A fluid flow system and a method for detecting air bubble and liquid are provided. The fluid flow system comprises a force sensor configured to monitor at least one of an air bubble or an occlusion in a flow tube. The fluid flow system comprises a controller to execute the method. The controller is configured to monitor an output signal of a force sensor of the fluid flow system, and the output signal comprises an Alternating Current (AC) component and a Direct Current (DC) component, and detect a change in the output signal to a new output signal based on a number of transitions to the new output signal, and a time duration of the new output signal. The controller compares the change in the output signal with one of a predefined number of transitions or a predefined time and determines a new threshold when the change in the output signal exceeds one of the predefined number of transitions or the predefined time.