Abstract:
A re-configurable pressure regulator for breathing apparatus having a valve housing with a connector at a first and a second end. A pressurized source of breathable gas is connected to either end and a removable blanking plug is connected to the other end of the housing. A double acting valve within the housing selectively opens a first or second opening in the housing, depending on which end the source of breathable gas is connected, which opening forms the inlet and outlet from the housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of Great Britain Patent Application No. 0621747.5 filed Nov. 1, 2006. 
     FIELD OF THE INVENTION 
     This invention relates to a pressure regulator for breathing apparatus, specifically but not exclusively for self-contained breathing apparatus such as can be used in environments which a user may need a supply of breathable gas. The invention is principally though not exclusively concerned with breathing apparatus such as can be used by divers in underwater environments. Other uses of breathing apparatus may include those in which the breathable atmosphere may be heavily polluted with combustion products and noxious gases, and is thus otherwise unbreathable. 
     BACKGROUND OF THE INVENTION 
     Self-contained breathing apparatus of the open circuit type generally employ regulator valves for regulating the pressure of the breathable gas contained in a pressurised cylinder or the like for presentation to the user at an appropriate pressure. 
     One particular type of pressure regulator is described in U.S. Pat. No. 4,041,978 which describes a pressure regulator for breathing apparatus having a source, i.e. a tank, containing a gaseous mixture of breathable gases, in which the regulator comprises a diaphragm case having an interior space, a diaphragm disposed in the diaphragm case, a valve housing, a moveable valve body disposed in the valve housing for opening and closing the regulator, and a control member for moving the valve body as a function of the position of the diaphragm with respect to the diaphragm case. The valve housing is divided by the moveable valve body into two or more chambers when the regulator is closed. A first chamber is adapted to communicate with the source of breathable gases and the second chamber communicates with the interior space of the diaphragm case. This regulator has an inlet for connecting the regulator to a tank containing a compressed mixture of breathable gases and an outlet for the gaseous mixture. A valve is provided for opening and closing the passage between the inlet and the outlet. The diaphragm operates the valve via a lever arrangement against the force of a valve spring. When the pressure at the outlet of the regulator becomes less than the ambient pressure acting on the diaphragm the diaphragm moves and this movement is transmitted via the lever to the moveable valve body in such a way that the valve opens. In this way breathable gas flows from the tank to the outlet of the regulator and to a mouthpiece for use by the user. As soon as the pressure at the outlet is increased so that it is approximately the same as the ambient pressure, for example during exhalation, the valve is closed by the valve spring. 
     The valve described in the above mentioned patent and other earlier published patents and applications, for example U.S. Pat. No. 5,503,142, US2004/0154669, EP1447320 and EP1484242, are inherently left or right handed in the sense that the valves are constructed with a single inlet on one side of the regulator valve body for connection to an inlet hose for delivering breathable gases to the regulator. In underwater and fireman&#39;s breathing apparatus the aforementioned regulator valve is often a second stage valve in the breathing circuit with a first stage valve being provided for reducing the pressure of the breathable gases in the tank from a high pressure to a low to intermediate pressure. However, the present invention is mainly concerned with so-called second stage regulator valves which deliver breathable gases at an appropriate pressure to the user via a suitable mouthpiece. 
     A problem that is often encountered with the aforementioned type of breathing apparatus regulator valve is that the valves are either left or right handed in the sense that the inlet is on one side of the valve body or the other, and while a left handed valve may be suitable for use with various different types of breathing apparatus it may not be suitable for others, and vice versa with respect to right handed valves. This can be a particular problem when divers or the like are likely to use the same pressure regulator valve with different breathing apparatus as known pressure regulator valves are not inherently re-configurable. Hitherto, it has been necessary for highly skilled technicians to dismantle and reassemble breathing apparatus regulator valves to change the configuration from say a left hand configuration to a right hand configuration, or vice versa. Re-configuration of the valve is therefore almost entirely impossible in the field and in the context of diving, particularly leisure diving, a mismatch between the actual and required configuration of the valve for use with a particular type of breathing apparatus may only become apparent at a late stage in the dive preparation, and thereby prevent the diver being able to use the available breathing apparatus resulting in cancellation of the intended dive. 
     There is a requirement therefore for a pressure regulator valve for breathing apparatus which can be readily reconfigured for connection of a breathing gas supply hose to either side of a valve housing. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the invention there is provided a re-configurable pressure regulator for breathing apparatus, said regulator comprising a valve housing having connection means at first and second ends thereof for connection, in use, at one of said ends to a pressurised source of breathable gas and at the other of said ends to a removable blanking plug, wherein in a first configuration the said first end is closed by a removable blanking plug and in a second configuration the second end is closed by said blanking plug with the other end being connectable to said breathable source of gases. 
     The pressure regulator according to the above aspect of the present invention is readily re-configurable in the sense that it may be used with different types of breathing apparatus including those types where the breathing gas supply hose is arranged to be fed over the right hand shoulder of the user, or in other apparatus where it is fed over the left hand shoulder, for connection to a connector on the pressure regulator on the respective right or left hand sides thereof. 
     In preferred embodiments the pressure regulator is of the type which further comprises a diaphragm case and a diaphragm located therein dividing the interior of the case to provide a first chamber having an inlet/outlet for communicating breathable gases to and from a user, the first chamber accommodating at least part of said valve housing, the interior of the valve housing defining a second chamber in communication with the first chamber and accommodating a dual acting valve means which in the first configuration is operable to open and close a valve opening at the second end of said valve housing for communication with the source of breathable gases and in the second configuration is operable to open and close a valve opening at the first end of said valve housing for communication with the source, and valve control means for regulating movement of the valve means in accordance with the deflection of the diaphragm in the diaphragm case. The dual acting valve means readily enables the pressure regulator to operate, without any noticeable change in performance, in either the first or second configuration. 
     Preferably, the dual acting valve means comprise a pair of relatively movable valve members which are movable with respect to the valve housing, between their respective open and closed positions, in dependence on the selected configuration of the regulator, by selective engagement of a respective one of the valve members by the said valve control means. Thus, in each configuration of the regulator only a selected one of the valve members is moveable with respect to the valve housing for opening and closing a valve opening at a respective end of the valve housing. This is achieved by the selective engagement of one of the valve members by the valve control means which engagement provides for movement of the engaged valve member in accordance with the deflection of the diaphragm in the diaphragm case. The other of the valve members remains stationery within the valve housing and is effectively redundant until such time that the pressure regulator valve is reconfigured and that valve member is then engaged by the valve control means and the moveable valve member of the previous configuration is disengaged. 
     Preferably, the valve members are coaxially aligned within the housing. This provides for a compact and simple arrangement and readily enables the respective valve members to be engaged/disengaged by the valve control means. 
     In preferred embodiments the valve members are telescopically arranged with respect to each other within the housing, and more preferably the valve members comprise a pair of mutually telescopic elongate cylindrical members. This readily provides for an extremely compact arrangement since the movement of the valve members is accommodated by the other of the valve members. This enables the principal dimensions of pressure regulator valves constructed in accordance with embodiments of the present invention to be no greater than existing regulator valves comprising a single valve arrangement for one sided operation. 
     In preferred embodiments the pressure regulator valve further comprises biasing means for biasing the valve members towards their respective closed positions. In this respect the biased closed position of each valve member may be considered to be the neutral position of that valve member. 
     In preferred embodiments the biasing means comprises a spring member coaxially arranged with respect to the valve members. The spring member preferably biases the valve members apart, and preferably the spring member comprises a coil spring coaxially disposed about the valve members. 
     In preferred embodiments the selective engagement of a respective one of the valve members by the valve control means is effected by the connection of said blanking plug to a respective end of the valve housing and adjustment of respective valve seat inserts which determine a neutral position of the valve means in the housing such that in the first configuration a first of the valve members is positioned such that it is engaged by the valve control means for movement with respect to the valve housing and in the second configuration a second of the valve members is engaged by the valve control means for movement with respect to the housing. The neutral position of the valve means is determined by the respective portions of the valve seat inserts which act against the respective valve members at the end of the valve housing. Adjustment of the valve seats, of at least one of the seats, causes movement of the valve members with respect to the valve housing and such movement causes disengagement of the valve control means with one valve member and engagement with the other. In this way not only does the blanking plug close the connection at one end of the valve but it also allows adjustment of the relative position of the valve members within the housing so that the valve control means selectively engages an appropriate one of the valve members for operation in that a configuration of the regulator valve. 
     In preferred embodiments a valve seat is provided at each end of said valve housing for engagement with a valve sealing face of a respective valve member, and wherein in both the first and second configurations the blanking plug extends within a respective one of said valve seats. The neutral position of the said valve means within the housing is determined by the selected configuration of the pressure regulator. In this respect the dual acting valve means may be considered to be repositioned in one direction along the elongate axis of the valve housing when the blanking plug is applied to one end of the housing and moved in the opposite direction when the blanking plug is applied to the other end thereof by adjustment of the position of the valve seats with respect to the housing. 
     In preferred embodiments the valve control means comprises a lever which moves in accordance with the position of the diaphragm. Conveniently, one end of the lever is engaged by the diaphragm and the other end engages one of the valve members so that deflection of the lever by the diaphragm causes the movement at the other end of the lever to be imparted to the valve member that is engaged by the lever. 
     Preferably, the lever selectively engages one of the valve members, in dependence on the configuration of the said regulator, such that deflection of the lever by the diaphragm moves the respective valve member to open the respective valve opening which is normally closed when the lever is in its un-deflected position. Thus, the pressure regulator according to preferred embodiments of the invention operates in a similar manner to known pressure regulators having a single acting valve and therefore the performance of the regulator, as perceived by the user, is not substantially different to that of a known regulator that is configured for connection to a breathing hose on one side of the regulator body only. 
     Preferably, the diaphragm case further comprises an exhaust valve for exhausting exhaled gases from the first chamber. In the case of open circuit breathing apparatus the exhaled gases the exhaled gases would be exhausted from the breathing circuit but in the case of closed circuit re-breathing apparatus the exhale gases would be exhausted for re-circulation through the breathing circuit as is well known in the art. 
     According to another aspect of the invention there is provided a method of reconfiguring a pressure regulator for use with different breathing apparatus, said regulator comprising a diaphragm case and a diaphragm located therein dividing the interior of the said case to provide a first chamber having an inlet/outlet for communicating breathable gases to and from a user, the said first chamber accommodating at least part of a valve housing having connection means at first and second ends thereof for connection, in use, at one of said ends to a pressurised source of breathable gas and at the other of said ends to a removable blanking plug, wherein in a first configuration the said first end is closed by a removable blanking plug and in a second configuration the second end is closed by said blanking plug with the other end being connectable to said breathable source of gases, the interior of the valve housing defining a second chamber in communication with the said first chamber and accommodating a dual acting valve means which in said first configuration is operable to open and close a valve opening at the said second end of said valve housing for communication with said source of breathable gases and in said second configuration is operable to open and close a valve opening at the said first end of said valve housing for communication with said source, and valve control means for regulating movement of the said valve means in accordance with the deflection of the said diaphragm in the said diaphragm case; the said method comprising the steps of removing the said blanking plug from said connection means at one end of said valve housing; adjusting the position of the said dual acting valve, means with respect to the valve housing; and, connecting the plug to the connection means and the other end of the housing. 
     The present invention therefore also contemplates the method of reconfiguring the valve mentioned above in relation to the first aspect of the invention. 
     In one example the valve may be reconfigured for use with breathing apparatus where the breathable gas supply hose is arranged to be connected to the right hand side of the pressure regulator or to the left hand side. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  is a cross-section view of a pressure regulator valve according to an embodiment of the present invention in a first configuration with the valve shown in a closed position; 
         FIG. 2  is a cross-section view of the valve of  FIG. 1  in the same configuration but shown with the valve in an open position; 
         FIG. 3  is a cross-section view of the valve of  FIG. 1  reconfigured in a second configuration shown with the valve closed; 
         FIG. 4  is a cross-section view of the valve of  FIG. 3  but with the valve in an open position; 
         FIG. 5  is a detailed cross-section perspective view of the valve of  FIG. 1  with the outer casing removed; 
         FIG. 6  shows the valve assembly of  FIG. 5  with the valve in an open position as in  FIG. 2 ; 
         FIG. 7  is a side elevation of the valve assembly shown in  FIG. 5 ; 
         FIG. 8  is a similar view to that of  FIG. 5  but with the valve assembly in the second configuration of  FIG. 3  and shown in the closed position of  FIG. 3 ; 
         FIG. 9  shows the valve assembly of  FIG. 8  in the open position of  FIG. 4 ; 
         FIG. 10  is a side elevation view similar to  FIG. 7  with the valve assembly in the second configuration of  FIGS. 3 ,  4 ,  8  and  9 ; and 
         FIGS. 11 and 12  are detailed perspective views of the moving parts of the valve assembly shown in  FIGS. 5 to 10  from a front and rear perspective respectively. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, in  FIG. 1  a pressure regulator valve  10  for breathing apparatus, for example underwater or fire-fighter&#39;s breathing apparatus, comprises a generally cylindrical cup-shape outer casing  12  through which a cylindrical tubular valve housing  14  extends. The axis of the valve housing  14  is essentially perpendicular to the axis of the housing  12  and therefore may be considered to extend along the diameter of the casing  12  from one side thereof to the other. 
     The valve housing  14  is mainly accommodated within the interior region  16  of the housing which defines a first pressure chamber of the regulator valve. The open end of the housing (towards the top of the drawing in  FIG. 1 ) is closed by a resilient disc shape diaphragm  18  which preferably comprises an elastomeric material. The centre region of the diaphragm  20  is reinforced to provide a bearing surface for contact with a lever on  22  of a valve control means to be described in more detail below. The diaphragm  18  is secured with respect to the casing  12  around its rim where it is located in an annular groove  24  at the open end of the housing  12  which also accommodates a frusto-conical shape cover element  26 . The rim of the cover element comprises an annular axially extending flange portion  28  which compresses the rim of the diaphragm  18  against the inner wall of the annular groove  24  to seal the diaphragm in the groove and hence provide a fluid tight seal between the exterior of the pressure regulator  12  and the interior  16 . At the other axial end of the casing  12  there is provided a tubular opening  30  for connection to a hose or mouthpiece (not shown) through which the user can breathe. In addition to the tubular opening  30  the end wall  32  of the casing is also provided with an exhaust valve  34  which is arranged to open, in a known manner, when the pressure within the interior region  16  exceeds the outside pressure, i.e. the ambient pressure acting on the exterior of the pressure regulator. 
     The valve housing  14  comprises part of a dual acting valve, the component parts of which will now be described in detail with additional reference to the drawing of  FIG. 5 . As can be seen in the drawings, both axial ends of the valve housing  14  are provided with external threads including an external thread  36  at one end of the cylindrical housing and an external thread  38  at the other axial end. The external thread  36  is provided on a part of the housing which extends beyond the casing  12  through an aperture  40  provided in one side of the casing. The external thread  36  provides a first connection means for connecting either a blanking plug  42  or a hose (not shown) for delivering breathable gases to the user via the regulator as will be further explained below. The external thread  38  at the other end of the housing is engaged by an internal thread  44  provided on a tubular valve housing extension part  46  which extends through the casing  12  through an aperture  48  on a diametrically opposite side of the casing to the aperture  40 . Extension part  46  may be considered to be part of the valve housing  14  with the valve housing being of two-part construction for the aid of assembly and disassembly of the pressure regulator. An O-ring  50  is positioned between the end of the cylindrical housing  40  and the extension part  46  to seal the interior of the housing at the threaded joint  38 ,  44  where the two parts are joined. The part of the tubular extension  46  furthest from the casing  12  comprises an external thread  52  which defines a second connection means for connection to either a blanking plug  42  or a breathable gas delivery hose (not shown) as previously mentioned in relation to the description of the other end of the housing  14 . 
     The tubular extension  46  is provided with an internal thread  54  which engages an external thread  56  provided on the outer surface of a tubular valve seat  58 . The valve seat  58  is screwed into the interior of the tubular extension  46  and is provided with screw adjustment means  104  in an end face thereof facing the open end of the extension  46  so that the axial position of the valve seat  58  with respect to the valve housing  14  and extension  46  can be adjusted by use of a suitable adjustment tool entering through the extension part  46 . An O-ring  60  is provided in an annular groove in the external surface of the valve seat at its end nearest the opening of the extension  46  on the external side of the exterior of the regulator valve. 
     A tubular valve seat  62 , similar to the valve seat  58  is provided at the other end of the valve housing  14  but in this case the valve seat  62  is located substantially within the threaded portion at the end of the tubular housing  14 . At this end of the valve assembly the valve seat  62  is threadably located within the valve housing by engagement of an external thread  64  with an internal thread  66  provided on a reduced diameter shoulder portion  68  on the interior of the tubular housing in the region of the outer casing  12 . As can be seen in the drawings, at both ends of the valve assembly the valve seats  58  and  62  extend a small distance into the interior region of the valve housing  14  for abutment with the sealing faces of respective valve members located therein as will now be described. 
     The dual acting valve means further comprises a pair of generally cylindrical telescopic valve members  70  and  72 . Both valve members are tubular in construction and have stepped internal and external diameters with the internal and external diameters of the valve member  70  progressively decreasing in the longitudinal direction of the valve from a sealing face end  74  thereof towards the other valve member. The internal and external diameters of the valve member  72  progressively increase in size from a sealing face end  76  thereof towards the valve member  70 . The valve members  70  an  72  are mutually telescopic in the sense that the progressively decreasing stepped outer diameter of the valve member  70  is dimensioned to fit closely within the progressively increasingly stepped inner diameter of the valve member  72 , with the clearance between the telescopic parts being sufficient to maintain the alignment of the dual acting valve members within the valve housing in use. The valve members are coaxially aligned within the valve housing and are further provided with a coil spring  78  disposed substantially about the overlapping region of the respective valve members for urging the valve members apart and into the closed position shown in  FIG. 1 , where the sealing face  76  of the valve member  72  is held in contact with the end face of the valve seat  58  and likewise the sealing face  74  of the valve member  70  is held in sealing contact with the end face of the valve seat  62 . 
     The coil spring  78  is preloaded to provide a closing force with its axial ends restrained between first and second circlips  80  and  82  located in respective grooves on the outer surface of the respective valve members  72  and  70 . The restoring force of the spring  78  is predetermined so that it provides for opening and closing of the respective valve openings without undue resistance. 
     In the configuration of the regulator shown in the drawings of  FIGS. 1 to 5 ,  6  and  7 , the right hand end (as shown in the drawings) of the valve is closed by the blanking plug  42  which comprises an end cap  84  and an axially extending cylindrical seal element  86  extending from the end cap into the interior of the valve seat  62  to provide a fluid tight seal between the end cap and the valve seat  62 . An enlarged diameter part of the seal  86  nearest to the end cap is provided with an annular groove in its outer surface for receiving an O-ring  88  for providing a fluid tight seal between the seal  86  and the internal surface of the housing in the region of the end cap. The end gap has an internal thread for engagement with one of the external threads  36  or  52 . 
     At the other end of the valve assembly the external thread  52  is available for connection to a breathing hose for delivery of breathable gases to the regulator as will be further described. 
     Referring now to  FIG. 2  which shows the pressure regulator valve in the same configuration as  FIG. 1  but with the valve in an open position for receiving breathable gases. The breathable gases are delivered to the regulator valve by connection of a breathing hose, shown schematically at  90 , from a source of breathable gases, for example a tank  92 , to the inlet at the right hand end of the regulator (as shown in the drawings of  FIGS. 1 and 2 ), namely by connection of the delivery hose to the external thread  52 . When the person using the breathing equipment inhales, the pressure in the interior region  16  of the casing is reduced and this reduction in pressure causes a pressure differential to develop over the area of the diaphragm  18 , since the other side of the diaphragm is exposed to fluid at ambient pressure. This reduction in the internal pressure causes the diaphragm to deflect and move towards the lever arm  22  of the valve control means. As the internal pressure further reduces due to the inhalation action of the user the diaphragm urges the lever towards the valve housing  14  as shown in  FIG. 2  and due to engagement of the other end (not shown in the drawings of  FIGS. 1 and 2 ) of the lever with part, or a connecting part, of the valve member  72 , the valve member  72  is caused to move within the valve housing against the restoring force of the spring  78  to open the valve opening at the end of the valve where previously the valve sealing surface  76  was in contact with the valve seat. In this open position breathable gases are delivered from the source  92  through the delivery hose  90  into the interior of the pressure regulator  10  by communication of the breathable gases through the interior of the valve housing  14  into the region  16 , by means of an oval shaped aperture  94  in the valve housing as shown in the drawing of  FIG. 7 . The valve member  72  remains open until the pressure in the interior region of the regulator reduces to the prevailing ambient pressure where the restoring force of the spring acts to close the valve due to the change in the pressure differential on the diaphragm  18 . The valve member  72  then returns to the closed position of  FIG. 1 , and as the user exhales the exhaled gases are exhausted from the interior of the regulator through the exhaust valve  34 . 
     Referring now to the drawings of  FIGS. 11 and 12  which show the moving parts of the valve assembly in greater detail. The lever  22  comprises a pair of parallel arms  22   a ,  22   b  which are joined by means of a lateral cross member  94  which is positioned between the lever arms at a point remote from the valve members  70 ,  72 . The lever arms each comprise a pair of adjacent limbs which are angled with respect to each other to provide an approximate L-shape structure as best seen in the drawing of  FIG. 1 . As previously mentioned the shorter limbs at the end of the lever are adapted to engage a central portion of the diaphragm  20  and at the other end the levers  22   a  and  22   b  each include an inward facing tab portion  96  which extend perpendicular to the plane of the arms  22   a ,  22   b  towards the valve members  70 ,  72 . The tabs  96  are provided on each side of the lever arm structure  22  such that they locate in a recess  100  defined between the circlip  82 , which is fixed to the valve member  70  to retain the spring  78 , and an end portion  98  of the valve member  72 . The gap  100  that is defined between the circlip  82  and end portion  98  is sufficiently large to accommodate the respective tabs  96  and permit movement of the dual acting valve assembly comprising the valve member  70  and  72  and coil spring  78  with respect to the valve housing and the control lever  22 . This arrangement enables the dual acting valve assembly to be repositioned within the valve housing  14  by adjustment of the axial position of one or more of the valve seats  58 ,  62  so that the inwardly projecting tabs  96  are bought into engagement with either the circlip  82  or an end face of the respective end portions  98  within the regions  100  on opposite sides of the valve assembly. In this way it is possible for the lever  22  to selectively engage either the circlip  82  for movement of the valve member  70  with respect to the valve housing or engage the end portion  98  of the valve member  72  for movement of that valve member with respect to the housing. This operation may be further understood with reference to  FIGS. 7 and 10  which show the relative positions of the lever arms  22   a  and  22   b  in both configurations of the pressure regulator. For example in the configuration of  FIG. 7 , which corresponds to that shown in  FIGS. 1 ,  2  and  5 , the left hand side of the valve is closed by the blanking member  42  and the position of the valve seat insert  62  is adjusted such that the valve assembly is moved to the right in the drawing of  FIG. 5 , along the longitudinal axis of the valve housing. Corresponding adjustments may be made to the valve seat  58  at the opposite end of the housing to accommodate this adjustment such that the distance between the two sealing faces, when the valve is in its closed configuration, remains the same whether the valve is configured for right or left hand operation. As shown in  FIG. 7  this causes the lever arm  22  to be moved in the same direction until further movement is prevented by engagement with the periphery of the square shape aperture  102  in the side of the valve housing  14  through which the tabs  96  pass to locate in the recessed regions  100 . In the configuration of the valve shown in  FIG. 7  this movement of the valve assembly causes the tabs to engage the respective adjacent surfaces of the end portions  98  of the valve element  72  so that depression of the lever  22  causes the valve member  72  to move relative to the housing, as shown in the drawings of  FIG. 2  and  FIG. 6 , thereby opening the valve opening at the opposite end of the valve housing. Similarly, when the valve is configured for connection to a delivery hose at the other end of the valve housing the blanking plug comprising the end cap  42  and inner seal element  86  is removed from the left hand side of the valve (as shown in the drawings) and secured to the opposite end (the left hand side of the drawings) by engagement with the external thread  52 . With the blanking plug removed the axial position of the respective valve seats can be adjusted by insertion of a tool through the respective open ends of the valve for engagement with adjustment tool engagement parts  104  at the respective ends of the valve seat elements furthest from the moveable valve members. Once the correct adjustment has been made the blanking plug can then be assembled onto the opposite end of the valve housing by engagement of the eternally threaded portion of the end cap with the external thread  52 . The adjustment of the axial position of the respective valve seat elements, in this configuration of the valve, causes the moving parts of the valve assembly to move towards the open end of the valve, that is to say towards the left hand side of the valve in the drawings such that the respective tabs  96  engage the opposite side of the square shaped aperture  102  as shown in the drawing of  FIG. 10 . In this configuration further movement of the lever arm is constrained by the apertures  102  such that as the moving parts of the valve assembly are further shifted towards the left by adjustment of the valve seats the tabs engage the circlip  82 , so that in this configuration of the pressure regulator when the lever  22  is depressed the lever acts on the circlip  82 , which is fixed in relation to the valve member  70 , which causes that valve member to move from the closed position shown in  FIGS. 3 and 8  to the open position shown in  FIGS. 4 and 9 .