Fluid handling – Processes
Reexamination Certificate
1999-06-24
2001-09-25
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Processes
C137S889000, C137S891000, C137S892000
Reexamination Certificate
active
06293294
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to apparatus and methods for mixing and dispensing fluids, and is particularly concerned with an apparatus and method for mixing fluids of differing viscosity such as various liquids, gases, or mixtures of liquids and gases.
Fluid mixing is required for many applications, such as in the chemical and petrochemical industries, foam producing for fire fighting, cleaning, bathing or the like, and aerated beverage production.
Fluid mixing systems may use pumps to achieve sufficient pressure for the particular application. For example, dog or other animal bathing systems must produce a foaming or soapy water output at sufficient pressure to penetrate matted hair and bring the detergent and water mixture to the skin surface. Sufficient agitation and lather is needed in order to cleanse the animal thoroughly. Other systems have utilized water line pressure and required driven devices for mixing the shampoo, water, de-fleaing agent or other chemicals. Such systems often have insufficient water pressure for agitation to produce complete cleansing.
Other fluid mixing devices have been proposed in the past which use venturi passages to draw fluids into a main fluid stream by suction or vacuum creation. For example, U.S. Pat. Nos. 3,822,217 and 3,853,784 of Rogers describe a foam-forming device in which a detergent inlet is provided at a smaller diameter portion of a venturi passage through which water is flowing. Detergent is injected in a thin jet into the passage, and mixes with the water. The mixture flows at higher velocity through the expanding portion of the venturi passage to produce a thorough mixing. Air is injected at a spaced location downstream of the detergent inlet.
In U.S. Pat. No. 2,800,313 of Targosh et al., a liquid mixing nozzle is described in which two diametrically opposite venturi passages are provided. A first inlet from a source of detergent is provided into one venturi passage, and an air inlet is provided into the other passage downstream of the detergent inlet. An air inlet opening is also provided into the first inlet, and this may be closed or partially closed by hand in order to vary suction drawing detergent into the passage.
It has been found that, when two fluid inlets for different viscosity fluids, which may be liquids and/or gases, are provided into the same venturi passage, back pressure from the lower viscosity fluid inlet can affect the amount of higher viscosity fluid drawn into the passage, even if the lower viscosity fluid inlet is downstream of the other inlet.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a new and improved device and method for mixing fluids of varying viscosities.
According to one aspect of the present invention, a fluid mixing device is provided which comprises an inlet passageway for connection to a first fluid supply, an outlet passageway, separate first and second venturi passageways each connected between the inlet and outlet passageways, each venturi passageway having a reduced area throat portion, a first venturi inlet for connection to a supply of a second fluid connected to the first venturi passageway and a second venturi inlet for connection to a supply of a third fluid connected to the second venturi passageway at the reduced area throat portion, whereby the second and third fluids are drawn into the first fluid flowing separately in the first and second venturi passageways, the outlet passageway being spaced a predetermined distance downstream of the venturi inlets to prevent substantial backflow of the lower viscosity fluid into the higher viscosity fluid passageway prior to mixing together of the two streams in the outlet passageway.
The length of each separate venturi passageway from the respective venturi inlet to the outlet passageway where the two flows mix together is critical, particularly where the second and third fluids, which are to be separately mixed into the first fluid or main flow, are of different viscosities. For example, consider the case where the second fluid is of lower viscosity than the first fluid. If the length of the venturi passageway, or distance of the outlet passageway from the venturi inlet, is too short, the lower viscosity fluid in the first venturi passageway may tend to be sucked back into the higher viscosity fluid in the second venturi passageway, thereby obstructing and interfering with creation of the vacuum and suction drawing the higher viscosity fluid into the second venturi passageway. This backflow or bleedover from one venturi passageway to the other will prevent proper drawing and mixing of the higher viscosity fluid into the main flow of the first fluid, and thus prevent the desired mixing proportions. Thus, the distance of the outlet passageway from the venturi inlets is predetermined to avoid any substantial backflow or bleedover.
In a preferred embodiment of the invention, a single venturi tube is provided with a septum or baffle dividing the tube into the separate first and second venturi passageways extending along at least part of the length of the tube. Preferably, an inwardly tapering inlet portion leads to the inlet ends of the two venturi passageways, and an outwardly tapering portion leads from each reduced area throat portion to the outlet passageway. Separate fluid inlets for connection to different fluids may be provided. In one example, where the device is used to produce foam, the inlet passageway may be connected to a water supply while the first and second venturi inlets are connected to supplies of air or oxygen and detergent or foaming agent, respectively. The second venturi inlet may be selectively connected to a plurality of different liquids and the liquid inlets are connected to the second detergent inlet via a multi-way valve so that different liquids may be mixed with the water. One of the liquid inlets may be connected to a container of detergent or shampoo, while the other inlets may be connected to containers of other liquids, such as conditioner and de-fleaing or insecticide agent, where the device is used for animal bathing purposes. If more fluids are to be mixed, the venturi tube may be divided into three or more separate passageways via a suitably shaped baffle.
The length of the baffle or septum from the venturi inlets to the outlet passageway at the end of the septum is selected based on minimizing backflow from the venturi passageway connected to the lowest viscosity liquid into the other venturi passageway. This will be dependent on flow conditions, size of the venturi passageways, and the actual viscosities of the fluids to be mixed, which may be liquids, gases, or both liquids and gases. In one preferred embodiment of the invention, the fluid mixing device is designed for producing a foam output, for example for cleaning or bathing purposes, or for firefighting or the like. Where the apparatus is used to create a foam, the length of the baffle is also critical for another reason.
If the baffle length beyond the venturi inlets is too long, bubbles forming in the water as the air or other gas is drawn in will tend to coalesce, leading to an undesirably large bubble size in the foam. Thus, in this particular application where air or other gas is mixed with water an detergent, the baffle length is selected so as to minimize backflow of air or gas or other lower viscous fluid, while also minimizing bubble coalescence prior to the foam outlet. It has been found that, for a venturi passageway of cross-sectional area 0.0051 sq. in. (3.3×10
−9
m
2
), the length of the passageway from the respective inlet to the downstream end of the septum or baffle must be greater than 0.8 inches (2.03×10
−2
m), and preferably no less than 1.0 inches (2.54×10
−2
m). Preferably, the length of the septum from the gas or liquid inlet is in the range from 1.0 inches to 2.0 inches (2.54×10
−2
to 3.08×10
−2
m). The ratio of the septum length to the venturi cross sectional area is preferably in
Giuntoli David M.
Loeb Robert D.
Williams Hugh O.
Brown Martin Haller & McClain LLP
Hepperle Stephen M.
Hydrosurge, Inc.
LandOfFree
Method and apparatus for fluid mixing and dispensing does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for fluid mixing and dispensing, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for fluid mixing and dispensing will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2524962