Abstract:
A fluid coupling system is provided including a fluid coupling having a cooperative key coding system and latching mechanism, a valve biasing mechanism with corrosion resistance, and other advantageous features. The key coding system permits interconnection of only matched coupling members while preventing the inadvertent interconnection of mismatched coupling members notwithstanding the presence of many coupling, both matched and mismatched. The coupling includes first and second coupling members that are releasably slideably, axially interfitted with their passageways in fluid communication. The key coding system includes key coding elements on the coupling members that are axially movable into matched interengagement when the coupling members are matched but are precluded from moving into matched interengagement when they are mismatched, all without rotation of the couplings or the key coding elements irrespective of the relative rotational positions of the couplings members or coding elements. The latching mechanism is movable axially and radially of the coupling members between latching and unlatching positions, again without relative rotation of the latching mechanism and coupling members. The key coding system allows the latching mechanism to move into latching position when the key coding elements match but precludes such movement when there is a mismatch. Although the key coding system and the latching mechanism do not require rotation to function, they allow relative rotation of the coupling members. Furthermore, the coupling incorporates a valve biasing mechanism that does not use a metallic spring or other corrodible parts in contact with the corrosive chemicals.

Description:
RELATED APPLICATION  
       [0001]    This application is a non-provisional application based on our provisional application filed Jul. 9, 1999, Application No. 60/143,127. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention pertains to a fluid coupling system and more particularly to a fluid coupling having a cooperative key coding system and latching mechanism, a valve biasing mechanism with corrosion resistance, and other advantageous features.  
         BACKGROUND  
         [0003]    Certain manufacturing processes require the use of many corrosive and highly reactive chemicals. In the semiconductor industry, for example, some fifteen to twenty liquid chemicals are typically stored in adjacent fifty-gallon supply drums from which they are dispensed during the manufacturing process. In the usual installation, sets of separate umbilical delivery lines for various chemicals are suspended above the drums with a particular set dedicated to a particular chemical. Each set of delivery lines is connected to its associated supply drum by a fluid coupling that has one coupling member on the delivery lines and a second coupling member on the drum.  
           [0004]    As each supply drum is emptied during the manufacturing process, a full drum is brought in to replace the empty one. Accordingly, the coupling members must be repeatedly connected and disconnected. Because of the incompatibility of the chemicals, it is critical that each set of delivery lines be connected only to its intended drum to avoid unsafe mixing and undesired contamination. Moreover, to maintain productivity, such connections and disconnections must be made quickly and routinely by production personnel.  
           [0005]    To insure correct connection of delivery lines to their intended supply drums, chemical extraction apparatus of the type described above uses fluid couplings that incorporate matching coding elements on the coupling members. Examples of such fluid couplings and their coding devices are shown and described in the U.S. Pat. No. 4,699,298 to Grant et al. and U.S. Pat. No. 5,108,015 to Rauworth et al. A significant disadvantage of these known couplings, however, is that they cannot be as quickly connected and disconnected as is desired. Although referred to as quick-connect couplings, they use threaded parts to secure the connection. Repeated threading and unthreading of couplings over a production run consumes a significant amount of valuable time and also can produce additional delays if the threads become fouled and otherwise fail to mesh properly.  
           [0006]    Fluid couplings that can be connected and disconnected without threading are of course available and are truly quick-connect and -disconnect couplings. Examples of known quick-connect couplings are disclosed in U.S. Pat. No. 4,436,125 to Blenkush and U.S. Pat. No. 5,052,725 to Meyer et al. Such known couplings of this type, however, are not suitable for the chemical extraction industry or other industries where matched connections are mandatory since they make no provision for coding, that is, insurance against making mismatches. Moreover, the latching mechanisms used in such known quick-connect couplings do not lend themselves to balanced and dependable two-handed operation by personnel in production processes such as described above.  
           [0007]    In addition, the parts of such fluid couplings that contact the harsh chemicals being carried must be resistant to such chemicals. Materials such as high density polyethylene (HDPE), ethylene polymers (EPDM), or “Teflon” PFA are commonly used and provide excellent chemical resistance. A coil spring is the common device used to close an internal poppet valve of the type under discussion. It has been recognized that if the coil spring is made of metal, it will corrode in the presence of the chemicals. Two solutions have been used, namely, to coat the metal spring with plastic or the use any entirely plastic coil spring, but neither is satisfactory. The coated springs, coated with “Teflon” PFA for example, may still be vulnerable to attack if the chemical is able to penetrate the plastic. Furthermore, entirely plastic springs, again made of “Teflon” PFA for example, are unable to maintain the valve closed, causing leakage.  
           [0008]    The U.S. Pat. No. 6,007,107 to Kazarian, and the co-pending application of Clancy et al., application Ser. No. 09/085,382, filed May 26, 1998 (hereinafter “Clancy et al. application”), both having a common assignee with the present application, provide solutions to the problems set forth above. The present application provides alternative solutions. Each of these prior co-pending applications is incorporated in its entirety in the present application.  
         SUMMARY  
         [0009]    A fluid coupling system is provided including a fluid coupling having a cooperative key coding system and latching mechanism, a valve biasing mechanism with corrosion resistance, and other advantageous features. The key coding system permits interconnection of only matched coupling members while preventing the inadvertent interconnection of mismatched coupling members notwithstanding the presence of many coupling, both matched and mismatched. The coupling includes first and second coupling members that are releasably slideably, axially interfitted with their passageways in fluid communication. The key coding system includes key coding elements on the coupling members that are axially movable into matched interengagement when the coupling members are matched but are precluded from moving into matched interengagement when they are mismatched, all without rotation of the couplings or the key coding elements irrespective of the relative rotational positions of the couplings members or coding elements. The latching mechanism is movable axially and radially of the coupling members between latching and unlatching positions, again without relative rotation of the latching mechanism and coupling members. The key coding system allows the latching mechanism to move into latching position when the key coding elements match but precludes such movement when there is a mismatch. Although the key coding system and the latching mechanism do not require rotation to function, they allow relative rotation of the coupling members. Furthermore, the coupling incorporates a valve biasing mechanism that does not use a metallic spring or other corrodible parts in contact with the corrosive chemicals.  
           [0010]    An object of this invention is to provide improvements in a fluid coupling system.  
           [0011]    Another object is to provide a coded quick-connect and disconnect coupling for use in a chemical extraction system involving supply drums of chemicals and separate delivery lines suspended above the drums.  
           [0012]    A further object is to improve the dependability, productivity, and safety of dispensing a plurality of incompatible chemicals through different delivery lines from different supply drums in a manufacturing process.  
           [0013]    A still further object is to simplify the construction, reduce the manufacturing costs, and improve the overall dependability of fluid coupling systems used in chemical extraction applications.  
           [0014]    An additional object is to provide a simplified and dependable key coding system for a fluid coupling.  
           [0015]    Another object is to provide a simplified and dependable latching mechanism for fluid coupling that uses a key coding system.  
           [0016]    A further object is to avoid the corrosive effects of harsh chemicals on a fluid coupling used to handle the chemicals.  
           [0017]    Yet another object is to provide a more dependable closure mechanism for the poppet valve in a fluid coupling wherein the closure mechanism is not made of materials that corrode in the presence of harsh chemicals while providing a dependable seal that does not leak.  
           [0018]    Another object is to provide an interactive key coding system and latching mechanism in a fluid coupling wherein the coupling members cannot be coupled and latched unless they match.  
           [0019]    Still another object is to provide a fluid coupling for fluid carrying lines that does not require threading or unthreading or rotation of the parts, and thus twisting of the lines, to couple, uncouple, latch or unlatch the coupling members but which allows relative rotation of the coupling members.  
           [0020]    An additional object is to provide a coupling that includes coupling members, a key coding system, and a latching mechanism that can operate with only axial and radial motions of the parts.  
           [0021]    Another object is to minimize the time required dependably to connect and disconnect matched coupling members of a coded coupling or to determine that the coupling members are mismatched and will not couple.  
           [0022]    An additional object is to provide a key coding system for a coupling that can handle many different combinations of matches and mismatches.  
           [0023]    A further object is to provide a resiliently yieldable biasing mechanism for the poppet valve in a fluid coupling that can be exposed to harsh chemicals without corroding.  
           [0024]    Still another object is to provide a resiliently yieldable biasing mechanism for a poppet valve that does not use metal or other corrodible materials in its construction.  
           [0025]    These and other objects, features and advantages of the present invention will become apparent upon reference to the following description, accompanying drawings, and appended claims. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0026]    [0026]FIG. 1 is a longitudinal vertical section of an extractor head, or one coupling member of the coupling of a fluid coupling system, shown connected to a fitting for one delivery line; a latching sleeve of a latching mechanism on the coupling member; and one embodiment of a yieldable, valve biasing mechanism shown in its valve closing position forcing the poppet valve of the extractor head into closed position, all in accordance with the principles of the present invention.  
         [0027]    [0027]FIG. 2 is a longitudinal vertical section of an extractor drum insert, or the other coupling member of the coupling of the subject fluid coupling system, and a key insert ring in the drum insert, both in accordance with the principles of the present invention.  
         [0028]    [0028]FIG. 3 is a plan view looking in the direction of arrow  3  in FIG. 1 but with the plug removed  
         [0029]    [0029]FIG. 4 is a fragmentary vertical section taken on line  4 - 4  in FIG. 1 showing the biasing band in retracted position.  
         [0030]    [0030]FIG. 5 is a longitudinal vertical section of the extractor head and drum insert of FIGS. 1 and 2 shown in their interfitted, coupled, and latched condition.  
         [0031]    [0031]FIG. 6 is a fragmentary section taken on line  6 - 6  in FIG. 5 with the lever removed to show parts beneath.  
         [0032]    [0032]FIG. 7 is a fragmentary vertical section taken on line  7 - 7  in FIG. 5, similar to FIG. 4 but showing the biasing band in expanded position.  
         [0033]    [0033]FIG. 8 is a transverse horizontal section taken on line  8 - 8  in FIG. 5.  
         [0034]    [0034]FIG. 9 is a longitudinal vertical section of the extractor head of FIGS. 1 and 5 taken on a plane ninety degrees displaced from the plane of FIGS. 1 and 5, showing the poppet valve closed like in FIG. 1, but showing the latching mechanism including the latching sleeve and latching balls fully retracted and ready to receive the extractor drum insert of FIG. 2.  
         [0035]    [0035]FIG. 10 is a longitudinal vertical section of an extractor head, or one of the coupling members of the coupling of the subject fluid coupling system, similar to FIG. 1, but showing another embodiment of a valve biasing mechanism of the present invention, the biasing mechanism being shown in its valve opening position wherein it pulls the poppet valve of the extractor head into open position.  
         [0036]    [0036]FIG. 11 is a fragmentary longitudinal vertical section of a portion of the extractor head of FIG. 1 but on a reduced scale and provided to facilitate a description of the key code used in the embodiments of FIGS. 1, 5 and  9 .  
         [0037]    [0037]FIG. 12 is a longitudinal vertical section of the extractor drum insert similar to FIG. 2, but on a reduced scale and provided along with FIG. 11 to facilitate description of the key code used in the embodiments of FIGS. 1, 5 and  9  and thus that matches the key code of the head of FIG. 11.  
         [0038]    [0038]FIG. 13 is a fragmentary longitudinal vertical section of a portion of an extractor head similar to FIG. 111 but even more abbreviated and showing just enough structure to facilitate explanation of a key code different from FIG. 11.  
         [0039]    [0039]FIG. 14 is a longitudinal vertical section of the extractor drum insert similar to FIGS. 2 and 12 but showing a key code that matches the key code of the head of FIG. 13.  
         [0040]    [0040]FIG. 15 is a view similar to FIG. 13 but showing a still different key code.  
         [0041]    [0041]FIG. 16 is a view similar to FIG. 14 but showing a key code that matches the key code of the head shown in FIG. 15. 
     
    
     DETAILED DESCRIPTION  
       [0042]    A preferred embodiment of the fluid coupling system of the present invention is generally indicated by the numeral  25  in FIGS. 1 and 2 and includes a fluid coupling generally indicated by the numeral  26 . The coupling is both a “quick-connect” and a “quick-disconnect” coupling. As is well known, such expressions as “quick-connect,” “quick-disconnect,” and “quick-release” couplings are commonly used to mean a coupling that has both quick-connecting and quick-disconnecting capabilities. Accordingly, the expression “quick connect” coupling is used herein to mean a coupling that is both quick to connect and quick to disconnect.  
         [0043]    The fluid coupling system  25  (FIGS. 1 and 2) is particularly suited for use in conducting chemicals in the semiconductor industry where a variety of highly corrosive and incompatible chemicals are used. Such chemicals include ammonium hydroxide; hydrogen peroxide; and hydrofluoric, phosphoric, nitric, hydrochloride and sulfuric acids. These chemicals are typically stored in a fifty-five gallon drum, as more fully illustrated in FIGS. 1 and 1a of U.S. Pat. No. 5,108,015. The process employed in the semiconductor industry for supplying these chemicals may involve from fifteen to twenty of the drums with each drum containing a particular chemical.  
         [0044]    The chemical extraction system or apparatus generally indicated in FIG. 1 herein includes a chemical supply or down tube or line  30  immersed in the chemical of one of the drums described above but not shown and extending up to the bunghole of the drum. The extraction system also includes a chemical delivery line or hose, not shown, attached to a delivery line fitting  34 , and an air or nitrogen feed line or hose, not shown, attached to an air fitting  36 , each of which is connected to the coded quick-connect coupling  26 . The chemical delivery hose extends from the drum to the work area of the semiconductor plant where the chemical in that drum is to be used. The air hose extends to a source of air or nitrogen under pressure, not shown.  
         [0045]    As is well known, the chemical and air delivery hoses, not shown, are suspended in an umbilical fashion above the drums, not shown, and are connected to their respective drums by a fluid coupling which in the present case is the coupling  26  in the fluid coupling system  25 . The subject coupling allows for the quick and dependable disconnection and reconnection of these umbilical hoses to the down tube  30  when a depleted drum is removed and a full drum replaces it, while ensuring that the chemical hoses for a particular chemical is connected to the corresponding drum containing that chemical.  
         [0046]    The fluid coupling system  25  (FIGS. 1 and 2) of the present invention in general provides the coupling  26  that includes an extractor head  50  connected to the chemical and air delivery hoses, not shown, via the fittings  34  and  36 , respectively; an extractor drum insert  52  connected to the drum, not shown, and its down tube  30 ; a latch or latching mechanism generally indicated at  54  for latching the extractor head and the extractor drum insert together when they are matched and interfitted; a poppet valve  56  that opens and closes upon connection and disconnection, respectively, of the extractor head and the extractor drum insert; a key coding system  58  that ensures connection of an extractor head and delivery hose for a certain chemical to a matched extractor drum insert and supply drum containing that chemical; and a yieldable, poppet valve biasing mechanism  60 .  
         [0047]    As with the coupling of the copending Clancy et al. application, the subject coupling is made almost exclusively of a corrosion-resistant, durable, and hard fluoropolymer plastic, such as “Teflon” PFA, that is perfluoroalkoxy, sold by the Dupont Corporation among others, or polyethylene. The only parts of this coupling that are not of this plastic material are isolated from the corrosive chemicals, as explained below. Of particular significance to the present invention is the fact that the biasing mechanism  60  does not use a metallic spring or metallic parts exposed to the harsh chemicals. Most of the parts of the coupling may be either molded or machined, although one of the major advantages of the subject coupling is that it may be readily molded rather than machined since the latter is more expensive.  
         [0048]    Prior to describing the details of the valve biasing mechanism  60  and the key coding system  58 , brief reference will be made to other parts of the extractor head  50  and extractor drum insert  52 , having in mind that these parts are very similar but not identical to corresponding parts in the Clancy et al. application, cited above. As such, where convenient, the same reference numbers as used in the Clancy et al. application have been used herein to describe similar parts. Thus, the extractor drum insert (FIG. 2) includes an outer, cylindrical, adapter fitting  66  having external threads  68  and a tubular male coupling member  74  concentrically fixed in the fitting by a radial wall  71  that interconnects the fitting and the coupling member. The fitting has an upper internal cylindrical wall  67  and a lower internal cylindrical wall  69 . The coupling member extends above and below the radial wall and provides a concentric main central fluid passageway  70  having a longitudinal central axis  72 . The coupling member also has a lower outside cylindrical surface  81 , a lower radial seat  82 , an upper outside cylindrical surface  83 , and an upper seat  84 . The fitting also has an internal annular seat  73  above the radial wall that joins the upper and lower walls  67  and  69 . The seats function as part of the key coding system  58  in a manner to be described. A spider  78  is incorporated at the upper end of the coupling member and is provided with a plurality of holes  79  to allow chemical or other fluid to flow upwardly from the down tube  30  through the main passageway of the male coupling member.  
         [0049]    The radial wall  71  (FIG. 2) has a plurality of longitudinal air passages or openings  80  extending therethrough and providing for the passage of air downwardly through the adapter fitting into the drum, not shown. The chemical from the drum, not shown, can thus be drawn upwardly from the drum through the main passageway  70  of the male coupling member  74  while air is forced downwardly through the air passages or openings in the radial wall and into the drum. The extractor drum insert  52  also has an annular, outer radial flange  85  projecting radially outwardly from the adapter fitting  66  and terminating in outer threads  86 . This flange also has a flat upper surface  87  and a lower surface  88 , the latter providing an annular sealing groove  89  immediately adjacent to the adapter fitting.  
         [0050]    The latching mechanism  54  (FIGS. 1 and 2) includes an inner latching ring  110  projecting upwardly from and integral with the radial flange  85  in radially outwardly spaced concentric relation to the male coupling member  74  and in radially inwardly spaced concentric relation to the outer threads  86  of the flange. This latching ring has an annular, radially outwardly opening, latching groove  112  that is approximately V-shaped in cross section thereby providing outwardly, upwardly and downwardly extending, divergent or beveled groove surfaces.  
         [0051]    The extractor head  50  (FIGS. 1 and 2) includes an upper radial end wall  120 , an upper outer cylindrical surface  124 , an intermediate outer cylindrical surface  125 , and a lower outer cylindrical surface  126 , these surfaces being of gradually reduced diameter from the upper to the lower surfaces, thereby forming axially spaced outer, upper and lower shoulders  127  and  128 . The extractor head also has a lower outer latching ring  130  that is a lower annular extension of the lower cylindrical surface but functionally forms part of the latching mechanism  54 . This outer latching ring provides a plurality of latching holes or bores  140 , six in this disclosed embodiment, that extend radially through the outer latching ring. These latching holes are equally angularly spaced about the outer latching ring so that with the six holes in this disclosed embodiment, the holes are spaced approximately sixty degrees apart. As with the latching mechanism in the Clancy et. al. application, these holes have inside chamfers that taper inwardly so that the inside diameter of each hole is slightly less than its outside diameter. The outer latching ring terminates in a lower radial end face  142 , and an annular radially outwardly opening retainer groove  144  is located in the outside face of the latching ring between the latching holes and the lower end face. A retainer ring  145  of rigid material is received in the retainer groove and projects slightly outwardly therefrom.  
         [0052]    The extractor head  50  (FIGS. 1 and 2) also has a lower female coupling member  150  providing a central, downwardly opening axial socket defining a central longitudinal axis  153  of the extractor head. The female coupling member is concentric with and radially, inwardly spaced from the outer latching ring  130  so as to define a downwardly opening latching annulus  154  therebetween. The female coupling member also has an inner, annular sealing groove facing into the socket and an outer annular sealing groove facing into the latching annulus. An inner O-ring  162  is positioned in the inner groove, and outer O-ring  164  is located in the outer groove. The extractor head also has a main or central fluid passageway  170  having an upper end in which the chemical delivery fitting  34  is connected and a lower end extending coaxially downwardly in fluid communication with a valve seat  172  and opening downwardly into the female coupling member  150 . It will be understood that the male and female coupling members constitute the fluid coupling  26  having a main central fluid passageway  70 / 170  when they are coupled.  
         [0053]    In contrast to the coupling of the Clancy et. al. application, the air delivery fitting  36  (FIG. 9) extends radially outwardly and then upwardly from a radial bore in the extractor head  150  but still communicates with one or more longitudinally extending air passages  186  having lower ends that open downwardly from the head through the female coupling member  150 . Furthermore, and with reference to FIG. 3, an air indicator fitting  192  extends radially outwardly from an air indicator bore  194  that extends radially inwardly of the head on the opposite side of the main passageway from the air delivery fitting  36 . An air passage  196  extends from the indicator bore longitudinally downwardly and communicates with a radial air duct  198  that opens through the intermediate surface  125  of the head above the lower shoulder  128 , all for a purpose to be described.  
         [0054]    The latching mechanism  54  of the subject fluid coupling system  25  (FIGS. 1, 2 and  5 ) includes a plurality of spherical, uniformly sized, latching balls  200  each having a diameter greater than the minimum, but less than the maximum, diameter of the latching holes  140 . The balls are individually located in the latching holes for movement radially of the extractor head  50 . The balls move between latching positions wherein portions of their spherical surfaces project into the latching annulus  154  (FIGS. 1 and 5) and retracted positions wherein the balls are entirely withdrawn into the latching holes so that none of the peripheries of the balls projects into the latching annulus (FIG. 9). Because the latching holes are tapered as described above, radial inward movement of the balls into the latching annulus is limited. That is, only spherical segments of the balls are allowed to project into the annulus, whereas the balls are free to move outwardly in the latching holes so as to drop out of the extractor head, except that they are retained therein in a manner described below.  
         [0055]    The latching mechanism  54  also includes a latching sleeve  205  (FIGS. 1 and 2) that is axially and rotatably, slideably mounted on the extractor head  50 . The sleeve includes an upper cylindrical section  212  slideably fitted around the intermediate surface  125  of the head and radially outwardly spaced from the lower surface  126  of the head. The sleeve also has a lower cylindrical section  218  providing an inside, lower, cylindrical bearing surface  224  that slideably engages the lower surface  126  of the extractor head  50  in their assembled condition. A lower radial shoulder  220  between the upper and lower sections of the sleeve is in downwardly spaced, opposed relation to the upper radial shoulder  128 . These two shoulders together with the lower section  126  of the head and the upper section  212  of the sleeve define an annular pocket  214  around the head. The upper section of the sleeve also is preferably externally knurled at  216  to facilitate manual handling. The sleeve is thus axially slideable on the head into and out of unlatched and latched positions as will be more fully described below. The sleeve and the head are also rotatable relative to each other throughout three-hundred and sixty degrees, although as will be seen, such rotation is not necessary to latch the coupling nor to test for a match between the extractor head  50  and the drum insert  52 .  
         [0056]    The upper section  212  of the latching sleeve  205  (FIG. 9) has an annular venting recess  229  circumscribing the extractor head  50  and an air port  230  extending radially outwardly from the recess and opening outwardly from the sleeve. When the latching sleeve is in its latching position, as shown in FIGS. 1 and 5, the venting recess does not register with the radial air duct  198  in the head (non-registry is not shown but may be visualized from FIG. 9), but when the latching sleeve is in its unlatched position, as shown in FIG. 9, the venting recess does register with the air duct. Air pressure applied through the fitting  192  will thus be felt by an operator whose hand is at the air port when the latching sleeve is in unlatched position, or conversely, no air will be felt at the air port when the latching sleeve is in latched position. Because the venting recess is annular, the presence or absence of air pressure at the port occurs irrespective of the relative rotational positions of the head and sleeve.  
         [0057]    Still further, the latching sleeve  205  has an inside cylindrical recessed surface  232  (FIGS. 1, 5,  9 ) of slightly greater diameter than the bearing surface  224  and extending endwardly, i.e., downwardly, therefrom. The bearing and recessed surfaces are joined by a radial annular shoulder  220 . The sleeve also has a lower outer skirt  236  that projects endwardly, i.e., downwardly, from the lower end of the sleeve in radially outwardly spaced relation to the recessed surface  232  and defining an annular space  238  with the portion of the sleeve that provides the recessed surface. A coiled compression latching spring  270  is received in the pocket  214  in circumscribing relation to the lower outer cylindrical surface  126 , bears against the upper and lower shoulders  127  and  128 , and yieldably urges the radial shoulder  220  against the retainer ring  145  and into its latching position. This spring may be of metal since it is isolated from the chemicals carried by the coupling  26 , but it may also be of plastic or of plastic-coated metal.  
         [0058]    The poppet valve  56  (FIGS. 1, 5,  6 ,  9 ) includes a generally hemispherical valve body  302  and upper and lower valve stems  304  and  306  extending respectively upwardly and downwardly from the valve body coaxially of the main passageway  170 . A piston or plunger  308  is slideably received in the main passageway above the poppet valve and has a lower central bore  310  extending upwardly about half-way into the piston from the lower end thereof and receiving the upper valve stem. The piston is elongated and cylindrical and has four elongated, outwardly opening, longitudinally extending corner fluid passageways  312  at its quadrants (FIGS. 6 and 9) and a single, elongated, internal, longitudinally extending offset fluid passageway  314  (FIGS. 5 and 6), all of these passageways extending entirely through the piston from the end-to-end thereof. The piston also has a transverse notch  316  above the central bore that extends entirely through the piston diametrically from side-to-side thereof and opens from the upper end of the piston. The piston provides a bearing ledge  318  (FIG. 5) in the notch at the side of the piston opposite from the side where the offset passageway is located and slightly elevated from the base  319  of the notch.  
         [0059]    In order to accommodate the valve biasing mechanism  60  of the present invention, the extractor head  50  has a transverse bore  320  (FIGS. 1, 5,  9 ) extending radially outwardly from the main passageway  170  in alignment with the notch  316  in the piston  308 . This transverse bore  320  opens outwardly of the head through the intermediate surface  125  just under the upper shoulder  127  and is closed by a side plug  322  that is preferably permanently attached, as by cementing, to the extractor head. The plug has an inner arcuate face  324  and an outer face that is shaped and positioned so as to form a smooth part of the cylindrical intermediate surface  125 . The extractor head also has an upper longitudinal bore  326  extending lengthwise of the head in offset, parallel relation to the main passageway  170 . This longitudinal bore  326  has a lower end communicating with the transverse bore  320  adjacent to the inner face of the plug and a upper end that opens outwardly through the upper end wall  120  of the head. A top plug  328  closes the upper end of this longitudinal bore and is also preferably permanently secured, as by cementing, to the head. This upper plug also has an outer surface that is smoothly coplanar with the upper end of the head. These plugs are of course not cemented in place until after the biasing mechanism  60  is installed in the bores  320  and  326 , as will be described.  
         [0060]    The transverse bore  320  (FIGS. 1, 5,  9 ) provides an annular groove  321  adjacent to its inner end just outside of the main passageway  170 , and an O-ring sealing fulcrum  348  is fitted in this groove so that it is thereby immediately adjacent to the main passageway. An elongated lever  350  extends through the fulcrum and is positioned within both the transverse bore  320  and the main passageway. The lever has a cylindrical inner end portion  352  fitted in the notch  316  of the piston  308 . The inner end portion is of a diameter slightly less than the width of the notch, allowing it freedom to move up and down in the notch, and has an end  353  engaging the ledge  318  in closely adjacent spaced relation to the wall of the main passageway  170 . The lever also has a cylindrical outer end portion  354  in the transverse bore  320 . The outer end portion has a diameter greater than the diameter of the inner end portion but less than the diameter of the bore, allowing it freedom to move up and down in the bore. The transition between the inner and outer portions provides an annular shoulder  355 . The outer end portion has a cylindrical neck  356  of reduced diameter in alignment with the longitudinal bore and an end face  359  in slideable engagement the side plug  322 . To strengthen the lever, which is made of non-corrosive material such as plastic, e.g., Teflon, a metallic pin  360 , e.g., a steel pin, is embedded lengthwise in the lever and is sealed therein by a plastic plug  361  at the end face of the lever, the pin and plug being shown in dashed lines in FIGS. 1 and 5.  
         [0061]    The sealing fulcrum  348  (FIGS. 1, 5,  9 ) is in circumscribing sealing engagement with the inner end portion  352  precluding passage of fluid chemical from the main passageway  170  into the transverse bore  320 . As above noted, the diameter of the outer end portion  354  is slightly greater than the diameter of the inner end portion so that engagement of the outer end portion with the fulcrum limits inward movement of the lever  350 . Engagement of the end face  359  with the side plug  322  of course limits outward movement of the lever. The transition between the inner and outer portions provides an annular shoulder  355  in sealing engagement with the fulcrum, thereby enhancing the seal between the main passageway and the transverse bore, especially against the outward fluid pressure from within the fluid passageway  170 .  
         [0062]    The width of the notch  316  (FIGS. 1, 5,  9 ) and its longitudinal dimension as well as the diameter of the main passageway  170  allows vertical movement of the inner end portion  352  in the main passageway within the notch. The vertical dimension of the transverse bore  320  is greater than the diameter of the outer end portion  354  and allows vertical movement of the outer end portion in the transverse bore. It will be understood that the lever is thus mounted for vertical pivoting movement, like a teeter-totter or seesaw, on the fulcrum  348  in the main passageway and in the transverse bore. During such pivoting movement, the inner end portion moves up and down in the notch  316  with the end bearing against the piston  308 , and the outer end portion moves up and down in the transverse bore  320  with the end face  359  sliding against the side plug  322 .  
         [0063]    With continued reference to FIGS. 1, 5, and  9 , the valve biasing mechanism  60  also provides a bar  365  extending transversely through the longitudinal bore  326  at its upper end and in upwardly spaced relation to the transverse bore  320 . An endless, resiliently expandable, elastic biasing band or bands  368  are extended around the bar, extends lengthwise of the longitudinal bore, and extend around the neck  356  of the lever  350 . Although one band may suffice, two bands are preferred since one is a back-up for the other. For simplicity, however, the bands may be collectively referred to in the singular. The circumference of the band is such that the band and thus the valve biasing mechanism have a normal valve closing position or condition wherein the band is retracted, i.e., relatively relaxed and under reduced or minimal tension (FIGS. 1 and 4), causing it to pull the neck  356  and thus the outer end portion  354  of the lever upwardly in the transverse bore  350 , thereby biasing the inner end portion  352  downwardly. In this normal valve closing position, the band is not completely unstressed but, as stated, is relatively relaxed and still sufficiently stressed enough to bias the inner end portion of the lever downwardly against the bearing ledge  316  of the piston  308 . This downward pressure of the inner end portion of the lever against the piston causes the piston to force the valve body  302  to seat in the valve seat  172  of the extractor head  50 , as shown in FIG. 1, thereby closing the valve  56 , provided however, that the coupling members  74  and  150  are not coupled, that is, the spider  78  is not pressing upwardly against the poppet valve  56  and forcing it open.  
         [0064]    In operation, the valve biasing mechanism  60  is normally in its valve closing position, as shown in FIGS. 1 and 9. When the extractor head  50  is coupled to the extractor drum insert  52 , as shown in FIG. 5, the spider  78  presses upwardly against the lower valve stem  306  to open the poppet valve  56 . This opening action is permitted by the valve biasing mechanism  60  since the bands  368  expand (FIGS. 5 and 7), allowing the piston  308  to tilt the lever  350  in a clockwise direction, as shown in FIGS. 1 and 5, and causing the neck  356  to pull the bands downwardly into a valve opening position or condition. With the poppet valve open, liquid chemical is of course allowed to flow from the drum, not shown, upwardly through the passageway  70 / 170  and out through the delivery fitting  34 . The liquid chemical flows through the passages  312  and  314  and the notch  316  of the piston and thus over the inner end portion  352  of the lever  350 , all of which are of materials resistant to the corrosive effects of the chemicals. The sealing fulcrum  348  blocks flow of chemical into the transverse bore  320 , but even if chemical were to enter this bore, the parts therein are likewise resistant to the chemicals. When the coupling members  74  and  150  are uncoupled, thereby removing the upward pressure of the spider  78  on the valve body  302 , the bands contract, pulling the neck upwardly, and pushing the inner end portion  352  downwardly, thereby pressing the piston  308  and thus the valve body into the valve seat  172 .  
         [0065]    It will thus be understood that the valve biasing mechanism  60  (FIGS. 1, 5,  9 ) replaces the typical coiled spring, such spring being coated or uncoated metal or entirely plastic, commonly used in the fluid couplings of the type here involved. As previously briefly noted, the extractor head  50  and drum insert  52 , the poppet valve  56 , the O-rings  162  and  164 , the valve seat  172  and the fitting and all parts of the valve biasing mechanism including the piston  308 , the lever  350  (except for the embedded metallic pin  360 ), the plugs  322 ,  328 , and  361 , the bar  365 , the bands  368 , and all of the parts of the coupling  26  that come in contact with the chemicals, are all made of non-corrosive materials, such as plastic, synthetics and the like, as again described above. Thus, contact by the corrosive chemicals being carried in the fluid coupling does not deteriorate the subject fluid coupling system  25 . Not only is the subject valve biasing mechanism corrosion-resistant, it positively and dependably maintains the poppet valve closed so that it does not leak when it is intended that the valve be closed.  
         [0066]    A second embodiment of the valve biasing mechanism is generally indicated by the numeral  60 ′ in FIG. 10. This valve biasing mechanism includes a tubular piston or plunger  308 ′ slideably fitted in the main passageway  170  and having a lower end  340  with a bore that receives the upper stem  304 ′ of the valve body  302  and four holes  342  at the quadrants providing fluid passage through the piston. The piston also has an upper end adjacent to the delivery line fitting  34 . The piston has a hollow interior above the lower end and a pair of opposed, elongated, longitudinally extending lateral slots  341  opening out of the interior. An elongated anchor rod  344  extends transversely of the main passageway  170  through the slots  341  of the piston and has opposite ends  345  and  346  anchored within the extractor head  50 . Although not shown, this anchor rod may also have an embedded reinforcing pin like the pin  360 . A bar  365 ′ extends transversely of and is mounted in the upper end of the piston in upwardly spaced relation to the rod. An endless, resiliently expandable, elastic band or bands  368 ′, again collectively referred to in the singular for simplicity, extends around the bar and the rod and lengthwise in the piston.  
         [0067]    The circumference of the band  368 ′ (FIG. 10) is such that when it is relatively relaxed and in minimal tension, as when the coupling members  74  and  150  are separated, a position not shown, the band pulls the piston downwardly forcing the valve body  302  into the valve seat  172 , thereby closing the valve. This is the retracted position of the band and thus the valve closing position of the biasing mechanism  60 ′. When the coupling members are connected, causing the spider  78  to push the valve body  302  open, the band  368 ′ expands against the fixed anchor rod  352 , allowing the piston  308 ′ to be lifted by the rising valve body. This is the expanded position of the band and thus the valve opening position of the biasing mechanism  60 ′. When the coupling members are uncoupled, the band again constricts thereby pulling the piston and thus the valve body back down into closed position.  
         [0068]    The second embodiment of the valve biasing mechanism  60 ′ (FIG. 10) is also entirely made of corrosion resistant materials such as plastics, synthetics or rubber. Even with the principal parts of the valve biasing mechanism located in the main passageway  170 , the mechanism is not deteriorated by the corrosive action of the chemicals being carried and thereby dependably and reliably performs its valve closing and opening functions. This second embodiment is provided if it is preferred that the valve biasing mechanism be located directly in the path of the flowing chemicals, as is traditional with the commonly used springs.  
         [0069]    With reference now particularly to FIGS. 1, 5,  8  and  11 - 16 , the key coding system  58  of the subject invention is described. The key coding system illustrated in the drawings and described below operates on the same general principal as disclosed in the above cited Kazarian Patent No. 6,007,107 in that only axial movement of the coupling members  74  and  150  is required in order to achieve a match between the coupling members or to realize that there is a mismatch and that coupling cannot be made. Another similarity is that the subject coding system is located inside the coupling  26  and yet is not in the main fluid passageways  70 / 170 . The differences between the subject key coding system and that of the Kazarian patent include, inter alia, the reduced number and increased size of the key coding elements and the compatibility of the subject key coding system with the latching mechanism  54  of the present application without incorporating the key coding elements on the latching sleeve  205 . The advantages of these differences include dependability in operation and reduced manufacturing costs while retaining the advantage of axial only, i.e., non-rotatable, coupling.  
         [0070]    The subject key coding system  58  (FIGS. 1, 5,  8  and  11 - 16 ) is provided in the coupling ends of the male and female coupling members  74  and  150  that face each other as they are about-to-be coupled and eventually mate when coupled. Thus, the female coupling member  150  has a radial end wall having an outside diameter  402  and an inside diameter  404  and a coding groove or coding element  410 . The coding groove has inside and outside diameters  411  and  412 , an axial length or depth  414 , and a radial width  415 . The inside and outside diameters  411  and  412  are intermediate to the inside and outside diameters  404  and  402  of the end wall. One of the ways that the code of the subject key coding system is changed is by varying the dimensions of the radial end wall and the groove and of their corresponding parts of the extractor drum insert  52 . The subject key coding system of the present invention thus involves variations in the radial dimensions and radial locations of the key coding elements.  
         [0071]    Thus, a key coded insert ring  420  (FIGS. 1, 5,  8  and  11 - 16 ) is positioned in the extractor drum insert  52  and has an annular base  422  resting on the radial wall  71  and against the inside cylindrical wall  69  of the adapter fitting  66 . The ring includes an annular coding key or tongue or coding element  424  projecting upwardly from the base and having inside and outside diameters  425  and  426 , an axial length  427 , and a radial width  428 , respectively matching the inside and outside diameters  411  and  412 , the depth  414 , and the width  415  of the coding groove  410  for matching key codes. Snap fasteners  430  project downwardly from the base through the air passages  80  and snap in a groove in the radial wall  71  of the adapter fitting  66 .  
         [0072]    When the male and female coupling members  74  and  150  are moved from an uncoupled position (FIGS.  1 / 2  and FIGS.  11 / 12 ) toward a coupled position (FIGS. 5 and 10), the coupling members will fully couple when the coding key  424  matches and fits within the coding groove  410 . As stated, the inside and outside diameters  425  and  426  of the key  424  are dimensioned relative to the inside and outside diameters  411  and  412  of the coding groove so that the key fits in the coding groove  410  if there is a match. If the key does not have the location and the dimensions that correspond to the location and dimensions of the coding groove, the key and the groove will not interfit and a match does not exist, thereby preventing the coupling members from moving into their fully coupled positions.  
         [0073]    The coding groove  410  and the coding key  424  shown in FIGS. 1, 2,  11  and  12  represent one code and may be regarded as key code number  1  for the purpose of this explanation. The subject key coding system  58  provides for multiple codes since there must be a separate code for every chemical being carried in the fluid coupling  26 , perhaps fifteen to twenty chemicals. Examples of two other codes, e.g., key codes numbers  2  and  3 , are shown in FIGS.  13 - 16 , wherein different key codes are obtained by shifting the radial positions of the coding groove  410  and the coding key  424 . That is, the end wall  400  and the insert ring  420  have different matching locations and dimensions, or more generally configurations, of the groove and the key.  
         [0074]    Three such configurations of the end wall  400  of the extractor head  50  and the key coded insert ring  420  are shown by way of example in FIGS.  11 - 16 , although the subject invention provides for many more configurations. The code of FIGS.  1 / 2 ,  5  and  11 / 12  is the same, but reference is made at this point in the description only to FIGS. 11 and 12 for this code, referred to herein as code  1 . Thus, the end wall  400  has an intermediate groove  410  (FIG. 11); the end wall  400 ′ has an outside groove  410 ′ (FIG. 13); and the end wall  400 ″ has an inside groove  410 ″ (FIG. 15). Correspondingly, the ring  420  has an outside ledge  436  (FIG. 12); the ring  420 ′ has an inside ledge  438  and an outside shoulder  440  (FIG. 14); and ring  420 ″ has an outside ledge  442  and an inside shoulder  444  (FIG. 16). Another way of characterizing the key coding system in the extractor drum is that there are a plurality of inside key code rings and a plurality of outside key code rings. In the present application, there are shown two outside rings and one inside ring, representing the three codes referred to above. As an example of how additional codes are provided, the subject system also employs a second inside ring, not shown, thereby making four rings, two inside and two outside. Correspondingly, the subject system employs a second intermediate groove, or fourth groove, not shown, in the end wall  400  to match the key in the fourth insert ring.  
         [0075]    More specifically, in FIGS. 11 and 12, showing key code number  1 , the coding groove  410  is located centrally of the end wall  400 , and the coding key  424  is similarly located centrally of the annulus between the fitting  66  and the male coupling member  74 , with this outside ring against the lower wall  69  of the fitting  66  and with the ledge  436  coplanar with the seat  73  of the fitting. In FIGS. 13 and 14, showing key code number  2 , the coding groove  410 ′ is located at the outside diameter  402  of the radial end wall  400 ′, and the annular key  424 ′ is similarly located on the outside of this outside key insert ring  420 ′. The ring  420 ′ is also against the lower wall  69  of the fitting with the shoulder  440  resting on the seat  73 . The groove  410 ′ and key  424 ′ of this key code number  2  have greater diameters than the groove  410  and key  424  of key code number  1 . Thus, when the male and female coupling members  74  and  150  including key code  2  are moved towards coupled positions, the coding key  424 ′ and the coding groove  410 ′ will interfit. If a female coupling member including key code  1  were to be attempted to interfit with a male coupling member including key code  2 , however, the insert ring  420 ′ would abut the end wall  400  and interfitting could not occur.  
         [0076]    Similarly in FIGS. 15 and 16, for key code  3  in this example, the coding groove  410 ″ is located on the inside diameter  404  of the radial end wall  400 ″. The key insert ring  420 ″ is an inside ring and the coding key  424 ″ is located on the inside of the ring  420 ″ with the ring against the male coupling member  74  and resting on the lower seat  82  and with the inside shoulder  444  resting on the upper seat  84 . The coding groove and annular key of FIGS. 15 and 16 have the same locations and diameters and will interfit when the coupling members are moved together, but this groove and key will not match and interfit a key or groove of key codes  1  and  2 .  
         [0077]    From the foregoing it will be understood how multiple key codes can be provided in the subject key coding system  58  (FIGS.  11 - 16 ). By fixing the location and dimensions of the coding groove  410  and the coding key  424  radially of their respective coupling members  74  and  150 , many different matched combinations may be obtained. In addition, by varying the axial length  427  and width  428  of the key and the corresponding depth  414  and width  415  of the coding groove, even more matched combinations can be obtained. Furthermore, as explained, if the key code of the female coupling member does not match the key code of the male coupling member, including the location and radial and longitudinal dimensions of the key code elements, the coupling members will not be able to be fully coupled.  
         [0078]    As above noted, the subject key coding system  58  is compatible with the subject latching mechanism  54 , in a manner now described. With particular reference to FIGS. 1 and 2, when the male and female coupling members  74  and  150  are separated, and not being manipulated by an operator, the latching sleeve  205  will be in its fully extended position wherein the radial shoulder  220  bears against the retaining ring  145 , preventing the sleeve from falling off from the extractor head  50  and forcing the balls  200  into the latching annulus  154 , preventing coupling. Prior to attempting to connect the coupling members  74  and  150 , i.e., the extractor head  50  and the extractor drum insert  52 , the operator manually retracts the latching sleeve by moving it axially upwardly along the extractor head, as can be visualized in FIG. 1 and as is shown in FIG. 9. In order to achieve coupling, the sleeve must be pulled upwardly against the action of the spring  270  far enough to place the recessed surface  232  opposite to the latching balls  200 , as shown in FIG. 9, allowing them to be moved out of the latching annulus. In this position, air exits the port  230  and can be felt on the operator&#39;s hands grasping the extractor head  50   
         [0079]    The operator then moves the extractor head  50  (FIGS. 9, 1,  2 ,  5 ) and thus the female coupling member  150  toward and over the male coupling member of the extractor drum insert  52 . If the coding groove  410  and coding key  424  match as they do in FIGS. 1 and 2, for example, the key will slip into the coding groove thereby allowing the latching annular  154  to be moved over the latching ring  110  and bringing the latching balls  200  into alignment with the latching groove  112 . The balls can then be moved into the latching groove  112  by releasing the sleeve and allowing the spring to force the latching sleeve downwardly on the extractor head. Downward movement of the sleeve causes the bearing surface  224  to force the balls into the latching groove, precluding their movement outwardly of the latching groove, and retaining them therein. As such, the coupling members are latched together in coupled condition whereby the poppet valve  56  is opened by the spider  78  against the action of the biasing mechanism  60  or  60 ′ as above explained.  
         [0080]    If, for example, coupling of a mismatched extractor head  50  and drum insert  52  (e.g., FIGS. 12 and 13) is attempted, following the sequence described in the preceding paragraph, the coding groove  410 ′ will not fit on or over the key  424 , the latching groove  112  in the latching ring  110  cannot be brought into alignment with the latching balls  200 , and the latching sleeve cannot be extended. That is, in attempting to make any mismatched coupling, the latching annulus can be brought down far enough to place the balls  200  opposite to the upper end of the latching ring, above the latching groove  112 , but no farther because of the interference of the mismatched key code elements. As such, the latching sleeve cannot move downwardly far enough the place the bearing surface  224  opposite to the balls since the shoulder  220  will engage the balls that are at this time precluded from retracting into their holes  140  by the presence of the upper end of the latching ring. Thus, the mismatched key and groove  424  and  410 ′ will prevent the coupling of the members  74  and  150  and will prevent the latching sleeve  205  from moving downwardly into a latching position. Accordingly, the operator will still feel air exiting from the port  230 , signaling that a mismatch is involved and that the wrong delivery lines are being attempted to be coupled to that drum.  
         [0081]    To review this air signal in the subject fluid coupling system  25  (FIG. 9), when the latching sleeve  205  is retracted, the venting recess  229  is brought into registration with the air duct  198 , causing air to flow through the air port  230  onto the operator&#39;s hands. This flow of air continues as long as the coupling members  74  and  150  are not fully interfitted and latched. However, when latching does occur, the sleeve  205  is allowed to move fully downwardly into its latching position thereby moving the venting recess out of registration with the air duct, cutting off the flow of air through the port, positively signaling to the operator that a match and latched condition has been achieved.  
         [0082]    In the foregoing description, it will be understood that coupling of the extractor head  50  and the drum insert  52  is achieved without twisting or swiveling of the extractor head or of the hoses, not shown, connected to the delivery line and air line fittings  34  and  36 . Nevertheless, swiveling is accommodated if the natural position of the hoses forces twisting, such as an untwisting action of the hoses. The latching sleeve  205  is allowed to rotate on the extractor head but such rotation is not necessary either to couple the coupling members  74  and  150  or to latch the same in their coupled positions. The subject fluid coupling system  25  allows for ease of operator action because the operator merely grasps the knurled actuating surface  216  with both hands thereby to squeeze the latching sleeve up against the upper shoulder  127  of the extractor head. This action is taken prior to attempting to couple the coupling members, but also when it is desired to uncouple the coupling members. In the later case, the upward squeezing of the latching sleeve causes the recessed surface  232  to be opposite to the balls  200  whereupon they can move outwardly from the groove  112  and whereupon the valve body  302  is forced into a sealing relation with the valve seat  172  under the action of the biasing mechanism  60  or  60 ′. Moreover, this coupling and uncoupling and latching and unlatching are achieved without any threaded or unthreading of the parts. The coupling, with the possible exception of the isolated spring  270  can be entirely and effectively molded out of chemically-resistant plastic as described, thus not only improving the dependability of the system but also minimizing manufacturing costs.  
         [0083]    Although preferred embodiments of the present invention have been shown and described, various modifications, substitutions and equivalents may be used therein without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.