In addition to the common ultrasonic air bubble detector for detecting plastic tubes, Siansonic also provides a bubble detector device dedicated to metal pipelines. When in use, the ultrasonic air bubble detector is connected in the middle of the detected pipe as a part of the liquid delivery channel of the pipe. After the fluid flows through the ultrasonic air bubble detector, the bubbles in the fluid are detected. The bubble detection accuracy is about one third of the inner diameter of the pipe. For example, if the inner diameter of the pipe is 9mm, the minimum detectable bubble diameter will be around 3mm. The applicable outer diameter of metal pipe is between 3mm and 30mm.