Abstract:
A relief valve coupled to a container is disclosed. The relief valve may include a valve body forming an internal chamber, an inlet portion connected to the chamber and configured to receive content flow from the container, a spring, a poppet including a seat disc, wherein a spring force exerted by the spring biases the seat disc towards the inlet portion, and a cap configured to include a plurality of passages.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 62/052,945, filed Sep. 19, 2014, and U.S. Provisional Patent Application No. 62/182,249, filed Jun. 19, 2015, both of which are incorporated herein by reference in their entirety. 
     
    
     BACKGROUND 
       [0002]    Relief valves are used to control or limit the pressure in a system or vessel which can build up in the vessel. In particular, relief valves are used on containers such as cryogenic cylinders containing industrial cryogenic liquids (Nitrogen, Argon, Oxygen, etc.) to allow pressurized gas built up in the container to flow out from the relief valve. This may help to prevent failure of the container. Cryogenic liquids stored in containers pose a particular challenge because pressure is always building in the container as the cryogenic temperature is around −295° F. It follows that relief valves can be found installed onto such containers to release gas pressure. 
         [0003]    Containers stored or installed indoors, such as at research facilities and hospitals, present an additional problem as the release of pressure from the relief valve can be noisy. When this takes place in a laboratory setting, for example, where delicate work is being conducted, the noise can disrupt the working environment. Further, current Occupational Safety and Health Administration (OSHA) requirements state that a permissible exposure limit is 90 decibels for an 8-hour shift; any exposure over this limit requires hearing protection. In addition, for each increase of 5 decibels above the 90-decibel limit, the exposure time is cut in half. Thus, a valve which can effectively relieve pressure in a pressurized container while reducing the discharging noise is desirable. 
       SUMMARY 
       [0004]    The present disclosure describes a pressure relief valve configured to control or limit pressure build up in a container. More specifically, a pressure relief valve is disclosed for use with containers, such as containers housing cryogenic liquids to allow pressurized gases within the container to be released through the pressure relief valve in the event of a pressure buildup. By allowing pressurized gas to be released through the pressure relief valve, this may help prevent failure of the container. The pressure relief valve described herein is designed to replace a first relief valve in a multi valve assembly used on pressurized containers. For example, the pressure relief valve described herein may be a first relief valve in a three-part valve assembly, where the first pressure relief valve cycles open and closed to keep the pressure controlled, a second valve corresponds to a second pressure relief valve which opens to protect the vessel if the pressure continues to build even with the first relief valve operating, and a third valve corresponds to a burst disc valve which discharges if the first two relief valves cannot handle the pressure built up in the container to protect the container from catastrophic failure. The pressure relief valve described herein may be installed on containers stored located indoors and/or placed near employees and/or in work areas. 
         [0005]    The pressure relief valve described herein is designed to reduce noise caused by the release of pressure from the container such that the noise level is within the range of normal conversation when discharging, for example, from a typical 200 liter container for storing cryogenic liquids. The pressure relief valve described herein may also be designed to reduce noise levels for a gas being released from a container to be within OSHA standards for sound exposure in a work environment. 
         [0006]    To reduce noise level, the valve disclosed herein includes a cap with a plurality of passages that change the direction of and evenly distribute the flow of gas out of the valve, resulting in a further slowing of the velocity of the gas escaping the valve and the noise associated with the escaping gas, and in turn reducing the noise level. The passages also provide a further safety advantage of directing flow from the valve through a plurality of outlets in various directions, rather than the full flow through a single outlet, such that if a user is close to the valve at discharge, the full stream of escaping gas will not be directed through the single outlet passage toward a user. The valve may also include an inlet that is smaller in diameter than a typical relief valve used in cryogenic containers, which reduces the flow of gas into the valve so that there is less gas creating flow noise. The inlet is still sized appropriately to allow sufficient flow from the container, but the reduced diameter as compared to a typical such relief valves provides a decrease in gas flow and corresponding noise. 
         [0007]    According to some embodiments, a relief valve coupled to a container is disclosed. The relief valve comprises a valve body forming an internal chamber, an inlet portion connected to the chamber and configured to receive content flow from the container, a spring, a moveable poppet, wherein a spring force exerted by the spring biases the poppet towards a closed position to close the valve, and a cap engaged to the valve body and including a plurality of passages, wherein each of the plurality of passages has a separate axis that is generally perpendicular to the central axis of the valve body. 
         [0008]    Other objects, advantages, features, properties and relationships of the invention will be obtained from the following detailed description and accompanying drawings which set forth illustrative embodiments that are indicative of the various ways in which the principles of the invention may be employed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  illustrates a cylinder having installed a relief valve in accordance with the present disclosure. 
           [0010]      FIG. 2A  is a front view of the relief valve of  FIG. 1 . 
           [0011]      FIG. 2B  is a top perspective view of the relief valve of  FIG. 1 . 
           [0012]      FIG. 3  is a cross-sectional front view of the relief valve of  FIG. 1 . 
           [0013]      FIG. 4  is a cross-sectional front view of a cap portion of the relief valve of FIG. 
           [0014]      FIG. 5  is cross-sectional view along Section  5 - 5  of  FIG. 4 . 
           [0015]      FIG. 6  is a cross-sectional front view of the relief valve showing air flow through the relief valve of  FIG. 1 . 
           [0016]      FIG. 7  is a partial cross-sectional top view of the cap portion of the relief valve of  FIG. 1  showing air flow through the cap portion. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    The description that follows describes, illustrates and exemplifies one or more embodiments of a pressure relief valve in accordance with its principles. This description is not provided to limit the pressure relief valve to the embodiments described herein, but rather to explain and teach the principles of the pressure relief valve in order to enable one of ordinary skill in the art to understand these principles and, with that understanding, be able to apply them to practice not only the embodiments described herein, but also other embodiments that may come to mind in accordance with these principles. The scope of the present disclosure is intended to cover all such embodiments that may fall within the scope of the appended claims, either literally or under the doctrine of equivalents. 
         [0018]      FIGS. 1-6  show a preferred embodiment of an improved noise reduction pressure relief valve  10  configured to be installed on a container  100  holding pressurized contents (e.g., cryogenic container storing pressurized gas). The relief valve  10  is a spring-loaded poppet relief-type valve coupled to a container  100 , such as a cryogenic cylinder containing industrial cryogenic liquids (e.g., Nitrogen, Argon, Oxygen). As container  100  is stored with cryogenic liquids, gas may form within container  100 , thus increasing a pressure within container  100 . Relief valve  10  is configured to allow the pressurized gases to flow from the relief valve  10  in the event of a pressure buildup to prevent failure of container  100 . 
         [0019]    Relief valve  10  may be a first relief valve in a multi-part relief valve assembly as described above. It follows that relief valve  10  is designed to open at a preset pressure, such that when a pressure in container  100  exceeds the preset pressure of relief valve  10  for causing release of gas from container  100 , relief valve  10  will open to allow the pressure in container  100  to be reduced by allowing gases to exit through relief valve  10 . The pressure within container  100  may have been caused due to ambient thermal warming of the cryogenic liquid stored within container  100 . 
         [0020]      FIG. 3  illustrates relief valve  10  including a valve inlet  28  located at a proximal end of a valve body  21  and configured to be connected to an interior of container  100 . A movable poppet  20  is disposed in chamber  23  formed in valve body  21 , and spring  30  is configured and located to exert a spring force down on a top seat  25  of movable poppet  20  so that seat disc  24  maintains a sealing engagement with valve seat  22  to close valve inlet  28 . At an opposite end of spring  30 , spring  30  contacts spring top  26  disposed within valve body  21 . When the pressure in container  100  exceeds the preset pressure of relief valve  10 , the force of the pressure within container  100  overcomes the spring force of spring  30  being exerted on movable poppet  20  to keep seat disc  24  over valve inlet  28 . Thus when the pressure in container  100  exceeds the preset pressure of relief valve  10 , movable poppet  20  is allowed to move up and seat disc  24  correspondingly is lifted off from the valve inlet  28  which allows pressurized gas from container  100  to flow through a chamber  23  defined by an interior of the valve body  21 , and out through a plurality of passages  42  included in a cap  40 . Cap  40  is located at a distal end of relief valve  10  that is opposite from valve inlet  28 , and may be connected thereto by means of threads. 
         [0021]    Spring top  26  may be an adjustable cam for adjusting the spring force exerted by spring  30  on seat disc  24 . For example, when spring top  26  is adjusted towards seat disc  24 , the compression of spring  30  increases and correspondingly the spring force exerted by spring  30  on seat disc  24  increases. This adjustment of spring top  26  can also be seen to be an adjustment to the preset pressure of relief valve  10  as now the pressure within container  100  must be greater to overcome the increased spring force exerted by spring  30  on seat disc  24  to lift seat disc  24  off the valve inlet  28 . Conversely, spring top  26  may be adjusted away from seat disc  24 , which decreases the compression of spring  30  and correspondingly decreases the spring force exerted by spring  30  on seat disc  24 . This adjustment of spring top  26  can be seen to be an adjustment to the preset pressure of relief valve  10  as now the pressure within container  100  can be less to overcome the decreased spring force exerted by spring  30  on seat disc  24  to lift seat disc  24  off the valve inlet  28 . 
         [0022]    As seen in  FIGS. 3-6 , relief valve  10  includes cap  40  having the plurality of passages  42 . Cap  40  is depicted in this embodiment as being generally round. The plurality of passages  42  changes the direction of, and distributes, the flow of gas flowing out of relief valve  10 . Each passage has its own axis  45  that is formed to be generally perpendicular to the central axis  44  of the valve body  21 , along which fluid will flow when relief valve  10  is open. Passages  42  are therefore configured to reduce the velocity of the gas escaping relief valve  10  and to reduce the noise associated with the escaping gas.  FIG. 5  is a cross-sectional view of cap  40  that is taken along Section  5 - 5  from  FIG. 4 .  FIG. 5  illustrates the plurality of passages  42 , and specifically twelve evenly-spaced passages around the circumference of cap  40 . The use of numerous, smaller passages such as the twelve depicted in this embodiment reduces the noise produced by relief valve  10  without reducing flow of the gas being released through relief valve  10 . For example, a configuration of twelve passages each having a diameter of 0.067 inch provides sufficient flow and achieves satisfactory lower noise levels for a typical cryogenic container. Such configurations may, for example, allow relief valve  10  to achieve reduced noise levels that meet the noise requirements of OSHA described herein. The use of additional passages having an even smaller diameter is also contemplated.  FIG. 6  shows the flow of gas coming up through valve inlet  28  from container  100 , up through a body of relief valve  10 , and distributed out of the plurality of passages  42  in cap  40 . 
         [0023]    A further advantage to aid in reducing noise is designing valve inlet  28  to have a smaller diameter. The diameter of valve inlet  28  is less than that of an inlet of other first relief valves used in cryogenic containers. One example of an orifice diameter for valve inlet  28  as contemplated herein is 0.141 inch. Other valve inlets for use in these applications have been known to have an orifice diameter of 0.281 inch. The reduced diameter of valve inlet  28  reduces the flow of gas entering into relief valve  10 , so that the velocity and volume of gas flowing out of the plurality of passages  42  is reduced, which translates to reduced noise of the gas when it is released through the plurality of passages  42 . Even so, valve inlet  28  is still sized appropriately to allow sufficient flow of gas being release out of container  100 , but the reduced diameter of valve inlet  28  when compared to an inlet of other known relief valves provides decreased gas flow and is therefore able to achieve reduced noise. 
         [0024]    The noise reduction features of relief valve  10  may reduce discharge noise of pressurized gas being released through the plurality of passages  42  to within a range of normal conversation and within the OSHA noise exposure requirements of 90 decibels per 8 hour period. Accordingly, relief valve  10  described herein provides a solution for placement and storage of cryogenic containers where noise level is of importance, such as research, hospital and other settings where the containers are stored or installed near employees and/or work areas. 
         [0025]    The passages  42  of cap  40  also provide a further advantage of redirection of the gas flowing from relief valve  10 .  FIG. 1  illustrates container  100  having relief valve  10  installed in relief outlet or port  15  in communication with the internal volume of container  100  and disposed adjacent gauge  16 . Port  15  has a port central axis  11  that is typically horizontal with respect to ground, and relief valve  10  has a separate valve central axis  12  that is preferably offset slightly lower than horizontal (e.g., 30 degrees below the horizontal port central axis  11 ). According to some embodiments, angle A may be any angle between 30-0 degrees (where 0 degrees is straight horizontal). The relief valve  10  is installed on its side so that gas being released from one or more of a plurality of passages  42  will not be released directly out towards a side of container  100  where a bystander may be standing. 
         [0026]    In addition,  FIG. 6  illustrates cap  40  being configured to discharge gas through the plurality of passages  42  at 90 degrees to the valve inlet  28 . This configuration enables gas discharging out from passages  42  to not be directed straight out from the container  100 . This configuration is further advantageous because only a fraction of the total gas flow discharging out passages  42  is directed towards any given point. If a person were to be close to relief valve  10  at discharge, in line with one of the passages  42 , only a small amount of flow would be directed toward them. 
         [0027]      FIG. 7  illustrates a top view of relief valve  10  and cap  40 . In this view, top seat  25  is shown to be designed to have a plurality of flow passages  27  defined by portions of top seat  25  and an inner wall of relief valve  10 . The plurality of flow passages  27  aid in directing and/or reducing a flow of pressurized gas through relief valve  10 . 
         [0028]    While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any equivalent thereof.