Warewash machine with controlled retention of liquid in suspension

Abstract

A warewash machine includes at least one collection tank for collecting wash liquid that is recirculated by a pump and sprayed for cleaning wares within a spray zone of the machine. An overflow path leads from the collection tank, and an automated valve controls flow along the overflow path. A controller is configured to control an open/closed state of the automated valve based at least in part upon status of pump operation

What is claimed is: 
     
         1 . A method of operating a warewash machine that includes at least one collection tank for collecting wash liquid that is recirculated by a pump and sprayed for cleaning wares within a spray zone of the machine, the method comprising:
 utilizing an automated valve to control overflow draining from the collection tank;   while the pump is operating to recirculate wash liquid, maintaining the automated valve in an open condition at least when fresh liquid is also being added to the machine to allow liquid to overflow from the tank as the water level in the tank rises due to addition of water by dilution or capture of final rinse liquid;   automatically closing the automated valve in conjunction with stopping operation of the pump so that at least some liquid in suspension falls into the collection tank and liquid level in the collection tank rises above a normal overflow level of the collection tank.   
     
     
         2 . The method of  claim 1  wherein the automated valve is closed substantially simultaneously with stopping operation of the pump, resulting in capture and retention of substantially all of liquid in suspension so that it is not lost to overflow. 
     
     
         3 . The method of  claim 1  wherein the automated valve is closed a set time period after stopping operation of the pump, so that only a portion liquid in suspension is precluded from following the overflow path. 
     
     
         4 . The method of  claim 1  wherein the automated valve is located either (i) in parallel with a manual valve of a drain line or (ii) in series with a manual valve of a drain line. 
     
     
         5 . The method of  claim 1  wherein in conjunction with restart of operation of the pump, the automated valve is automatically opened. 
     
     
         6 . The method of  claim 5  wherein the automated valve is opened substantially simultaneous with restart of operation of the pump. 
     
     
         7 . The method of  claim 5  wherein the automated valve is opened after restart of operation of the pump. 
     
     
         8 . The method of  claim 5  wherein the automated valve is either (i) opened a set time period after restart of operation of the pump or (ii) opened when liquid level in the collection tank falls to a set level due to resuspension of some liquid. 
     
     
         9 . The method of  claim 1  wherein the warewash machine includes multiple spray zones with respective collection tanks, a cascading sequential overflow from tank to tank and a final overflow path to drain from an initial spray zone of the machine, the automated valve controls flow along the final overflow path to drain, and at least twenty gallons of liquid in suspension in the machine is retained within the machine as a result of closing of the automated valve. 
     
     
         10 . The method of  claim 9  wherein at least thirty gallons of liquid in suspension in the machine is retained within the machine as a result of closing of the automated valve. 
     
     
         11 . A warewash machine, comprising:
 at least one collection tank for collecting wash liquid that is recirculated by a pump and sprayed for cleaning wares within a spray zone of the machine;   an overflow path leading from the collection tank;   an automated valve to control flow along the overflow path; and   a controller configured to control an open/closed state of the automated valve based at least in part upon status of pump operation.   
     
     
         12 . The machine of  claim 11  wherein the controller is configured to maintain the automated valve in an open state during operation of the pump for ware cleaning and at least when fresh liquid is being added to the machine, and to close the automated valve in conjunction with stopping operation of the pump. 
     
     
         13 . The machine of  claim 12  wherein the controller is configured to close the automated valve substantially simultaneously with stopping operation of the pump, resulting in capture and retention of substantially all of liquid in suspension so that it is not lost to overflow. 
     
     
         14 . The machine of  claim 12  wherein the controller is configured to close the automated valve a set time period after stopping operation of the pump, so that only a portion liquid in suspension is precluded from following the overflow path. 
     
     
         15 . The machine of  claim 11  wherein the automated valve is located either (i) in parallel with a manual valve of a drain line or (ii) in series with a manual valve of a drain line. 
     
     
         16 . The machine of  claim 11  wherein controller is configured to open the automated valve in conjunction with restart of operation of the pump. 
     
     
         17 . The machine of  claim 16  wherein the controller is configured to open the automated valve simultaneous with restart of operation of the pump. 
     
     
         18 . The machine of  claim 16  wherein the controller is configured to open the automated valve after restart of operation of the pump. 
     
     
         19 . The machine of  claim 18  wherein the controller is configured to open the automated valve either (i) a set time period after restart of operation of the pump or (ii) when liquid level in the collection tank falls to a set level due to resuspension of some liquid by operation of the pump. 
     
     
         20 . The machine of  claim 11  wherein the warewash machine includes multiple spray zones with respective collection tanks, a cascading sequential overflow from tank to tank and a final overflow path to drain from an initial spray zone of the machine, the automated valve controls flow along the final overflow path to drain, and at least twenty gallons of liquid in suspension in the machine is retained within the machine as a result of automatic closing of the automated valve.