Beer dispensing instrumentalities and method
United States Patent [191 Nezworski lll] 3,878,970  
 [451 Apr. 22, 1975 BEER DISPENSING INSTRUMENTALITIES AND METHOD [21] Appl. No.: 441,140  
 [52] US. Cl. 222/61 [51] Int. Cl 867d l/04 [58] Field of Search 222/64, 55, 56, 65, 66,  
 [56] References Cited UNITED STATES PATENTS Hixon et al. l37/266 3.l94,434 7/l965 Evanson 137/256 X Primary Examiner-Stanley l-I. Tollberg 5 7 ABSTRACT A method of dispensing beer out of a single faucet from one, or from a number of kegs separately connected by suitable duets with a header communicating with the faucet. A control valve device for each keg has a chamber forming a part of its duct. Float valves, one in each chamber, are operable upon decrease in the amount of fluid in their chambers to interrupt communication between the chamber outlets and the header. Differential pressure actuated valve means in each chamber functions to interrupt communication between its interior and the chamber inlet in response to decrease in pressure at said inlet.  
 21 Claims, 6 Drawing Figures PATENTED APR22 I975 SHEET 3 if M50461 d0 Pm03 u OP BEER DISPENSING INSTRUMENTALITIES AND METHOD BACKGROUND OF THE INVENTION This invention relates to apparatus for dispensing liquids from pressurized containers thereof. and has more particular reference to beer dispensing systems.  
  Multiple barrel beer dispensing systems are now in widespread use because of their convenience to the bartenders and other persons who dispense beer. With a number of barrels, or kegs, supplying a common faucet, tapping need not be performed as frequently as when but one barrel at a time is connected to the faucet. In fact, it is often possible with multiple barrel dispensing to leave the tapping chore to the delivery man who usually calls on his customers in accordance with a prearranged schedule to substitute full kegs for emp-&#39; ties.  
  However, all multiple barrel dispensing systems in use in the past have had serious disadvantages.  
  In the most widely used multiple barrel dispensing system heretofore employed, the kegs were connected in series between the dispensing faucet and the source of gas pressure. As a result, the beer flowing from each keg to the adjacent downstream keg had to be introduced into the latter through the gas passage of its tapping device.  
  With tapping devices such that of the Taubenheim US. Pat. No. 3,596,810, satisfactory dispensing of beer from multiple barrel series type dispensing systems was possible because the gas and beer passages in those tapping devices were arranged concentrically with respect to one another. This enabled the gas passage in those tapping devices to have a cross sectional area large enough to enable beer to flow through it without being unduly restricted.  
  The widely used Hoff-Stevens tapping devices of the Stevens, Jr. US. Pat. No. 3,228,413, however, have the gas and beer passages formed by side-by-side parallel bores, and as a result the gas passage is too small to satisfactorily accomodate the flow of beer. Consequently, connection in series of a number of beer kegs equipped with Hoff-Stevens tapping devices so seriously reduced beer dispensing rates as to render such a system completely unacceptable, even with objectionably high gas pressure on the endmost keg of the series.  
  It is this objection to the Hoff-Stevens tapping de vices which led to the development of a multiple keg beer dispensing system in which the several kegs are individually connected with the source of gas under pressure, and their beer passages are selectively and separately connectable with a single faucet through an electrically operated multiport distributor valve mechanism having manual selector means remote therefrom but readily accessible to the bartender at the dispensing station behind the bar. Thus, whenever one keg becomes empty, the bartender actuates the selector means to effect disconnection of the empty keg from the faucet and connection of a full keg with the faucet.  
  But that selector valve system has a serious objection in addition to its high cost. As in all single barrel dispensing systems, a considerable amount of beer in the supply line leading to the faucet is lost each time a keg connected therewith empties. When that occurs, the supply line fills with an excessively foamy and unsaleable product, and issue thereof from the faucet constitutes the only warning that the empty keg must be replaced by a full one; as through the selector valve of the new system.  
  The only way to purge the foam from the supply line was to draw fresh beer from the newly connected keg. Since supply lines feet or more in length are not uncommon, considerable time was spent in such purging, along with the loss of a substantial amount of beer.  
 SUMMARY OF THE INVENTION With these objections and observations in mind, it is a purpose of this invention to provide an improved method of dispensing beer from one or from a number of barrels thereof, the practice of which method eliminates the objections to and disadvantages of past dispensing systems as well as those presently in use.  
  More particularly, it is an object of the invention to provide a beer dispensing system which features a novel control valve device for each barrel ofa beer dispensing system, which for the first time makes possible the advantageous connection of a number of barrels in parallel with the supply line leading to the dispensing faucet.  
  It is another purpose of the invention to provide novel control valve means by which one or a plurality of beer kegs can be connected with a faucet in a system far superior to any heretofore available.  
  With these observations and objectives in mind, the manner in which the invention achieves its purpose will be appreciated from the following description and the accompanying drawings, which exemplify the invention, it being understood that changes may be made in the precise method of practicing the invention and the specific apparatus disclosed herein without departing from the essentials of the invention set forth in the appended claims.  
  The accompanying drawings illustrate several complete examples of the embodiments of the invention constructed according to the best modes so far devised for the practical application of the principles thereof, and in which:  
  FIG. 1 somewhat diagrammatically illustrates a system which is typical of the parallel type multi-keg beer dispensing method of this invention;  
  FIG. 2 is a sectional view through one of the control valve devices, taken on the line 2-2 of FIG. 1;  
  FIG. 3 is a diagrammatic view of the control valve devices which make possible the parallel connection of a number of beer barrels with a single faucet, indicating the valve devices as housed in a single body;  
  FlG. 4 is a fragmentary sectional view illustrating the way in which the control valves can be gang connected, with their outlets providing a common delivery header; and  
  FlGS. 5 and 6 are modified types of control valve devices in which solenoid type outlet valves are employed.  
  Referring now to the accompanying drawings, the numeral 10 generally designates a walk-in cooler containing a battery of beer kegs ll, 12 and 13. Ducts 14, one for each keg, connect the tapping units 15 of the individual kegs with a common supply line 16 leading to a faucet 117. A dispensing system comprising three kegs has been shown by way of example only, as this invention makes possible connection of several more with the supply line, if desired.  
  Carbon dioxide gas under pressure, from a cylinder not shown, is supplied to the gas passage in each tapping unit through its nipple 18 and a tube 19 connecting the tapping unit with a common gas supply line 20. A shut-off valve V is connected in each of the tubes 19.  
  According to this invention, the kegs or barrels are communicated with the beer supply line 16 leading to the faucet 17 through control valve devices 25, one for each barrel, having a chamber 26 inits interior forming in effect a part of the duct 14 by which its barrel is communicated with the beer supply line. Since these control valve devices are identical, a description of one will suffice for all.  
  The control valve device comprises a body 27 which, for example, can be made of complementary upper and lower body sections 28 and 29, respectively, having telescoping parts held together by screws 30 and sealed against leakage by an O-ring 31. The body can, if desired, be of rectangular or square cross section, and it is elongated vertically, with its chamber 26 in an upright position.  
  An inlet 33 opens laterally to the top of the chamber, and an outlet 34 opens downwardly from its bottom into a crossbore 35 in the lower portion of the body, which crossbore extends entirely therethrough from one side of the body to the other.  
  As shown in FIG. 1 and indicated in phantom lines in FIG. 2, the several valve devices 25 are mounted in a holding bracket 36 which is adapted for attachment to one of the walls 37 of the walk-in cooler at a location near the barrels, and in a way that leaves a space 38 behind the bracket. The inlets 33 of the valve devices open rearwardly toward the wall 37 to enable the ducts 14 from the barrels to be run up through the space 38 and have concealed connections (not shown) with the valve inlets 33.  
  It should be noted that the valve devices have been illustrated as separate self-contained units, much as sectional hydraulic valves which are stacked together in a bank. However, they can also comprise the desired number of valve mechanisms contained in a housing common to all of them, as seen more or less diagrammatically in FIG. 3.  
  In the present case, the valve bodies are confined by the walls of the holding bracket 36 in snug side-by-side relationship, with their crossbores in register with one another. Annular couplers 39 seen best in FIG. 4, have their opposite axial ends received in counterbores 40 to which the crossbores open. O-rings 41 encircling the end portions of the couplers establish leakproof seals between the crossbores of each pair of adjacent valve bodies.  
  The bores 42 of the couplers provide uninterrupted communication between the crossbores, so that they can be said to cooperate in the provision of an outlet manifold or header 43 common to all the control valve devices.  
  The supply line 16 is coupled to the header at the right hand end of the bank of valves by any suitable connecting means 44. The counterbore in the other end of the header is closed by a removable plug 45, held in place by the adjacent end wall 46 of the holding bracket 36 or in any other suitable way.  
  From the description thus far, it will be seen that the kegs 11, 12 and 13 are connected in parallel with the beer supply line 16, so that it is possible for beer from any one of the kegs to enter the inlet 33 of its associated control valve device and flow down through the chamber 26 therein to the outlet manifold 43 defined by the crossbores 35 in the valve bodies and the connecting couplers 39.  
  Such flow through any one of the valve devices, however. can only take place at times when the faucet 17 is opened, and a hollow float member 47 in the valve chamber 26 is in what can be termed a neutral or floating position, between upper and lower limits of mo&#39;Jon within said chamber. Preferably the float member has ears 47&#39; projecting from its sides to engage the side wall of the valve chamber and keep the float member centered therein.  
  The upper and lower limits of float motion are defined by the top and bottom annular valve seats, 48 and 49, respectively, in each chamber 26, through which beer entering the chamber must flow to reach its outlet 34. An O-ring 50 encircling the upper portion of the float 47 is engageable with the upper seat 48 to close off communication between the inlet and outlet of its chamber. In like manner, a similar O-ring 51 encircling the lower portion of the float is engageable with the bottom seat 49 to disrupt communication between the inlet and outlet of the chamber.  
  It will be noted that the valve seat 48 is defined by an upwardly convergent conical wall surface in the upper portion of the chamber 26; and that the lower valve seat 49 is similarly defined by a downwardly convergent substantially conical wall surface in the bottom portion of the chamber.  
  At the time the beer dispensing system of this invention is initially placed in use, beer under pressure in the kegs will not flow through the chamber 26 of any of the control valve devices to the beer supply line 16 for the reason that keg pressure at the inlets of the control valve devices will hold the float valves 47 thereof downwardly in their outlet closing positions.  
  For this reason, at least one of the control valve devices must be provided with a plunger mechanism 53 by which the float therein can be manually lifted off of its lower seat 49. This plunger mechanism comprises a plunger 54 which extends through a downwardly opening hole 56 in the bottom of the valve body, coaxial with but smaller in diameter than the outlet port 34. The outer end of the plunger is fixed to the end wall of a cup shaped cap 56 having its side wall telescopingly engaged over the side wall of a smaller cup 57 whose end wall is in engagement with the underside of the valve body and has a central aperture therein to receive the plunger. A spring 58 encircling the outer end portion of the plunger is confined between the end walls of the two cups 56 and 57 to thereby yieldingly urge the plunger downwardly to an inoperative position defined by the engagement of a collar 59 on its inner end with the shoulder formed by the function between the outlet port 34 and the smaller diameter hole through which the plunger passes.  
  A reduced upper end portion 60 on the plunger projects into the outlet port 34 toward the underside of the float member 47, but terminates a slight distance short of it when the float is in its downward limit of motion engaging seat 49.  
  It will thus be seen that upward manual actuation of the cap 56 will engage the upper end portion 60 of the plunger with the float member and lift it off of its seat 49. When this is done, beer from the inlet 33 in that valve device whose float has been thus lifted will flow into the chamber 26 thereof and beneath the float member to the crossbore 35 thereunder, and hence to the outlet manifold 43. The plunger mechanism 53 can then be released, for the pressures in the upper and lower (inlet and outlet) portions of all the valve chambers 26 will at that time be equalized to allow the float valves to assume floating positions intermediate their upper and lower limits. This is to say that the buoyancy of the float valve in each control valve device will then hold it in its neutral position.  
  All three kegs are thus simultaneously in parallel with the outlet manifold 43 and beer supply line 16. For well known reasons, however, beer will first flow from and empty the keg 13 which is closest to the faucet. The keg 12 next in line will be the second to empty, and the keg 11 will be the last.  
  It is one of the features of the dispensing system of this invention that the float valve in each of the control valve devices will remain in its neutral position as long as beer fills, or is at a high level in its chamber 26.  
  As soon as keg l3 empties, for example, the duct l4 connected therewith will fill with a non-liquid gas and foam emulsion, and the liquid level in the chamber 26 of its associated control valve device will descend. When it reaches a low level designated L in FIG. 3, its float valve will engage the lower seat 49 and close off the chamber from the outlet manifold and supply line 16. It is important to observe that this will occur before all of the liquid beer has left the chamber 26.  
  This seated condition of the float valve can be observed, for example, by having at least the lower section 39 of each valve body made of clear plastic material, and by applying a suitable coloring (red or orange) to the float member 47 therein. Merely by way of example, the hollow float member has been shown as having a cylindrical wall also of clear plastic, with an orange strip 61 of paper or the like confined in its lower interior portion to be readily visible therethrough.  
  When any float is in its lowermost position, its colored portion can be seen through a suitable cut-out forming a window 62 in the front wall of the holding bracket 36 in which the valve devices are mounted.  
  As soon as the keg 13 is emptied, therefore, the float in its associated control valve will close off the outlet of the chamber therein. as shown in FIGS. 3. This prevents gas in the keg from entering the supply line 16 and creating the foamy condition in the beer in said line that heretofore rendered the beer unusable. Beer from the second keg 12 will automatically then be dispensed as required, without loss or deterioration of the beer in the supply line 16.  
  Though not essential at this time, the tapping unit can then be removed from the keg l3 and installed in a fresh keg of beer.  
  During the time the empty keg 13 remains connected by its duct 14 with the chamber of its associated control valve, gas pressure from the manifold will act upon the float valve 47 in said chamber to firmly hold it in its outlet closing position against the equal pressure of beer in the crossbore 35 beneath the float valve. This is possible because the area at the top of the float valve exposed to gas pressure is substantially greater than the area at the underside of the float valve exposed to pressure of beer in the outlet manifold.  
  At the time the tapping unit is to be removed from the empty keg 13, the valve V in the gas line leading to that keg is first closed. As a result, the upper chamber portion of the associated control valve device will then no longer be communicated with the source of gas under pressure. Consequently, the float valve will be immediately driven upwardly to its inlet closing position in response too the pressure of beer in the manifold 43. The upwardly seated float valve will then prevent beer under pressure in the manifold from reaching the inlet 33 of the control valve device associated with the empty keg 13.  
  Upon replacement of the empty keg 13 with a fresh one, there will be a small amount of foam in the short duct 14 connecting it with the inlet of its control valve device. According to this invention, such foam present in the duct 14 after the new keg has been installed can be quickly eliminated by depression of a second plunger mechanism 65 on the associated control valve device, there being one required on the top of each. The plunger mechanism 65 is generally like the mechanism 53 described earlier, except that depression of its plunger 66 disengages a valve member 67 from a seat against which it is spring urged, to thereby establish communication between the upper or inlet portion of chamber 26 and a vent port 68. The inner end 69 of the plunger is reduced in diameter, and long enough that when depressed, it will force the float valve off of its upper seat 48 for a purpose to be later discussed.  
  The plunger mechanism 65 need only be held depressed for a second or two, which is ordinarily long enough to enable pressurized liquid from the new keg to expel the foam from its short duct 14 and from the upper portion of its valve chamber. As seen best in FIG. 1, the vent ports 68 can, if desired, be connected with a common waste line 70.  
  It is believed to be obvious from the description thus far, that neither keg 12 nor 13, when emptied, need be at once replaced with a fresh keg. The contents of the third one ll of the three parallel connected kegs will. of course, be available for dispensing from the faucet when the kegs l2 and 13 become empty.  
  The valve devices described are constructed in a way that facilitates cleansing thereof and of the ducts 14 and 16 connecting therewith. For such cleansing, the kegs are disconnected from the system, either by detachment of the outer components of their tapping units 15 or by detachment of the ducts 14 from said outer tapping components.  
  To clean the manifold and supply line 16, the plug 45 at the dead end of the manifold can be replaced by an adapter to enable cleansing liquid under pressure to be directed into the manifold. When the faucet is then opened, cleansing liquid will flow through the manifold and the duct 16, and discharge from the faucet.  
  If the faucet is then closed, depression of each of the plunger mechanisms 65 in turn, will cause cleansing liquid in the manifold to flow up through the associated valve chamber 26 for discharge of part of the liquid through the vent port 68 and drain line 70, and the remainder of the liquid through the associated duct 14, providing the latter is disconnected from its keg. This, of course, will enable the chambers 26, the drain line 70, and the ducts 14 to be cleaned.  
  Such cleansing of the mechanism and ducts can also be accomplished with the manifold plug 45 in place, by introducing the cleansing liquid into the system through the faucet l7. If the outer tapping components or coupler&#34; are of the type disclosed in the Taubenheim US. Pat. No. 3,596,810 issued Aug. 3, 197 l they as well as the ducts l4 connecting therewith can be cleansed in the manner described providing the check valves in the couplers are held open to allow cleansing fluid to discharge past them.  
  lnasmuch as thorough cleaning of the interior of each control valve device will entail passage of cleansing liquid through its chamber for a more or less extended period of time, the plunger mechanisms 65 are preferably provided with latch mechanisms, generally designated 75, to enable them to be releasably held in depressed condition.  
  Each such latch mechanism 75 has been shown as comprising a screw 76 threaded downwardly into the top of the valve body alongside the cap 77 of the plunger mechanism. An upwardly facing ledge 78 on the cap 77 is engageable under the head 79 on the screw to hold the plunger mechanism in its depressed condition.  
  The head 79 of the screw is normally received in a depression 80 in the side of the cap, which depression constitutes a localized interruption in the ledge 78. For this reason, the cap must be turned slightly after it has been fully depressed, to bring an uninterrupted portion of its ledge under the screw head. To release the plunger mechanism from the latch, it is only necessary to turn the cap 77 to the position at which its depression 80 registers with the head 79 of the screw. The spring acting upon the plunger mechanism will then return it to its outward position at which it closes off the chamber 26 from the vent port 68.  
  In cases where the components of two or more complete systems such as illustrated in FIG. 3 require cleaning, their valve devices and outlet manifolds can be cleansed simultaneouly by connecting the latter either in series or in parallel with the source of cleaning liquid under pressure.  
  It should here be emphasized that because the beer kegs are connected in parallel with the beer supply line 16 and with the gas pressure source, the dispensing system of this invention can comprise more than the three kegs shown in the drawings by way of example, as long as each keg has its own control valve device 25.  
  Moreover, the system of this invention is ideally suited for dispensing beer from single keg installations. This follows from the fact that the float valve in the control valve device for the single keg will descend to its downwardly seated position as soon as the level of beer in its chamber 26 drops to the level where it will no longer float the valve. As mentioned earlier, this must occur before all of the beer has left the chamber, to prevent the beer in the supply line from becoming foamy and unusable, as it does in conventional dispensing systems, with attendant loss of profit, at the time the keg connected therewith becomes empty.  
  The modified embodiments seen in FIGS. and 6 also provide for dispensing of liquids under pressure. such as beer, in accordance with the method of this invention. Briefly stated, this method is characterized by flowing beer (or other liquid under pressure) downwardly through a chamber to a faucet connected beer supply line, and interrupting communication between the inlet and outlet of the chamber at such times as the liquid therein falls to a predetermined low level.  
  In FIG. 5, a control valve device 90 which&#39;will perform this important step of the method in a single barrel installation, is characterized by a normally closed electromagnetic valve 91 in the outlet 92 from its chamber 93. The chamber has an inlet port 94 in an upper portion thereof, to enable downward flow of beer therethrough, providing the electromagnetic valve 91 is open.  
  The solenoid 95 of the valve 91 is energizable from a current source 96 whenever a pair of electrodes 97, 98 is electrically bridged by beer in the chamber 93. These electrodes are located opposite one another, about one-half way between the inlet 93 and outlet 92. When bridged in this manner, an energizing circuit is completed for the solenoid 95 to effect opening of valve 91. This enables beer to flow through a supply line connected with the outlet 92, to a faucet for dispensing as desired.  
  The valve 91 will remain open as long as the chamber is filled with beer. When the beer barrel empties, the level of beer in the chamber 93 will fall until the electrodes 97, 98 are no longer electrically bridged thereby. When that occurs, the energizing circuit for the solenoid 95 is broken, and the valve&#39;9l returns to its normally closed position while there is still a small amount of beer in the chamber. This is an important feature of the invention, as it prevents foam formation in the supply line leading to the faucet from the outlet 92 of the control valve device, and thus assures against loss of the beer therein.  
  A plunger mechanism is also mounted on the top of the valve body, to provide for venting the upper portion of the chamber 93 for the reasons discussed hereinbefore.  
  It will be seen therefore, that the valve device is like those previously described in that its outlet is controlled by valve means at the dictate of detector means (electrodes) under the control of the liquid level in the chamber 93. The float in the first described embodiment of the invention similarly constitutes detector means having the same purpose.  
  The control valve device 190 of FIG. 6 also features an electromagnetic valve 100 to control flow of beer through the outlet 101 of the chamber 102 in the interior of the device. Again in this case, a beer inlet port 103 opens to the top of the chamber to enable beer to flow downwardly therethrough for discharge through its outlet 101 providing the electromagnetic valve 100 is open.  
  The valve 100 is of the normally open type, and it is adapted to close upon establishment of an energizing circuit for its solenoid 104. The solenoid is in an energizing circuit controlled by a reed switch 106, which extends coaxially down into the chamber 102 from its top. The contacts of the reed switch are normally open, and are closed by the field of a permanent magnet 107 here shown as mounted in the bottom portion of a float 108 which encircles the envelope of the reed switch.  
  Beer in the chamber 102 normally raises the float 108 to a level such as shown, at which its magnet has no influence upon the contacts of the reed switch. The switch thus remains open as long as beer in the chamber is at a level well above the outlet 10].  
  The level of beer in the chamber will descend, as the beer keg connected therewith becomes empty. At that time, the float 108 will likewise descend, until its magnet 107 comes opposite the contact ends of the arms in the reed switch. When that occurs, the switch closes to energize the solenoid 104 and effect closure of the valve 100. Such closure of the valve 100 will again occur before the level of beer in the chamber 102 drops far enough to cause foaming of the beer in the outlet l] and the supply line connecting the same with a faucet.  
  Here again, the magnetically controlled reed switch constitutes detector means on the order of the float type of level detector in the first described embodiment of the invention; and a plunger mechanism 65&#39; is also provided to effect venting of the space in the upper portion of the chamber 102, whenever necessary.  
  From the foregoing description. together with the accompanying drawings. it will be readily apparent to those skilled in the art that this invention provides a vastly improved dispensing system for beer and other liquids under pressure.  
 The invention is defined by the following claims:  
  1. A control instrumentality to govern communication of a dispensing device with a container holding liquid under pressure, characterized by:  
 A. means defining a chamber through which liquid from the container must flow to reach a dispensing device, said chamber having inlet and outlet means in upstream and downstream portions thereof, respectively, to provide for such flow;  
 B. first valve means adjacent to the chamber outlet means to govern flow of liquid out of the chamber;  
 C. means to govern actuation of said valve means between open and closed positions, comprising detector means sensitive to the presence and amount of liquid in the chamber for effecting opening of said valve means in consequence ofliquid in the chamber above a predetermined level. and to effect closure of said valve means in consequence of decrease in the amount of liquid in the chamber to a lower level that leaves it only partially filled with liquid;  
 D. second valve means to control communication between the chamber and the inlet means;  
 E. and means to effect closure of said second valve means in consequence of drop in pressure at the inlet means to a valve below that prevailing at the outlet means.  
 2. The control instrumentality of claim 1, further characterized by:  
 A. said inlet and outlet means comprising opposing valve seats in top and bottom portions. respectively. of the chamber;  
 B. said detector means comprising a float member in said chamber;  
 C. and said first and second valve means comprising valve members carried by the float member, at top and bottom portions thereof, for cooperation with said valve seats.  
 3. The control instrumentality of claim 2, further characterized by:  
 A. said chamber having walls defining a valve body;  
 B. and means on the body by which said float member can be manually lifted to effect opening of the outlet means.  
  4. The control instrumentality of claim 2, further characterized by manually operable means for venting the upper portion of the chamber.  
  5. A control instrumentality to govern communication ofa dispensing device with a plurality of containers holding liquid under pressure, characterized by:  
 A. means defining a plurality of chambers. one for each container. through which liquid from its container must flow to reach a dispensing device, each chamber having inlet and outlet ports in upstream and downstream portions thereof, respectively, to provide for such flow;  
 B. means providing a common header connecting said outlet ports, through; which liquid can flow to a dispensing device;  
 C. first valve means adjacent to the outlet port of each chamber, between said chamber and the header;  
 D. means to govern actuation of said first valve means between open and closed positions, comprising detector means sensitive to the presence and amount of liquid in the chamber, for effecting opening of said first valve means in consequence of filling of the chamber with liquid, and to effect closure of said first valve means in consequence of a predetermined decrease in the amount of liquid in said chamber;  
 E. and second valve means for each chamber, adjacent to its inlet port, to effect closure thereof in consequence of drop in pressure at said inlet port to a value below that prevailing in the header.  
 6. The control instrumentality of claim 5, further characterized by:  
 A. said inlet and outlet ports of each chamber comprising opposed upper and lower valve seats, respectively;  
 B. said detector means comprising a float member in each chamber;  
 C. and said first and second valve means comprising valve members carried by each float member. at top and bottom portions thereof. for cooperation with the valve seats.  
 7. The control instrumentality of claim 6. further characterized by:  
 A. manually operable means for effecting venting of the upper portions of each of each chambers;  
 B. and manually operable means for lifting the float member in one of said chambers from a position. closing its outlet port to a position at which its outlet port is open.  
 8. In combination with the control instrumentality of claim 1:  
 A. said container comprising a beer keg under carbon dioxide gas pressure;  
 B. a first duct connecting the outlet of said keg with the inlet means of said chamber;  
 C. a faucet from which beer can be dispensed;  
 D. a second duct connecting the faucet with the outlet means of the chamber;  
 E. and said first valve means, when closed, serving to prevent gas from entering said second duct.  
 9. In combination with the control instrumentality of claim 5:  
 A. a plurality of beer containers under carbon dioxide gas pressure;  
 B. a faucet common to said containers, from which beer therein can be dispensed;  
 C. a plurality of supply ducts, one for each container to connect the outlet thereof with the inlet port of its associated chamber;  
 D. a supply line connecting said header with the faucet;  
 E. and said second valve means of one of said chambers being actuatable to its inlet closing position under the influence of fluid pressure in the header at times when the container associated with said one chamber is being replaced by a full container.  
  10. The combination of claim 9, further characterized by means providing a signal to indicate when said outlet ports are closed by said first valve means.  
  11. The combinations of claim 10, further characterized by:  
 A. said first valve means for each chamber being located therein and having indicia thereon;  
 B. and each chamber having a transparent wall portion located to enable the indicia on said first valve means therein to be viewed when the latter is in its closed position.  
  12. A control instrumentality to govern communication ofa dispensing device with a container holding liquid under pressure, characterized by:  
 A. a body having a chamber with an inlet for connection with a container of liquid under pressure, and an outlet for connection with a dispensing device;  
 B. valve means adjacent to the outlet of said chamber for governing flow of liquid through the outlet;  
 C. means governing opening and closing of said valve means. comprising detector means influenced by the presence and the amount of liquid in the chamher, and adapted to effect opening of said valve means in consequence of liquid filling the chamber to a high level and to effect closure of the valve means in consequence of decrease in the volume of liquid in the chamber by an amount which leaves it only partially filled with liquid at a lower level;  
 D. and manually operable means for effecting venting of the chamber at a location adjacent to its inlet.  
 13. The control instrumentality of claim 12, further characterized by:  
 A. said valve means comprising an electromagnetic valve which is closed except upon completion of an energizing circuit therefore;  
 B. and said detector means comprising a pair of electrodes which project into said chamber to provide for the establishment of an energizing circuit for said electromagnetic valve when liquid in the chamber completes an electrically conductive path between the electrodes.  
 14. The control instrumentality of claim 12, further characterized by:  
 A. said valve means comprising an electromagnetic valve which is open except upon completion of an energizing circuit therefor;  
 B. and said detector means comprising a reed switch instrumentality having its contact end in said chamber, a float in the chamber. and a permanent magnet carried by said float to effect closure of the reed switch and establishment of an energizing circuit for the electromagnetic valve upon descent of the float to a predetermined low level in the chamber.  
 15. The control instrumentality of claim 12, further characterized by:  
 A. said valve means comprising an electromagnetic valve;  
 B. and an energizing circuit for said electromagnetic valve, controlled by said detector means.  
 16. The combination with a container of pressurized liquid, a faucet, and duct means communicating the faucet with the container, of control instrumentalities operable to interrupt communication of said container with the faucet when the volume of liquid in the container is reduced to a predetermined minimum, said control instrumentalities comprising:  
 A. a valve body having a chamber forming a part of said duct means, and having inlet and outlet means opening to the chamber and respectively communicating with said container and with the dispensing means;  
 B. a valve seat in the chamber, between said inlet and outlet means;  
 C. valve means movable to and from engagement with said valve seat to thereby close off communication between the container and the dispensing means; 7  
 D. the chamber being filled with liquid when that length of the duct means connecting the chamber with the container is filled, and the volume of liquid in the chamber diminishing when said length of the duct means is no longer filled with liquid;  
 E. means responsive to a predetermined decrease in the volume of liquid in said chamber to effect seating of said valve means;  
 F. and means on the body providing for manually disengaging said valve means from its seat.  
 17. The combination of claim 16, further characterized by:  
 A. other valve means in the chamber movable toward and from a position closing the inlet means thereof;  
 B. said other valve means being pressure responsive and being actuatable to closed position whenever pressure at the inlet means drops to a value below the pressure at the outlet means.  
  18. In combination with a container of liquid under pressure and dispensing means for said liquid including duct means connectng the same with the container:  
 A. means providing a chamber which is connected in said duct means to form a part thereof;  
 B. valve means in said duct means adjacent to the downstream-side of said chamber, movable to and from a position closing said duct means;  
 C. means governing opening and closing motion of said valve means, comprising detector means located in said chamber to be influenced by the amount of liquid therein, and adapted to effect opening of said valve means in consequence of liquid filling said chamber and to effect closure of said valve means in consequence of a predetermined decrease in he amount of liquid in said chamber;  
 D. and manually operable means for effecting venting of the upstream side of said chamber.  
  19. A method of controlling communication ofa plurality of containers holding liquid under pressure with a common header from which the liquid can be dispensed, which method is characterized by:  
 A. for each container, providing a chamber which has an inlet port in an upper portion thereof, an outlet port in a lower portion thereof, a buoyant valve device to close the outlet port when the liquid level in the chamber drops to a predetermined low, and to close the inlet port whenever outlet port pressure exceeds inlet port pressure;  
 B. ducting the inlet port of each chamber with the outlet of its container whereby liquid therefrom will be able to flow to the outlet port of its chamber as long as equal liquid pressures prevail at the inlet and outlet ports thereof;  
 C. and communicating the chamber outlet ports with the header, and with one another, whereby pressurized liquid in the leader will be capable of holding the valve device in one of said chambers in an inlet closing position at times when its associated container is being replaced by a full container and pressure is relieved at the inlet port of said one chamber.  
  20. A method of dispensing liquid through a common dispensing means from a plurality of pressurized containers for said liquid, which method comprises:  
 A. for each container. providing a control valve having a hollow body. an inlet port; an outlet port, and a movable valve member engageable with a seat to close off communication between the said ports;  
 B. ducting each container with the inlet port of its respective control valve so that the interior thereof is full of liquid as long as the ducting for said container is filled with liquid;  
 C. commonly connecting the outlet ports of said control valves with a supply line that leads to the dispensing means, so that as long as the movable valve member of one of said control valves is off its seat, pressurized liquid is available at the dispensing means;  
 D. and in response to reduction in the volume of liquid in the interior of each control valve, effecting seating of its respective valve member, so that with the emptying of the last to empty container, the dispensing means is no longer communicated with any of the containers but the supply line leading from the control valves to the dispensing means remains filled with liquid.  
  21. A method of controlling communication of a plurality of containers holding liquid under pressure with a supply line from which the liquid can be dispensed, which method is characterized by:  
 A. constraining liquid from each container to flow through a separate chamber having its outlet connected with the supply line;  
 B. closing the outlet of each chamber at times when the level of liquid therein reaches a predetermined low level above the chamber outlet;  
 C. and closing the inlet of any one chamber at times when pressure at said inlet falls to a value below the pressure of liquid at the outlet of any other chamber.