Patent Publication Number: US-2004050438-A1

Title: Back flow preventing eductor

Description:
FIELD OF THE INVENTION  
       [0001] This invention relates to back flow preventing eductors for mixing of liquid chemicals with water, where the water source must be protected against contamination by backflow.  
       BACKGROUND OF THE INVENTION  
       [0002] Eductors are used for mixing liquid chemicals with water. For instance, such devices are used in the custodial arts to formulate small batches of cleaning solutions by mixing a chemical concentrate with water. Water running through the venturi causes the liquid concentrate to be drawn into the venturi, where it is mixed with water and subsequently discharged. In this manner, a dilute solution is formed.  
       [0003] The drawback to mixing devices of this type is the potential for negative water source pressure, or “back siphoning” of chemicals into the source of the water supply. When such a drawback occurs, the entire water supply is in jeopardy of contamination. In order to alleviate such a potential hazard, air gap eductors are used to prevent any negative source pressure from drawing chemicals or contaminated water back into the water source. Such devices prevent the drawback of chemicals to the upstream source. Many water regulatory authorities require such devices to be used when diluting and dispensing chemicals in this manner.  
       [0004] Yet such air gap eductors themselves exhibit certain problems. One problem encountered in the use of such devices is the undesired mixture of air along with the chemical concentrate and the water. The introduction of air into the venturi system during operation causes the production of excessive foam. This phenomenon is undesirable, as it prematurely causes the container to be filled with foam rather than liquid. The foam rapidly fills the container and results in an overflow, while the container is only partially filled with the liquid mixture. Such a process is inefficient and causes a loss of both time and product.  
       [0005] Another related problem is the tendency for air gap devices to mist or spit water outwardly of the air gap device. This spray, and the resulting drips are annoying, and over a period of time can cause damage to the wall on which the device is mounted, or puddles on the floor.  
       [0006] These problems with air gap eductors were claimed to have been minimized by the anti-foam, splash-proof venturi device of U.S. Pat. No. 6,240,893. The &#39;893 patent describes a venturi device with a resilient sleeve check valve between the water inlet and the venturi. The asserted benefits of this sleeve are threefold. First, upon water flow, the sleeve expands to seal off air from flowing into the supplied water and, it is asserted, effectively reduces the amount of foam produced at the outlet of the venturi. The second claimed asserted benefit of the &#39;893 patent is the elimination of leakage previously experienced in some open air gap eductors. The sleeve used in this device acts as a barrier and confines all fluids to the interior of the venturi device. The last asserted benefit of the &#39;893 patent is that the sleeve insert acts to seal the water flow passage and thus opens the venturi to outside air, providing a siphon-break preventing backflow when water is not flowing through it.  
       [0007] Despite the improvements that the &#39;893 device is alleged to have made to venturi-type eductors, there are difficulties with that device. Sleeve wear and degradation occur over time periods shorter than desired and new parts are required. Degradation may be a result of large portions of the sleeve being forced through the air gaps or ports during water flow. As the sleeve is bulged outwardly and comes into contact with the rough edges of the housing, that relative motion results in abrasion to the sleeve, which leads to undue sleeve wear. Such degradation results in adverse performance and eventually complete failure of the system.  
       [0008] Debris in the water flow passage defined between the sleeve and the internal rigid barrel can prevent the sleeve from fully sealing on the barrel where water flow ceases. This can leave passages open to the undesirable contaminating backflow. Thus. debris in the water flow passage is significantly problematical.  
       [0009] Another problem with devices such as in the &#39;893 patent is the tortuous water path. In that device, the water must flow into a rigid support barrel, make a right turn outwardly through ports toward the resilient sleeve, then make another right turn between the expanded sleeve and support barrel. The turbulence caused by this arrangement restricts the water flow capacity of the device.  
       [0010] Another problem with the &#39;893 patented device is in the manner of the connection of the lower venturi section to the upper air gap/breaker section. These units are joined by hose end threads, making it too easy for the venturi to be disconnected and connected directly to a water source, but without the breaker. This eliminates the function and safety of the breaker, defeating the purpose of the device disclosed.  
       [0011] Moreover, this type of coupling makes the angular orientation of the backflow breaker and of the venturi section or rigid coupling. This may make alignment of the chemical inlet with the portions of the dispensing system a difficult, cumbersome task. Also, twisting of the outlet tube at the end of the venturi is restricted.  
       SUMMARY OF THE INVENTION  
       [0012] A preferred embodiment of the invention includes a backflow preventing eductor having an improved anti-backflow housing, a venturi section or housing, an improved resilient sleeve for sealing the system against backflow, an improved sleeve support barrel for directing water flow, and improved structure interconnecting the anti-backflow housing with the venturi housing.  
       [0013] More specifically, the improved anti-backflow housing is provided with elongated air vents in which cross-bars effectively define smaller vents or windows which are less susceptible for intrusion by the expanded sleeve which would prematurely wear the sleeve.  
       [0014] The improved resilient sleeve is contoured in thickness, tapering toward its distal end to a thinner wall section. The thinner section at the distal end is more compliant, providing a better seal around any debris in the water passage, and accommodating increased water flow for any given pressure over that provided by prior uniformly thick sleeves. The rigid sleeve support barrel has water outlet ports directed toward the sleeve. These ports are extended into the flange of the barrel, thus providing a straighter, less turbulent water path resulting in an increased flow, for any given size of barrel and openings, over the prior device.  
       [0015] A transition area in the anti-backflow housing supports the thinner distal end of the expanded sleeve at the lower end when the expanded sleeve seals against the housing. This, too, reduces wear of the sleeve on that seal where water is flowing in the sleeve.  
       [0016] Finally, the anti-backflow housing is rotatably secured together with the venturi section by a flange and seal so the venturi section can be rotated with respect to the anti-backflow, facilitating orientation of the chemical inlet and twisting of the outlet tube.  
       [0017] The above and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
     [0018]FIG. 1 shows the invention in its condition when water is not flowing;  
     [0019]FIG. 2 shows the invention in its condition when water is flowing; and  
     [0020]FIG. 3 is an enlarged view of the encircled area of FIG. 1. 
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS  
     [0021] Turning now to the drawings, there is shown in FIG. 1 an improved anti-backflow eductor  10  having an anti-backflow housing  11  and a venturi section or housing  12 . Anti-backflow housing  11  includes an inlet end  13  comprising an internally threaded coupling for interconnection with a water supply, such as a faucet nozzle or hose end (not shown). Housing  11  includes a distal end  14  configured as will be described, for operative rotational interconnection to the inlet end  15  of the venturi housing or section  12 .  
     [0022] The details of the anti-backflow housing  11  and the components associated therewith will now be described. Between the threaded coupling  13  and the distal end  14 , the housing  11  includes a plurality of windows or ports  18  defined in sidewalls  19  of the housing  11 . The windows are further defined in part by a series of crossbars  20  which extend across the elongated windows and serve to break up the larger windows into smaller openings or ports.  
     [0023] The distal end  14  of housing  11  is provided with an inwardly tapering section  22 , as shown, leading smoothly to a seat  23 , as will be described. A covering flange  24  extends radially outwardly from the housing  11 . A shoulder  25  also extends radially outwardly from the housing  11 . From the shoulder  25 , a tapering surface  26  tapers inwardly for facilitating the insertion of the housing  11  into the venturi housing  12 , as will be described. The O-ring seal  27  is disposed in a groove  28  for sealing against an internal surface of the venturi housing.  
     [0024] Proceeding now with the description of the venturi housing or section  12 , the inlet end  15  is provided with a groove  31  for receiving the shoulder  25 , as shown in FIGS. 1 and 2. The radial extent of the shoulder  25 , extends outwardly past the internal surface  32 , for rotationally capturing the air gap housing  11  within the venturi housing  12 .  
     [0025] In particular, the internal surface  32  is a termination of inwardly tapering surface  33 . The outer diameter of the shoulder  25  of housing  11  is greater than the inner diameter of the internal surface  32 . When the housing  11  is assembled to the housing  12 , the tapering surface  26 , leading shoulder  25  thereof, engages the tapering surface  33  of the housing  12  and the dimensions are selected, such that there is a slight expansion of the surfaces  32  radially outwardly, allowing the placement of the shoulder  25  in the groove  31 . The shoulder  25  snaps into groove  31 . Thus, the anti-backflow housing  11  is not threaded into the venturi section  12 , but during assembly, is snapped therein so that it is not removable. Moreover, it will be appreciated that the housing  11  is rotatable with respect to the venturi section  12 , seal  27  providing sealing between the two.  
     [0026] The distal end  14  of the housing  11  defines a plenum  36  through which water flows into the venturi throat  37 . Venturi throat  37  is in operative communication with a chemical inlet  38 , which communicates with a threaded inlet  39  in the housing  12 . Thereafter, the venturi housing includes an operably connected diverging passage  40  leading to an outlet  41  of the housing. At its distal end, the housing is provided with a flange 42 , to facilitate securing the discharge end or outlet end  41  to a discharge hose for the diluted chemical mixture provided by operation of the eductor.  
     [0027] Turning now to a description of the fluid controlling components of the eductor  10  of FIGS. 1 and 2, it will be appreciated that the invention includes a barrel  46  disposed in anti-backflow housing  11 . Barrel  46  has a blind end  47  and a radially outwardly extending flange  48 . Barrel  46  is configured with a surrounding relieved area  49  and, at its upper end as shown in FIG. 1, comprises a plurality of windows  50  in the cylindrical barrel surface. The upper ends  51  of the windows  50  extend into the radially extending flange  48 .  
     [0028] An elastomeric or resilient sleeve  56  made of any suitable resilient material surrounds the barrel  46 . Sleeve  56  has an open discharge end  57  and a radially extending flange  58  at its inlet end.  
     [0029] As shown in FIG. 1, the sleeve  56  is snugly disposed on the barrel  46  in such a way that the barrel flange  48  overlies the sleeve flange  58 . A seal  59 , such as an elastomeric washer, is disposed in the coupling end  13 , upstream of the barrel flange  48 . Accordingly, a seal is provided between the shoulder  60  of the coupling  13 , the sleeve flange  58 . the barrel flange  48  and the seal  59 .  
     [0030] As best seen in FIGS. 1 and 3, the sleeve  56 . near its distal or discharge end  57 , has a thin section  64 , which is thinner in cross section than the upper part of the sleeve  56 . This is provided by the taper  61  from the wider thickness of the sleeve down to the narrower thickness  64 .  
     [0031] It will be appreciated that the barrel  46 , at its blind end  47 , has an enlarged end  63  which is greater in external diameter than upper portions of the barrel, as shown. Sleeve  56  seals around enlarged end  63  as shown in FIGS. 1 and 3.  
     [0032] As shown in FIG. 1 and more particularly in FIG. 3, when the eductor is at rest, or is not flowing water therethrough, the sleeve  56  engages and seals around the enlarged end  63  of the blind barrel  46  and the outer surfaces of the sleeve are slightly spaced from the tapering sections  22  of the anti-backflow housing  11  and the seat  23 . Accordingly, the plenum  36  communicates around the exterior surface of the sleeve  56  and between the sleeve and the seat  23 , with the windows or ports  18 . The plenum  36  is thus vented to the ambient atmosphere. In this condition, where the sleeve seals around the enlarged end  63  of the blind end barrel  46 , the plenum is vented and there is no back pressure in the system to withdraw any chemical from the venturi section  12  back up into the water supply. Moreover, any backflow is prevented by the sealing engagement of the sleeve  56  with barrel end  63 .  
     [0033] It will be appreciated that the only avenue back to the water supply of the inlet or coupling end  13  is between the resilient sleeve  56  and the barrel  46 , and through windows  50 . Nevertheless. since the resilient sleeve  56  is now sealing the enlarged end  63  of the barrel, there is no passageway for any chemical or other fluids in the plenum  36  to communicate with the coupling  13  or the water supply associated therewith.  
     [0034] Turning now to FIG. 2, it will be appreciated that a water pressure has been applied to the coupling  13  to provide a flow  66  of water through the eductor  10 . In this figure, it will be appreciated that the water flow is introduced to the upper end of the blind end barrel  46  and flows through the windows  50  outwardly toward the resilient sleeve  56 . The water pressure expands the sleeve  56  outwardly, so that water flows between the interior surface of the sleeve  56  and exterior surface of the barrel  46  and out into plenum  36  through the open discharge end  57  of the sleeve.  
     [0035] At the same time, the water pressure internally of the sleeve compresses the sleeve against the seat  23 , which surrounds the sleeve, thereby sealing off the plenum  36  from the ports or air gaps  18 . This prevents ingress of air into the water stream. The pressure of the water flow illustrated, for example, at  56 , expands the open discharge end  57  of the resilient sleeve  56  to fill the plenum with pressurized water. From there, the water flow moves into the throat  37  of the venturi, creating a negative pressure at the chemical inlet  38 , which draws up any chemical connected to the inlet  39  into the water flow. The mixed water and diluted chemical stream moves through the diverging passageway  40  to the outlet  41 , which can be surrounded by a hose for dispensing end filling purposes.  
     [0036] It will be appreciated that the seal provided by the elastomeric sleeve  56  against the seat  23  facilitates the flow pressure of the water flow in the plenum  36  and through the venturi housing  12 .  
     [0037] Moreover, it will be appreciated with respect to this water flow, that the windows  50  extend into the outwardly extending radial flange  48  of the barrel  46 . In this manner, the water flow, as illustrated in FIG. 2, moves through a relatively gently bending path rather than at right angles. The flow is thus less turbulent than in prior devices. This results in the capacity to flow more water for any given sized system.  
     [0038] Moreover, it will be appreciated that the discharge end  57  of the elastomeric sleeve  56 , together with the thinner wall thickness thereof, serves to provide a substantial seal against the seat  23  while, at the same time, being thin and thus relatively even more resilient. This better accommodates any debris which might be present in the water flow between the sleeve  56  and the enlarged end  63  of the blind barrel  46 . Thus, when the water pressure or source is cut off, the sleeve resiliently returns to a sealing engagement with the enlarged end  63  of the barrel  46 . Should there be any debris between the thinner wall section  64  of the sleeve at the enlarged end  63 , the sleeve will tend to mold itself around and even further seal off any return passage through the open discharge end  57  while, at the same time, opening the passageways between the exterior surface of the sleeve  56  and the seat  23  to vent the plenum  36  through the windows or vents  18 .  
     [0039] In addition, it will be appreciated that the interconnection of the anti-backflow housing  11  to the venturi housing  12  is a more permanent coupling than a threaded coupling. for example, making the two sections difficult, if not impossible. to remove by the ordinary user. Thus. the venturi section  12  cannot be inadvertently or purposefully connected to a source of water supply without benefit of the anti-backflow function provided by the components in anti-backflow housing  11 , including the barrel  46  and the sleeve  56 .  
     [0040] Moreover, this interconnection nevertheless provides for some rotation capability between the anti-backflow housing  11  and the venturi section  12 . This facilitates the orientation of the chemical inlet  39  in a desired angular position, regardless of the angular orientation of the housing  11  with respect to its coupling to the water source. Moreover, any twisting of the outlet tube (not shown) interconnected with the discharge outlet  41  of the venturi housing can be accommodated by this rotational movement.  
     [0041] Accordingly, the improved anti-backflow eductor  10  as disclosed above provides numerous features and enhancements not before available. Sealing of the system, when no water flow is present, has been enhanced, even in the presence of debris within the air gap eductor, to further insure there is no backdraft of any chemically-tainted fluid into the water supply.  
     [0042] Moreover, it will be appreciated that the construction of the anti-backflow housing  11 , when taken together with the improved elastomeric sleeve  56  and the barrel  46 , provides a number of advantages. First, with respect to the barrel, the extension of the top edges of the windows  50  into the radial flanges  48  provides for a more gentle, less tortuous water path and thus, for any particular size of components, relatively more water flow.  
     [0043] The construction of the housing  11  with the cross bars  20  provide adequate venting at the same time with relatively smaller windows. Thus, when the sleeve  56  is pressurized by water flowing through the system and pushed out against those vents  18  to seal them the sleeves are not so flexed into the ports so relative motion between the sleeve and the port edges causes the sleeve to abrade against the sharp corners of the openings of the windows  18 , as it would if those windows were larger. Thus the life of the sleeve is improved by reduction of the degradation and abrasion of its exterior surface.  
     [0044] As well, the tapering thin wall discharge portion of the sleeve permits better sealing of the sleeve with respect to the barrel and facilitates the seal of the sleeve against the seat  23 , enhancing the overall function of the safety of the eductor and facilitating water flow.  
     [0045] The rotational, relatively non-detachable interconnection between the anti-backflow housing  11  and the venturi housing  12  facilitates the orientation of the eductor  10  with respect to the chemical source and with respect to the twisting of any discharge tube associated with the housing  12  while, at the same time, inhibiting the inadvertent or purposeful direct connection of the venturi section  12  to a water supply without benefit of the anti-backflow functions within the housing  11 .  
     [0046] These and other modifications and advantages will become readily apparent to those of ordinary skill in the art without departing from the scope of this invention and the applicant intends to be bound only by the claims appended hereto.