Challenge Problem – 10/23

Tank Fill/Drain Application

Tank Fill & Drain

Sequence of OperationDevices – Fill Pump Motor, Lower Level Float Switch, Upper Level Float

Switch, Fill Pump Motor Start PB, Cycle Stop PB

Operation – Manual Fill cycle. Fill Pump motor is activated by operation of the Fill Pump Motor Start PB. The Fill Pump Motor Start PB is held allowing the pump to run under manual control until either the Upper Level Float Switch is tripped or the Fill Pump Motor Start PB is released. If the Upper Level Float Switch is tripped the Fill Pump Motor ceases to operate regardless of the position of the Fill Start PB. Under normal operator control the Fill Pump Motor Start PB should be released when the fill level is between the Upper Level and Lower Level Float Switches. When this occurs the Fill Pump will automatically maintain the level between the Upper Level and Lower Level Float Switches under Automatic Control.

Note: When the pump is run the tank begins to fill (and drain) simultaneously. Since the tank drains at only 10 GPM and fills at 20 GMP accumulation of red dye #9 begins to occur and tank begins to fill.

Sequence of Operation

Automatic Operation – When in Automatic Control (no operation of Fill Pump Start PB and liquid level between the two float switches), the Pump will run until the Upper Level Float Switch is tripped at which time the pump is shut off. The Pump will remain off until the Lower Level Float Switch is not tripped. Upon the release of the Lower Level Float Switch the Pump is activated and the fill cycle begins again.

Successive cycles will maintain the level of the red dye #9 between the Upper and Lower Level Float Switches.

A “Cycle Stop” Pushbutton is available to stop the Pump Motor under all conditions of the float switches and allow for draining of the tank.