Series SX2 Ultrasonic Flowmeter Detectors are paired with Series UXF1 and UXF3 converters in order to utilize the transit-time method for measuring flow rates in pipes from the outside. Two ultrasonic sensors are mounted on the pipe exterior, and each transmits an ultrasonic pulse to the opposite sensor. The difference in the transit times of the two waves is used to calculate the flow velocity. Paired with the UXF1 or UXF3 Series converters, Series SX2 detectors provide ultrasonic flowmeter sensors for both small diameter needs as well as high-temperature applications.