Patent Application
20090065065
This invention relates to apparatus and methods for dispensing and mixing liquids, and more particularly to such apparatus and methods that dispense and mix chemicals, and even more particularly to dispensing and mixing cleaning chemicals.
It is common practice to purchase concentrated cleaning chemicals and to mix them with other liquids such as water to achieve the desired usage concentration for cleaning. A variety of proportioning dispensers have been developed to achieve this. The dispensers often employ venturi-type devices sometimes called eductors to draw the concentrated liquid chemical and mix it with the water stream. Examples of such eductors include those shown in Sand U.S. Pat. Nos. 5,522,419, 5,253,677, 5,159,958, and 5,862,829, all of which are assigned to the Assignee of the present invention and are expressly incorporated herein. Water traveling through the central, constricted portion of the venturi creates a vacuum therein which is used to draw concentrate liquids such as cleaning or other chemicals into the water stream and a mixture of water and chemical is discharged.
The structure of such eductors is generally fixed, and thus, for a given water stream flow rate, the amount of concentrated liquid chemical drawn is a function of the fluid resistance, typically created by a small orifice in the flow path of the concentrated liquid chemical. Such orifices may be fixed or adjustable to vary the proportionate flow.
Achieving the proper proportion of chemical with selection of a particular metering orifice is complicated by factors which vary per application, such as the desired usage concentration, the viscosity of the concentrated liquid chemical, and the temperature of the concentrated chemical, to name a few. Using metering orifices to control dilution in the typical dilution ranges or ratios desired means that very small metering orifice sizes are required. Table 1 of
Metering orifices have sometimes been used to achieve dilution ratios about 1 down to about 1000:1. More dilute mixtures are constrained by the volume rate of water available and by the smallest practical size of the metering orifices. Very small orifices are susceptible to clogging such as from contaminant particles or artifacts in the concentrated chemicals. In addition, the viscosity of the chemical imposes minimum size limitation of the orifice size.
Devices to prevent clogging from contaminants and other particles have been developed. An example of one such device is that disclosed in Sand U.S. Pat. No. 6,238,081, which is assigned to the Assignee of the present invention and is expressly incorporated herein
In addition, many modern day chemicals are produced to be mixed with water in a very specific range of dilution ratios. One example of such a chemical would be a sanitizer which if diluted too lean would not produce the desired sanitizing result thereby possibly causing health issues, and if diluted too rich, could cause chemical contamination issues a well as the cost of using excessive chemical. The dilution ratios of some such chemicals are controlled by Local Health Departments. They may dictate certain ratios without regard to the availability of equipment having the capacity to produce diluted mixtures at those ratios. Therefore the ability to meter the chemical with the water in a more exact ratio is highly desirable. An example of this would be a dilution ratio of 140:1. Note that the practical orifice sizes shown in Table 1 in
Chemical flow rate through the orifices and orifice clogging are not the only negative issues encountered with this type of system. Typically as the water pressure presented to an eductor increases, the volume of water flowing through the eductor also increases. Chart 1 of
The liquid pressure introduced to an eductor based system is dependent upon the installation. Many variables can affect the water pressure to an eductor. Some of these variables can include but are not limited to the size of the plumbing supply piping (which causes pressure drops), and the placement of the eductor based system in the building. For example, systems installed on the top floor of a multi-leveled building may have less pressure than a similar system installed on a lower level of the same building. In addition water usage can affect the pressure to the system. When the system is in operation and an additional device in the water line, such as a toilet, is used the additional water used by the toilet will reduce the water flow resulting in both the pressure to drop and less flow thru the system.
As noted above, an eductor creates a vacuum which draws in the chemical and mixes it with the water stream. The vacuum created is related to the fluid flowing through the eductor. Chart 2 of
The maximum vacuum that can be produced is approximately 30 in-Hg. Eductors in general have a maximum vacuum level of about 27 in-Hg. This effectively caps concentrate flow and thus increases dilution ratios for high flows of diluent.
When pressure supplied to the eductor system varies the eductor (diluent) flow varies as shown in
Dilution ratio is computed by dividing the fluid (diluent) flow through the eductor by the chemical flow thru metering orifice that is then mixed with the first fluid. Table 2 of
This table of
It is much easier to see this relationship of Flow as it relates to Dilution Ratio in graphical format, thus is supplied Chart 4 of
There are devices which will limit the upper pressure limit of diluent introduced into an eductor. An example of such a device would be a pressure regulator such as that produced by Watts Regulator Company of Andover, Mass., under model designation “Watts Series 26A”. Chart 5 of
Pressure regulators can be costly devices. Since they are mechanical and have moving parts they must be adjusted or replaced on a periodic basis which adds to both equipment and maintenance costs.
Use of the pressure regulator with an eductor produces constant flow when the input pressure to the regulator is above the set-point of the regulator, thus maintaining a constant flow above the pressure input set-point.
As stated previously, cleaning chemicals are produced in various viscosities. Viscosities of these agents can range from 1 centipoise which is the consistency of water to 3000 centipoise which is like honey. This variation in viscosity makes the selection of the correct size of metering orifice for each chemical difficult for all of the various field applications of the system. In other words, use of a single metering orifice size will not satisfy a wide variety of field applications, even with a constant diluent pressure and flow.
To further complicate the selection of metering orifice size, the viscosity of many chemicals changes as temperature changes. The systems that use these devices may be installed in kitchens or laundry rooms which may have temperatures close to 100 degrees Fahrenheit or in meat rooms and produce facilities which have temperatures as low as 40 degrees Fahrenheit. An example of such viscosity changes are shown in Table 3 of
Consequently, if all variables as discussed above are not taken into account, chemicals are mixed either too rich in which case additional chemical usage and costs are incurred or the mix is too lean in which case the solution does not perform properly or properly treat targeted health hazards due to insufficient cleaning.
It is thus one object of the invention to provide apparatus and methods for more accurate dilution in such dispensing and mixing systems.
A further object of the invention is to provide methods and apparatus for producing wider ranges of dilution ratios in a proportioner with fixed chemical metering orifices than hereto possible and with increased accuracy.
A yet further objective of the invention is to provide am for producing accurate dilution ratios in fixed orifice proportioners despite variation in diluent flow and chemical viscosity and temperature.
To these ends, the invention contemplates structure and apparatus capable of producing a wide range of accurately diluted chemical mixes by cycling flow of the chemical through an eductor during diluent flow in response to a predetermined or commanded dilute ratio and in response to a variety of sensed parameters of fluid flow and viscosity. The result of this invention is the provision of a wide range of dilute ratios which are available through the use of a fixed orifice but are not so limited as, and are far more diverse than, a system which constantly draws chemical through that orifice. The results produced include ratios as rich as can be achieved through the given orifice at the highest of diluent flows and highest chemical viscosities and as lean as can be achieved through that orifice at the lowest diluent flows and lowest viscosities of the chemical used.
Moreover, the dilute ratios are not limited to mixes produced where the chemical is introduced to the diluent during the entire duration of diluent flow.
Such apparatus and methods thus provides a wide range of ratios meeting the arbitrary regulations of health and other organizations and without the bother of multiple orifices, pressures regulators and the like.
In one embodiment of the invention, a user simply selects the dilution required and the viscosity of the chemical to be diluted (if the automatic temperature viscosity rate change selector to be described is not used). He then starts the water flow and the controller cycles a control valve in the chemical line to cycle chemical flow to an eductor based on the noted parameters and dilution ratio selected. The method thus contemplates the provision of a wide range of diluent-to-chemical mix ratios through cycling the chemical flow into the diluent.
These and other objectives, embodiments and advantages will become readily apparent from the following detailed description of embodiments of the invention and from the drawings in which:
Turning now to
In this
A chemical source or container 20 is coupled to or receives a chemical pick up tube or draw conduit 21. A chemical control valve 22 is operably disposed in conduit 21 between the chemical source 20 and a metering orifice 23 at the eductor (not shown in detail). Orifice 23 is operatively connected to pass chemical from conduit 21 into the eductor 14 at the venturi portion thereof.
An electronic control 30 is operatively connected through line 31 to transducer 13 for receiving a signal from the transducer representing fluid flow. Control 30 is operatively coupled through lines 32, 33 to chemical control valve 22 for cycling that valve between open and closed positions to selectively open and close chemical conduit or pickup tube 21. On/off operation of valve 2 effectively cycles chemical flow into the eductor when diluent is flowing therethrough.
A cabinet 40 covers the components comprising the valve 12, transducer 13, eductor 14 and portion of the discharge tube 15 as desired, with the on/off control valve being operationally accessible from outside the cabinet. While not shown, the cabinet 40 may be extended or compartmented to house control 30 and chemical control valve 22.
The transducer 13 is preferably a flow transducer or flow sensor. A pressure transducer could be used, however, it would require more electronic circuitry as such transducer output typically comprises an analog signal. Also, the output of a pressure transducer is generally not linearly proportioned to the flow in “GPM” (as used herein, “GMP” refers to “gallons per minute”).
Another advantage of using a flow transducer is that it produces signal pulses which could be transferred to control 30 by wire or by the use of wireless technology where desired. Such electrical pulses or signals are operably transmitted to the control 30 as will be described.
One particular form of flow transducer which is useful is that transducer marketed as the GEMS flow sensor by GEMS Sensors, Inc. of Plainville, Conn.
Eductor 14 may comprise any useful eductor, preferably capable of consistent operation at 1 GPM or at 4 GPM. Such eductor could be as described in the aforementioned patents.
The control 30 preferably includes a plurality of components including a temperature sensor 36, a cycle duration controller 38, a dilution ratio selector 40, a viscosity selector 42, a temperature/viscosity rate change selector 44 and a microprocessor or programmable logic controller 46. Subject to the following, all these components could be mounted on a circuit board 48 or on other components or through other technologies for operatively mounting and/or coupling electronic components and chips, such as surface mount technology. Such technology itself does not comprise part of this invention.
The temperature sensor 36 could be a board 48 mounted sensor. This type of sensor is economical and is produced by many manufacturers. One such sensor is manufactured by the Minco Company, headquartered in Minneapolis, Minn. and marketed under the model name Minco S102404. The temperature sensor should be capable of sensing temperatures from 40 degrees F. to 120 degrees F. Typical applications would be a meat packing room in a grocery store that can operate as low as 40 degrees F. or a restaurant kitchen which may reach temperatures of 120 degrees F. This sensor may be mounted on the circuit board or may be removed from the circuit board to closer orientation with the chemical source and transmit the temperature signal via wire or with wireless technology. In this embodiment the circuit board 48 mount was selected for the low cost. Another embodiment would be the placement of the temperature sensor in the chemical container or in direct contact with the chemical in the fluid path. Such a location of the temperature sensor would add cost to the system. One such remote sensor is also made by the Minco Company under Model S56NA.
The Temperature/Viscosity Rate Change Selector 44 is a variable device preferably mounted to the circuit board 48 and is used to input the change of viscosity of the chemical as it changes with temperature. As stated earlier the viscosity of some chemicals change with temperature. The viscosity change cause the chemical flow rate to change. Each chemical has a unique temperature to viscosity rate change. A typical rate change is shown in Chart 7 of
The typical rate of viscosity change responsive to temperature is shown by the equation y=−8x+1070. Where y is the viscosity, x is the temperature and “1070” is a constant. In this case the value “−8” and “1070” are input to the microprocessor 46 by way of Rate change selector. This selector 44 may be mounted on the circuit board 48 as noted. In this embodiment the circuit board 48 mount was selected for the low cost. Such a temperature/viscosity rate change selector 44 can be of any suitable construction. One such selector is marketed by the Grayhill Company of LaGrange, Ill. under Model No. 76SB10T.
The viscosity selector 42 is a variable device preferably mounted to the circuit board 48 and is used to input the viscosity of the chemical to be mixed. In this embodiment the selection is made via dip switches. The viscosity value to be selected could be from 1 to 3000. The viscosity selector 42 could also be a rheostat or other variable device. The dip switch was selected due to the low cost and ease of use.
The temperature sensor 36, Temperature/Viscosity Rate Change Selector 44 and viscosity selector 42 could all be replaced with a single unit. Under this embodiment, the single unit could be remotely mounted and connected to the circuit board with wires or could transmit the data with wireless technology. One such single unit is made by Vectron Company of Hudson, N.H. under the Model Name ViSmart.
The dilution ratio selector 40 is a variable device mounted to the circuit board 48 which is used to input the desired dilution ratio. That is the ratio of water to chemical. Any suitable and adjustable electronic input apparatus could be used. One such unit found useful is the selector made by Grayhill Company of LaGrange, Ill. as Model No. 76B10T.
Finally, the cycle duration controller 38 is simply a selector for manually setting the duration of any dispensing cycle as desired, such as a timer. One such selector found useful is the selector made by Grayhill Company of LaGrange, Ill. as Model No. 94HBB16WT.
All these components are preferably operatively connected to a microprocessor 56 or programmable logic controller, as desired, to control valve 22. The control valve 22 preferably comprises a quick open/quick close fluid valve, electronically actuated. In one embodiment it is a solenoid operated valve. Other types such as motor operated ball valves could be used in this application. The valve has a flow area of at least 0.030″ in cross section to prevent clogging. The valve is normally closed and receives a signal from the microprocessor 46 to open. The duration of the open state is governed by input to the microprocessor 46 from the flow/pressure transducer 13, temperature sensor 36, temperature/viscosity rate change selector 44, viscosity selector 42, and dilution ratio selector 40 and cycle duration controller 38.
Microprocessor 46 or compatible programmable logic controller can be any suitable microprocessor or controller. One such useful microprocessor is that made by Microchip Technology Incorporated of Chandler, Ariz. under Model No. 12F683.
As used herein, the term “cycling” generally refers to the stopping and starting of chemical flow to the eductor for mixing with diluent.
In the current embodiment (see
As water flows into the flow transducer 13, the transducer 13 transmits a signal proportional to the water flow. In the case of a flow transducer 13, the rate of flow in gallons per minute (GPM) is linearly proportional to the output signal (pulses). Chart 6 of
As stated previously, the dilution ratio is the amount of water divided by the amount of chemical mixed and dispensed. The traditional way to achieve this was to change the size of the metering orifice in a typical system. According to the invention, however the improved method contemplates controlling the chemical to mix with the water at timed intervals. For example, if for a dispense of 2 minutes long the chemical were to flow for the complete time, a mix ratio may be about 40:1. If the chemical were shut off after the first minute of operation and water only for the last one minute of operation, the dilution ratio for the same system would be 80:1. Therefore by varying the open time for valve 22 to allow for the chemical to mix with the water the final dilution ratio of the water/chemical mixture can be infinitely varied.
Table 4 of
If dispensing at water flow rates of less than 4 GPM, the above run times shown in Table 4 would not produce the desired ratios. The solution to this is to cycle the chemical control valve in even shorter increments. Table 5 of
A control valve cycle of at least 4 times per minute is recommended to achieve accurate dilution ratios. Otherwise, a premature operator commanded water shutoff may adversely affect a desired ratio.
The cycle duration control 38 changes the cycle time for the control valve. This is shown as a rheostat but dip switches or other means to vary the cycle time could be incorporated. This time is preferably adjustable from 1 second to 60 seconds.
While the invention as described will maintain constant dilutions at pressures where the eductor has achieved full (25 in-Hg) vacuum, there is still a variable issue presented when the water pressure is not high enough for the eductor 14 to generate full vacuum. Referring once again to Chart 2 of
One possible solution to this problem is to use an algorithm that determines the vacuum of each eductor at a specific flow rate. This algorithm is a non-linear equation and is specific for each eductor. Thus the electronics for the device must be programmed and matched to a specific eductor design.
Another unique solution according to the invention is to use an eductor which obtains full vacuum at a low flow rate/pressure than eductors typically used in proportioners. A pressure vs. vacuum curve for such an improved eductor is shown in Chart 8 of
Such eductor achieves its upper vacuum very quickly at very low flow rates. With the use of such an eductor, the vacuum is relatively constant from low flow to high flow (the so-called “ramp-up” time being reduced as well as fluctuation of diluent pressure), thus giving uniform chemical flow through the valve at any reasonable flow rate. Performance is still not constant at very low flow rates where the vacuum has not reached it's maximum but this pressure is about 15 psi lower than almost all typical chemical dispensing installations, and front end performance up to 25 PSI does not adversely affect the operation practically.
Such an eductor is not known to have been used in proportioning systems in the past. One such eductor useful in this regard is that manufactured by Hydro Systems Company of Cincinnati, Ohio under Part No. 440300.
The operation of the invention requires electrical power. Many installations do not have available electric power or the installation of electrical equipment must be made by a licensed electrician. These requirements add substantially to the installation cost of the system and to the marketability of such a system. Batter power is the solution. Small, economical and easy to find batteries are preferred. The system preferably will operate on “AA” size batteries. PWM (pulse width modulation) technology, which is not new to electrical circuits can be used to activate the control valve thus substantially increasing the life of the battery.
Accordingly, the invention provides apparatus and methods for producing accurate dilution control of a concentrated liquid chemical over a variety of conditions and through a wide range of dilution ratios not heretofore possible with fixed orifices.
These and other modifications, methods and apparatus will become readily apparent from this application without departing from the scope of the invention and applicant intends to be bound only by the claims appended hereto.
