Warewash machine with soil detection

Abstract

A conveyor-type warewash machine includes a conveyor mechanism for moving wares through a plurality of spray zones including at least one spray zone having spray nozzles for spraying recirculated liquid from a collection tank in the spray zone and a downstream final rinse zone with spray nozzles for spraying final rinse liquid. A sensor arrangement is located for monitoring condition of liquid of the collection tank. A control is operatively connected with the sensor arrangement and configured to vary flow rate of final rinse liquid sprayed from the final rinse nozzles based upon condition of liquid as indicated by the sensor arrangement.

1 . A conveyor-type warewash machine, comprising:
 a conveyor mechanism for moving wares through a plurality of spray zones including at least one spray zone having spray nozzles for spraying recirculated liquid from a collection tank in the spray zone and a downstream final rinse zone with spray nozzles for spraying final rinse liquid;   a sensor arrangement for monitoring condition of liquid of the collection tank; and   a control operatively connected with the sensor arrangement and configured to vary flow rate of final rinse liquid sprayed from the final rinse nozzles based upon condition of liquid as indicated by the sensor arrangement.   
     
     
         2 . The conveyor-type warewash machine of  claim 1 , wherein the machine includes:
 a wash zone and a post wash zone downstream of the wash zone, the final rinse zone downstream of the post wash zone, wherein the spray zone is one of the wash zone or the post wash zone, the wash zone includes spray nozzles for spraying recirculated wash liquid from a collection tank in the wash zone, the post wash zone includes spray nozzles for spraying recirculated post wash liquid from a collection tank in the post wash zone.   
     
     
         3 . The conveyor-type machine of  claim 1  wherein the machine is arranged such that some final rinse liquid sprayed from the spray nozzles of the final rinse zone is collected in the collection tank of the post wash zone, the sensor arrangement is located for monitoring condition of post wash liquid of the collection tank of the post wash zone, and the control is configured to increase flow rate of final rinse liquid sprayed from the final rinse nozzles in response to the sensor arrangement indicating a soiled condition of the post wash liquid in order to reduce soil level of post wash liquid of the collection tank of the post wash zone. 
     
     
         4 . The conveyor-type machine of  claim 1  wherein the control is operatively connected with a valve or pump that is connected in line to vary flow rate to the spray nozzles of the final rinse zone. 
     
     
         5 . The conveyor-type machine of  claim 1 , including:
 a bypass flow path line extending from the collection tank of the post wash zone to an upstream zone of the machine for selectively delivering post wash liquid to the upstream zone under control of a pump;   wherein the sensor arrangement is located along the bypass flow path line.   
     
     
         6 . The conveyor-type machine of  claim 1  wherein the sensor arrangement is located in the collection tank. 
     
     
         7 . A conveyor-type warewash machine, comprising:
 a conveyor mechanism for moving wares through a plurality of spray zones including at least a wash zone, a post wash zone downstream of the wash zone, and a final rinse zone downstream of the post wash zone, wherein the wash zone includes spray nozzles for spraying recirculated wash liquid from a collection tank in the wash zone, the post wash zone includes spray nozzles for spraying recirculated post wash liquid from a collection tank in the post wash zone and the final rinse zone includes spray nozzles for spraying final rinse liquid and having a pump or valve for controlling flow of final rinse liquid, the collection tank of the post wash zone arranged such that some final rinse liquid sprayed from the spray nozzles of the final rinse zone is collected in the collection tank of the post wash zone;   a sensor arrangement for monitoring condition of post wash liquid of the collection tank of the post wash zone; and   a control operatively connected with the sensor arrangement and the pump or valve, the control configured to control the pump or valve to increase flow rate of final rinse liquid sprayed from the final rinse nozzles upon the sensor arrangement indicating a soiled condition of the post wash liquid in order to reduce soil level of post wash liquid of the collection tank of the post wash zone.   
     
     
         8 . The conveyor-type machine of  claim 7 , including:
 a flow path line extending from the collection tank of the post wash zone to the wash zone for selectively delivering post wash liquid from the post wash tank to the wash zone under control of a pump;   wherein the sensor arrangement is located along the flow path line.   
     
     
         9 . The conveyor-type machine of  claim 8  wherein the wash zone is one of a pre-wash zone or a main wash zone. 
     
     
         10 . The conveyor-type machine of  claim 7  wherein the sensor arrangement is located in the collection tank of the post wash zone or in a drain line associated with the collection tank of the post wash zone. 
     
     
         11 . A method of controlling soiling level of water in a conveyor-type warewasher having a conveyor mechanism for moving wares through a plurality of spray zones including at least a wash zone, a post wash zone downstream of the wash zone, and a final rinse zone downstream of the post wash zone, the wash zone includes spray nozzles for spraying recirculated wash liquid from a collection tank in the wash zone, the post wash zone includes spray nozzles for spraying recirculated post wash liquid from a collection tank in the post wash zone and the final rinse zone includes spray nozzles for spraying final rinse liquid, and the collection tank of the post wash zone arranged such that some final rinse liquid sprayed from the spray nozzles of the final rinse zone is collected in the collection tank of the post wash zone, the method comprising:
 delivering final rinse liquid from spray nozzles at a first flow rate during washing;   detecting a soiled condition of liquid of the post wash tank; and   in response to detection of the soiled condition, at least temporarily delivering final rinse liquid from the spray nozzles at a second flow rate during washing, the second flow rate higher than the first flow rate, so as to increase collection of sprayed final rinse liquid in the collection tank of the post wash zone in order to reduce soil level of the post wash liquid in the collection tank of the post wash zone.   
     
     
         12 . The method of  claim 11 , wherein the detecting step involves utilizing a sensor arrangement located in a flow path line that extends from the post wash tank to the wash zone for selectively delivering post wash liquid from the post wash tank to the wash zone under control of a pump. 
     
     
         13 . The method of  claim 11 , wherein the detecting step involves utilizing a sensor arrangement located in the collection tank of the post wash zone or in a drain line associated with the collection tank of the post wash zone.