Patent Grant
10165925
Dishmachines, particularly commercial dishmachines, have to effectively clean a variety of articles such as pots and pans, glasses, plates, bowls, and utensils. These articles include a variety of soils, including protein, fat, starch, sugar, and coffee and tea stains which can be difficult to remove. At times, these soils may be burned or baked on, or otherwise thermally degraded. Other times, the soil may have been allowed to remain on the surface for a period of time, making it more difficult to remove. Dishmachines remove soil by using strong detergents, high temperatures, sanitizers, or mechanical action from copious amounts of water. It is against this background that the present disclosure is made.
The present disclosure relates to a dishmachine that includes at least two tanks and methods of using the tanks to isolate, substantially isolate, or incrementally isolate different chemistries from each other during a cycle. The disclosed dishmachine design and method allows for the use of two different, and potentially incompatible or reactive chemistries to be used in the same dishmachine cycle.
In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize specific features relevant to the disclosure. Reference characters denote like features throughout the Figures.
The present disclosure relates to a dishmachine that includes at least two tanks and methods of using the tanks. The dishmachine design allows for more than one chemical composition to be used during the dishmachine cycle where the two compositions can be isolated, substantially isolated, or incrementally isolated from each other. Separating the two chemistries in this way allows an operator to use incompatible, reactive, or offsetting chemistries in the same cycle to achieve an improved cleaning result. Exemplary chemistries are described in U.S. Pat. No. 8,092,613 directed to Methods and Compositions for the Removal of Starch. U.S. Pat. No. 8,092,613 describes soil removal using compositions in an alternating pH sequence. Such a system experiences improved soil removal but uses excessive amounts of water and neutralizes the detergent in a dishmachine with one tank. Once an alkaline detergent neutralized, it is not as effective at removing soil. Likewise, certain chemical compositions, such as bleaching agents and enzymes, may be incompatible with other compositions used in the dishmachine, and therefore must remain separated to be effective.
Using the dishmachine disclosed herein with the different compositions allows for a system that uses less chemicals, less water, and less energy while providing excellent cleaning and rinsing results.
Method of Cleaning
The disclosed dishmachine design separates two different compositions and prevents them from mixing. Conventional door-type dishmachines and undercounter machines have one wash tank that contains an alkaline detergent that is circulated over the dishes. The disclosed invention provides for the addition of a second tank to a door-type or undercounter dishmachine where the second tank may contain different chemistry. Using the second tank enables different methods of cleaning articles in dishmachines that will now be discussed. For purposes of describing the disclosed method, the following abbreviations may be used: Tank A refers to the wash tank with the main detergent or composition (A).
This is most likely an alkaline detergent but may be neutral, or may be a unique formula that complements or is synergistic with the second tank chemical. For example, some of the ingredients of the alkaline detergent may be better formulated into the second composition, or vice versa.
Tank B refers to the tank containing the second composition (B). An acidic product has been found to provide special advantages, but other chemistries are also advantageous. Examples of chemical compositions include bleaches, enzymes, or chelating agents. Tank B may additionally collect or contain fresh rinse water.
Wash A refers to the recirculation of water and chemicals from tank A onto the dishes. Note that water circulated from tank A mostly returns to tank A and, similarly, water that circulates from tank B mostly returns to tank B. Thus, mixing of the two tanks is minimized, but may not be completely eliminated. Wash A is further illustrated in
Wash B refers to the recirculation of water and chemicals from tank B onto the dishes. Note that wash B does not necessarily come after wash A in the sequence of events. Wash B is further illustrated in
Rinse A refers to the spray of fresh water onto the dishes. This may also be referred to as the final rinse. It may contain rinse additive, sanitizer, or other GRAS materials. Rinse A is further illustrated in
Rinse B refers to the spray of water containing chemical B onto the dishes. This is a direct spray and is not circulated like a wash step. This could be a dynamic addition of chemical B into a fresh water stream (as shown in
Rinse A and Rinse B can be a fresh water supply under pressure, or can be a tank of fresh water that is pumped into the dishmachine.
The chemical addition to all tanks can be accomplished in a number of ways including with a conductivity controlled dispenser, timed or periodic addition of chemical, or injection of chemical into the water stream before or after the tank.
In the method, tank A and tank B are at least partially isolated from each other. Separation of tank A and tank B can be achieved by various methods. Note that complete or 100% separation of tank B from tank A is not required for the machine. Even a partial separation with partial mixing of the two tanks has been found to be incrementally beneficial. In some embodiments, tank A and tank B are separated and the dishmachine provides a separation so that the mixing is reduced or minimized. In some embodiments, the dishmachine provides at least 80%, at least 90%, at least 99.9%, or at least 99.99% separation of the tank A and tank B fluids. Said differently, in some embodiments, no more than 20%, no more than 10%, no more than 0.1%, or no more than 0.01% of the tank A and tank B fluids mix.
A dishmachine cycle in a typical door- or hood-type dishmachine or under counter machine has two main steps: a wash and a rinse. Using the definitions from above, this sequence may be illustrated as:
In the disclosed method with a dishmachine with at least two tanks, several steps may be added to this cycle, although certain features can be embodied in only one or two additional steps. It should be noted that the overall total dishmachine cycle length does not need to be increased, regardless of the number of steps in the process. Improved results can be seen with multiple steps without increasing the total cycle length. In some embodiments, a process with several steps can be generically described as follows:
The six steps of this cycle sequence are outlined as follows:
1. Wash A circulates a solution of composition A from tank A
2. Wash B circulates a solution of composition B from tank B
3. Rinse B sprays a mixture of composition B and fresh water onto the dishes
4. Repeat step 1 with a potentially different time duration
5. Repeat step 2 with a potentially different time duration
6. Rinse A sprays fresh water onto the dishes—final rinse
In some embodiments, a specific example of this six-cycle sequence can use an alkaline detergent as composition A and an acidic detergent as composition B. This process could include the following:
1. Wash A circulates the alkaline A detergent onto the dishes. The purpose of this step is to penetrate the alkaline sensitive soils and to wash off the bulk of the food soils.
2. Wash B circulates the acidic B detergent onto the dishes. The main purpose of this step is to wash off and neutralize the alkalinity from the dishes. Neutralizing the alkalinity in this step allows the following Rinse B step to be more effective and to be shorter in duration. That directly reduces the amount of chemical B and the amount of water used to deliver composition B, which is a significant water, chemical, and energy cost reduction.
3. Rinse B sprays a concentrated solution of acid B onto the dishes. The strong acid penetrates and loosens acid-sensitive soils. In this example, fresh water is used to deliver the acid B. As mentioned above, since wash B neutralizes the alkalinity on the dishes, the duration of Rinse B can be quite short, saving chemicals, water, and energy for the overall system.
4. Wash A again circulates the alkaline A detergent onto the dishes. This step removes soils loosened in the previous step and further strips off alkaline sensitive soils.
5. Wash B again circulates the acidic B detergent. The acidic nature of the B detergent is particularly useful at removing and neutralizing the alkaline detergent from the dishes. Therefore, the wash B step duration can be relatively short, but more importantly, it allows the final rinse A step duration to be reduced tremendously with respect to time and/or water volume. By pre-neutralizing the alkaline detergent from the dishes, the final rinse A step can be very short since most of the hard-to-rinse materials are already removed or neutralized. Providing for a short final rinse water spray brings huge savings since this water is typically heated to high temperatures (180° F.), thus saving a large amount of energy as well as water.
6. Rinse A sprays hot fresh water onto the dishes. The energy required to heat this water is the single most expensive part of the dishwashing operation. Having an acidic wash B step beforehand allows the volume of water used in the rinse A step to be significantly reduced. Either the duration of rinse A can be reduced, or the water flow rate of rinse A can be reduced, with the overall result of using less water.
Note that the circulated wash A solution ultimately drains into tank A, and that the wash B and rinse B solutions ultimately drain into tank B, either completely or partially. The means of obtaining this separation is explained below.
In the above example, fresh acid is delivered only in the rinse B step, but is captured and re-utilized advantageously in both the wash B steps. This saves on the overall amount of chemistry needed. Not only does the acid not mix with the alkalinity, thus neutralizing it, but the acid is utilized in other steps. The current trend in dishmachine development is to use lower amounts of water, both in the wash tank and in the fresh rinse volumes. Smaller amounts of wash water mean that the wash tanks are dirtier and have high amounts of alkalinity, thus making the dishware harder to rinse clean. Smaller amounts of rinse water make it especially more challenging to get the dishes rinsed clean. This method addresses those challenges. By utilizing an acidic wash before the final rinse, significantly lower amounts of water can be used while achieving excellent cleaning and rinsing results. The duration time for each of the steps is adjustable and is dependent on the particular chemistry employed and on the water and washing action of the machine. An alternative to adjusting the step duration is to adjust the flow rate of each step. A lower flow rate can be equivalent to a shorter duration in terms of the amount of water or wash solution being utilized in the step. In some steps it may be advantageous to change the duration where in other steps it may make sense to change the flow rate. Therefore, step durations and step flow rates are preferably independently adjustable. Some examples of changing step durations include the following:
The above example illustrates just one possible sequence of steps. In general the wash B and rinse B steps can be inserted in three different places: (1) at the beginning of the cycle; (2) in the middle of the cycle (as shown in the example above); or (3) before the final rinse cycle (as shown in the example above). Numerous combinations can be envisioned with the B steps inserted into one, two, or all three of the above-mentioned places in the sequence. Some of them are explained below.
2nd Example Sequence with B Steps First
In this example, the wash B and rinse B steps are first in the dishmachine cycle. Some soils react better when the acid step is first as opposed to second in the sequence. For example, this sequence could be employed in a type of restaurant serving high levels of protein, whereas the acid-second sequence would be employed in a restaurant serving high levels of starch. Furthermore, depending on the mechanical configuration and on the chemistry employed, either both wash B and rinse B can be separately employed, or they can be combined into one single wash B step. This example sequence is shown immediately below:
3rd Example Sequence with Combined B Steps
The combined B steps can be employed when tank B is completely isolated from tank A and from rinse A. When tank B is totally separated and regains all of its water each step, then there is no need for the rinse B step to add more water and composition B. The chemical B can be delivered into tank B instead of into rinse B with the resulting elimination of the rinse B step. The advantages are (1) elimination of the water consumption introduced in the rinse B step, and (2) conservation of chemical B usage. The chemical would be re-used over and over again, assuming that nearly 100% of the B solution is recovered each cycle. This sequence would also work well with the “level control” method described below.
Other useful sequence combinations are shown below, but the list is not all inclusive as the possible configurations are too numerous to list:
Example Sequence with 9 Steps
Example Sequence with 8 Steps
Example Sequence with 7 Steps
Example Sequence with 6 Steps
Example Sequence with 5 Steps
Example Sequence with 4 Steps
Example Sequence with 3 Steps
It is important to note that each of the individual steps in the sequences can adjustably be shorter or longer and have higher or lower flow rates, depending on the chemistry and mechanical configuration. The above sequences are adaptable mainly to a high temperature door-type or hood-type dishmachines, or undercounter dishmachines, but other single tank machines can be utilized. For example, a low temperature, chemical sanitizing door-type dish machine could be used where the temperature of this type of machine is lower, but the wash B and/or rinse B steps include the addition of chemical sanitizer. Also, the tank B or rinse B water could be heated. If the tank B water is heated, the wash B step contributes to the overall thermal sanitizing impact of the dishmachine. Heating tank B will ultimately allow the usage of even less final rinse water A since the rinse A step will then not require as much water or contact time to complete the sanitation requirements. Likewise, a heated rinse B step contributes to sanitization with the resulting usage of less final rinse water and ultimately less water usage overall for the dishmachine. The B steps listed above could be heated to 165° F. to have this contribution effect, or could be heated as high as 180° F. for a larger contribution. The disclosed methods could also be adapted for use in glass washers, or other batch-style machines.
Dishmachine Designs for Separating Tank a and Tank B
Water Overflow Method
With this method, the intention is to keep tank B substantially full to the top with composition B and water, thereby preventing wash A water from entering the tank. By ensuring that tank B is full during the wash A step(s), the wash water from tank A will be prevented or restricted from flowing into and mixing with tank B. Conversely, by design, tank B is not completely full during the wash B or rinse B step(s) and the B water will deliberately be directed to refill tank B
The design and drawings for this “water overflow” method are shown in
During the dishmachine operation, water is circulated from tank B 16 with a pump 18 during the wash B step. Thus, as the pump 18 draws wash water from tank B 16, the level in tank B falls, thereby allowing the wash B water to return and refill the tank. There may be some loss of water so the tank may not completely refill itself. The rinse B step or rinse A step can be used to refill the tank B to the top. Any excess water will overflow into tank A. Whenever tank B 16 is completely full the cascading water from the floor 30 flows over the top of tank B 16 and falls into tank A 12. This overflowing of water is particularly advantageous when the wash A step is being conducted since it is desirable to minimize the mixing of the wash A solution into the wash B solution, and vice versa. This method of separating tank A and tank B can be further described using the following sequence:
1. Wash A circulates a solution of composition A from tank A 12. Since tank B 16 is full, most if not all of the wash A water flows over tank B 16 and returns to tank A P.
2. Wash B circulates a solution of composition B from tank B 16. The pump 18 draws water from tank B 16 thus lowering the level of tank B 16. Water returning from the pump spray is directed from the floor 30 over the top of tank B 16 and mostly enters into tank B 16 since the tank is not full at the time.
3. Rinse B sprays a mixture of composition B and fresh water onto the dishes. The rinse B spray falls and is also directed toward tank B 16 thus completely filling the tank to the top. Any excess wash solution overflows into tank A 12. This is the mechanism for keeping tank B 16 full and for adding composition B to tank B 16.
4. Repeat step 1 with a potentially different time duration
5. Repeat step 2 with a potentially different time duration
6. Rinse A sprays fresh water onto the dishes during the final rinse. Like the rinse B step, the rinse A step fills tank B 16 to the top and any excess overflows into tank A 12. In this manner, the rinse A water keeps tank B 16 and tank A 12 clean by adding fresh water to each tank every cycle.
Additional drawings for various designs of the top of the cover 34 of tank B 16 are shown in
Positive Diverter Method
In this embodiment, a mechanically activated diverter plate or plates are used to positively direct all fluid to the tank of choice (tank A, tank B, or a combination thereof). All or some water drawn from tank A, tank B, rinse A, or rinse B could be diverted into tank A, tank B, or a combination thereof. The mechanical diverter can be driven by a motor, electromagnetic device, a physical action such as a linkage driven by the door opening or closing action, some other device, or a combination of these. Since the water flows are directed mechanically, there is very little (less than 0.1%/per cycle) mixing of tank A and tank B. As a result, tank B would lose very little water and would not need to be refilled as often. The final rinse A water would be used to replenish the losses from both tanks, and the rinse B step would not be needed to refill tank B. Periodically composition B would need to be added to tank B and likewise composition A would need to be added to tank A.
The gutter 46 is a continuous fluid catch around the perimeter of the strainer 70. The gutter 46 has at least one fluid outlet port, which may be located in one of the corners of the opening 64 or along one of the sides of the opening 64. The outlet port is sized to permit leakage into a single tank at a rate greater than would be expected to enter the gutter 46. The amount of leakage into this gutter and into the desired tank may be in the range of 0.4 ounces/second to 1.0 ounce/second. In some embodiments, the gutter drains onto the diverter 44 and then into the desired tank or directly into the desired tank. This is accomplished by allowing two overflow edges on the gutter (as seen in
In some embodiments, the gutter drains exclusively into tank A 12. This would mean that some of wash B would drain into tank A 12 and not tank B 16. This may be acceptable since the amount of fluid circulated from tank B 16 is considerably smaller than the amount of fluid circulated from tank A 12, making any leakage from the gutter 46 during wash B minimal. In a preferred embodiment, there is no leakage from tank A to tank B or from tank B to tank A beyond the water that is adhered to the surfaces of the wash chamber and water that does not drain completely to either tank.
Level Control with a Float and Refill Valve Method
In some embodiments, the flow of additional water to tanks A and B is controlled with a level control design similar to the overflow method above. This embodiment uses a float inside the tank to trigger an electric signal to refill the tank automatically when it gets too low. Accordingly, some of the wash B water would return to tank B for re-use, but the tank would then automatically refill to the top with fresh water and more of composition B. Therefore, the rinse B step would not be needed to fill the tank to the top and would not be needed to charge tank B with chemical. The chemical would be added to the tank, not to the rinse step. This embodiment is beneficial because it refills the tank only as needed to compensate for water lost during the dishmachine cycle. The level control design would save additional water above what the overflow design saves, due to the removal of the Rinse B step.
Float Driven Deflector Method
In some embodiments, flow to tanks A and B is controlled with a float system as shown in
Floating Tank B Method
In some embodiments, tank B 16 actually floats within tank A 12, as shown in
Total Fluid Capture and Control Method
The Water Overflow Method and the Water or Pump Actuated Deflector Method shown in
Motor Driven Stopper Method
In some embodiments, the opening(s) 36 in tank B 16 can be further controlled by including an automated valve 90 or device that seals the openings 36 when a cycle is occurring that includes a fluid that is not desired to enter tank B 16. This valve 90 can automatically open when a cycle is occurring that includes water desired to enter tank B 16 as shown in
Reducing Residual Water
Following a step in any of the wash and rinse processes, water and chemical solution remain on the interior surfaces of the machine and on the ware that is being washed. It is preferable to have this solution routed to the desired tank in order to further reduce or eliminate contamination of the tank solutions. The following methods can be employed to collect this residual water and direct it to the correct tank. In some embodiments, the start of the subsequent step in the wash process is delayed to allow more time for water to drain from the just-completed step into the appropriate tank. For example, after completion of the alkaline wash spray, the diverter 44 in
In some embodiments, the diverter 44 is kept in the position to divert the wash solution into the appropriate tank for the start of the next step in the wash process. This is preferable in cases where it is acceptable to have a small amount of contamination of one tank with the wash solution from the other tank, but not acceptable to contaminate in the opposite direction. For example, if it is preferable to have some contamination of the alkaline tank with acidic wash solution, but it is not acceptable to contaminate the acidic wash tank with alkaline wash solution, the diverter 44 could be positioned to divert the first fraction of a second or seconds of acidic wash into the alkaline tank. This would result in the residual alkaline solution on the interior of the wash chamber and ware, plus the initial acidic solution, being diverted to the alkaline tank, and reducing contamination of the acidic tank with the residual alkaline solution.
In some embodiments, fresh water could be used at the end or beginning of a cycle for a short period of time. This would reduce the contamination even further. For example, following an alkaline wash step, a short spray of a fraction of a second or seconds of fresh water would rinse much of the residual alkaline solution into the alkaline tank without contamination of the alkaline tank by acidic solution. The residual solution in the wash chamber at the end of this step would primarily be fresh water, so when the acidic step was started, the diverter 44 could be positioned to immediately route the wash solution into the acidic tank.
The present invention may be better understood with reference to the following examples. These examples are intended to be representative of specific embodiments of the invention, and are not intended as limiting the scope of the invention. Variations within the disclosed concepts are apparent to those skilled in the art.
Example 1 quantified the tank to tank leakage in a dishmachine with the design of
The result was a worst case leakage amount from tank A to tank B of 35.2 ml at the 38.0 gpm and 3600 second test condition representing 2280 gallons of circulated fluid. This shows that the diverter drained gutter system is over 99.9% effective at diverting water back into either tank.
Example 2 determined the product and water usage of a simulated dual tank dishmachine versus a single tank dishmachine. For this example, a dual tank machine was simulated by using two dishmachines side-by-side. The first dishmachine contained alkaline detergent in its wash tank. The second dishmachine contained an acidic product in its wash tank. After washing the rack of dishes in the first dishmachine, the rack was immediately slid into the second dishmachine for the acidic product and final rinse. The following test parameters were used for the example:
Conventional Steps: Use One Single-Tank Dishmachine
1. Alkaline Wash: 45 seconds
2. Pause: 2 seconds
3. Fresh Water Final Rinse: 11 seconds
Dual Tank Steps: Use Machine-1 and Machine-2:
1. Alkaline Wash 45 seconds
2. Pause 2 seconds
3. Acid Power Rinse 6 seconds (recirculated and re-used)
4. Fresh Water Final Rinse 5 seconds
General Conditions:
This example measured product and water usage for the simulated dual tank system that dosed twice the detergent as the single tank system, but used one-half as much fresh final rinse water per cycle. 20 cycles were run for both the single and simulated dual tank systems and the results were averaged. Product usage was determined by measuring the weight loss of the product with a balance. Water usage was determined using water meters attached to the inlet of the machines. The single tank wash used 1000 ppm of Solid Power alkaline detergent, which is considered a normal usage level for the industry. The final water rinse was set at 0.82 gallons of water in 11 seconds and the actual water rinse was measured at 0.82 gallons. The simulated dual tank test used 2000 ppm of Solid Power alkaline detergent, which is twice the normal usage level in the industry. The final water rinse was set at 0.42 gallons in 5 seconds. This final rinse was divided between the alkaline machine and the acidic machine with two seconds of final rinse water sprayed onto the dishes while in the acidic machine and three seconds of final rinse water sprayed onto the dishes while in the alkaline machine. The rack was first rinsed in the second, acidic machine and then the rack was moved back to the alkaline machine and rinsed again. The pH of the acidic tank was maintained at pH 4.0+/−0.5 by taking manual pH measurements each cycle and manually adding acid to maintain the target pH. Six dinner plates were placed into a dish rack for each test. The results are shown in Table 2.
Table 2 shows that the simulated dual tank dishmachine used less detergent, but more acid and approximately half the water of the single tank machine. The one-half water usage is significant not only in the water savings but also in the energy savings associated with having to heat half the amount of water. The detergent and acid usage can be further reduced my minimizing any carryover of acidic composition to the alkaline tank and vice versa. This emphasizes the importance of a system design that minimizes carryover between the two tanks.
Example 3 compared the cleaning performance of the simulated dual tank system with a single tank system.
For this example, tea stains were deposited onto ceramic tiles by preparing according to the following method. Three 2-liter beakers were filled with 180° F. 17 grain hard water and 50 teabags of Lipton brand black tea were placed into each beaker and allowed to steep for 5 minutes. After five minutes, the beakers were emptied into a hot water bath. 40 ceramic tiles were suspended on racks and lowered into the tea water bath. The tiles were allowed to remain in the tea water bath for 1 minute and then they were raised and allowed to remain outside of the tea water bath for 1 minute. This process was repeated for a total of 25 dip/raise cycles. The tiles were removed from the rack and allowed to air dry for at least one day and as long as two to three days.
Soil removal was calculated by taking photos of the tiles before and after cleaning and using digital image analysis. The digital image analysis is conducted by comparing digital photos of the stained tea tiles before and after washing. To calculate a percent soil removal number, the number of dark pixels (stained) on the AFTER pictures is subtracted from the number of dark pixels on the BEFORE pictures, and divided by the number of dark pixels on the BEFORE pictures:
(BEFORE−AFTER)/(BEFORE)×100=% Soil Removal
The same procedure and dishmachine cycle settings were used as in Example 2. The final rinsing was done completely in Machine 1 for the single tank method and completely in Machine 2 for the simulated dual tank method.
For the test, the single tank method used Solid Power alkaline detergent at concentrations of 1000, 1200, and 1400 ppm and a measured final water rinse of 0.92 gallons in 11 seconds. The dual tank method used Solid Power at 1600, 1800, and 2000 ppm and a measured final water rinse of 0.46 gallons in 5 seconds. The results are shown in Table 3.
Tea stains on ceramic are very difficult for most detergents to remove at normal dosage levels. The single tank method was effective only at the highest concentration level. But, at 1400 ppm, the alkaline detergent can leave an alkaline residue on the dishware item. The simulated dual tank method was effective at removing the tea stains, but without leaving any alkaline residue on the coupons as shown in Example 4.
Example 4 determined the amount of residual alkalinity remaining on dinner plates after the final rinse cycle. For this example, a concentrated solution of Indicator P, also known as phenolphthalein indicator, was sprayed onto the dinner plates immediately after the rack and plates were removed from the dishmachine. Indicator P turns bright pink when the pH is 8.3 or above and is clear or colorless below pH 8.3. Photos were taken within 1 second of spraying Indicator P. The amount and intensity of the pink color was then rated by comparing the photos of each plate. A rating of 1 is perfect with no pink color visible. A rating of 10 is the worst with a large amount of dark pink color.
The same procedure and dishmachine cycle settings were used as in Example 2. For this example, the single tank method used Solid Power alkaline detergent at concentrations of 1000 and 2000 ppm. This example varied the length of the final rinse and measured results after an 11 second, 9 second, 7 second, 5 second, and 3 second rinse. The flow rate was set to 0.82 gallons in 11 seconds. The dual tank method used Solid Power at 1000 and 2000 ppm. This example also varied the length of the final rinse for the simulated dual tank method and measured results after a 7 second, 5 second, and 3 second rinse. The flow rate was set to 0.82 gallons in 11 seconds. The results are shown in Table 4.
Table 4 shows that a short rinse in the single tank method leaves alkaline residue on plates. For the single tank method, a longer rinse (and thus more water) is needed in order to remove the alkalinity, especially the alkalinity levels needed to remove the tea stains in the single tank example in Example 3. The dual tank method has very little alkaline residue, even at the 3 second rinse and even when 2000 ppm of alkaline detergent was used.
The above specification provides a complete description of the disclosure. Since many embodiments of the disclosure can be made without departing from the spirit and scope of the invention, the invention resides in the claims.
This application is a continuation of U.S. application Ser. No. 13/712,375, filed Dec. 12, 2012, entitled “Method of Separating Chemistries in a Door-Type Dishmachine,”, now U.S. Pat. No. 9,357,898 issued on Jun. 7, 2016, which claims the benefit of U.S. Provisional Application No. 61/569,892, filed Dec. 13, 2011, entitled “Method of Separating Chemistries in a Door-Type Dishmachine,” both of which are incorporated by reference herein in their entirety.
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| Child | 15147017 | US |
