A shut-off valve cassette

Abstract

There is provided a shut-off valve cassette 1 for a fluid flow system (2, figure 5). The shut-off valve cassette comprising a valve 3 located in a flow path through the shut off valve cassette. The va

Description

Technical Field of the Invention The present invention relates to a shut-off valve cassette, and in particular a shut-off valve cassette for a heat exchange system such as, but not limited to, a heat pump system. Background to the Invention In the UK traditional domestic heating solutions have included combustion of fuels such as oil, liquified petroleum gas (LPG), and natural gas. Such solutions have a maximum efficiency of around 95%. In recent years, there has been a global demand for implementing greener energy solutions. In a bid to meet this demand, the UK heat pump market has become a growing sector for providing greener domestic heating solutions. Heat pumps offer an alternative heating solution to traditional domestic heating solutions. Heat pumps work by extracting energy from the surroundings using a medium known as a refrigerant. Heat pumps offer a more efficient heating solution compared to traditional heating solutions and can reach efficiencies of up to 300% to 400%. One refrigerant commonly used in domestic heat pumps is Propane, also known as R290. R290 is a natural refrigerant with good thermal transfer efficiency, making it suitable for use in domestic heat pumps. However, R290 is flammable and under certain conditions can be volatile. As such, there are strict standards in the UK, namely EN60335-2-40, which states that the maximum amount of R290 which may leak into a dwelling is 151g. It is known to provide heat pumps with an automatic air vent to allow any leaked R290 to vent to the atmosphere as opposed to into the dwelling’s heating system. One issue with the use of automatic air vents for this purpose is the automatic air venting system has limitations due to Propane / water separation, and the release rate of vented fluid may be unpredictable in the first pass through of Propane / water. The present invention seeks to overcome or ameliorate some of the issues outlined above. Summary of the Invention According to a first aspect of the present invention there is provided a shut-off valve cassette for a fluid flow system, the shut-off valve cassette comprising: 1. a valve located in a flow path through the shut off valve cassette and comprising: a. a valve seat b. a valve member, wherein when the valve member is seated in the valve seat, the valve is closed, and fluid cannot flow therethrough; and 2. a valve locking mechanism comprising a first locking structure and a second locking structure configured to lock the valve member in the closed position preventing the valve member from returning to an open position. According to a second aspect of the present invention there is provided a housing configured to receive a shut-off valve cassette, wherein the shut-off valve cassette comprises: 1. a valve located in a flow path through the shut off valve cassette and comprising: a. a valve seat b. a valve member, wherein when the valve member is seated in the valve seat, the valve is closed, and fluid cannot flow therethrough; and 2. a valve locking mechanism comprising a first locking structure and a second locking structure configured to lock the valve member in the closed position preventing the valve member from returning to an open position. According to a third aspect of the present invention there is provided a fluid flow system comprising: a heat exchanger, a pre-heat exchanger manifold, and a postheat exchanger manifold, wherein the post-heat exchanger manifold comprises a housing configured to receive a shut-off valve cassette, the shut-off valve cassette comprising: 1. a valve located in a flow path through the shut off valve cassette and comprising: a. a valve seat b. a valve member, wherein when the valve member is seated in the valve seat, the valve is closed, and fluid cannot flow therethrough; and 2. a valve locking mechanism comprising a first locking structure and a second locking structure configured to lock the valve member in the closed position preventing the valve member from returning to an open position. Provision of an invention according to any of the first to third aspects is particularly advantageous as it provides a single use shut-off valve cassette having a shut-off valve mechanism which once triggered, cannot be reset, released or re-used. As the shut-off valve cassette is a safety-critical component, this is particularly advantageous as it means that once the locking mechanism is triggered, the entire system must be checked to ensure that the system has returned to a safe operating level, and the shut-off valve cassette must be replaced by a trained operator. This minimises the risk of an untrained user re-starting the system in unsafe operating conditions. The shut-off valve cassette may comprise a first end and a second end. The first end may comprise a flow opening. The second end may be at least partially blocked. Preferably, the second end may be completely blocked. The shut-off valve cassette may be elongate. The shut-off valve cassette may be substantially cylindrical. The shut-off valve cassette may comprise one or more side walls. The shut-off valve cassette may comprise a plurality of side walls. One or more of the plurality of side walls may extend from the first end to the second end of the shut-off valve cassette. One or more of the plurality of side walls may define a bore therethrough. The bore may extend longitudinally from the first end to the second end of the shut-off valve cassette. The bore may comprise a substantially constant width along its length. In one form, the shut-off valve cassette may be generally cylindrical in external shape. As such, in this embodiment, the shut-off valve cassette may only comprise a single side wall. The provision of a bore through the shut-off valve cassette may give a hollow configuration, albeit one or more transverse walls may be provided within the hollow shut-off valve cassette. One or more of the plurality of side walls may comprise at least one outlet aperture. One or more of the plurality of outlet apertures may extend longitudinally over a length of the shut-off valve cassette. One or more of the plurality of outlet apertures may be elongate. More than one outlet aperture may be equally spaced about the circumference of one or more or each side wall. One or more of the plurality of side walls may have a shape selected from the group comprising: circular, ovular, rectangular, allantoid (i.e., pill shaped, or sausage shaped), or the like. One or more of the plurality of side walls may comprise at least one annular groove configured to receive a sealing ring. One or more of the plurality of side walls may comprise a plurality of annular grooves configured to receive a sealing ring. Each annular groove may be provided on an outer surface of one or more or each side wall. One or more of the plurality of annular grooves may extend about at least a portion of the circumference of one or more of the plurality of side walls. Preferably, one or more of the plurality of annular grooves may extend about the entire circumference of one or more of the plurality of side walls. Additionally or alternatively, one or more of the plurality of side walls may comprise at least one sealing ring. Each sealing ring may be provided on the outer surface of the one or more of the plurality of side walls. One or more of the plurality of sealing rings may extend about at least a portion of the circumference of one or more of the plurality of side walls. Preferably, one or more of the plurality of sealing rings may extend about the entire circumference of one or more of the plurality of side walls. The valve seat may be provided at or towards the first end of the shut-off valve cassette. The valve seat may project from one or more of the plurality of side walls. The valve seat may be a shaped depression to correspond to the shape of a valve head or member. The valve seat may be integrally formed with, or mounted to, one or more of the plurality of side walls. The valve seat may be an annular seat defining an aperture therethrough. The valve seat may comprise at least one seal. The valve seat may comprise a plurality of seals. One or more of the plurality of seals may be configured to seal the valve member against the valve seat. This may minimise the volume of fluid leaking through the valve when the valve member is in the closed position and may ‘shut-off’ the flow of fluid through the shut-off valve cassette. The valve seat may be formed from a material selected from the group comprising: brass, stainless steel, carbon steel, cast iron, PVC, or similar. The shut-off valve cassette may comprise a transverse end wall. The end wall may be provided at or towards the second end of the shut-off valve cassette. The end wall may comprise an opening through which at least a portion of the valve member may project. The end wall may be provided with a spacing lip or wall or flange or similar. The spacing lip or wall or flange or similar may extend from one or more or each side wall, past the end wall. A free end of the spacing lip or wall or flange or similar may abut a retaining cap. The retaining cap may be removable. The retaining cap may be a push fit or a screw fit. The retaining cap may be configured to hold the shut-off valve cassette in place within the housing. The shut-off valve cassette may function as a valve body against which a valve head or member may seal when in the closed position. That is to say the shut-off valve cassette may comprise a valve seat adjacent to a flow opening, and a valve member provided therethrough with the valve member mounted to or relative to the shut-off valve cassette. The valve member may be elongate, comprising a first end and a second end. The valve member may comprise an enlarged head or plug and an elongate stem with a tip. The enlarged head or plug may be provided at or towards the first end of the valve member. The tip may be provided at or towards the second end of the stem of the valve member. The valve member may be formed from a material selected from the group comprising: brass, stainless steel, carbon steel, cast iron, PVC, or similar. The stem may be elongate. The stem may comprise substantially the same width along its length. Alternatively, the stem may comprise a changeable width along its length. For example, the stem may comprise a bulbous portion at or toward the second end of the valve member, and / or one or more radially extending portions, and / or one or more depressions or notches. The stem may extend through the aperture in the valve seat. The stem may at least partially extend through the opening in the end wall. In the open position, the stem may be oriented in the longitudinal direction of the bore. At least a portion of the stem may comprise a cross-sectional shape selected from the group comprising: circular, ovular, triangular, square, pentagonal, hexagonal, heptagonal, or octagonal. At least a portion of the stem may comprise a regular cross-sectional shape. The valve member, or more specifically, the stem of the valve member may be received through a guide portion within the shut-off valve cassette. The guide portion may comprise a tubular portion mounted concentrically within the shut-off valve cassette. The tubular portion may extend from an inner side of the end wall at the second end of the shut-off valve cassette, towards the first end of the shut-off valve cassette. The enlarged head or plug may be shaped and sized to be seated on the valve seat in the closed position to seal the valve. The enlarged head or plug may comprise at least one seal and / or sealing ring configured to seal the valve member against the valve seat. The enlarged head or plug may comprise a plurality of seals and / or sealing rings configured to seal the valve member against the valve seat. This may minimise the volume of fluid leaking through the valve when the valve member is in the closed position and may ‘shut-off’ the flow of fluid through the shut-off valve cassette. The valve may be a uni-flow valve mechanism. The valve may be a one-way valve mechanism. The locking mechanism may be provided at any position along the length of the shut-off valve cassette. The locking mechanism may be provided at or toward the first end of the shut off valve cassette. The locking mechanism may be provided at or toward the second end of the shut off valve cassette. The first locking structure and the second locking structure may be configured to lockingly engage when the valve member is in the closed position. The first locking structure and the second locking structure may be configured to irreversibly engage or lock together when the valve member is in the closed position. The valve member may be configured to move from the open position to the closed position in response to the locking mechanism being triggered. The locking mechanism may be triggered in response to experiencing a pressure exceeding a threshold value. The threshold value may be at least 500 kPa, at least 1000 kPa, at least 1500 kPa, or at least 2000 kPa. The threshold value may be no more than 2500 kPa, no more than 2000 kPa, no more than 1500 kPa, or no more than 1000 kPa. The threshold value may be in the range of 500 kPa to 2500 kPa, or in the range of 1000 kPa to 2000 kPa. Preferably, the threshold value may be approximately 500 kPa. The first locking structure may be provided on the shut-off valve cassette. The first locking structure may be integrally formed with, or mounted to, the shut-off valve cassette. The first locking structure may be provided on at least one of: one or more or each side wall, the end wall, and the valve seat. The second locking structure may be provided on the valve member. The second locking structure may be integrally formed with, or mounted to, the valve member. The second locking structure may be provided on at least one of: the enlarged head or plug, the stem, and the tip. At least one of the first locking structure and / or the second locking structure may be deformable. This may allow the valve stem to pass through the opening in a first direction but to prevent movement in the opposite direction when the first locking structure is locked to the second locking structure. The first locking structure may comprise at least one flange. The first locking structure may comprise a plurality of flanges. One or more of the plurality of flanges may be formed by the end wall. One or more of the plurality of flanges may extend about at least a portion of the one or more of the plurality of side walls. Preferably, one or more of the plurality of flanges may extend about the entire circumference of the one or more of the plurality of each side walls. One or more of the plurality of flanges may be annular and define a hole therethrough. The hole may conform in shape to the shape of the stem. The stem of the valve member may at least partially extend through the hole(s). At least a portion of the at least one flange may be deformable. This may allow the valve stem to pass through the opening in a first direction but to prevent movement in the opposite direction when the first locking structure is locked to the second locking structure. The second locking structure may comprise at least one deformable arm or chevron or similar. The second locking structure may comprise a plurality of deformable arms or chevrons or similar. One or more of the plurality of deformable arms or chevrons or similar may be configured to deform upon contact with the at least one flange and biased into an extended locking condition to abut the at least one flange and lock the valve member in the closed position. The second locking structure may comprise at least one corresponding slot. The second locking structure may comprise a plurality of corresponding slots. One or more of the plurality of slots may be configured to receive one or more of the plurality of flanges. The second locking structure may comprise at least one circumferential slot or grove about a portion of the valve stem. Where two or more flanges and corresponding slots are provided, this may provide a rachet mechanism whereby as the pressure on the valve member increases, the flanges may lockingly engage with slots provided closer to the first end of the shut-off valve cassette. The second locking structure may comprise at least one retaining clip. The second locking structure may comprise a plurality of retaining clips. One or more of the plurality of retaining clips may be configured to receive one or more of the plurality of flanges. Alternatively, the second locking structure may comprise at least one flange. The second locking structure may comprise a plurality of flanges. One or more of the plurality of flanges may extend about at least a portion of the valve member. Preferably, one or more of the plurality of flanges may extend about the entire circumference of the valve member. One or more of the plurality of flanges may be radial. The first locking structure may comprise at least one corresponding slot. The first locking structure may comprise a plurality of corresponding slots. One or more of the plurality of slots may be configured to receive one or more of the plurality of flanges. Where two or more flanges and corresponding slots are provided, this may provide a rachet mechanism whereby as the pressure on the valve member increases, the flange may lockingly engage with slots provided closer to the first end of the shut-off valve cassette. The first locking structure may comprise at least one retaining clip. The first locking structure may comprise a plurality of retaining clips. One or more of the plurality of retaining clips may be configured to receive one or more of the plurality of flanges. Additionally or alternatively, the first locking structure may comprise one or more teeth, barbs, or the like. The first locking structure may comprise a plurality of teeth, barbs, or the like. The second locking structure may comprise one or more corresponding receiving portions. The second locking structure may comprise a plurality of corresponding receiving portions. One or more of the plurality of corresponding receiving portions may be sized and positioned to receive one or more of the plurality of teeth, barbs, or the like. One or more of the plurality of receiving portions may comprise a plurality of ridges and / or grooves and / or openings. The plurality of ridges and / or grooves and / or openings may be configured to engage one or more or each teeth, barbs, or the like. Alternatively, the second locking structure may comprise one or more teeth, barbs, or the like. The second locking structure may comprise a plurality of teeth, barbs, or the like. The first locking structure may comprise one or more corresponding receiving portions. The first locking structure may comprise a plurality of corresponding receiving portions. One or more of the plurality of corresponding receiving portions may be sized and positioned to receive one or more of the plurality of teeth, barbs, or the like. One or more of the plurality of receiving portions may comprise a plurality of ridges and / or grooves and / or openings. The plurality of ridges and / or grooves and / or openings may be configured to engage one or more of the plurality of teeth, barbs, or the like. Additionally or alternatively, the first locking structure may comprise one or more clips or the like. The first locking structure may comprise a plurality of clips or the like. The second locking structure may comprise one or more corresponding receiving sockets. The second locking structure may comprise a plurality of corresponding receiving sockets. One or more of the plurality of receiving sockets may be sized and positioned to receive one or more of the plurality of clips or the like. Alternatively, the second locking structure may comprise one or more clips or the like. The second locking mechanism may comprise a plurality of clips or the like. The first locking structure may comprise one or more corresponding receiving sockets. The first locking structure may comprise a plurality of corresponding receiving sockets. One or more of the plurality of receiving sockets may be sized and positioned to receive one or more of the plurality of clips or the like. Additionally or alternatively, the first locking structure may comprise a socket. The socket may be configured to receive at least a portion of the valve member. The socket may be configured to receive the tip of the valve member. The socket may be provided on the end wall. The second locking structure may comprise the tip of the valve member. The tip of the valve member may comprise at least one of a surface texture or shape configured to engage with the socket. The housing may be configured to releasably house the shut-off valve cassette. The housing may be shaped and / or sized to closely conform to the shape and / or size of the shut-off valve cassette. This may allow the housing to securely house the shut-off valve cassette. The housing may be configured to house the shut-off valve cassette using at least one of: a friction fit, a push fit, corresponding threads, an O-ring and corresponding retaining clip, or the like. The housing may comprise at least one aperture. The housing may comprise a plurality of apertures. One or more of the plurality of apertures may be configured to allow fluid flow flowing through one or more of the plurality of outlet apertures provided in the shut-off valve cassette to flow therethrough. One or more of the plurality of apertures may be shaped and / or sized to conform to one or more of the plurality of outlet aperture provided in one or more of the plurality of side walls of the shut-off valve cassette. The housing may comprise at least one sealing ring. The housing may comprise a plurality of sealing rings. One or more of the plurality of sealing rings may be housed by one or more of the plurality of annular grooves provided on the outer surface of one or more of the plurality of side walls of the shut-off valve cassette. One or more of the plurality of sealing rings may be provided on an inner surface of the housing. One or more of the plurality of sealing rings may extend about at least a portion of the circumference of the inner surface of the housing. Preferably, one or more of the plurality of sealing rings may extend about the entire circumference of the inner surface of the housing. The number and / or position of one or more of the plurality of sealing rings provided on the housing may conform to the number and / or position of annular groove(s) provided on one or more of the plurality of side walls of the shut-off valve cassette. Additionally or alternatively, the housing may comprise at least one annular groove. The housing may comprise a plurality of annular grooves. One or more of the plurality of annular grooves may be configured to house one or more of the plurality of sealing rings provided on one or more of the plurality of side walls of the shut-off valve cassette. One or more of the plurality of annular grooves may be configured to house one or more of the plurality of sealing rings provided on the outer surface of one or more of the plurality of side walls of the shut-off valve cassette. One or more of the plurality of annular grooves may extend about at least a portion of the circumference of the inner surface of the housing. Preferably, one or more of the plurality of annular grooves may extend about the entire circumference of the inner surface of the housing. The number and / or position of one or more of the plurality of annular groove(s) provided on the housing may conform to the number and / or position of sealing ring(s) provided on one or more of the plurality of side walls of the shut-off valve cassette. The housing may comprise a release mechanism. The release mechanism may comprise the retaining cap. The release mechanism may be selected from the list comprising: a release code, a lock and key mechanism, or the like. The release code and / or key may only be available to trained operators. As such, when the locking mechanism is triggered and the valve is provided in the closed position, this may minimise the risk of an untrained user replacing the shut-off valve cassette without conducting the necessary safety checks and allowing the fluid flow system to function in unsafe operating conditions. The housing may be formed from any durable material. The housing may be formed from a material selected from the group comprising: brass, stainless steel, carbon steel, cast iron, PVC, or similar. The fluid flow system may be a heat exchange system. The fluid flow system may be a boiler system. The fluid flow system may be a heat pump system. The fluid flow system may be a domestic fluid flow system. Alternatively, the fluid flow system may be a commercial fluid flow system. The fluid flow system may comprise an internal portion and an external portion. The internal portion may be provided within a dwelling and / or built structure. The external portion may be provided external to the dwelling and / or built structure. The fluid flow system may be configured to fluidly connect the heat exchanger, the pre-heat exchanger manifold, and the post-heat exchanger manifold. The fluid flow system may be configured to fluidly connect the heat exchanger, the pre-heat exchanger manifold, and the post-heat exchanger manifold via at least one of a conduit, pipe, or hose. The fluid flow system may be configured to transport fluid therethrough. The fluid flow system may be configured to transport water therethrough. The heat exchanger may be a plate heat exchanger. Alternatively, the heat exchanger may be selected from the group comprising: a coil heat exchanger, a co-axial heat exchanger, or the like. The heat exchanger may comprise a refrigerant. The refrigerant may be Propane (R290). The heat exchanger may comprise a heating medium. The pre-heat exchanger manifold may be configured to fluidly connect to the heat exchanger. The pre-heat exchanger manifold may be configured to fluidly connect a return pathway of the fluid flow system to the heat exchanger. The pre-heat exchanger manifold may be configured to return cooled fluid to the heat exchanger. The pre-heat exchanger manifold may comprise a non-return valve and / or a check valve. The non-return valve and / or check valve may be configured to prevent backflow of pressure within the system. The pre-heat exchanger manifold may comprise a pressure sensor. The pre-heat exchanger manifold may comprise a flow sensor. The post-heat exchanger manifold may be configured to fluidly connect to the heat exchanger. The post-heat exchanger manifold may be configured to transport heated fluid away from the heat exchanger. The post-heat exchanger manifold may be configured to transport heated fluid away from the heat exchanger towards the dwelling and / or built structure. The post heat exchanger manifold may be provided in the external portion of the fluid flow system. The post-heat exchanger manifold may comprise a refrigerant separation vessel configured to separate refrigerant from the fluid in the fluid flow system. For example, the refrigerant separation vessel may be configured to separate refrigerant which may leak from the heat exchanger into the fluid flow system. The refrigerant separation vessel may comprise a cyclone and / or vortex separator. The cyclone and / or vortex separator may be configured to generate a cyclone and / or vortex within the refrigerant separation vessel. The cyclone and / or vortex may cause the refrigerant and fluid to be separated based on their respective densities. The refrigerant separation vessel may comprise an air vent configured to vent refrigerant from the refrigerant separation vessel to the atmosphere. The air vent may be an automatic air vent. Provision of such an air vent may allow low-pressure refrigerant leaks such as those which do not trigger the locking mechanism to be dealt with automatically. The refrigerant separation vessel may be provided in the external portion of the fluid flow system. As such, any vented refrigerant may be released into the outdoor atmosphere and may not be contained within the dwelling and / or built structure where it may pose a flammability risk. The post-heat exchanger manifold may comprise a pressure relief valve. The pressure relief valve may be provided on the refrigerant separation vessel. The pressure relief valve may be configured to open to relieve excess pressure within the post heat exchanger manifold in response to the pressure exceeding an operating threshold. The operating threshold may be at least 150 kPa, at least 200 kPa, at least 250 kPa, or at least 300 kPa. The operating threshold may be no more than 350 kPa, no more than 300 kPa, no more than 250 kPa, or no more than 200 kPa. The operating threshold may be in the range of 150 kPa to 350 kPa, or in the range of 200 kPa to 300 kPa. The refrigerant separation vessel may comprise the housing and the shut-off valve cassette. As such, if the pressure in the refrigerant separation vessel exceeds the operating threshold, any leaks may be prevented from contaminating the fluid entering the fluid flow system, as these may be stopped by the shut-off valve cassette. In particular, the shut off valve cassette may work in conjunction with the non-return valve and / or check valve provided in the pre-heat exchanger manifold to retain the pressure within the heat exchanger and the refrigerant separation vessel until a trained operator can ensure that safe de-pressurisation of the fluid flow system has occurred and replace the shut-off valve cassette. The post-heat exchanger manifold may comprise at least one pump. The at least one pump may be configured to pump fluid through the fluid flow system. Detailed Description of the Invention In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 shows a cross-sectional view of a shut-off valve cassette according to the present invention; Figure 2 shows a cross-sectional view of the shut-off valve cassette of figure 1 provided in a housing wherein the valve is in an open position; Figure 3 shows a cross-sectional view of the shut-off valve cassette of figures 1 and 2 provided in a housing wherein the valve is in a closed position; Figure 4 shows an enlarged view of the shut-off mechanism of the shut-off valve cassette of figures 1 to 3; and Figure 5 shows a schematic view of the fluid flow system according to the present invention. With reference initially to figure 1, there is provided a shut-off valve cassette 1 for a fluid flow system 2 (seen in figure5). The shut-off valve cassette 1 comprises a valve 3 located in a flow path through the shut-off valve cassette 1. The valve 3 comprises a valve seat 4 and a valve member 5. The valve 3 is shown in an open position in figure 1 however, when the valve member 5 is seated in the valve seat 4, the valve 3 is closed and fluid cannot flow therethrough (seen best in figure 3). The shut-off valve cassette 1 also comprises a valve locking mechanism 6 comprising a first locking structure 6a and a second locking structure configured to lock the valve 3 in the closed position and prevent the valve 3 from returning to the open position. Provision of such a shut-off valve cassette 1 is particularly advantageous as it provides a single use shut-off valve cassette 1 having a shut-off valve locking mechanism 6 which once triggered, cannot be reset, released or re-used. As the shutoff valve cassette 1 is a safety-critical component, this is particularly advantageous as it means that once the shut-off valve locking mechanism 6 is triggered, the entire system 2 must be checked to ensure that the system 2 has returned to a safe operating level, and the shut-off valve cassette 1 must be replaced by a trained operator. This minimises the risk of an untrained user re-starting the system 2 in unsafe operating conditions. The shut off valve cassette 1 comprises a first end la comprising a flow opening, and a second end lb which is at least partially blocked. In this embodiment, the shutoff valve cassette 1 comprises a single side wall 7 which extends from the first end la to the second end lb and defines a bore 8 therethrough which provides a substantially hollow configuration. The bore 8 extends longitudinally from the first end la to the second end lb of the shut-off valve cassette 1 and comprises a substantially constant width along its length. The single side wall 7 forms a generally cylindrical shape. Nevertheless, it will be appreciated by the skilled person that in alternative embodiments, the shut-off valve cassette 1 may comprise a plurality of side walls, for example four side walls which may form a cubic or cuboidal shape. The side wall 7 comprises a plurality of outlet apertures 9 which are elongate and extend longitudinally over a length of the shut-off valve cassette 1. In this embodiment, the outlet apertures 9 are equally spaced about the circumference of the side wall 7 and comprise an allantoid (i.e., pill shaped, or sausage shaped) shape. An outer surface of the side wall 7 comprises at least one, and in this particular embodiment three, annular grooves 10 configured to receive a sealing ring 11 (shown in figure 2). The annular grooves 10 extend about the entire circumference of the side wall 7. Although in this embodiment, the side wall 7 comprises an annular groove 10 configured to receive a sealing ring 11, it will be understood that in alternative embodiments, the side wall 7 may comprise at least one sealing ring 11, or a plurality of sealing rings 11 configured to be housed by corresponding annular grooves on a different body, for example on a housing 12 such as that shown in figure 2. The valve seat 4 is provided at the first end la of the shut-off valve cassette 1, and is integrally formed with, and projects from the side wall 7. The valve seat 4 is a shaped depression which is annular and has an aperture therethrough. Although not shown, the valve seat 4 may comprise at least one seal configured to seal the valve seat 4 against the valve member 5. This may minimise the volume of fluid leaking through the valve 3 when the valve member 5 is in the closed position and may ‘shut-off’ the flow of fluid through the shut-off valve cassette 1. The shut off valve cassette 1 also comprises a transverse end wall 13 provided towards the second end lb of the shut-off valve cassette 1. The end wall 13 comprises an opening through which at least a portion of the valve member 5 projects. The end wall 13 comprises a spacing lip or wall or flange or similar 14 which extends from the side wall 7, past the end wall 13 and abuts a removable retaining cap 15 (shown in figure 2). The retaining cap 15 is a release mechanism configured to hold the shut-off valve cassette 1 in place within the housing 12 (shown in figure 2). The shut-off valve cassette 1 functions as a valve body against which a valve head or member may seal when in the closed position. That is to say the shut-off valve cassette 1 comprises a valve seat 4 adjacent to a flow opening, and a valve member 5 provided therethrough with the valve member 5 mounted to or relative to the shut-off valve cassette 1. The valve member 5 is elongate, comprising a first end and a second end. The valve member 5 comprises an enlarged head or plug 16 at the first end, a tip 17 at the second end, and an elongate stem 18. The stem 18 is substantially the same width along its length and extends through the aperture in the valve seat 4 and extends at least partially through the opening in the end wall 13 in the open position. In the open position, the stem 18 is oriented in the longitudinal direction of the bore 8. The stem 18 of the valve member 5 is received through a guide portion 19 within the shut-off valve cassette 1. The guide portion 19 comprises a tubular portion mounted concentrically within the shut-off valve cassette 1. The tubular portion extends from an inner side of the end wall 13 at the second end lb of the shut-off valve cassette 1 and projects towards the first end la of the shut-off valve cassette 1. The enlarged head or plug 16 is shaped and sized to be seated on the valve seat 4 in the closed position to seal the valve. Although not shown, the enlarged head or plug 16 may comprise at least one seal and / or sealing ring configured to seal the valve member 5 against the valve seat 4. This may minimise the volume of fluid leaking through the valve 3 when the valve member 5 is in the closed position and may ‘shutoff’ the flow of fluid through the shut-off valve cassette 1. It will be appreciated that the valve seat 4 and valve member 5 may be formed from any suitable material such as a material selected from the group comprising: brass, stainless steel, carbon steel, cast iron, PVC, or similar. The valve 3 is a one-way valve mechanism. With additional reference now to figures 2 to 4, the locking mechanism 6 may be provided at any position along the length of the shut-off valve cassette 1. However, in this embodiment, the locking mechanism 6 is provided toward the second end lb of the shut-off valve cassette 1. The first locking structure 6a and the second locking structure 6b are configured to lockingly engage when the valve member 5 is in the closed position. The valve member 5 is configured to move from the open position to the closed position in response to the locking mechanism 6 being triggered. The locking mechanism 6 is triggered in response to experiencing a pressure exceeding a threshold value of around 500 kPa. This value corresponds to a high-pressure refrigerant leak in a fluid flow system such as that seen in figures 3 to 5 however, the skilled person will appreciate that alternative fluid flow systems may have different pressure requirements and as such, the threshold value may be adjusted accordingly. The first locking structure 6a is provided on the shut-off valve cassette 1 and the second locking structure 6b is provided on the valve member 5. In this embodiment, the first locking structure 6a is integrally formed with the side wall 7 of the shut-off valve cassette 1. The first locking structure 6a comprises a flange which in this embodiment is formed by the end wall 13 comprising one or more teeth, barbs, or the like projecting therefrom. The flange extends about the entire circumference of the side wall 7 and is annular in shape, defining a hole therethrough into which the teeth, barbs or the like project. The second locking structure 6b comprises a corresponding receiving portion configured to receive and lockingly engage with the flange and one or more teeth, barbs or the like when the valve member 5 moves from the open position to the closed position. The skilled person will appreciate that a variety of suitable locking mechanisms may additionally or alternatively be provided in other embodiments, and that these locking mechanisms may be provided at any position along the length of the shut-off valve cassette 1. There is provided a housing 12 configured to releasably house the shut-off valve cassette 1. The housing 12 is shaped and sized to closely conform to the shape and size of the shut-off valve cassette 1, allowing the housing 12 to securely house the shut-off valve cassette 1 via a friction fit. The housing 12 comprises at least one, or a plurality of apertures (not shown) which are configured to allow fluid flow flowing through the outlet apertures 9 in the side wall 7 of the shut-off valve cassette to flow therethrough. One or more of the plurality of apertures may be shaped and sized to conform to one or more of the plurality of outlet apertures 9. The housing also comprises three sealing rings 11 which are configured to be housed by the annular grooves 10 provided on the outer surface of the side wall 7. The sealing rings 11 are provided about the circumference of an inner surface of the housing 12 and the number and position of the sealing rings 11 conforms to the number and position of the corresponding grooves provided on the side wall 7 of the shut-off valve cassette 1. It will be appreciated that the housing 12 may be formed from any suitable material such as a material selected from the group comprising: brass, stainless steel, carbon steel, cast iron, PVC, or similar. With reference now to figure 5, the fluid flow system 2 is provided. The fluid flow system comprises a heat exchanger 20, a pre-heat exchanger manifold 21, and a post-heat exchanger manifold 22. The post-heat exchanger manifold 22 comprises the housing 12 shown in figure 2. The fluid flow system 2 is a heat exchange system, and in this particular embodiment, the fluid flow system is a domestic heat pump system. However, the skilled person will appreciate that in other embodiments, the heat exchange system may alternatively be a commercial fluid flow system. The fluid flow system 2 comprises an internal portion which is provided within a dwelling (but may equally be provided within a built structure in alternative embodiments) and an external portion which is provided external to the dwelling (or built structure). The fluid flow system 2 is configured to fluidly connect the heat exchanger 20, the pre-heat exchanger manifold 21, and the post-heat exchanger manifold 22 via a plurality of conduits, pipes and / or hoses 23. The fluid flow system 2 is configured to transport fluid such as water therethrough. The heat exchanger 20 in this particular embodiment id a plate heat exchanger 20 which comprises a refrigerant and operates according to known thermodynamic principles. The refrigerant in this embodiment is Propane (R290) although the skilled person will appreciate that the other suitable refrigerants may also be provided. The pre-heat exchanger manifold 21 is configured to fluidly connect a return pathway of the fluid flow system to the heat exchanger 20 such that cooled fluid may be returned thereto. The pre-heat exchanger manifold 21 also comprises a non-return valve and / or a check valve 24 configured to prevent backflow of pressure within the system 2. The pre-heat exchanger manifold 21 also comprises a pressure sensor 25 and a flow sensor 26. The post-heat exchanger manifold 22 is configured to fluidly connect to the heat exchanger 20. The post-heat exchanger manifold 22 is configured to transport heated fluid away from the heat exchanger 20 towards the dwelling. The post-heat exchanger manifold 22 comprises a refrigerant separation vessel 27 configured to separate refrigerant from the fluid in the fluid flow system 2. In this embodiment, the refrigerant separation vessel 27 is configured to separate refrigerant which may leak from the heat exchanger 20 into the fluid flow system 2. The refrigerant separation vessel 27 comprises a cyclone or vortex separator (not shown) configured to generate a cyclone and / or vortex within the refrigerant separation vessel 27 which causes the refrigerant and fluid to be separated based upon their respective densities. The refrigerant separation vessel 27 comprises an automatic air vent 28 configured to vent gaseous refrigerant from the refrigerant separation vessel 20 to the atmosphere. Provision of such an air vent 28 may allow low-pressure refrigerant leaks, such as those which do not trigger the locking mechanism 6, to be dealt with automatically. The refrigerant separation vessel 20 is provided in the external portion of the fluid flow system 2 and as such, any vented refrigerant may be released into the outdoor atmosphere and may not be contained within the dwelling where it may pose a flammability risk. The refrigerant separation vessel 20 also comprises a pressure relief valve 29 configured to open to relieve excess pressure within the post heat exchanger manifold 22 in response to the pressure exceeding an operating threshold. In this embodiment, the operating threshold is around 150 kPa. It will be understood that alternative fluid flow systems may have different pressure requirements and as such, the operating threshold value may be adjusted accordingly. The refrigerant separation vessel 27 also comprises the housing 12 and shut-off valve cassette 1 provided in a lower portion. As such, if the pressure in the refrigerant separation vessel 27 exceeds the operating threshold, any leaks may be prevented from contaminating the fluid entering the fluid flow system 2, as these may be stopped by the shut-off valve cassette 1. In particular, the shut off valve cassette 1 may work in conjunction with the non-return valve and / or check valve 24 provided in the pre-heat exchanger manifold 21 to retain the pressure within the heat exchanger 20 and the refrigerant separation vessel 27 until a trained operator can ensure that safe depressurisation of the fluid flow system 2 has occurred and replace the shut-off valve cassette 1. The post-heat exchanger manifold 22 also comprises a pump 30 configured to pump fluid through the fluid flow system 2. The one or more embodiments are described above by way of example only. Many variations are possible without departing from the scope of protection afforded by the appended claims.

Claims

1. A shut-off valve cassette for a fluid flow system, the shut-off valve cassette comprising:

1. a valve located in a flow path through the shut off valve cassette and comprising:a. a valve seatb. a valve member, wherein when the valve member is seated in the valve seat, the valve is closed, and fluid cannot flow therethrough; and2. a valve locking mechanism comprising a first locking structure and a second locking structure configured to lock the valve member in the closed position preventing the valve member from returning to an open position.

2. A shut-off valve cassette according to claim 1 further comprising one or more side walls defining a cylindrical shape and a hollow interior in which the valve member is at least partially mounted.

3. A shut-off valve cassette according to claim 2 wherein the valve seat is provided at or towards a first end of the shut-off valve cassette and is shaped to correspond to a portion of the valve member.

4. A shut-off valve cassette according to any preceding claim wherein the valve seat is an annular seat at the first end of the one or more side walls defining an aperture therethrough.

5. A shut-off valve cassette according to any preceding claim wherein the valve member or the stem is received through a guide portion within the shut-off valve cassette.

6. A shut-off valve cassette according to any preceding claim wherein the valve is a one-way valve mechanism.

7. A shut-off valve cassette according to any preceding claim wherein the lockingmechanism is provided at any position along the length of the shut-off valvecassette.

8. A shut-off valve cassette according to any preceding claim wherein the first locking structure and the second locking structure are configured to lockingly engage when the valve member is in the closed position.

9. A shut-off valve cassette according to any preceding claim wherein the valve member is configured to move from the open position to the closed position in response to experiencing a pressure exceeding a threshold value, and wherein the locking mechanism is triggered when the valve member is in the closed position.

10. A shut-off valve cassette according to any preceding claim wherein the first locking structure is provided on the shut-off valve cassette, and the second locking mechanism is provided on the valve member.

11. A shut-off valve cassette according to any preceding claim wherein the valve member comprises an enlarged head or plug and an elongate stem with a tip.

12. A shut-off valve cassette according to claim 11 wherein the first locking structure comprises at least one flange defining an opening through which the elongate stem is received.

13. A shut-off valve cassette according to claim 12 wherein the second locking structure comprises at least one deformable arm or chevron or similar configured to deform upon contact with the at least one flange and biased into an extended locking condition to abut the at least one flange and lock the valve member in the closed position.

14. A housing configured to receive the shut-off valve cassette according to any preceding claim.

15. A housing according to claim 14 wherein the housing is configured to releasably house the shut-off valve cassette.

16. A housing according to any one of claims 14 or 15 wherein the housing is shaped and / or sized to closely conform to the shape and / or size of the shut-off valve cassette.

17. A housing according to any one of claims 14 to 16 wherein the housing is configured to house the shut-off valve cassette using at least one of: a friction fit, a push fit, or the like, and wherein the housing comprises at least onesealing ring which is housed by one or more grooves provided on the shut-off valve cassette.

18. A housing according to any one of claims 14 to 17 wherein the housing comprises a release mechanism and wherein the release mechanism comprise a retaining cap configured to hold the shut-off valve cassette in place within the housing.

19. A fluid flow system comprising: a heat exchanger, a pre-heat exchanger manifold, and a post-heat exchanger manifold, wherein the post-heat exchanger manifold comprises the housing according to any one of claims 14 to 18 and the shut-off valve cassette according to any one of claims 1 to 13.

20. A fluid flow system according to claim 19 wherein the fluid flow system is a heat exchange system to exchange heat from a refrigerant to a heat transport fluid in the fluid flow system.

21. A fluid flow system according to claim 20 wherein the heat exchanger is a plate heat exchanger comprising a refrigerant and wherein the refrigerant is Propane (R290).

22. A fluid flow system according claim 20 or claim 21 wherein the pre-heat exchanger manifold comprises a non-return valve and / or a check valve configured to prevent backflow of pressure within the system.

23. A fluid flow system according to any one of claims 20 to 22 wherein the postheat exchanger manifold comprises a refrigerant separation vessel configured to separate refrigerant from the fluid in the fluid flow system.

24. A fluid flow system according to claim 23 wherein the refrigerant separation vessel comprises a cyclone and / or vortex separator to separate refrigerant from heat transport fluid.

25. A fluid flow system according to any one of claims 23 or 24 wherein the refrigerant separation vessel comprises the housing and the shut-off valve cassette.A

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