Techincal Notes The IRIS 9000 employs an ultrasonic immersion pulse echo technique. The ultrasonic transducer is contained in a test head, which fits into and is centered in the heat exchanger tube. The ultrasonic pulses are emitted along a path parallel to the tube axis. A rotating 45-degree mirror then reflects these pulses so that they are directed radially onto the tube wall. Reflections from the inner and outer walls follow the same path back to the transducer. The time interval between the first echo from the internal surface of the tube and the first echo from the outside surface of the tube can be used to represent the tube wall thickness. As the mirror rotates, the ultrasonic beam is traversed around the tube circumference and each successive pulse is mapped out as a horizontal scan line on the screen of the IRIS 9000. There are 192 readings per revolution and 2400 revolutions per minute. When the probe is advanced along the tube at the optimum inspection rate of 2.54 meters (100") per minute, the ultrasonic pulses paint a continuous helical path on the tube wall ensuring 100% coverage. The results are the most definitive yet to be invented for the inspection of air cooled and liquid cooled tube bundle heat exchanger.. BACK