Patent Publication Number: US-2021190250-A1

Title: Improved coupling with pressure relief

Description:
FIELD OF THE INVENTION 
     The present disclosure relates to coupling for break-away valve assemblies. In particular it relates to couplings for break-away valve assemblies comprising a valve biased in a first direction and a second direction. 
     BACKGROUND OF THE INVENTION 
     Fluid transfer systems are used to transfer a fluid from a source to a destination. Dry disconnect or break-away coupling assemblies are used in fluid transfer systems to provide dry couplings and break-away couplings. Break-away coupling assemblies generally comprise a first and second coupling half, herein described as a coupling and an adapter. A break-away coupling is adapted to facilitate a controlled breaking point between the coupling and adapter if the fluid transfer system is exerted to a force that otherwise would risk the fluid integrity of the fluid transfer system. 
     To form a fluid conduit the coupling and the adapter are connected together. The connection of the coupling to the adapter actuates valves in the coupling and the adapter which open and allow fluid flow through the assembly. 
     On break-away of the coupling from the adapter the valves are closed automatically. For dry disconnect couplings the valves can be closed either automatically or via actuation means present on either the coupling or the adapter or both. This closure of valves in both the coupling and the adapter leads to the closure of the fluid path and thus fluid cannot leak from the coupling or the adapter during the break-away. 
     However, such systems are prone to surge pressures. The sudden reduction in fluid volume of the system leads to an increase in pressure. This pressure can damage pumps, valves or other systems in connection with the fluid system. 
     Pressure relief valves such as that shown in U.S. Pat. No. 9,310,000 B2 are known in the field of break-away assemblies. However, such pressure relief valves require additional bores in the body of the coupling which add to the complexity of the coupling, and may furthermore release fluid directly towards the radial outside of the coupling, that is, towards a user. 
     U.S. Pat. No. 3,818,939 discloses a self-sealing coupling comprising a two-part valve assembly where an additional and separate relief valve is provided for the release of fluid. 
     Improved and simpler systems are thus desirable. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention preferably seeks to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination and solves at least the above mentioned problems by providing a coupling for a break-away valve assembly comprising a coupling and an adapter, said coupling comprising: a valve arranged in an annular body, the annular body having a valve seat comprising a first portion and a second portion, adjacent to the first portion, of greater internal diameter relative to the first portion, the valve being biased in a first direction to seal against the valve seat on disconnection of the coupling from the adapter, characterised in that the valve is biased in a second direction, and in that valve is adapted to extend past the first portion into the second portion of the valve seat to release a volume of fluid if the pressure acting on the valve exceeds a predetermined surge pressure threshold. 
     A method for relieving surge pressure in a coupling is also provided. 
     Further advantageous embodiments are disclosed in the appended and dependent patent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects, features and advantages of which the invention is capable will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying drawings, in which 
         FIG. 1  is cross sectional perspective view of a valve assembly with a coupling according to an aspect. 
         FIG. 2  is a cross sectional perspective view of a coupling, having a closed valve, according to an aspect where the valve and valve seat are shown in detail. 
         FIG. 3  is a cross-sectional perspective view of a coupling, having a valve where a volume of fluid can pass the valve, where the valve and valve seat are shown in detail. 
         FIG. 4  illustrates a cross sectional perspective view of a coupling, having a closed valve according to an aspect. 
         FIG. 5  illustrates a cross sectional perspective having a valve wherein a volume of fluid can pass the valve. 
     
    
    
     DETAILED DESCRIPTION 
     The leakage of a small volume of fluid has traditionally been avoided in for example break-away and dry disconnect systems. Break-away couplings could as described herein could for example be so called breaking pin couplings, cable release couplings, or PERC (powered emergency release coupling). The present inventors have, however, identified that a small volume of controlled leakage is acceptable when it means that other elements of a fluid transfer system such as pumps and other valves are not damaged. At disconnection of for example a break-away coupling the coupling  2  is released from the adapter  3  closing the path for the liquid. This sudden restriction stopping the flow momentarily creates a rapidly increasing pressure at the valve in the coupling  2 . 
       FIG. 1  shows a valve assembly  1  comprising a coupling  2  and an adapter  3 . During operation, the valve assembly  1  forms a fluid conduit for the transfer of fluids. The valve assembly  1  may be a dry disconnect, or break-away, type assembly. On connection of the coupling  2  to the adapter  3  a fluid flow path is defined through the coupling  2  and the adapter  3 . Generally fluid flows from the coupling  2  to the adapter  3 , that is, the direction of fluid flow is generally left to right in  FIG. 1 . A pump (not shown) may be provided in fluidic connection with the coupling  2  and/or the adapter  3 . 
     As shown in  FIGS. 1 to 3 , the coupling  2  comprises a valve  100  arranged within a body  200 . The body  200  is generally cylindrical, having an internal bore or cavity within an annular wall  201  defining a fluid path. The longitudinal axis of the body is aligned with the direction of fluid flow through the body  200 . The coupling  2  has a tube end  202  and an adapter end  203 . The tube end  202  of the coupling  2  is generally provided in connection with a tube or other fluid conduit (not shown). The adapter end  203  is adapted to engage with the adapter  3  of the valve assembly  1 . 
     The body  200  is provided with a valve seat  204 . The valve seat  204  is provided on the annular wall  201  in the internal bore of the body. The valve seat  204  comprises a first portion  205  having a diameter adapted to seal against the perimeter of the valve  100 . The valve seat  204  comprises a second portion  206 , adjacent to the first portion  205 . The second portion  206  may have an internal diameter which is greater than the internal diameter of the first portion  205 . That is, the second portion  206  may have a slightly larger bore with respect to the first portion  205 . The second portion  206  may be proximal to the adapter end  203  of the coupling. The first portion  205  may be distal to the adapter end  203  of the coupling  2 . The valve seat  204  is fixed with respect to the body. 
     The valve  100  is a main flow valve, that is, it is a valve which controls the main flow of fluid through the coupling  2 . The coupling  2  does not comprise a separate relief valve. If the valve  100  is closed, no fluid may flow through the coupling  2 . The valve  100  may be a valve  100  comprising a valve stem  101  and a valve head  102 . The valve head  102  may be disc formed. The perimeter of the valve head  102  may seal against the valve seat  204 . The valve stem  101  may be aligned with the centre of the valve head  102 . The valve head  102  and the valve stem  101  may be integral, that is, they may be formed from a single piece of material. The form of the valve  100  may be considered a poppet valve. The valve  100  is biased in a first direction (to the right in  FIG. 1 ) such that the valve head  102  of the valve  100  seals against the first portion  205  of the valve seat  204 . The biasing may be achieved by a first biasing means  103  such as a spring. The first biasing means  103  may be a valve closing spring. The first biasing means  103  acts on the rear  104  of the head of the valve. The first biasing means  103  may act continuously on the valve  100 . The first biasing means  103  may be arranged around the stem  101  of the valve  100 . The first biasing means  103  may urge the valve  100  towards the adapter end  203  of the coupling  2 . 
     The sealing of the valve head  102  to the valve seat  204  may be improved by an annular gasket or O-ring  105  provided in the perimeter of the valve head  102  sealing against the first portion  205  of the valve seat  204 . The valve head  102  may comprise an annular groove  106  adapted to receive the annular gasket or O-ring  105 . 
     During fluid transfer operation, to enable continuous flow of a fluid through the coupling  2 , the valve  100  is unseated from the first portion  205  of the valve seat  204 . The valve  100  may be displaced longitudinally within the body  200 , against the biasing in the first direction, such that the valve  100  is displaced to a large-bore region  207  of the body  200  having an internal diameter substantially greater than the diameter than the diameter of the valve  100 . This opens the valve  100  such that fluid can flow past the valve  100  and through the coupling  2 . 
     As opposed to previous break-away valves, the valve  100  may be biased in a second direction. The biasing is achieved by a second biasing means  107 , such as a spring. The second biasing means  107  may be arranged around the stem  101  of the valve  100 . The second direction is generally opposite to the first direction (to the left in  FIG. 1 ). The second biasing means  107  may urge the valve  100  to the tube end of the coupling. During fluid transfer operation and continuous flow of fluid through the coupling, the biasing means does not necessarily act on the valve. The second biasing means  107 , does therefore not necessarily act continuously on the valve  100 . This can be seen in  FIG. 1  where the rear  108  of the valve stem  101  is not engaged with the second biasing means  107 . 
     On removing the adapter  3  from the coupling  2  the valve  100  is displaced towards the adapter end  203  of the coupling  2 . The displacement is actuated by the first biasing means  103 . The valve  100  engages with the valve seat  204  and seals the valve  100  such that fluid cannot flow from the coupling  2 . As described above, in some instances this sudden sealing of the valve  100  may create a high pressure, or surge pressure, which acts on the rear  104  of the valve  100 . 
     If the pressure acting on the valve  100  exceeds a predetermined surge pressure threshold the valve  100  is adapted to extend past the first portion  205  into the second portion  206  of the valve seat  204  to release a volume of fluid. During incidents of surge pressure acting on the valve  100  the valve  100  may extend longitudinally past the first portion of the valve seat  204  to the second portion  206 . The force of the surge pressure is opposed by the biasing in the second direction by the second biasing means  107 . As the second portion  206  has an internal diameter greater than the diameter of the valve  100  a volume of fluid will flow past the valve  100  out of the coupling  2 . The reduction in fluid volume in the coupling  2 , and optionally, the fluid conduits in connection with the coupling  2 , reduces the surge pressure in the coupling  2 . The biasing in the second direction subsequently reseats the valve  100  on the first portion  205  of the valve seat  204 . 
     The volume of fluid which may flow past the valve  100 , out of the coupling  2 , flows in to the region  208  of the coupling  2  where fluid normally passes and is normally in contact with during operation. Small residual volumes of fluid may be present on this region  208  of the coupling  2  after disconnection. As the leaked volume of fluid is present in this region  208  of the coupling  2  where fluid residues may be anyway after disconnection there is limited risk to a user. This is, in comparison to systems with separate pressure relief valves, where the fluid may exit the coupling from a bore provided in the body of the coupling, and thus potentially in to the path of a user. 
     As, during a surge pressure incident, fluid can pass between the valve  100  and the second portion  206  around the circumference of the valve  100  a pressure release can occur rapidly. Even a relatively large volume of fluid can pass the valve  100  in a very short time, rapidly decreasing pressure in the system. 
     The flow of fluid during normal operating conditions, that is when the coupling  2  is connected to an adapter  3 , and during a surge incident, occurs via the space between the internal wall of the body  200  and the valve  100 . 
     The second biasing means  107  is generally adapted to engage the valve  100  when the valve head  102  reaches the first portion  205  of the valve seat  204 . The rear portion  108  of the valve stem  101  may be provided with a flange  109  for engaging with the second biasing means  107 . The flange may be, as is shown in  FIGS. 1-3 , a bolt attached to the rear  108  of the stem. The spring constant of the second biasing means  107 , the force with which it opposes pressure on the rear  104  of the valve head  102 , is selected such that it corresponds to the force of any expected surge pressure in the system. The force of the fluid acting on the rear  104  of the valve head  102  is opposed by the second biasing means  107 . The spring constant is also selected such that at pressures lower than the working pressure the second biasing means  107  is not actuated. 
     The second biasing means  107  may be a spring such as a coiled wave spring having a plurality of turns. The second biasing means  107  may be referred to as a pressure relief valve spring. 
     The first  103  and second  107  biasing means are different biasing means. That is, they are not the same, for example, spring. This enables the valve  100  to be biased by two separate and predetermined spring constants. The spring constant of the second biasing means  107  is generally greater than the spring constant of the first biasing means  103 . This is as the first biasing means  103  needs generally only to urge the valve  100  closed in the direction of fluid flow and therefore is assisted in its closing by the pressure of the fluid flow. The second biasing means  107 , as it acts in the opposite direction, must resist the pressure of the fluid. 
     The first portion  205  of the valve seat  204  may have a cylindrical wall profile. It may be substantially flat, and have a substantially constant diameter. The second portion  206  of the valve seat  204  may comprise a tapered region  209 , proximal the first portion  205  of the valve seat, which has a tapered wall profile, increasing the internal diameter of the second portion  206  relative the first portion  205 . The profile of the tapered region  209  is thus a frustum having a circular base. The tapered region  209  may be considered a shoulder. The tapered region  209  allows better sealing of the valve  100  after the pressure in the coupling  2  has dropped below the surge pressure level. The second portion  206  may comprise a cylindrical region  210 , having a cylindrical wall profile. The cylindrical region  210  may not be tapered. The internal diameter of the cylindrical region  210  is dimensioned such that the valve head  102 , and/or any gasket or O-ring  105  provided at the valve head  102 , does not fluidically seal against the cylindrical region  210  of the second portion  206 . 
     The valve head  102  may comprise a projection  110  for engaging with a portion of the adapter  3 . The valve head  102  may be provided with a tapered portion connecting an outer radial portion of the valve head to the projection  110 . This tapered portion improves fluid flow properties. The projection  110  may extend from the centre of valve head  102  in the direction of the adapter end  203  of the coupling  2 . The projection  110  may engage with a similar projection provided on a valve in the adapter  3 . 
     The coupling  2  may comprise a support  211  extending from the body  200  to the internal bore of the coupling  2  provided with an aperture  214  for receiving the stem  101  of the valve  100 . The support  211  may be fixed rigidly and be not moveable during operation with respect to the body  200 . The first biasing means  103  may be provided on the adapter side of the support, that is, the side proximal to the adapter  3  during use. The support  211  may act as an abutment for the first biasing means  103 . The second biasing means  107  may be provided on the tube side of the support, that is, the side distal the adapter  3  during use. The support  211  may act as an abutment for the second biasing means  107 . A collar  212  provided with an annular slot  213  may be provided around the valve stem  201  and in connection to the support  211 . The first biasing means  103  may be received in the annular slot  213  in the collar  212 . 
     The coupling  2  may comprise a first portion  205  that has a length allowing the main flow valve  100  to be biased within the first portion  205  for a distance D before releasing a volume of fluid. This would be advantageous, as the distance D would allow the volume inside the coupling  2  to increase if the pressure increases, thereby relieving a small surge pressure without any leakage occurring and thereby absorbing pressure. If the pressure increases even more a small volume of fluid will be released but, in such embodiment, only until the pressure dropped under the point wherein the main flow valve is biased back into the first portion  205 . The perimeter of the head  102  of the valve  100  is in contact with the first portion  205  throughout the length of the distance D. The distance D may be several times as long as the length of the second portion  206 . The distance D can for example be between 2 cm and 8 cm. The volume created through moving the valve the distance D absorbs the pressure through increasing the volume inside the coupling  2 . 
     The surge pressure threshold is pre-determined by the second biasing means  107 . The surge pressure threshold may depend on the coupling  2  size, the expected working pressure of the assembly  1 , the pump specifications, the weight of the fluid that currently is in transfer in the fluid transfer system but has not yet passed the coupling  2 , the flow speed etc. A typical fluid transfer system as described herein could for example designed for a pressure class of 16, 25, or 40 bar. The burst pressure of such as system is at least five times the working pressure, i.e., for example at least 80, 125, or 200 bar. The surge pressure threshold may for example be between 16 to 200 bar, 40 to 200 bar, 25 to 125 bar, 16 to 80 bar, or any other suitable threshold. 
     A method for relieving surge pressure in a break-away valve assembly  1  will now be discussed. The assembly  1  comprises a coupling  2  as described herein. The method comprises braking-away or disconnecting the coupling  2  from the adapter  3 , the valve  100  subsequently seals on the valve seat  204  of the coupling  2 , therein, the flow of fluid is stopped. If the pressure acting on the valve  100  of the coupling  2  exceeds a predetermined limit the method further comprises allowing a small volume of fluid to flow past the valve  100 , therein re-closing the valve  100  against the valve seat  204 . The valve  100  may be re-closed by the second biasing means  107  described above. 
     The method for relieving surge pressure, wherein the predetermined limit comprises a predetermined sub limit, wherein if the pressure acting on the valve of the coupling  2  exceeds the predetermined sub limit, increasing the volume inside said coupling  2  through actuating said valve  100 , wherein the predetermined sub limit is a lower pressure limit than the predetermined limit. 
     The term coupling  2  as used herein refers to a valve assembly for controlling fluid flow which is generally connectable to a pump system. A coupling  2  may be used in a break-away coupling assembly in which two separate valve assemblies are disconnectable from each other and thereupon the flow of fluid through the two valve assemblies is restricted by internal valve closing systems. The pressure relief valve as described herein may be suitable for use in a non-pumping side valve assembly, such as an adapter. 
     Although, the present invention has been described above with reference to specific embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the invention is limited only by the accompanying claims. 
     In the claims, the term “comprises/comprising” does not exclude the presence of other elements or steps. Additionally, although individual features may be included in different claims, these may possibly advantageously be combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. In addition, singular references do not exclude a plurality. The terms “a”, “an”, “first”, “second” etc do not preclude a plurality. Reference signs in the claims are provided merely as a clarifying example and shall not be construed as limiting the scope of the claims in any way.