System and method of surfactant dosing

Abstract

A system and method of processing laundry by the determination of surface tension in a dynamic environment for surfactant concentration in industrial laundry applications. The dosage system is able to control the surfactant concentration for a recycle wash tank and preferentially the washer tank using surface tension measurements, temperature control, and correlation to the percentage of active matter based on a full dose of a commercial surfactant for the wash runs. The dosage system preferably uses a surface tensiometer able to monitor surfactant levels and to constantly dose surfactant for use in subsequent washes.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a process for central processing of home laundry that improves efficiency and reduces environmental impact by recycling water and chemicals.

BACKGROUND OF THE INVENTION

[0002] The United States is increasingly burdened with higher potable water demands and more costly downstream water treatment processes. As a practical matter, the costs for water treatment and supply are ultimately borne by the consumer. Reductions in these costs, where economically feasible, draw strong political and commercial support.

[0003] Military, industrial, and residential sources generate voluminous quantities of “gray water” from dishwashers, wash vessels, sinks, showers, and bathtubs. These devices generate gray water and typically lack any form of recycling system. A large number of states have adopted codes for reuse of gray water. Therefore, the impetus for developing robust and economical separation strategies is a reality. The Department of Energy (“DoE”) is pushing the private sector to develop more efficient, lower-water usage washing machines with minimal byproducts that are capable of using cold water.

[0004] There exists a need to reuse water in a system for washing consumer laundry outside of the home. Reuse of the water used in laundry applications would recycle surfactant to the washing machines. As a result, there exists a need to develop a method to monitor surfactant content in the recycled water to allow appropriate dosing of detergent to the washing machines.

SUMMARY OF THE INVENTION

[0005] The present invention provides a system and method of processing laundry by the determination of surface tension in a dynamic environment for surfactant concentration in industrial laundry applications. Using the system and method, an operator is able to reduce surfactant cost in his process by delivering the correct dosage for subsequent washes via the continual adjustment of detergent concentration in the recycle wash tank. The dosage system is able to control the surfactant concentration for a recycle wash tank using surface tension measurements, temperature control, and correlation to the percentage of active matter based on a full dose of a commercial surfactant for the wash runs. In a preferred embodiment, the dosage system, using a surface tensiometer able to constantly monitor surfactant values in reference to a target surface tension set point, sends an output to an external pump to constantly dose a recycle tank. The adjusted surfactant dosage in the wash tank is then available for use for subsequent washes.

[0006] The determination of surface tension in a dynamic environment holds many possibilities as a control mechanism for surfactant concentration in industrial laundry applications. In a commercial laundry process, a surfactant dosage system is needed to maintain the economic advantage of delivering a correct dosage of surfactant to subsequent wash runs of a recycle wash operation. It is preferable to accomplish this without the verification of the surfactant concentration using standard wet chemistry analytical methods that would be too expensive for a commercial operation. Using the system and method described herein, an operator is able to reduce surfactant cost in his process by delivering the correct dosage for subsequent washes via the continual adjustment of detergent concentration in the recycle wash tank.

[0007] The present invention includes a surfactant dosing system using the nonequilibrium continuous monitoring of surface tension values correlated to surfactant concentration based on the percentage of active matter in an industrial laundry process. In one embodiment, standard laboratory methods are used to correlate surface tension measurements to active matter determination at selected temperatures for a commercial detergent. This method allows for the determination of a curve for predicting percentage active matter based on nonequilibrium surface tension measurements for selected samples at defined temperatures. The determining of the surface tension for a full dose of detergent and correlating this value to a percentage of active matter at a standard temperature allows for the operator to determine a baseline for proper monitoring of surfactant concentration in an industrial process.

[0008] The dosage system is able to control the surfactant concentration for a recycle wash tank using surface tension measurements, temperature control, and correlation to the percentage of active matter based on a full dose of a commercial surfactant for the wash runs. Specifically, the dosage system using the surface tensiometer is able to constantly monitor surfactant values and basis a target surface tension set point, send an output to an external pump to constantly dose a recycle tank. The adjusted surfactant dosage in the wash tank is then available for use for subsequent washes.

[0009] In another embodiment, the system and method is capable of analyzing a wash recycle collection tank and determining a surface tension at any instant. After developing a correlation curve of active matter to surface tension, the present invention may read the surface tension value and adjust surfactant concentration using electronic algorithms. Using these algorithms to determine the delivery dosage of detergent scaled to a specific concentration, the liquid detergent is metered to provide a percentage of stroke length of the dispenser, thus providing an adjusted dose to individual washers from a wash recycle tank.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof, which are illustrated in the appended drawings and described herein. It is to be noted, however, that the appended drawings illustrate only some embodiments of the invention and are therefore not to be considered limiting of its scope, because the invention may admit to other equally effective embodiments.

[0011] FIG. 1 is a preferred embodiment of the surfactant dosage system;

[0012] FIG. 2 is another embodiment of the surfactant dosage system;

[0013] FIG. 3 is another embodiment of the surfactant dosage system;

[0014] FIG. 4A is a partial embodiment of the surface tension module;

[0015] FIG. 4B is a partial embodiment of the surface tension module;

[0016] FIG. 5 is a graph comparing surface tension with detergent concentrations and bubble rates related to TABLE 2; and

[0017] FIG. 6 is a graph comparing surface tension with detergent concentrations and bubble rates related to TABLE 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0018] Though those skilled in the art will recognize that the teachings and scope of this invention are not limited to the following, this disclosure provides some of the preferred embodiments of the invention.

[0019] Surface tension varies as active surfactants are used. Surfactants are used because of their ability to reduce surface tension in water-based and solvent-based formulations. Dynamic surface tension, rather than equilibrium surface tension, can be measured in turbulent environments such as laundry processing since it may require several minutes for surfactant molecules to diffuse to the interface and lower the surface tension to an equilibrium level. Dynamic surface tension directly impacts the quality of spreading and adhesion. Surfactants used in fluid formulations tend to be quite surface active, and can vary significantly with respect to diffusion rate, depending on molecular weight and structure.

[0020] The system shown in FIG. 1 shows an application of using a tensiometer 10 in a laundry processing application. Using an automatic surface tensiometer 10, such as an IP6000 manufactured by 2000 SensaDyne Instrument Division, the user can then program a set point to send a signal to a commercial pump and dose a collection tank, thereby constantly monitoring the surfactant concentration for subsequent wash runs. Any tensiometer, including in-process, on-line tensiometers, may be used with the present invention. In a preferred embodiment, the tensiometer may have the capability to control formulation additive and concentration levels using integrated analog outputs for surface tension and temperature. Moreover, the tensiometer may include high and low set point alarms that may be used for a variety of applications such as surface tension and temperature.

[0021] During subsequent washes the wash water is released from the washer 16 to a dump chest 18 and processed through a lint screen or lint trap 20 and separatory filter 22. The measuring probes 24 attached to a sampling chamber 26 on the recycle wash tank 28 constantly monitor the surface tension and temperature. As the filtered water enters the recycle wash tank 28 via a pump, the surface tension monitors the value and compares it to the set point. If the surface tension value reads above the set point, the tensiometer 10 sends a signal that is captured by the black box converter 30 and configured into an acceptable signal for a dispenser 32 such as the Knight dispenser shown in FIG. 1.

[0022] Surface tension measurements generated using a Dynamic Surface tensiometer are preferably taken in a non-turbulent (quiet) zone in order to reduce variations in fluid flow across the sampling chamber during measurement. As bubbles are generated in the process, it is desirable to maintain a consistent less turbulent flow through the sampling chamber, so that the bubbles are completely formed and interpreted correctly by the system. In a preferred embodiment, it is possible to achieve this quiet zone by taking a slip stream (preferably about 100 ml/min) from the bulk of the recycled water being pumped around the recycle wash tank to provide a pressurized supply to refill the washing machine. This slipstream may be routed into the bottom of sampling chamber 26, which in turn could overflow back into the recycle wash tank. This procedure not only provides a most preferable quiet zone but also provides a constant water level in the sample chamber.

[0023] When the dispenser 32 receives the signal to begin pumping, the dispenser 32 turns on for a selected amount of time. Those skilled in the art recognize that the duration may vary widely or even be unlimited in the case of continuous dosing. In a preferred embodiment, a typical range of times for dosing may be from about one to about five seconds in duration with a typical evaluation time of about fifteen to about thirty seconds before redosing the tank. These times are only an example of one embodiment and are expected to vary widely depending on numerous variables.

[0024] During the design of the process the operator has two dosing options. The operator may elect to dose directly into the washer 16 or to dose directly into the recycle wash tank 28. The latter option may negate the effect of temperature variations on nonequilibrium surface tension in the recycle wash tank 28.

[0025] The tank 28 should be kept at a semi-constant temperature during operation by the constant exchange of filtered water at temperature. However, the delivery mechanism can easily be set up ahead of time to accommodate delivery to the washer 16 also. It is preferable that only one delivery option may be used at any one time.

[0026] In a preferred process, a dose of surfactant is sent to the recycle wash tank 28 that is then evaluated against the set point and the monitoring and dosing process begins again until the set point is reached. The evaluation time is determined from preliminary work and is the amount of time between surface tension readings and comparisons to the set point.

[0027] Referring to FIG. 2, a preferred embodiment of the surfactant dosing system, a controller interfaces with the surface tensiometer 10. The controller monitors surfactant level within a tank 28. The controller is preferably capable of activating a pump at a desired surface tension and issuing a surfactant dose relevant to time. The task is preferably accomplished by using a Versamax Micro Programmable Logic Controller along with a signal-conditioning transmitter.

[0028] Though those skilled in the art will recognize that while many methods may be used to accomplish this task, two methods are preferable. First, the tensiometer 10 preferably provides a 0 to 10-volt output that can be used as an input to a signal conditioner. The conditioner is preferably capable of converting this input to a 4 to 20-ma signal that was sent to the programmable logic controller. Ladder logic may be used to compare the signal to a constant. In the event that the signal was greater than or equal to the constant, a pump may activate for a desired time and disperse surfactant. It is advantageous to include a pause time in the logic between dispersions to allow adequate mixing.

[0029] Alternatively, using preferred digital outputs from the tensiometer 10 enables the operator to select a desired surface tension using the keypad of the tensiometer 10. Once the desired surface tension is reached, the output can activate an input to the programmable logic controller, which would begin the logic sequence as previously discussed.

[0030] The present invention allows for correlating the percentage of active matter for a standard detergent use concentration with surface tension at standard temperatures in an industrial cleaning process. Using this data and determining the surface tension and the percentage of active matter determination for a full dose of detergent, a curve can be constructed using surface tension measurements correlated to active matter analyses for selected sample points in the process.

[0031] In the development of this process, this was accomplished using a hand held surface tensiometer, manufactured by SITA Messtechnik GmbH in a preferred embodiment, set at a standard bubble rate to measure the surface tension at a set bubble rate and desired temperature for the collected samples. The procedure may be automated using a tensiometer such as the Sensadyne model IP6000 tensiometer set to a standard bubble rate. This allows the user to program a tensiometer set point that can be used to activate a pump to deliver surfactant when the surface tension is too high.

[0032] Referring to FIG. 3, a larger scale embodiment of the present invention is shown. Those skilled in the art will recognize the piping shown in FIG. 3 is but one arrangement of the elements of the invention and substitution, rearrangement, addition, and/or deletion of elements, including pipes, valves, drain, controllers, and any other element depicted herein, are considered to be within the scope of the invention. Streams 100-112 interact with the system. The figure is presented in a clockwise fashion showing how the soft water 100, dirty rinse water 102, dirty wash water 104, liquid detergent 106, recycle rinse water 108, return loop 110, and recycle wash water 112 interact with the system.

[0033] As shown a rinse water sump pump 118 is connected to a rinse water sump 120 that in turn is connected to the rinse water lint screen 122. Dirty rinse water moves into the rinse water sump 120. The rinse water lint screen is connected to the rinse feed tank 124 while diverting lint and other foreign particles to the wet unit to dumpster 126.

[0034] From the rinse feed tank 124, a rinse feed pump 128 can direct flow back to the rinse feed tank 124 or via a rinse circulation pump 130 to the rinse filter 132. The rinse filter is connected, amongst other things, the recycle rinse water tank 134.

[0035] The recycle rinse water tank 134 is connected to the recycle rinse water tank pump 136 which is capable of moving recycle rinse water 108 fluid to, amongst other locations, the rinse water ultraviolet (“UV”) unit 138. Nearby, a back flush pump 140 is connected at a valve prior to the rinse water pump 136 that allows for the movement of liquid to the rinse feed pump 128/rinse circulation pump 130 and the wash circulation pump 154/wash feed pump 156.

[0036] As shown, the wash water heater 142 is connected to the wash water UV unit 144 such that the recycle wash water pump 146 can move recycle wash water 112 to the wash water heater 142. The wash water heater 142 is connected to the recycle wash water tank 148. Soft water 100 enters the system into the recycle rinse water tank 134 and the recycle wash water tank 148.

[0037] The liquid detergent metering pump 150 can also move liquid detergent 106 into the recycle wash water tank 148. With these elements described and shown in FIG. 3, the use of a surface tension module 200 as shown in communication with the recycle wash water pump 148 allows for the surface tension module 200 to activate the liquid detergent metering pump 150 consistent with the teachings of this invention. The recycle wash water tank is also connected to the wash filter 152 which is capable of filtering wash water from the wash feed tank 158 via the wash circulation pump 154 and the wash feed pump 156 and from return loop 110.

[0038] As arranged in the rinse portion of FIG. 3, a wash water lint screen 160 is connected to the wash feed tank 158 which accepts liquid from the wash water sump pump 162 and is capable of diverting lint and other particulates to the wet unit to dumpster 126.

[0039] A wash water sump 164 collects dirty wash water 104 and in turn allows the wash water sump pump 162 to move the dirty wash water to the wash water lint screen 160. The clean-in-place tank 166 receives feed from both the rinse circulation pump 130 and the wash feed tank 158.

[0040] An electrical layout of the surface tension module 200 is shown in FIGS. 4A and 4B. The front 202 of the surface tension module 200 may contain indicators such as the Start indicator 204 and the Stop indicator 206 shown herein. These indicators are connected to the programmable logic controller 208. As shown herein, the programmable logic controller 208 uses a 24-volt DC power supply. The programmable logic controller 208 is connected to a signal conditioner 212 that is in turn connected to a sensor 214 such as the SensaDyne sensors described herein. The programmable logic controller 208 is finally connected to the liquid detergent pump 150 as previously discussed for use in the invention.

[0041] Though those skilled in the art will recognize that the benefits of present invention may be enabled in various embodiments, one embodiment allows for analyzing a wash recycle collection tank and determining a surface tension at any instant. Through previous work with the development of a correlation curve of active matter to surface tension, it is possible to read this surface tension value and adjust surfactant concentration using electronic algorithms. The detergent in the wash recycle tank is evaluated and compared to a full dose of detergent. The algorithms determine the delivery dosage of detergent scaled to a specific concentration and metered by stroke length on a delivery pump. The programmable logic controller then sends a signal to pump for a specific time as a percentage of stroke length equal to a full dose. Further, through the use of this method, it is possible to adjust a full dose of detergent and deliver this adjusted dose to individual washers from a wash recycle tank. This method offers more flexibility in that only the make-up dosage of surfactant is delivered to an individual washer rather than a full dose as previously described herein. It is possible that more equipment and electronics may be needed to perform this embodiment.

EXAMPLES

[0042] Through a continual monitoring of surface tension the user can design a system to maintain a wash water supply tank at a constant surfactant level for subsequent washes. Using a Sensadyne laboratory tensiometer, the surface tensions of different concentrations of a standard laundry detergent were tested at different bubble rates. The percentage mass flow concentration compared to the bubble rates expressed bubbles/second were: 1 TABLE 1 Mass Flow Concentration Comparison to Bubbles Per Second Mass Flow Concentration Bubbles/second  7% 1  9% 2 25% 5 60% 10 99% 15

[0043] Expected results were that higher nonequilibrium surface tensions would be obtained at higher bubble rates due to less time being available for surfactant to diffuse to the interface to reduce the surface tension. The desired outcome was to use this dynamic surface tension measured at an optimum bubble rate in a one-to-one correlation with detergent concentration in the concentration range of interest.

[0044] The results were consistent and expected in that dynamic surface tension decreased with increasing detergent concentration and decreasing bubble rate, i.e., increasing bubble age. However, at a given bubble rate, a one-to-one correlation of surface tension and detergent concentration was obtained.

[0045] The results were plotted and produced curves that may serve as a calibration curve to monitor changes in surfactant concentration over time in the laundry process. Additionally, Liquid Tide® HE samples were sent and tested independently at the Sensadyne laboratories. Results from the SensaDyne testing produced more extensive results.

[0046] Liquid Tide® HE was chosen as the test surfactant. This detergent contains 22.8% alcohol ethoxysulphate based on Neodol 25-2, 4.2% coco soap and 4% alcohol ethoxylate. The rest of the product is primarily water and propylene glycol with a few other minor non-surfactant ingredients. Standard use concentration is 4.36 g/L.

[0047] In the studies, surface tension readings were measured at 1, 3, 5, and 8 bubbles/second at detergent concentrations at and below the standard use concentration. Deionized water was used as the solvent, and measurements were performed at room temperature.

[0048] The procedure involved calibrating the tensiometer to a specific bubble rate, evaluating the different test concentrations at the set bubble rate, changing the bubble rate, re-calibrating the instrument, and measuring the test concentrations at this new bubble rate. In order to produce a curve this procedure was repeated for 1, 3, 5, and 8 bubbles/second. Additionally, a sample of Liquid Tide® detergent was tested at various concentrations and bubble rates over time.

[0049] From these tests, the following data was developed: 2 TABLE 2 Determination of Surfactant Concentration Using Dynamic Surface Tension Surfactant concentration Bubbles/second % 1 3 5 8 0.436 39.2 46.2 47.5 47.4 0.336 40.6 48.2 49.6 51.2 0.236 43.3 52.3 53.6 55.6

[0050] These results have been plotted in FIG. 5, showing the relationship of surfactant concentration, surface tension, and bubble rate.

[0051] A neat solution of Liquid Tide® detergent was diluted to a specific concentration to explore surface tension as the bubble rate changes over time. The procedure involved using the Dynamic Surface Tensiometer with an automatic dispensing unit. Using a mass flow controller on the instrument set a specific bubble rate. The mass flow controller was set to a calibrated percentage equal to a pre-determined bubble/second measurement. The dispenser unit used could only be set up in equal incremental percentages. Therefore, a concentration range from 0.05% concentration to 0.5% concentration, in 11 incremental steps of 0.05% concentration each, was chosen. The bubble/second range was evaluated at 1, 2, 5, 10, and 15 bubbles/second.

[0052] Similarly, the following results were obtained using Liquid Tide® detergent as a surfactant: 3 TABLE 3 Determination of Surfactant Concentration Using Dynamic Surface Tension Surfactant Bubbles/second concentration % 1 2 5 10 15 0.05 72.75 72.88 72.78 72.81 72.69 0.1 54.73 62.38 69.25 70.29 67.97 0.15 50.18 57.16 64.77 68.79 67.24 0.2 46.65 52.48 60.75 67.53 67 0.25 44.16 49.62 58.37 66.65 66.6 0.3 42.51 47.81 55.53 64.81 65.61 0.35 41.52 46.44 54.23 62.89 65.47 0.4 39.6 45.4 52.29 61.02 65.12 0.45 38.75 44.85 51.19 59.59 64.22 0.5 38.34 44.11 50.04 58.41 63.7 0.55 37.94 43.44 49.29 57.56 62.87

[0053] These results have been plotted in FIG. 6, showing the relationship of surfactant concentration, surface tension, and bubble rate.

[0054] A closed loop cleaning pilot plant was used to test the efficiency of the unit along with the quality of the finished products (consumer clothing). During this period, a target of 75% water recovery was maintained for the entire system. This target was maintained by purging 25% of the wash cycle water, remaking the wash water volume with rinse water and then remaking the rinse water volume with fresh softened water. Surfactant recovery during this period was 24%.

[0055] Previous testing and calculations had determined a full dose of Tide® detergent for 10 pounds of soiled material would be 70 grams into about 10 gallons of water. During the test period stated, 91 loads of wash were processed using an average of 53 grams Tide® detergent added per load. This yields a surfactant recovery of 24% for the period.

[0056] Numerous aspects of the invention may be varied without departing from the scope of the invention. The parameters may be varied, depending on the situation and the specific parameters desired. With regard to each parameter, a preferred parameter or range has been shown, but those skilled in the art should recognize that these parameters are not definitive, but illustrative of the benefits of a preferred embodiment of the invention.

Claims

1. A system of surfactant dosing for maintaining a set point of surfactant level in a laundry application comprising:

a washer tank;

a recycle wash tank connected to the washer tank;

a dispenser; and

a tensiometer wherein:

the tensiometer is capable of measuring the surfactant level in the recycle wash tank;

the tensiometer is capable of comparing the surfactant level to the set point; and

the tensiometer is capable of sending signals to the dispenser.

2. The system of claim 1 wherein the dispenser is capable of pumping surfactant to the recycle wash tank.

3. The system of claim 1 wherein the dispenser is capable of pumping surfactant to the washer tank.

4. The system of claim 1 further comprising a converter disposed between the tensiometer and the dispenser capable of configuring and forwarding signals to the dispenser.

5. The system of claim 1 further comprising a controller disposed between the tensiometer and the dispenser wherein:

the controller is capable of monitoring the surfactant level; and

the controller is capable of activating the dispenser.

6. The system of claim 5 wherein the controller comprises a programmable logic controller and a signal-conditioning transmitter.

7. The system of claim 6 wherein the programmable logic controller is capable of using ladder logic to compare the signals to a constant.

8. The system of claim 1 further comprising a programmable logic controller and wherein the tensiometer comprises:

a keypad; and

at least one digital output;

wherein the digital output from the tensiometer is capable of activating the programmable logic controller.

9. The system of claim 1 further comprising:

a dump chest connected to the washer tank;

a lint screen or a lint trap connected to the dump chest; and

a separatory filter connected the lint screen or lint trap and connected to the recycle wash tank;

wherein the recycle wash tank comprises a sampling chamber such that the tensiometer is capable measuring the surfactant level of the recycle wash tank via the sampling chamber.

10. The system of claim 2 wherein the dispenser is capable of dosing a calculated percentage of a stroke length of the dispenser.

11. A method of surfactant dosing for maintaining a set point of surfactant level in a laundry application that comprises the steps of:

(a) measuring the surfactant level by using a tensiometer is capable measuring the surfactant level;

(b) comparing the surfactant level to the set point;

(c) pumping surfactant if the surfactant level is lower than that the set point.

12. The method of claim 11 wherein Step (a) is accomplished by measuring the surfactant level in a recycle wash tank, wherein the recycle wash tank is connected to a washer tank.

13. The method of claim 12 wherein Step (c) is accomplished by pumping surfactant into the recycle wash tank.

14. The method of claim 12 wherein Step (c) is accomplished by pumping surfactant into the washer tank.

15. The method of claim 11 wherein Step (b) further comprises the steps of:

producing signals with the tensiometer;

converter the signals from the tensiometer; and

delivering the converted signals to a dispenser capable of performing Step (c).

16. The method of claim 11 which further comprises the step of using a controller connected to the tensiometer to accomplish Step (b).

17. The method of claim 16 wherein the controller comprises a programmable logic controller.

18. The method of claim 17 which further comprises the step of using ladder logic to compare the signals to a constant.

19. The method of claim 11 which further comprises correlating a percentage of active matter to the measured surfactant level from Step (a).

20. The method of claim 17 which further comprises the step of constructing a curve of the correlation of percentage of active matter to the measured surfactant level measurements.

21. The method of claim 11 which further comprises the step of adjusting surface tension using electronic algorithms to deliver an adjusted dosage.

22. The method of claim 21 which further comprises the steps of:

developing a correlation curve of active matter to surface tension; and

metering the dosage as a percentage of a stroke length.

23. A system of surfactant dosing for maintaining a set point of surfactant level in a laundry application comprising:

a washer tank;

a dump chest connected to the washer tank;

a lint screen or a lint trap connected to the dump chest;

a separatory filter connected to the lint screen or lint trap;

a recycle wash tank connected to the separatory filter and connected to the washer tank;

a sampling chamber connected to the recycle wash tank;

a tensiometer wherein the tensiometer comprises measuring probes disposed in the sampling chamber; and

a dispenser capable of pumping surfactant to the recycle wash tank;

wherein the tensiometer is capable measuring the surfactant level and comparing the surfactant level to the set point; and

wherein the tensiometer is capable of sending signals to the dispenser.

24. The system of claim 23 further comprising a converter connected to the tensiometer and the dispenser wherein the converter is capable of converting signals from the tensiometer and sending the converted signals to the dispenser.

25. The system of claim 23 further comprising a programmable logic controller.