Abstract:
A secondary valve unit is provided to interconnect a front/finish assembly and an existing wall outlet for supplying medical gases. The secondary valve unit includes a cylindrical body containing a secondary valve assembly to prevent gas leakage when the front unit that contains a primary valve is removed for services. The secondary valve unit is pre-assembled and threadedly connected to the wall outlet. The threaded connection is locked by an indexing plate which is attached to the wall and provides indexing connection with the front unit to avoid mistakenly connecting a wrong front unit for different gases. The secondary valve unit is especially used in renovations of medical gas systems in hospitals, and able to be installed to an existing wall outlet without breaking the wall so that the cost for renovations is significantly reduced. The connector assembly for gases using the secondary valve unit provides a great gas flow and achieves a more secure connection over a long period of time.

Description:
TECHNICAL FIELD 
     This invention relates to medical gas service outlets and, more particularly, to an adaptor kit for medical gases used to connect an existing wall outlet back body of a medical gas piping system to a front/finish assembly having a valve tube type of interface. 
     BACKGROUND OF THE INVENTION 
     It is normal in most hospitals today to provide in-room service of a various medical gases such as oxygen, air, nitrous oxide, as well as a source of vacuum for suction equipment. The gases are generally provided under pressure or vacuum from a central source. A user can conveniently plug in the various equipment that utilize the particular service with a specially designed, keyed adapter that is generally connected to medical tubing for delivery to its end use device. 
     A typical connector assembly for medical gases usually includes a wall outlet having a cylindrical housing in fluid communication with a specified gas source and being fixed in the wall during construction, and a front unit which is a gas specific portion for gases such as oxygen, nitrous oxide and air, defining diameter-indexed two-stage bores. 
     A primary valve is provided within a tubing of the front unit which is usually in a closed position and can be pressed-open by a plunger of the adapter at the ends of hoses or gas-using devices. 
     A secondary valve is provided within the cylindrical body installed in the wall, which is pressed in an open position by the tubing of the front unit when the front unit is connected to the wall outlet. The secondary valve returns to a closed position to prevent gas leakage through the wall outlet when the front unit is removed from the wall outlet for services, such as cleaning or repair. 
     Typical examples of the connector assemblies for medical gases are described in U.S. Pat. No. 3,563,267 which issued to Thompson on Feb. 16, 1971, U.S. Pat. No. 4,190,075, which issued to Kayser on Feb. 26, 1980 and U.S. Pat. No. 5,236,005, which issued to Berg on Aug. 17, 1993. 
     As technology develops, the connector assemblies for medical gases are improved. New connector assemblies with updated technologies can be conveniently installed during construction of buildings. However, it is not convenient to install new connector assemblies for replacing old ones in renovations of the medical gas systems in hospitals. A wall outlet containing the secondary valve is usually welded to a gas supply pipe, both being buried within the wall. The decorative exterior of the wall, surrounding the wall outlet, has to be demolished and the existing wall outlet has to be cut from the pipe in order to substitute a new connector assembly. After the wall outlet of the new connector assembly is welded to the pipe in the wall, the wall must be mended with new cladding material. It is a costly process. 
     Therefore, a structure of connector assemblies for medical gases is desirable to enable the connector assemblies to be detachably connected with existing wall outlets in order to avoid the demolition process during renovations of medical gas systems. 
     Improved connector assemblies for gases which can be conveniently connected to an existing wall outlet of one type is described, for example, in U.S. Pat. No. 4,562,856, which issued to Garvey et al., on Jan. 7, 1986. A major aspect of the device described in this U.S. Patent, is to incorporate the primary valve and the secondary valve into a single cylindrical body which has a threaded front end conforming to D.I.S.S. (Diameter Indexing Safety System) standard and a threaded rear end for threadedly engaging a corresponding threaded connector defined in an existing wall outlet. This ensures that the internal indexing diameters are not removed during servicing because the cylindrical body is to be left affixed to its primary attachment. 
     The single body structure, however, leads to problems regarding safety issues. A liquid thread locker, Loctite  271 , is applied on the threaded rear end of the cylindrical body to lock the threaded connection with the wall outlet after the liquid becomes solid. The thread locker is an inflammable material, especially in an oxygen-rich environment. The high operating pressure, at 50 psi required in an oxygen system in hospitals increases the risks of igniting the material. It is apparent that the device is not suitable for use relating to an oxygen supply system. After a long period of time, the solid material ages and loses its locking function. Frequent engaging and disengaging adapters to and from the threaded front end of the cylindrical body may eventually loosen the threaded connection between the rear end of the cylindrical body and the wall outlet. Therefore, there is a risk of suddenly losing the connection, and the device under the pressure of 50 psi may eject from the wall outlet. 
     A structure of a connector assembly for medical gases with improvements regarding a large gas flow is also desirable. A pressure drop through the connector assembly is expected not more than 4 psi according to the standard. Most devices in prior art have a pressure drop of about 8 to 12 psi and the device suggested in U.S. Pat. No. 4,562,856 has a pressure drop ranged from 6 to 8 psi. 
     SUMMARY OF THE INVENTION 
     It is one object of the present invention to provide a connector assembly for medical gases, which overcomes the shortcomings in the prior art. 
     It is another object of the invention to provide a connector assembly for medical gases, which improves the gas flow. 
     It is a further object of the invention to provide a connector assembly for medical gases, which is an improvement in respect to safety issues. 
     It is yet a further object of the invention to provide an adapter kit for a connector unit for gases which is used to connect a front unit having a primary valve in a tubing to an existing wall outlet in fluid communication with a medical gas source, so to eliminate the need for extensive renovations of medical gas systems and reduce the cost thereof. 
     It is yet a further object of the invention to provide a pre-assembled connector unit including a secondary valve to be installed to an existing wall outlet in fluid communication with a medical gas source and adapted to receive a front unit having a primary valve so to eliminate the need for extensive renovations of medical gas systems and reduce the cost thereof. 
     In general terms, a cylindrical body is provided to contain all inner parts of the secondary valve therein and adapted to be conveniently and detachably connected to an existing wall outlet of a gas system for detachably receiving a front unit. 
     More specifically, according to one aspect of the invention, a kit is provided for a connector unit for gases which is used to connect a wall outlet of a gas system to a front unit having a primary valve tube, the kit comprising: a cylindrical body adapted to be detachably connected with the wall outlet, and defining an axial passage extending therethrough; a secondary valve adapted to be secured to by the cylindrical body, the secondary valve being biased to close the axial passage when the cylindrical body is connected to the wall outlet and being always open when the front unit is mounted to the wall and the primary valve tube is inserted into the passage of the body; a seal adapted to be contained within the cylindrical body for sealing an exterior of the primary valve tube when the front unit is mounted to the wall; and means for securing the connector unit to the wall outlet when the cylindrical body is connected to the wall outlet. 
     The kit preferably includes a plate, having an aperture, adapted to be attached to a front end of the cylindrical body, with the aperture aligned with the passage of the cylindrical body, for securing the connector unit to the wall while permitting the tubing of the front unit to be inserted through the aperture into the passage of the cylindrical body; and indexing means provided with the plate, adapted for co-operation with corresponding indexing means of the front unit to ensure that a front unit only specified for use with a gas of the type supplied from the wall outlet is enabled to be connected to the connector unit. 
     The connector unit assembled using the kit is preferably threadedly connected at a rear end of the cylindrical body to the wall outlet, and a holding bracket and resilient gasket firmly secure the cylindrical body to the plate to prevent the cylindrical body from rotation relative to the plate which is attached to the wall. Therefore, the threaded connection of the cylindrical body with the wall outlet is safely locked. 
     The connector unit for gases according to the invention advantageously facilitate renovations of existing medical gas systems in hospitals. A kit may include parts for different connector units which can be conveniently installed to different vintages and manufacturers of medical gas wall outlets without the wall demolition process, and all the adaptor kits accept the AMICO front/finish assembly specified for different types of medical gases. Thus, the estimated average cost for upgrading the existing wall outlet assembly, according to the present invention, is significantly reduced. 
     The risk of losing connection is eliminated because not only the cylindrical body is prevented from rotation by the attachment to the plate but also the engaging or disengaging action on the front unit has little effect in respect to the threaded connection between the upgrade kit and the wall outlet. The upgrade kit according to the invention is able to provide a large gas flow and the total pressure drop is reduced to a range from 1.9 to 2.0 psi. 
     Other features and advantages of the invention will be apparent from the description of the preferred embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Having thus generally described the nature of the invention, reference will now be made to the preferred embodiments thereof and the accompanying drawings, in which: 
     FIG. 1 a  is a longitudinal cross-sectional view of the preferred embodiment of the invention, in which a secondary valve is in an open position; 
     FIG. 1 b  is a partial longitudinal cross-sectional view of the embodiment in FIG. 1 a , in which the secondary valve is in a closed position; 
     FIG. 2 is a front elevational view of the embodiment in FIG. 1 a  showing the indexing plate; 
     FIG. 3 is a cross-sectional view of the valve body taken along line  3 — 3  in FIG. 1 a , showing the axial flow passages thereof; 
     FIG. 4 is a cross-sectional view of the rear end of the valve body taken along line  4 — 4  in FIG. 1 a , showing the opposed flat surfaces thereof for being gripped by a wrench during assembly of the secondary valve unit; 
     FIG. 5 a  is a partial cross-sectional view of the embodiment in FIG. 1 a  to be connected to an existing wall outlet of one type; 
     FIG. 5 b  is a partial cross-sectional view of the embodiment in FIG. 1 a  to be connected to an existing wall outlet of another type; 
     FIG. 6 is a longitudinal cross-sectional view of another preferred embodiment of the invention, which is installed within a housing of an existing wall outlet of a third type; 
     FIG. 7 appears on the sheet of FIGS. 3 and 4 and is a front view of the valve body in FIG. 6; 
     FIG. 8 a  is a perspective view of a tool used especially for assembly or disassembly of the embodiment in FIG. 1; 
     FIG. 8 b  is a perspective view of an interchangeable tool tip for the tool shown in FIG. 8 a ; and 
     FIG. 8 c  appears on the sheet of FIG. 1 b  and is a rear view of the tool in FIG. 8 a.   
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, there is shown in FIG. 1 a , a pre-assembled secondary valve unit  10  which includes a cylindrical body  12  having a front portion  14 , a rear portion  16  and a middle portion  18 . Each of the portions  14 ,  16  and  18  has an external diameter and an internal diameter and those external and internal diameters decrease in a sequence from the front portion  14  to the rear portion  16  as to form a front radial section  20  and a rear radial section  22  as well as an axial passage  24  extending through the cylindrical body  12 . 
     An annular resilient seal  26  is provided within the front portion  14  abutting, at its rear side, against the inner surface of the front radial section  20  and is covered by a washer  28  at its front side. The washer  28  is in turn axially restrained by an annular spring retainer  30  which is received in an annular groove  32  inside the front portion  14  at the front end. An annular ridge  34  has an external diameter slightly smaller than the outer diameter of the front portion  14  and protrudes axially from the front end of the cylindrical body  12 , fitting into an aperture  36  (see FIG. 2) of an indexing plate  38  which is attached to the cylindrical body  12  using a recessed bracket  40 . 
     The bracket  40  has a central aperture  42  for receiving the middle portion  18  of the cylindrical body  12  extending therethrough, and bent in a shape, as shown in FIG. 1 a  to abut the external surface of the front radial section  20 . The bracket  40  is fastened to the indexing plate  38  using screws (not shown) through the bores  44  defined in the indexing plate  38  and the bracket  40 , respectively. The bores  44  defined in the bracket are threaded and, therefore, no nuts are needed to threadedly fasten the screw in the bores  44 . 
     A gasket  46  is received in an annular groove provided on the exterior of the annular ridge  34  adjacent the front end of the front portion  14  of the cylindrical body  12 . The gasket  46  is compressed between the indexing plate  38  and the front end of the cylindrical body  12  to ensure a firm and secure attachment so as to prevent the cylindrical body  12  from rotation relative to the indexing plate  38  that is attached to the wall. 
     A valve body  48  generally is a cylindrical stem having a front portion  50  and rear portion  52 . The front portion  50  has an external diameter fitting into the internal diameter of the rear portion  16  of the cylindrical body  12  and permitting the valve body  48  to slide therealong. Axial flow passages  54  are provided, which allow the gas to flow through. The axial flow passages  54 , as illustrated in FIG. 3, are four axially extending grooves on the front portion  50  of the valve body and circumferentially spaced apart from one another by the radially extending portions which guide the axial movement of the valve body  48 . The rear portion  52  of the valve body is provided with an O-ring seal  56  which is restrained between two annular ridges  58  and  60 . 
     An annular recess  62  is defined between the front portion  50  and the rear portion  52  to provide an annular passage for the gas entering the axial flow passages  54 . 
     An annular seating surface  64  is defined on the rear end of the rear portion  16  of the cylindrical body  12  to which the O-ring seal ring  56  will abut to close the passage for the gas entering the axial flow passages  54 , when the valve body  48  is axially moved towards the left to its final position, shown in FIG. 1 b.    
     The annular ridge  58  has an outer diameter smaller than that of the annular ridge  60  to avoid interference with the sealing when the Q-ring seal  56  abuts the seating surface  64 . 
     Another annular ridge  66  is provided behind the annular ridge  60  to retain a front end of a spiral spring  68 . A rear end of the spiral spring  68  will reach an inner end of the cylindrical housing  222  of a wall outlet  220  (FIG. 5 a ) and force the valve body  48  to move towards the left to close the secondary valve when the secondary valve unit  10  is inserted into the cylindrical housing  222 . 
     A valve retainer  70  is provided to prevent the valve body  48  from being separated from the cylindrical body  12 . The valve retainer  70  has an external diameter slidably fitting into the inner diameter of the middle portion  18  of the cylindrical body  12 , and a threaded rear end detachably engages a threaded bore  72  (shown in FIG. 3) which axially and inwardly extends from the front end of the valve body  48 . A plurality of bores  74  extend axially through the valve retainer  70 , and are circumferentially spaced apart from one another, acting as to diffuse the gas flow. 
     Threads  76  are provided on the exterior of the rear portion  16  of the cylindrical body  12  for threadedly engaging the corresponding threads provided within the cylindrical housing of the wall outlet to secure the secondary valve unit  10  to the wall outlet. Four axial recesses  78  are provided on the annular ridge  34  for receiving a tip of a special tool  300  shown in FIG. 8 a  to rotate the cylindrical body  12  to engage or disengage the secondary valve unit to or from the existing wall outlet body. The rear end of the rear portion  52  of the valve body is provided with two opposed flat surfaces  80 , as shown in FIG. 4 to be gripped by a wrench during assembly or disassembly of the secondary valve unit  10 , which will be explained hereinafter with reference to FIG. 8 a.    
     The inner diameter of the middle portion  18  of the cylindrical body  12  and the inner diameter of the annular seal  26  are determined in accordance with the external diameter of the tubing  82  of the AMICO front/finish assembly  84 . The inner diameter of the annular seal  26  is slightly smaller than the outer diameter of the tubing  82  so that the annular seal  26  firmly seals the exterior of the tubing  82  when the tubing  82  is inserted into the cylindrical body  12 . 
     Indexing holes  86  are provided in the indexing plate  38  and the bracket  40 . The number, size and position of the indexing holes  86  are determined by the configuration of the indexing pins on the AMICO front/finish assembly respective of the type of gases and enabled to receive the corresponding indexing pins  88  of the front/finish assembly  84  which is enabled to be connected only for the gas of the type which is supplied from the wall outlet through the secondary valve unit  10 . The front/finish assembly is not part of the invention and is known as AMICO products. 
     In operation, the valve body  48  with the valve retainer  70 , is forced to the extreme left position, as shown in FIG. 1 b , and the O-ring seal  56  abuts the seating surface  64  to close the axial passage  24  of the cylindrical body  12  when the secondary valve unit  10  is connected to the wall outlet and the spiral spring  68  is compressed by the inner end of the cylindrical housing of the wall outlet. This is to permit the front/finish assembly to be easily removed from the wall unit without any gas leakage. 
     In a normal condition, however, the front/finish assembly is installed to the wall outlet and the tubing  82  is inserted into the cylindrical body  12  to press the valve retainer  70  and the valve body  48  back to the extreme right position, shown in FIG. 1 a , or intermediate positions therebetween so that the secondary valve remains open. The primary valve (not shown) in the tubing  82  of the front unit  84  normally is closed and, therefore, the gas is not able to escape even though the secondary valve normally remains open. When an adapter of gas equipment, not shown, is connected to the end  90 , a plunger of the adapter will open the primary valve in the tubing  82  to permit the gases to flow through the secondary and the primary valves into the equipment. 
     Mounting bores  92  are provided in the indexing plate  38  to receive two rivetnuts which are rivets having central bores with inner threads. The rivetnuts received in the mounting bores  92  permanently fasten the indexing plate to the wall, which meets the requirement of the standard to reduce the risk that the unit  10  is accidentally removed from the wall outlet. Mounting bores  94  are provided in both of the indexing plate  38  and the bracket  40  for receiving two rivetnuts, the inner threads of which are adapted to engage two threaded bolts to secure the front/finish assembly to the indexing plate  38 . 
     The secondary valve unit  10  is especially used for two types of existing OHMEDA wall outlets as shown in FIGS. 5 a  and  5   b . One type of wall outlet  220 , shown in FIG. 5 a , includes a cylindrical housing  222  welded to a pipe  224  which is in fluid communication with a medical gas source. The cylindrical housing  222  has inner threads  226  which engages a retainer  228 . The retainer  228  includes a central bore  230  defining a valve seat to receive a ball valve  232 . The ball valve  232  is biased by a spring  234  to the closed position as shown. 
     A pair of diametrically opposed recesses  236  are provided at the front end of the retainer  228  for engaging a tool tip to loosen or tighten the retainer  228 . During a renovation of the medical gas system, the retainer  228 , valve ball  232  and the spring  234  are removed from the cylindrical housing  222 , and the pre-assembled secondary unit  10  (only partially shown) is inserted into the cylindrical housing  222 . The screws in bores  44  (see FIG. 2) in the indexing plate  38  are not tightened in the pre-assembled unit and the cylindrical body  12  is permitted to rotate relative to the indexing plate  38  so that the threads  76  of the cylindrical body  13  is able to engage the threads  226  of the cylindrical housing  222 . An O-ring seal (not shown) may be provided to seal the connection. After the threaded connection is tightened, the screws in bores  44  are tightened to prevent the cylindrical body  12  from rotation. There is no need for applying the Loctite 271 to the threaded connection as is required with other manufacturers kits and the fire risk is eliminated. 
     In order to ensure a large gas flow over the secondary valve unit, a minimum gas flow cross-sectional area in the secondary valve unit  10  should be close to, preferably not smaller than, a minimum (limiting) gas flow area in the gas system at upstream with respect to the unit  10 . The minimum (limiting) gas flow area in the existing system using OHMEDA wall outlets, is the area indicated as M, equal to the cross-section of the inner passage of the pipe  224  minus the area overlapped by the threaded rear end of the retainer  228 . The area M remains about the same when the secondary unit  10  is connected. Therefore, the gas flow area defined respectively by the axial flow passages  54  and bores  74 , especially defined by the interface of the passages  54  and bores  74 , is preferably greater than the area M. 
     The second type of OHMEDA wall outlet  240  shown in FIG. 5 b  includes a body  242  welded to a pipe  244  which is in fluid communication with a medical gas source. Threads  246  are provided to connect an existing unit  248  which includes a secondary valve (not shown). The threaded connection is locked by the screw  250 . After the screw  250  is loosened or removed, the unit  248  is removed. Following the procedure described with reference to FIG. 5 a , the secondary valve unit  10  which is partially shown in FIG. 5 b  is installed to the body  242 . 
     In FIG. 6, there is another embodiment in accordance with the present invention, especially used for a third type of OHMEDA wall outlets. The secondary valve assembly  100  includes a cylindrical body  102 , which is restrained within a cylindrical body  200  of an existing wall outlet by a washer  104  and an annular spring retainer  106  after all existing inner parts (not shown) within the cylindrical body  200  are removed. The cylindrical body  200  is welded to a pipe  201  connected with a medical gas source and is a type different from the cylindrical body  222  and the body  242  of the existing wall outlets  220  and  240  described above. Therefore, the cylindrical body  102  is configured differently from the cylindrical body  12  in the secondary valve unit  10  and, particularly, the exterior and the two ends thereof have to fit into the interior of the cylindrical housing  200 . 
     An O-ring seal  107  is provided between an annular shoulder on the exterior of the cylindrical body  102  and an annular step on the interior of the cylindrical body  200  to further restrain and seal the cylindrical body  102  to prevent gas leakage. An annular resilient seal  108  is snugly received in the cylindrical body  102  at the front end and axially restrained between the washer  104  and an annular step  110  on the interior of the cylindrical body  102 . 
     The annular seal  108  serves as both a seal which sealingly receives the tubing of the front/finish assembly (not shown) to be inserted therethrough and a valve seat which receives a valve body  112  to be seated thereon. The valve body  112  is a plastic cylindrical sleeve with a closed front end. A plurality of axially extending ridges  14  are provided on the external periphery of the valve body  112 , and circumferentially spaced apart from one another, as shown in FIG.  7 . The valve body  112  is slidable in an axial passage  116  of the cylindrical body  102 , being guided by the axially extending ridges  114 . 
     Adjacent ridges  114  define gas flow passages  118  extending axially therebetween. The closed front end of the valve body  112  includes an annular shoulder  120  to snugly fit into the rear end of the annular seal  108  to close the axial passage  116  of the cylindrical body  102 . A plurality of projecting members  122  radially extending on the closed front end of the valve body  112 , are adapted to guide the valve body  112  to be properly seated on the rear end of the annular seal  102 . 
     A spiral spring  124  is placed between the valve body  112  and an inner end  202  of the cylindrical body  200  to maintain the valve body  112  to be seated at the rear end of the annular seal  108  and close the axial passage  116 . When the tubing of the front/finish assembly is inserted into the axial passage  116  of the cylindrical body  102 , the tubing moves the valve body  112  rearwards against the spring force to an open position, shown in broken lines, in which the gas flow is able to pass the valve body  112  through the gas flow passages  118  between the ridges  114 . 
     The gas flow area defined by the gas flow passages  118  is close to, or preferably not smaller than, the gas flow area defined by the pipe  101  to ensure a great gas flow. 
     The cylindrical body  200  is already attached to a wall plate  204  in the existing wall outlet using an annular retainer  206 . Existing indexing bores (not shown) in the wall plate  204  is not adapted for use with the AMICO front unit and, therefore, new indexing bores  208  are drilled in the wall plate  204  and adapted to receive the corresponding indexing pins of the AMICO front unit. The indexing bores  208  can be accurately drilled using a set of templates, also provided. Mounting bores  210  are already provided in the existing wall plate. 
     It is convenient to provide a kit including all parts for the different secondary valve units adapted for the respective manufacturers of wall outlets during a renovation project. The kit may further include a tool especially for use in assembly and disassembly of the secondary valve units according to the invention. 
     In FIG. 8 a , a tool  300 , designed especially for such a purpose, includes a cylindrical body  302  which has an external diameter about equal to that of the front portion  14  of the cylindrical body  12  in the embodiment shown in FIG. 1 a . A middle portion  303  of the cylindrical body  302  has a greater diameter for being gripped by a user&#39;s hand to apply torque to the tool  300 . A stem  304  axially extends from one end of the cylindrical body  302  and has a length greater than a distance from the extremity of the front end of the cylindrical body  12  to the retainer  70  that is in the right most position, as shown in FIG. 1 a . A tip  306  for wall outlets is secured to the end of the stem  304  using a screw (not shown) received in a central bore  308 . A ridge  310  extends radially across the outer end of the tip  306  for engaging the diametrically opposed recesses  236  of the retainer  228  (see FIG. 5 a ) for applying a torque to loosen the retainer. 
     Another tip  312  is provided for interchanging with the tip  306 . The tip  312 , shown in FIG. 8 b , similar to tip  306 , is cylindrical and has a central bore  314  axially extending therethrough for receiving a screw to secure the tip to the stem  304 . A projecting member  316  which is also included in tip  306  but is not shown, is provided on the inner end of the tip  312 , extending radially to cooperate with a female member (not shown) inside the stem  304  for transmitting a torque applied to the tool. Two pins  318  are provided at the outer end of the tip  312 , which are adapted to fit into a pair of diametrically opposed bores  74  in the retainer  70  in FIGS. 1 a  and  1   b . The outer diameter of the tip  312  is slightly smaller than the inner diameter of the annular seal  26  to enable the tip to be easily inserted into the passage  42  of the cylindrical body  12 . 
     At the other end of the cylindrical body  302 , is provided a tip  320 . Four male members  322  are provided at the outer end of the tip  320  and a central bore  324  is included for receiving a fastening screw (not shown), which is more clearly shown in FIG. 8 c . The four male members  322  are adapted to fit into the recess  78  of the annular ridge  34  of the cylindrical body  12  in FIG. 1 a  to apply a torque to the cylindrical body  12  to rotate the same for threadedly engaging or disengaging from a cylindrical body of the wall outlet. Similar to the projecting member  316  on the tip  312 , a projecting member (not shown) is provided on the tip  320  for torque transmission. 
     When the retainer  70  and the valve body  48  are to be assembled or disassembled, a wrench (not shown) is to be used to grip the two opposed flat surfaces  80  (see FIG. 4) at the rear end of the valve body  48 , and the tip  312  attached to the tool  300  is inserted into the axial passage  24  until the two pins  318  engage the corresponding bores  74  in the retainer  70 . Thus, a torque is enabled to be applied to the retainer to rotate the same for threadedly engaging or disengaging from the valve body  48 . 
     The embodiments described above may be used for oxygen, vacuum, air and any other type of the medical gases, and are examples only for illustrating the principles of the invention. Modifications and improvements to the above-described embodiments of the invention, may become apparent to those skilled in the art. The foregoing description is intended to be exemplary rather than limiting. The scope of the invention is therefore limited solely by the scope of the appended claims.