OCS-3F Ultrasonic oxygen sensors use the time difference method to detect binary gas concentrations and flows.

As shown, two sensors are installed at both ends of the pipe. The sensors work alternately and serve as transmitters and receivers for ultrasonic signals.

When the ultrasonic signal propagates on the upstream side, the direction is opposite to the direction of the medium, and the propagation time (T1) becomes longer. On the other hand, when the ultrasonic

signal propagates on the downstream side in the same direction as the medium, the propagation time (T2) is short. That is, the flowing medium delays or accelerates the ultrasonic signal. The time of "T1" and "T2" and the diameter of the tube can be converted into the concentration and flow rate of the binary gas.