Patent Publication Number: US-6336468-B1

Title: Chemical supply tube isolation system

Description:
BACKGROUND 
     1. Field of Invention 
     This invention relates generally to chemical dispensing systems and specifically to a method and system for flushing chemicals from a liquid chemical delivery system. 
     2. Description of Related Art 
     Liquid chemical delivery systems are used to automatically deliver a plurality of viscous chemicals to one or more destinations. Examples of a liquid chemical delivery system having a single manifold and a single distribution tube and the advantages thereof are described in commonly owned U.S. Pat. No. 5,014,211, incorporated herein by reference. FIG. 1 shows a chemical delivery system  100  of the type disclosed in U.S. Pat. No. 5,014,211. When it is desired to deliver a chemical stored within the container  102  to, for instance, the washer  110 , the chemical pump  142  is operated in a forward direction so as to pump the chemical from the container  102  into the manifold  130 . The transport pump  132  pumps the chemical from the manifold  130  to the destination washer  110  via the feed tube  150 . In some embodiments, the transport pump  132  has a larger pumping capacity than the chemical pump  142  and therefore draws water into the manifold  130  from the break tank  116  while pumping the chemical from the manifold  130  to the feed tube  150 . In this manner, chemicals from the container  102  are diluted before being delivered to the washers  110 - 112 . 
     After one or more chemicals are successfully delivered to the washers  110 - 112 , it is desirable to flush the chemical pumps  142 - 146  with water to remove residual chemicals therein. Thus, after delivery of a chemical from the container  102  to the washer  110 , the corresponding chemical pump  142  is operated in a reverse direction to pull water from the manifold into the chemical pump  142  and thereby remove any chemical residual within the pump  142 . Minimizing the time that the pump  142  is exposed to chemicals sourced from the container  102  maximizes the useful life of both the chemical pump  142  and its associated pump tube. 
     In an industrial laundry system such as, for instance, system  100  of FIG. 1, it is desirable to use highly concentrated detergents in order to minimize storage and transportation costs. However, high concentration detergents such as, for instance, the commercially available detergent “CLAX Ultima,” are non-ionic surfactant chemicals that tend to thicken or “gel” when exposed to water. Thus, flushing the chemical delivery system  100  with water immediately after a non-ionic surfactant detergent is delivered using the system  100  may be problematic. Specifically, water is likely to flow into the chemical supply containers  102 - 106 , and therefore likely to come into contact with the detergent therein, while respective pumps  142 - 146  are operated in the reverse direction. The resultant gelling of a non-ionic surfactant detergent at or near the outlet of the containers  102 - 106  may not only compromise the proper concentration of the detergents therein but also lead to a blockage of that outlet and, thus, disrupt subsequent detergent flow from the supply containers  102 . 
     Prior “solutions” to problems resulting from this “gelling” of non-ionic detergents are not entirely satisfactory. Some solutions simply avoid the use of chemicals that gel upon contact with water. This approach, however, undesirably limits the range of chemicals that may be used with the delivery system  100 . Other solutions include using a non-flushed chemical injection system, or using steam injection systems, to flush the chemical pumps  142 - 146 . These approaches, however, are complicated and expensive. 
     SUMMARY 
     A supply tube isolation system is disclosed for use with a chemical delivery system having a manifold connected to one or more chemical pumps which, in turn, are connected to corresponding supply containers via supply tubes. Present embodiments include feedback tubes connected between the manifold and each of the supply tubes of the delivery system. A controllable valve means is provided at or near the junction of the feedback tube and the supply tube so as to effectively segment the supply tube into first and second portions, where the first supply tube portion is that which is connected between the valve means and the manifold, and the second tube portion is that which is connected between the valve means and the supply container. 
     While one or more chemicals are being delivered to predetermined destinations within the delivery system, the valve means is positioned so as to allow a forward pumping action of the chemical pumps to effect chemical flow from corresponding supply containers to the manifold via the supply tubes and chemical pumps, and thereafter to the predetermined destinations via a feed tube. After the chemical is successfully delivered, the valve means is positioned so as to allow a reverse pumping action of the chemical pumps to draw water from the manifold into the chemical pumps and then back to the manifold via the first portions of the supply tube and the feedback tube. The second portions of the supply tubes are closed and thereby isolate the chemicals stored in the supply containers from the water. In this manner, present embodiments allow the chemical pumps and supply tubes of a suitable chemical delivery system to be flushed with water without exposing chemicals stored within the supply containers to water and, therefore, without an undesirable gelling of non-ionic surfactant chemicals. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of a chemical delivery system in accordance with the above-referenced U.S. Patent; 
     FIG. 2 is a block diagram of a supply tube isolation system in accordance with one embodiment of the present invention; and 
     FIGS. 3A and 3B are block diagrams of a supply tube isolation system in accordance with another embodiment of the present invention. 
    
    
     Like components in the Figures are similarly labeled. 
     DETAILED DESCRIPTION 
     The present invention is described below in the context of the chemical delivery system  100  of FIG. 1 for simplicity only. It is to be understood that embodiments of the present invention are not limited to specific examples provided herein, but rather are applicable to other suitable chemical delivery systems. Further, although present embodiments are described below as delivering CLAX Ultima detergent, it is to be understood that present embodiments are suitable for use with the delivery of chemicals other than CLAX Ultima detergent. 
     As discussed above, since CLAX Ultima detergent gels when exposed to water, as do non-ionic surfactant chemicals, it is problematic to flush the delivery system  100  with water when the delivery system  100  is delivering CLAX Ultima detergent to the washers  110 - 112 . Present embodiments alleviate this problem by isolating the supply containers  102 - 106  from the chemical pumps  142 - 146  and manifold  130  while the system  100  is flushed with water. Specifically, present embodiments employ feedback tubes between the manifold  130  and the supply tubes of the delivery system  100 . Controllable valve means provided near the supply tube-feedback tube junctions allow the manifold  130  and chemical pumps  142 - 146  to be flushed with water while minimizing contact between water and the CLAX Ultima detergent (as well as other chemicals) stored in the containers  102 - 106 . By sufficiently minimizing gelling of non-ionic surfactant detergents used within delivery system  100 , present embodiments allow the system  100  to be used with a wider range of chemicals, thereby increasing its universality and, thus, its commercial potential. Further, present embodiments allow delivery systems such as the system  100  to take advantage of the low storage and transportation costs of highly concentrated detergents which, as mentioned above, are typically non-ionic surfactant chemicals. 
     A supply line isolation system  700  in accordance with a first embodiment of the present invention is shown in FIG.  2 . The isolation system  700  replaces portion  190  of the delivery system  100  of FIG.  1 . Only one container  102  and its associated pump  142  of the isolation system  700  are shown in FIG. 2 for simplicity; actual embodiments may be employed in suitable delivery systems having a plurality of container-pump pairs. The isolation system  700  includes a pump supply tube  702  connected between the container  102  and the pump  142  and a feedback tube  704  connected between the manifold  130  and the pump supply tube  702 . A first valve  706  is provided within the feedback tube  704  near its junction  705  with the pump supply tube  702 . A second valve  708  is provided within the pump supply tube  702  between the junction  705  and the supply container  102 , thereby segmenting the supply tube  702  into a first portion  702   a  between the manifold  130  and the junction  705  and a second portion  702   b  between the junction  705  and the supply container  102 . 
     The supply tube isolation system  700  operates within the delivery system  100  of FIG. 1 as follows. During delivery of a chemical such as the CLAX Ultima detergent from the container  102  to one of the destination washers  110 - 112 , the first valve  706  is in a closed position and the second valve  708  is in an open position. The chemical pump  142  is operated in a forward direction so as to pull the CLAX Ultima detergent from the container  102 , through the supply tube  702  and the pump  142 , and into the manifold  130 . Referring also to FIG. 1, the transport pump  132  is operated in a forward direction to pump the CLAX Ultima from the manifold  130  to the destination washers  110 - 112 . As discussed in U.S. Pat. No. 5,014,211, the flow capacity of the transport pump  132  is greater than that of the chemical pump  142  so as to dilute the CLAX Ultima within the manifold  130  by drawing water from the break tank  116 . A conductivity cell  152  verifies that the chemical pump  142  has been primed and also verifies that the CLAX Ultima detergent is being successfully pumped from the supply container  102 . Additional operational details of the delivery system  100  during this “delivery” phase are described in U.S. Pat. No. 5,014,211. As noted above, the first valve  706  is closed during the delivery phase, thereby precluding detergent flow to the supply tube  702  via the feedback tube  704 . 
     After CLAX Ultima detergent is successfully delivered to the destination washers  110 - 112 , the delivery system  100  enters a “flushing” phase during which, as described in U.S. Pat. No. 5,014,211, the manifold  130  and chemical pump  142  are flushed with water by running the chemical pump  142  in a reverse direction. During the flushing phase, first valve  706  is in an open position and the second valve  708  is in a closed position. Accordingly, when the pump  142  is run in the reverse direction, water drawn from the break tank  116  is pumped into the manifold  130  and then into the chemical pump  142  via the exit tube  710 . The water exits the chemical pump  142  through the first supply tube portion  702   a , enters the feedback tube  704  via the first valve  706 , and is then removed from the manifold  130  by the transport pump  132  which, accordingly, continues to operate in the forward direction. In this manner, water from the break tank  116  flushes CLAX Ultima detergent residuals from the manifold  130  and the chemical pump  142  which, as mentioned above, advantageously prolongs the useful life of the chemical pump  142 . 
     Since the second valve  708  is in the closed position during the flushing phase, water is precluded from coming into contact with CLAX Ultima detergent stored within the container  102 , thereby greatly reducing the gelling of CLAX Ultima detergent near the outlet of the container  102 . Indeed, the isolation system  700  results in a minimal amount of residual gelled detergent which, in turn, is pumped out of the delivery system  100  during subsequent delivery phases. Thus, including the isolation system  700  of FIG. 2 within the delivery system  100  of FIG. 1 allows the manifold  130  and chemical pump  142  of the system  100  to be flushed with water while nearly eliminating detergent gelling problems discussed above with respect to the prior art. 
     Preferably, the first and second valves  706  and  708  are non-return valves configured to open and close as described above in response to the pumping direction of the pump  142 , i.e., the first valve  706  is closed and the second valve is open when the pump  142  operates in the forward direction, and the first valve  706  is open and the second valve  708  is closed when the pump  142  is operating in the reverse direction. The isolation system  700  is a passive system since external control signals are not required. 
     FIGS. 3A and 3B show an isolation system  800  in accordance with another embodiment of the present invention which may replace the portion  190  of the delivery system  100  of FIG.  1 . Only one container  102  and chemical pump  142  pair are shown for simplicity. Here, the first and second valves  706  and  708  are replaced with a three-way, motor-driven ball valve  802 . Specifically, the ball valve  802  is provided within the junction of the supply tube  702  and the feedback tube  704  and thereby segments the supply tube  702  into first and second portions  702   a  and  702   b , respectively, as indicated in FIGS. 3A and 3B. The ball valve  802 , which is of conventional design, selectively connects the first supply tube portion  702   a  to either the second supply tube portion  702   b  or to the feedback tube  704  in response to a control signal CTRL which, in some embodiments, also determines whether the chemical pump  142  operates in the forward direction or the reverse direction. 
     Prior to and during the delivery phase of the delivery system  100  (FIG.  1 ), the control signal CTRL is in a first state which causes the chemical pump  142  to operate in the forward direction. This first state of the control signal CTRL also forces the ball valve  802  to be positioned so as to connect the first supply tube portion  702   a  to the second supply tube portion  702   b , as shown in FIG.  3 A. Here, the feedback tube  704  is closed. In this manner, the forward pumping operation of the pump  142  draws CLAX Ultima detergent from the container  102 , through the supply tube  702  and the pump  142 , and into the manifold  130  for delivery to the destination washers  110 - 112  via the transport pump  132 , as discussed above and more fully described in U.S. Pat. No. 5,014,211. 
     After completion of the delivery phase of the delivery system  100 , the control signal CTRL transitions to a second state which, in turn, causes the chemical pump  142  to operate in the reverse direction and, in addition, changes the positioning of the ball valve  802  so as connect the first supply tube portion  702   a  to the feedback tube  704 , as shown in FIG.  3 B. Here, the second supply tube portion  702   b  is closed. In this manner, water drawn from the break tank  116  is pumped into the pump  142  via the exit tube  710  and then back into the manifold  130  via the first supply tube portion  702   a  and the feedback tube  704 . Here, the ball valve  802  entirely precludes water from coming into contact with the CLAX Ultima detergent within the container  102 . In this manner, the undesirable gelling of non-ionic surfactant detergents during the flushing phase is eliminated. 
     The embodiment depicted in FIGS. 3A and 3B is an active system in that external control signals, e.g., signal CTRL, are required to control the position of the ball valve  802 . For applications where a complete elimination of detergent gelling is desired, the expense and complexity of the ball valve  802  (FIG.  3 ), as compared with the first and second non-return valves  706  and  708  of the passive system  700  (FIG.  2 ), is offset by the superior reduction in gelled detergent residue achieved by the active system  800 , as compared to the passive system  700 . Further, use of either the passive system  700  or the active system  800  eliminates the need for more expensive and complex flushing systems such as, for instance, steam injection flushing systems, thereby resulting in lower equipment cost associated with the delivery system  100 . 
     While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as fall within the true spirit and scope of this invention.