A vacuum breaker having inlet port arrangements for accepting either a single input flow or multiple input flows, and adapted to vent multiple input flow substantially independently of one another, and further adapted for mounting within the open upper ends of waste standpipes of different diameters.

BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a vacuum breaker having a universal inlet port, a one port embodiment for handling a single high rate fluid flow, and a two port embodiment for handling a plurality of low rate fluid flows, as in a dialysis unit application for venting to atmosphere both patient waste fluids and reverse osmosis (RO) waste water, the vacuum breaker further having a universal mounting arrangement for location of the vacuum breaker inside the upper ends of either relatively small or relatively large standard size waste standpipes. 
     2. Description of the Prior Art 
     Prior art vacuum breakers that discharge into a waste standpipe usually are mounted by forcing them onto the upper end of the standpipe, deforming the material of which the vacuum breaker is made to provide a clamping action. This makes them susceptible to tipping and inadvertent detachment. Furthermore, the clamping force must be overcome to remove them from the standpipe, which slows the process of removing one vacuum breaker and substituting another. This is a particular problem in an installation where a plurality of vacuum breakers are in use, such as in an installation comprising many dialysis units. 
     Dialysis units perform a well known function in various applications. In particular, such a unit filters the blood, essentially performing for the dialysis patient that which the kidneys do in a healthy individual. The kidney cleansing procedure generates both patient waste fluids and reverse osmosis (RO) waste fluid, the integral RO unit being present to facilitate proper operation of the dialysis unit. 
     In a dialysis unit the discharge lines from the patient's body fluids and the RO waste water both empty into the same waste standpipe. Where several dialysis units are combined in a single installation, the discharge lines empty into separate waste standpipes, with each unit being periodically removed upon completion of the cleansing procedure for replacement by another. 
     The discharge lines are commonly secured within each waste standpipe by means of screw clamps or banding. These must be individually tightened to prevent inadvertent separation. Tedious mounting procedures are time consuming. This poses a serious problem where only one nurse or medical assistant is available for servicing several dialysis units. The mounting or attachment means must also fit onto waste standpipes of at least the two most standard sizes, i.e. 1½ inches and 2 inches in diameter. 
     A need exits for a vacuum breaker that can be fitted quickly and easily onto standpipes and just as readily be detached when necessary. 
     Vacuum breakers are known for venting waste water flow from a reverse osmosis unit, but applicant is not aware of any vacuum breaker that operates like two separate vacuum breakers to simultaneously drain and vent RO waste water and patient fluids from a dialysis unit. 
     It is common to vent water flowing at a high rate from a washing machine, dishwasher or water softener, as disclosed in U.S. Pat. No. 3,411,524 for “Vacuum Breaker”, invented by Robert E. Raine and applicant. However, nothing comparable appears to exist for venting two different fluid streams with a single vacuum breaker, and that acts like two separate vacuum breakers to achieve simplicity of operation, reduced cost and ease of installation. Somewhat analogous but far from similar devices are disclosed in my U.S. Pat. Nos. 5,592,964 and 5,176,165. 
     SUMMARY OF THE INVENTION 
     According to the invention, one embodiment of the present vacuum breaker or air gap device operates in a manner similar to that of the air gap device of U.S. Pat. No. 3,411,524, venting a single rapidly flowing fluid. 
     In a preferred embodiment, however, the air gap device includes twin input ports adapted to receive two different fluid streams, such as the patient waste and RO discharges from a dialysis unit. 
     The effluent from these air gap devices can be emptied into two different standard sizes of waste standpipes, such as 1½ and 2 inches in diameter. 
     For this purpose, the housing is provided with tapered ribs adapted to engage the curved inner surfaces of two sizes of standpipe to securely hold the device in position. The ribs include two sets of shoulders or stops to precisely locate the device vertically and in proper position in the respective standpipes. Furthermore, even when fully installed within the larger pipe size the upper stops are strategically located below the (C/L) location to allow for desirable standpipe venting. 
     The device includes internal stiffening sections to reinforce sections of the device against bending or deflection, also includes a partition to isolate and vent two different fluid flows in the region of the air gap openings, such that the single housing air gap device acts like a dual vacuum breaker. 
     Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the features of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the vacuum breaker or air gap device according to the present invention; 
     FIG. 2 is a rear elevational view of the air gap device of FIG. 1; 
     FIG. 3 is a top plan view of the air gap device; 
     FIG. 4 is bottom plan view of the air gap device; 
     FIG. 5 is a view taken along the line  5 — 5  of FIG. 1; 
     FIG. 6 is a view taken along the line  6 — 6  of FIG. 5; and 
     FIG. 7 is a view similar to FIG. 5, but illustrating the mounting of the air gap device to one or the other of two standard size waste pipes shown in phantom outline. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, one embodiment of the present air gap device is shown in FIG.  5 . It is illustrated as it would appear when slipped onto the upper end of a relatively large diameter waste standpipe  10 . In this position a portion of the air gap is located outside the standpipe  10  so that space remains for insertion of a high fluid flow discharge line  12 , such as the line from a water softener or the like (not shown). This adapts the present air gap device for service in certain household applications, such as that disclosed by me and my coinventor in U.S. Pat. No. 3,411,524. 
     Alternatively, if desired, the air gap device could be provided with a top cap having a single large inlet port so that the line  12  need not be located on the rim or lip of the standpipe, but can instead be attached to the single port. This will direct the flow into the air gap device where it can be vented as it travels through the device toward the outlet. 
     However, in the preferred embodiment of FIGS. 1-4 and  7 , multiple inlet flows such as patient waste and RO flows from a dialysis unit (not shown) can be accepted through a twin inlet port top cap  16 . This embodiment is also characterized by an air gap device having a bottom portion that can be slipped or dropped within the upper portion of the interior of the standpipe. The device can be slipped not only into the top of the large standpipe  10 , as seen in phantom outline in FIG. 7, but also into the top of the smaller waste standpipe  13 , as also seen in phantom outline. 
     Being able to simply allow the device to be dropped into proper vertical position under the force of gravity greatly facilitates easy insertion and removal of such devices. This is particularly desirable where, for example, several of the dialysis units are being used and their rapid servicing is important. 
     In the preferred embodiment the dual effluent flows of patient fluid and reverse osmosis (RO) waste water would be discharged from the dialysis unit and vented through opposed or confronting air gaps  17 , and then emptied into one of the associated waste pipes  10  or  13 , as the case may be. In a hospital employing multiple dialysis units, the waste from each unit is emptied into a separate standpipe. 
     The air gap device is molded or otherwise formed in one piece from suitable plastic material. It includes a housing  18 , having the air gaps  17 , and also the top cap  16 , which is mounted upon the upper end of the housing  18 . 
     The top cap  16  includes a pair of inlet ports  20  and  22  and preferably is slightly canted or tilted away from the axes of discharge of the ports  20  and  22  to minimize splattering of incoming fluids out of the air gaps  17 . 
     As best seen in FIGS. 3 and 6, the pair of inlet ports  20  and  22  carried by the top cap  16  are conveniently arranged side by side to receive the patient fluid and RO discharges, respectively. The top cap  16  is preferably molded separately of the housing  18 , and thereafter fixed in position on the housing  18  with adhesive, as seen in FIGS. 1,  2 , and  5 - 7 . 
     The cap  16  includes a stiffener web or wall  19 , as best seen in FIG. 6, for added strength and resistance to bending of the barbed shafts of the inlet ports  20  and  22 , which might otherwise occur from the weight of connecting hoses (not shown) which are generally several feet long. 
     The cap  16  also includes a slot (not shown) which closely receives a vertically oriented wall or divider  24  that is fixed in position with adhesive, as best seen in FIGS. 6 and 7. The divider  24  further rigidities the cap  16 , but its main purpose is to isolate the patient fluid and RO discharge flows from each other in the vicinity of the air gaps  17 . 
     The divider  24  is located between the air gaps  17  and preferably extends close to the front and rear walls of the housing  18 . It also extends downwardly approximately to the critical level (C/L) of the air gap device. The C/L level is located just below the lower edges of the air gaps  17 . If a downstream blockage occurs, or if a vacuum occurs at either of the inlet ports  20  or  22 , both fluid flows entering the air gap device will be vented to atmosphere through the pair of air gaps  17 , respectively, just as would occur if two vacuum breakers had been used. 
     An upper section  28  of the housing  18  defines the air gaps  17 , and a lower section  30  includes an integral, vertically elongated conduit  32 . The conduit  32  forms a downward continuation of the upper section  28  for draining fluids from the upper section and discharging them out of the lower end of the conduit  32 . 
     The downwardly projecting conduit  32 , as best seen in FIG. 4, has a curvilinear inner wall  34 . In the embodiment of FIG. 5, wherein the air gap device clamps onto a wastepipe, the inner wall  34  is adapted to engage the curved inner surface of the upper extremity of the smaller standard size waste standpipe  13 , i.e. the one having the one and one-half inch diameter. The lower section  30  includes a curvilinear outer wall  36  opposite the wall  34 . The wall  36  is adapted to engage the curved outer surface of the standpipe  13  whereby the standpipe may be snugly received in a pipe recess  38  formed between the inner and outer walls  34  and  36 . The lower housing section  30  and the conduit  32  are joined at the top of the pipe recess  38  by a pair of webs or stops  53 . The stops  53  are adapted to engage the top of the standpipe  10  to rigidify the structure and properly locate the air gap device relative to the standpipe  10 . The rigidity provided by the webs  53  prevent unwanted widening or narrowing of the pipe recess  38 . 
     In preferred embodiments, the air gap device fits within the upper end of the associated standpipe. For this purpose the lower housing section  30  includes five vertically elongated, radially outwardly directed, and circumferentially spaced apart ribs  40 . Guide or upper portions  54  are located above the middle rib  40  and above the two outer ribs  40 , respectively, and extend upwardly to the top of the housing  18 . The lower ends of these upper portions  54  define shoulders or stops  44  which are dimensioned to engage the upper rim of the larger standpipe  10  when, as best seen in FIG. 7, the air gap device is dropped or otherwise placed within the upper end of the standpipe  10 . This arrangement supports the air gap device on the stops  44  in stable vertical position within the upper end of the standpipe  10 . There is no tendency of the air gap device to tip or tilt and thereby misdirect the stream of fluids coming out of the lower end of the conduit  32 . If desired, the ribs  40  can be tapered or made larger at their upper extremities in order to fit snugly in the top of the standpipe  10 . 
     The lower ends of all five ribs  40  are dimensioned to form shoulders or stops  48  which are adapted to rest upon the upper end of the smaller standpipe  13  when the smaller standpipe  13  is used. This arrangement allows dropping or locating of the air gap device within the upper end of the standpipe  13  for support of the air gap device by resting of the stops  48  on the top of the standpipe  13 . If desired, the lower portions of the ribs  40  can be tapered to snugly fit within the standpipe  13 . 
     Below the stops  48  all five ribs  40  are of reduced dimension so that as nearly as is possible they engage or are in close proximity with the curved inner surface of the standpipe  13 . 
     Any suitable means may be used to attach drain lines to the inlet ports  20  and  22 , according to the size of the drain lines and whether they are flexible or rigid. In addition, rather than using the illustrated combination of the externally barbed ports  20  and  22  with flexible plastic tubing (not shown), plastic pipe may be used in a slip fit arrangement with or without adhesive. Also, complemental components may be used that are joined in a compression fit, or the so-called John Guest push-in type of fitting can be used. 
     However, in the low flow applications contemplated by the present invention, a leak-tight connection is easily achieved by pushing flexible tubing over the barbed inlet ports  20  and  22 . 
     As described above, the air gap device is versatile in that it can be mounted upon either of the two most widely used standard sizes of standpipe, whether the standpipe is made of plastic or of metal, and whether the standpipe is threaded or unthreaded. The structure of the air gap device is relatively strong and rigid, establishes positive seating and support of the device, and ensures that the device will not be tilted from its normal vertical position during use. 
     There are other features of this particular housing design which are important. The particular design and location of the rails  54  is such that the rails extend clear to the top of upper housing  18 , adding structural rigidity to the otherwise more flexible upper housing portion. 
     In the embodiment of FIG. 5, stops  53 , as best seen in FIG. 4 are located at each end of the mounting slot  38 . The stops  53  help to maintain a uniform slot width throughout the length of the slot, and they provide solid and positive stops for the unit when the unit is inserted over either size of standpipe. Thus, the unit cannot easily be tilted away from its desired vertical position. 
     While several forms of the invention have been illustrated and described, it will be apparent that various modifications can be made without departing from the spirit and scope of the invention.