An ultrasonic flow meter is disclosed comprising adjustable rotating blocks and a piezoelectric wafer mounted in connection with each rotating block. The piezoelectric wafers or chips are used for transmitting and/or receiving upstream and downstream ultrasonic waves. The rotating blocks adjust the incident angle of the piezoelectric wafers to account for installation in connection with different pipe sizes. By adjusting angle in a linked and continuous manner, no translational sensor movement is required for an optimal ultrasonic wave reflection for the downstream transducer to receive a signal from the upstream transducer and the upstream transducer to receive a signal from the downstream transducer. As such, the devices and methods described enable measurement of liquid flowing in pipes across a range of different diameter pipes so as to greatly increase the convenience and the extent of application or technology adoption.