following description for convenience only and is not limiting. The words “lower” and “upper” and “top” and “bottom” designate directions in the drawings to which reference is made. The terminology includes the words above specifically mentioned, derivatives thereof and words of similar import. 
     Where a term is provided in the singular, the inventors also contemplate aspects of the invention described by the plural of that term. As used in this specification and in the appended claims, the singular forms “a”, “an” and “the” include plural references unless the context clearly dictates otherwise, e.g., “a cap” may include a plurality of caps. Thus, for example, a reference to “a method” includes one or more methods, and/or steps of the type described herein and/or which will become apparent to those persons skilled in the art upon reading this disclosure. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods, constructs and materials are now described. All publications mentioned herein are incorporated herein by reference in their entirety. Where there are discrepancies in terms and definitions used in references that are incorporated by reference, the terms used in this application shall have the definitions given herein. 
     Referring first to  FIG. 1 , depicted is an exploded perspective view of cap assembly  100  in accordance with one embodiment of the present invention. Cap assembly  100  includes, inter alia, nut  102 , grommet  104 , washer  106 , and body  108 . Cap assembly  100  is designed to temporarily seal refrigerant pipes or lines (hereinafter referred to as “refrigerant pipes or piping”) such as those used to connect a condenser or heat pump to an evaporator coil. When installed on a refrigerant pipe, cap assembly  100  provides an air tight seal capable of withstanding high pressures within the pipe of 25 pounds per square inch, however, typically there will be no pressure in the pipe when cap assembly  100  is installed since the system is typically not operational. 
     Also, cap assembly  100  can be quickly coupled to a refrigerant pipe. The speed of installation is beneficial, for example, when replacing a portion of an existing refrigerant pipe or replacing an outdated refrigerant/condenser with a newer refrigerant/condenser. To do this, the refrigerant is first removed from the system. Then, the pipe is cut in the proximity of the component to be repaired or replaced. As soon as possible after the pipe is cut, an airtight seal is applied to the open ends created by the cuts to minimize contamination of the refrigerant. Contamination can occur because, in systems utilizing R410-A, or any Hydrofluorocarbon (“HFC”) refrigerant that utilizes a polyester oil, the refrigerant oil (i.e., the polyoester) in the system is hygroscopic. That is, it removes water from the surrounding atmosphere. Therefore, as air enters the cut end of the pipe and contacts the refrigerant oil that remains in the system after the refrigerant has been removed for repair or component replacement, moisture is removed from the ambient air and absorbed by the refrigerant oil thereby causing contamination thereof. Refrigerant oil that has been contaminated with moisture cannot be used in a refrigeration system and must be either cleaned or replaced. Therefore, installing the cap assembly on a cut end of a pipe in a relatively short time frame, reduces the amount of air contamination within the refrigerant oil, which allows the refrigerant oil to be reused. 
     Turning now to  FIG. 2 , depicted is a perspective view of cap assembly  100  installed on an exemplary refrigerant pipe  202 . However, cap assembly  100  may also be installed on pipes other than refrigerant pipes without departing from the scope of the present invention. It is envisioned that cap assembly  100  may be manufactured having a plurality of sizes to accommodate attachment to and sealing of pipes having varying outside diameters including, but not limited to, ⅜″, ⅝″, ¾″, ⅞″, and 1⅛″. For example, a user of the present invention may carry a full set of cap assemblies  100  (i.e., at least one or two cap assemblies for each outside pipe diameter). This will allow a user to easily and quickly seal any size pipe via the method discussed in greater detail below. Each differently sized cap assembly  100  may be marked with information regarding the size of pipe for which it is appropriate. Additionally, the components of differently sized cap assembly  100  may be color coordinated using a separate, distinct color for each cap assembly  100  so that the user may easily locate the appropriate cap assembly components required to seal a pipe of any diameter. 
     Turning now to  FIGS. 3 ,  4 , and  5 , depicted are side elevational, top, and cross-sectional views, respectively, of cap assembly  100  fitted to exemplary refrigerant pipe  202 . As depicted, body  108  is a tubular body of anodized aluminum (or other materials including, but not limited to, polyvinyl chloride (“PVC”) and extruded plastics) machined to the free state shape illustrated in  FIGS. 3 ,  4 , and  5 . As best seen in  FIG. 5 , body  108  has a large diameter open end  458  with a substantially horizontal upper surface  402 . The innermost border of surface  402  intersects with grommet cavity  460 . Grommet cavity  460  is bound by frusto-conical inner wall  404 , the latter of which slopes axially downward and radially inward at an angle of approximately 30 degrees until point  406 . From point  406 , inner wall  404  extends axially downward with a substantially fixed radial diameter to corner  408 . At corner  408 , inner wall  404  transitions in a substantially perpendicular manner to substantially horizontal wall  410 , which extends radially inward until it intersects recess  412 . Recess  412  is substantially cylindrical and is recessed in wall  410 . Inner wall  414  of recess  412  extends axially downward with a substantially fixed radial diameter until it intersects in a substantially perpendicular manner with horizontal floor  416 . The circumference of inner wall  414  is machined to substantially mate with or match the circumference of outer wall  428  of the pipe  202  to be sealed by cap assembly  100 . That is, recess  412  is machined to accept the open end of pipe  202 . A clearance between the circumference of inner wall  414  and the outer diameter of pipe  202  of approximately 0.10 inches allows a user to quickly slide body  108  over the open end of pipe  202 . 
     Still referring to  FIG. 5 , the outermost border of upwardly facing surface  402  intersects substantially perpendicularly with threads  418  of exterior wall  420 . Threads  418  are machined to mate with nut  102  as discussed in greater detail below. As best seen in  FIG. 3 , from the bottommost edge of threads  418 , substantially cylindrical exterior wall  420  proceeds axially downward with a substantially fixed radial diameter. The bottommost end of exterior wall  420  intersects substantially perpendicularly with substantially horizontal downwardly facing surface  422 . 
     Exterior wall  420  includes wrench surfaces  426 , as best seen in the bottom view of  FIG. 8 . As seen in  FIG. 8 , each wrench surface  426  forms a substantially planar chord passing through exterior wall  420  and downwardly facing surface  422 . The substantially planar nature of surfaces  426  allows a user to tightly grip body  108  with a wrench during the installation process. That is, each planar surface  426  is designed to engage opposing inner surfaces of the head of a wrench. 
     Although the depicted body  108  is made of anodized aluminum, other materials may be substituted without departing from the scope of the present invention including, but not limited to, polyvinyl chloride, acrylonitrile butadiene styrene, brass, or stainless steel. 
     Referring now to  FIG. 6 , depicted is a top plan view of washer  106 . In the depicted embodiment, washer  106  is manufactured of rubber and it is ring-shaped. That is, in the depicted embodiment, washer  106  is an O-ring. In one embodiment of the present invention, the thickness of washer  106  is approximately 0.10 inches. The diameter of washer  106  will vary depending upon the particular size of cap body  108 . However, varying shapes of washer  106  may be substituted without departing from the scope of the present invention. Also, washer  106  may be made of a material other than rubber without departing from the scope of the present invention. Further, a solid rubber plug sized to plug into the cut pipe end may be substituted for washer  106  without departing from the scope of the present invention. 
     When cap assembly  102  is assembled as discussed in greater detail below, washer  106  is compressed between floor  416  of recess  412  and the bottommost surface  454  of the open end of exemplary refrigerant pipe  202 . This position and compression allows the ring-shaped washer to completely contact the ring-shaped outer wall of exemplary refrigerant pipe  202  such that washer  106  cushions the open end of refrigerant pipe  202  to prevent, or minimize, damage thereto caused by recess  412 . It also forms a substantially airtight secondary seal between the open end of refrigerant pipe  202  and body  108  and/or cap assembly  100 . 
     Referring again to  FIGS. 4 and 5 , nut  102  is made of anodized aluminum (or other material including, but not limited to, PVC or extruded plastic) and is machined to the free-state shape illustrated therein. Nut  102  has a smaller diameter open end with a centrally located aperture  430  and threaded cavity  452 . Aperture  430  is bounded by inner wall  432 . The bottommost end of inner wall  432  intersects substantially perpendicularly with downwardly facing surface  434 . Downwardly facing surface  434  proceeds radially outward in a substantially horizontal manner until outer corner  436 , at which it intersects with substantially cylindrical inner wall  438 . Inner wall  438  proceeds axially downward with a substantially fixed circumference with the exception of threads  440 . As depicted in  FIG. 5 , threads  440  facilitate coupling of body  108  to a nut such as nut  102 . That is, body  108  is coupled to nut  102  via threading of threads  418  of body  108  into the substantially cylindrical, inversely threaded cavity of nut  102 . 
     At its topmost end, inner wall  432  intersects in a substantially perpendicular manner with upwardly facing surface  444 . Upwardly facing surface  444  is substantially horizontal. At the outermost perimeter of surface  444 , it intersects in a substantial perpendicular manner with outwardly facing surface  446 . As best seen in  FIG. 3 , outwardly facing surface  446  includes a plurality of wrench surfaces  448 . Each wrench surface  448  forms a chord passing through outwardly facing surface  446  and upwardly facing surface  444  in a substantially planar manner as seen in  FIG. 4 . The substantially planar nature of surfaces  448  allows a user to tightly grip nut  102  with a wrench during the installation process. That is, each planar surface  448  is designed to engage opposing inner surfaces of the head of a wrench. 
     Grommet  104  is molded to the free form state illustrated in  FIGS. 5 and 7 . Grommet  104  is composed of an elastomeric material such as extruded rubber (e.g., extruded Butyl Rubber). Grommet  104  has a substantially cylindrical inner wall  450  with a central aperture  456 . The elastomeric nature of the material of grommet  104  allows cap assembly  100  to be coupled to the open end of a cut pipe  202  without contaminating, deforming, or marring internal surface  462  or external surface  428  of pipe  202  in any manner as described in further detail below with reference to  FIG. 9 . At the topmost end of wall  450 , grommet  104  transitions in a substantially perpendicular manner to upwardly facing surface  702 . When grommet  104  is inserted into grommet cavity  460 , upwardly facing surface  702  is located approximately three sixteenths of an inch ( 3/16″) above substantially horizontal upper surface  402 . This relative sizing enables nut  102 , when tightened, to compress downwardly facing surface  718  of grommet  104  against substantially horizontal surface  410  of body  108 , thereby creating the primary airtight seal discussed herein below with respect to  FIG. 9 . 
     Surface  702  proceeds radially outward in a substantially horizontal manner until outer perimeter  704 . At outer perimeter  704 , surface  702  intersects with outwardly facing surface  706 , the latter of which converges radially inward and axially downward at an angle of approximately 30 degrees until edge  708 . At edge  708 , outwardly facing surface  714  transitions in a substantially perpendicular manner to downwardly facing surface  718 . Substantially horizontal downwardly facing surface  718  proceeds radially inward until it intersects with the bottom most end of inner wall  450 . 
     Referring lastly to  FIG. 9 , depicted is a flowchart of the steps of a method for using a cap assembly such as cap assembly  100  in accordance with one embodiment of the present invention. Process  900  starts at  902 , at which a refrigerant pipe or other fluid conduit requires replacement or modification. As previously discussed, refrigerant pipes must be repaired if they become damaged or corroded by the surrounding environment. Additionally, modification to previously existing refrigerant pipes or other fluid conduits may be required due to installation of new components or replacement of an outdated refrigerant and/or condenser with a newer refrigerant and/or condenser. 
     Process  900  then proceeds to  904 , at which a pipe such as exemplary pipe  202  is cut. The pipe may be cut using a pipe cutter or any other suitable method or tool as is commonly known in the art. Whatever means used to cut the pipe, it should be performed in a relatively short time frame in order to minimize air contamination as discussed above. After pipe  202  is cut, the following steps are performed relatively quickly to minimize contamination of the refrigerant. 
     Next, at step  906 , a nut (e.g., nut  102 ) is installed on the open end of a pipe such as pipe  202 . In our exemplary embodiment, nut  102  is installed on pipe  202  by sliding the open end of pipe  202  through aperture  430  until it exits threaded cavity  452  to a sufficient distance to allow the other components of cap assembly  100  to also be passed over the open end of pipe  202 . That is, upwardly facing surface  444  is farther from the open end of the pipe than threaded cavity  452 . Again, this step should be completed quickly to minimize air contamination. 
     Next, at step  908 , grommet  104  is installed on the open end of pipe  202 . Grommet  104  is installed on pipe  202  by sliding the open end of pipe  202  through aperture  456  of grommet  104  to a sufficient distance to allow the other components of cap assembly  100  to also be passed over the open end of pipe  202 . That is, grommet  104  is oriented so that upwardly facing surface  702  is farther from the open end of pipe  202  than downwardly facing surface  716 . When installing grommet  104 , in addition to allowing sufficient distance for the other components of cap assembly  100  to be passed over the open end of the pipe, grommet  104  should be located as close to its final position as possible to allow it to easily slide into grommet cavity  460  of body  108  in the next step. Again, this step should be completed quickly to minimize air contamination. 
     Next at  910 , body  108  is installed on the open end of pipe  202 . As previously discussed above, washer  106  is contained in recess  412  and rests on floor  416  of recess  412 . Body  108  is installed by sliding the smaller diameter open end  458  of body  108  over the open end of pipe  202  until the bottommost surface  454  of pipe  202  contacts washer  106 . That is, the open end of pipe  202  slides inside recess  412  until it contacts washer  106  contained therein. Simultaneously, grommet cavity  460  of body  108  encases grommet  104  previously fitted to pipe  202  in a manner that contact is made between surfaces  706 ,  710 ,  714 , and  718  of grommet  104  and walls  404  and  410  of body  108 , thereby creating a primary airtight seal between the refrigerant system and the outside environment. Grommet  104  forms a compression fitting for pipe  202 , and its material allows it to flex and form this primary airtight seal which may later be easily released without damaging pipe  202 . Additionally, as body  108  is installed, body  108  may force grommet  104  away from the open end of pipe  202  as required to achieve proper fit. That is, the pressure applied by body  108  as it is passed over the open end of pipe  202  forces grommet  104  to move further away from the open end of pipe  202  as needed until the bottommost surface  454  of pipe  202  contacts washer  106 . The contacting of washer  106  by surface  454  of pipe  202  may cause a secondary airtight seal to be created between the refrigerant system and the outside environment as further discussed above. In this manner, the possibility of refrigerant contamination is reduced or completely eliminated. In some alternate embodiments of the present invention, the surface  454  of pipe  202  compresses washer  106  in addition to contacting washer  106  to form a tighter seal. 
     Process  900  then proceeds to  912  at which threads  418  of the exterior wall  420  of body  108  are coupled with threads  440  of the inversely threaded cavity  452  of nut  102 . The threads are coupled by rotating nut  102  in a clockwise direction relative to the position of body  108 . Nut  102  can be rotated by hand, by a wrench, or via a combination thereof. To couple nut  102  and body  108 , opposing inside surfaces of the head of a wrench engage planar wrench surfaces  426  of body  108 . This allows an installer of cap assembly  100  to hold body  108  in a stationary position while nut  102  is threaded onto body  108 . If nut  104  is tightened by a wrench, planar wrench surfaces  448  of nut  102  may also be engaged by opposing inside surfaces of the head of a second wrench to allow nut  102  to be rotated via rotation of the arm of the wrench while body  108  is maintained in a stationary position via the first wrench. That is, body  108  is maintained in a static position while nut  102  is rotated. Alternatively, any other method for engaging the threads of nut  102  and body  108  can be substituted without departing from the scope of the present invention. As nut  102  is coupled to body  108 , downwardly facing surface  434  of nut  102  contacts and compresses upwardly facing surface  702  of grommet  104 . 
     As nut  102  and body  108  are coupled, the space therebetween is reduced causing compression of grommet  104  by the inner surfaces of nut  102  and body  108 . As grommet  104  is compressed, pressure is exerted on the outer wall  428  of exemplary pipe  202 . That is, the pressure exerted on surfaces  702 ,  706 ,  710 ,  714 , and  718  of grommet  104  by the inner surfaces of the other components of cap assembly  100  causes pressure to be exerted on the outer wall  428  of pipe  202  by internal wall  450  of the grommet. The pressure exerted on outer wall  428  of pipe  202  clenches the end of pipe  202 ; thereby preventing cap assembly  100  from being dislodged. In this manner, cap assembly  100  is securely retained on the open end of pipe  202  without damaging the pipe in any manner. That is, the elastomeric nature of the material of grommet  104  does not contaminate, deform, or mar internal surface  462  or external surface  428  of pipe  202  in any manner as  104  includes no teeth and does not require welding or adhesive for installation thereof. 
     In addition to clenching the open end of pipe  202 , the pressure exerted by the threading of nut  102  and body  108  creates the primary airtight seal. This airtight seal between the surrounding atmosphere and the inside of pipe  202  is the primary method of preventing contamination. 
     After the bottommost surface  454  of exemplary pipe  202  contacts washer  106  in step  908  and/or nut  102  is completely threaded on to body  108 , a secondary airtight seal may be created. The threading of nut  102  to body  108  as well as the compression of pipe  202  by grommet  104  couples cap assembly  100  to pipe  202  in a manner that prevents accidental dislodgement of  100  from  202 . In this manner, the internal pressure in pipe  202  may be maintained and the potential of refrigerant contamination due to the external atmosphere is minimized or eliminated. 
     It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.