Abstract:
An O-ring shield system and method of protecting O-rings in a high pressure refrigerant system are disclosed. The system may include first and second pipes coupled together. An O-ring may be disposed on one of the pipes. A compressible shield ring may be positioned upstream a flow of refrigerant from the O-ring.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention generally relates to refrigerant systems and more particularly, to an O-ring shield system and method. 
         [0002]    A common industry practice is to seal refrigerant system component joints using a radial type O-ring. The O-ring is typically placed in a gland (O-ring groove) that is machined in to the male fitting. The ring is then inserted into a female fitting where the O-ring is compressed between the inner diameter of the female fitting and the bottom of the groove. After the engagement, both halves (male and female fittings) are bolted together. Constant high pressure may damage the O-ring. Additionally, the refrigerant may contaminate the O-rings compromising the structure of the O-ring. Compromised O-rings may permit refrigerant to leak into undesirable portions of the pressurized system causing costly diagnosis and repair. 
         [0003]    As can be seen, there is a need for a system that protects O-rings in high pressure refrigerant systems from damage and contamination. 
       SUMMARY OF THE INVENTION 
       [0004]    In one aspect of the present invention, an O-ring shield system comprises a first pipe; a second pipe including one or more circumferential grooves positioned on an exterior surface of the second pipe; one or more O-rings disposed in the one or more circumferential grooves; and a shield ring at a joint of the first pipe and the second pipe, the shield ring being compressible under a predetermined pressure, the shield ring positioned upstream a flow of refrigerant of the one or more O-rings. 
         [0005]    In another aspect of the present invention, an O-ring shield system comprises a first pipe including a threaded female boss; a second pipe including a threaded male boss configured for receipt in the female boss, the second pipe further including one or more grooves positioned on an exterior surface of the second pipe; a beveled surface on an end of the male boss; one or more O-rings disposed in the one or more grooves, wherein the O-rings are disposed to be torqued into position within the female boss; and a shield ring over the beveled surface, the shield ring being compressible under a predetermined pressure, and the shield ring positioned upstream a flow of refrigerant of the one or more O-rings. 
         [0006]    In still yet another aspect of the present invention, a method of protecting an O-ring in a refrigerant system includes determining the pressure in the refrigerant system will exceed a predetermined threshold; providing a shield ring that will compress under the determined pressure without breaking; positioning the selected shield ring upstream of the O-ring. 
         [0007]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a cross-sectional view of an O-ring shield system in accordance with an exemplary embodiment of the present invention; and 
           [0009]      FIG. 2  is a series of steps of a method in accordance with an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]    The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to e taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
         [0011]    Various inventive features are described below that can each be used independently of one another or in combination with other features. However, any single inventive feature may not address any of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below. 
         [0012]    The present invention generally provides a layer of protection for gaskets. In one aspect, gaskets, for example, O-rings in high pressure aerospace-based refrigerant systems may be protected from rapid pressure changes. Exemplary aerospace-based refrigerant systems that may benefit from aspects of the following disclosure may include those using liquid and oil mixed refrigerants. In high pressure refrigerant systems O-rings may be permeable, thus inclined to absorbing refrigerant. Contamination of an O-ring with refrigerant may cause leaks and in some cases, may result in explosive decompression of the O-ring during rapid changes in pressure in the system. 
         [0013]    Referring to  FIG. 1 , an exemplary embodiment of an O-ring shield system  10  is shown. The O-ring shield system may include a pipe  20  and pipe  30  coupled together by a fastener  60 . The O-ring shield system  10  may also include one or more O-rings  55  and a shield ring  50 . In the O-ring shield system  10 , the flow of refrigerant is flowing through pipe interior walls  34  and  24  from pipe  30  to pipe  20 . Thus, in one exemplary embodiment, the O-ring shield  50  is positioned upstream of the O-rings  55 . 
         [0014]    In an exemplary embodiment of the O-ring shield system  10 , the pipe  20  may include a male boss  28  and the pipe  30  may include a female boss  38 . The male boss  28  may include a threaded exterior surface  21  configured for within a threaded interior surface  31  of female boss  38 . The male boss  28  may include circumferential grooves or glands  25  adapted to receive the O-rings  55 . The male boss  28  may also include a beveled end  27 . The female boss  38  may include a beveled seat surface  35  configured to complement the beveled end  27  when the male boss  28  is coupled to the female boss  38 . When coupled, the exterior surface  21  and interior surface  31  may define an inclined-plane passage  33  between the beveled end  27  and the O-rings  55 . The beveled end  27  and the beveled seat  35  may be spaced apart. The O-ring shield ring  50  may be positioned between the beveled end  27  and the beveled seat  35 . A gap  29  may be defined by the spacing between the O-ring shield ring  50  and the beveled end  27 . The gap  29  may be in communication with the passage  33 . 
         [0015]    The O-ring shield ring  50  may be, for example, a washer selected from compressible material that may deform under predetermined pressure. For example, the O-ring shield ring  50  may be made of material that will decompress under pressures of approximately 600 pounds per square inch (psi) without breaking. One exemplary material used may be copper. The O-ring shield  50  may also be configured to withstand pressure changes of approximately 100 psi/sec. In one exemplary embodiment, coupling the male boss  28  into the female boss  38  may provide torque onto the O-ring shield ring  50  engaging the O-ring shield ring  50  onto the beveled end  27  and the beveled seat  35 . During rapid pressure changes for example, pressure drops, the O-ring shield ring  50  may deform and at least partially fill the gap  29  while maintaining a barrier between the passage  33  and pipe interior wall  34 . 
         [0016]    Referring now to  FIG. 2 , a method  200  is shown in accordance with an exemplary embodiment of the present invention. A system employing aspects in accordance with the disclosure may be analyzed for a range of typical operating pressure. The upper and lower threshold limits of operating pressure may be determined in step  210 . An exemplary operating pressure in the system may be in the range of approximately 8-350 pounds per square inch absolute (psia). In step  220 , compressibility of a material suitable in the system may be determined based on the threshold operating pressure limits determined in step  210 . In step  230  a shield ring may be selected that includes the material with suitable compressibility determined in step  220 . The selected shield may then be positioned in a boss end of a pipe of the system so that the shield ring is within a fluid flow, upstream of an O-ring (step  240 ). The boss end of the pipe may be coupled to an adjoining pipe end and torqued into place so that a torque pressure is applied to the shield ring (Step  250 ). 
         [0017]    It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.