Professional ultrasonic level gauge stockist - Shanghai Feibo Level Gauge - The power voltage of the ultrasonic level gauge (transmitter) must not exceed 28 volts DC. The controller marked as FLOWLINE on the ultrasonic level gauge (transmitter) and the voltage for the ultrasonic level gauge is a fixed 24 volts DC. During calibration and operation, the transmitter can also use another controller and power supply with a minimum output of 14 volts DC.