initiated by one of the machines 72 if the stack indeed contains flags the program inquiries determine whether there is more than one machine requesting product in which case control system 74 disables all but the 34 bottom 34 first machine in the fifo stack that is control system 74 in effect puts all but one machine 34 on hold 34 so that it can focus its attention on the machine which made the first request or interruption as represented by the 34 bottom 34 set of flags in the fifo stack once the latecomers are disabled if necessary valve 70 is activated if necessary to connect the inlet of valve 70 to the proper outlet so that the appropriate machine 72 is serviced pump 27 is then activated preferably pump 27 is capable of running dry without causing excessive wear to its internal components a diaphragm pump can be used for this purpose the program then inquiries whether a liquid or solid product is being requested assuming detergent is being requested the control system 74 opens valve 58a to allow a spray of water to dissolve a portion of the detergent within container 200a the resulting detergent solution drains from the bottom of container 200a through the associated drain line 64a and into the sump 62 a product timer determines a 34 dispensing period 34 during which valve 58a is held in its open state and valve 58b is maintained in its closed state also during this time pump 27 transfers the relatively dilute approximately 2 to 5 detergent solution from the sump 62 through discharge line 25 to the three way valve 70 valve 70 is controlled by control system.