Abstract:
Foaming and lateral water leakage during the filling of a container with a foam-prone water/chemical mixture is minimized by using, at the inlet of the venturi nozzle which draws the chemical into the water, a water authority-approved resilient-sleeve air gap which furnishes air-free water to the venturi while providing a siphon-breaking air gap if water is not flowing into the venturi.

Description:
FIELD OF THE INVENTION 
     This invention relates to a splash-proof anti-foam venturi device for mixing chemicals with water while filling containers with the mixture. 
     BACKGROUND OF THE INVENTION 
     In many situations, as for example in housekeeping activities for hotels, containers such as spray bottles need to be filled at frequent intervals with a cleaning solution or other mixture of water and liquid chemicals. Typically, such mixtures are obtained by passing a stream of water through a venturi which draws a liquid chemical from a concentrate source into the water stream that is discharged into the container. 
     If air is allowed to be entrained with the water/chemical stream discharged into the container, many cleaning solutions and other mixtures tend to foam quite strongly. As a result, foam overflows the container even if the container is nowhere near filled with liquid. Consequently, much time is wasted because either the container must be filled unnecessarily often, or the operator must fill the container very slowly. 
     Another related problem arises from the fact that the venturi devices require an air gap, i.e. a device which breaks any accidental siphon, so as to prevent water in the venturi from flowing back into the public water supply. In practice, the filling apparatus is typically mounted on a wall. Most conventional air gap devices of the type useful in such filling apparatus have a tendency, albeit small, to spit and splash spray water outwardly of the air gap device. This spray, and the resulting drip, is annoying and, over a period of time, tends to damage the wall and make the apparatus unsanitary. 
     Prior to the present invention, water public safety authorities would only approve for this purpose a completely open air gap device which would cause the above-described foaming, spitting and splashing. With the use of the present invention, applicants have been successful in obtaining local and national water authority approvals for anti-foaming splashproof venturis throughout the United States and many parts of the world. 
     SUMMARY OF THE INVENTION 
     The invention overcomes the above-mentioned problems of the prior art by combining a venturi with an air gap of the pipe interrupter type. That type of backflow preventer prevents water from exiting the air gap except through the venturi, and it also prevents air from being drawn into the water stream before it reaches the venturi. By thus keeping air out of the water/chemical stream exiting the venturi, foaming of the mixture as it is discharged into the container is greatly reduced. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a vertical section through the venturi-and-airgap combination of this invention; 
     FIG. 2 is a detail section along line  2 — 2  of FIG. 1; 
     FIG. 3 a  is a detail section along line  3 — 3  of FIG. 1 when water is flowing; 
     FIG. 3 b  is a detail section along line  3 — 3  of FIG. 1 when water is not flowing; and 
     FIG. 4 is a horizontal section along line  4 — 4  of FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As will be seen from FIG. 1, the device  10  of this invention consists of an air gap section  12  and a venturi section  14 . Water from the municipal water supply enters the air gap section  12  through an inlet plenum  16  and flows into the interior of a barrel  18  that is sealed at its bottom end  20  but has lateral openings  22  near its upper end  24 . The barrel  18  is surrounded by a cylindrical elastic sleeve  26  whose inner diameter is a little larger than the outer diameter of the upper and intermediate portions  28 ,  30  of barrel  18 , but smaller than the outer diameter of the bottom portion  32  of the barrel  18 . The barrel  18  has an annular flange  34  at its top, and the sleeve  26  has a similar flange  36  at its top. When the air gap section  12  is assembled, the flange  36  is compressed between the flange  34  and the shoulder  38  at the top of the cage  40  (see FIG.  2 ). Air enters the cage  40  through the lateral slots  42 , but water cannot spray outwardly through the slots  42  because the water is contained on the inside of the sleeve  26  throughout the length of the slots  42 . 
     Below the air inlet slots  42 , the air gap section  12  has an inwardly directed annular flange  44  which has an inner diameter slightly larger than the outer diameter of the sleeve at that point. This is the smallest outer diameter of the sleeve  26 , because at that point it encircles the recessed portion  43  of the barrel  18  which is the smallest-diameter portion of the barrel  18 . 
     When the water is turned on, it flows into the barrel  18  and fills it quickly. Additional water then exits through the lateral openings  22  in an essentially laminar flow into the space  45  between the barrel  18  and the sleeve  26 . With water flowing into it, the sleeve  26  expands, and its outer surface eventually contacts the flange  44 , sealing the plenum  46 , and hence the venturi section  14 , against the entry of any air from the slots  42  (FIG. 3 a ). 
     Thus, as long as water  47  flows toward the venturi section  14 , that water is free of air. If a siphon action occurs in the municipal water line, the sleeve  26  is pulled tight against the outer surface of the barrel  18  (FIG. 3 b ). This seals off the barrel  18  and the water inlet, and at the same time opens the plenum  46  to the ambient air through the space  49  between the collapsed sleeve  26  and the flange  44 . 
     In the venturi section  14 , the water flows from the plenum  46  into the throat  48  of the venturi  50 . A passage  52 , to which a cannula  54  (FIG. 4) coming from a source (not shown) of liquid chemical is connected, enters the venturi  50  at  51  just below its throat  48 , where the sucking action of the venturi  50  draws the chemical into the water stream and mixes it with the water. 
     The water/chemical mixture exits the venturi  50  as a coherent, air-free stream which can fill a container such as a spray bottle (not shown) with a minimum of foaming. At the same time, no water can escape the inventive device other than through the venturi outlet  56 , because as long as the water flows, the slots  22  are sealed off from the water stream. 
     It is understood that the exemplary anti-foam container filler described herein and shown in the drawings represents only a presently preferred embodiment of the invention. Indeed, various modifications and additions may be made to such embodiment without departing from the spirit and scope of the invention. Thus, other modifications and additions may be obvious to those skilled in the art and may be implemented to adapt the present invention for use in a variety of different applications.