Problem 1-18 A large storage tank is filled manually by an operator. The operator first opens a valveon a supply line and carefully watches the level on a level indicator until the tank is flled (a long timelater). Once the flling is complete, the operator closes the valve to stop the fllng. Once a year theoperator is distracted and the tank is overfilled. To prevent this, an alarm was installed on the level gaugeto alarm the operator to a high-level condition. With the installation of the alarm, the tank now overfillstwice per year. Can you explain?