Timed window ultrasonic gas meter with nose cone

摘要

An ultrasonic fluid flow meter (50) measures the flow speed of a fluid by measuring the time, in each direction, for a sequence of ultrasonic pulses (55) to pass between two transducers (54A,54B) positioned in a measuring tube (52) in the fluid flow path. The second and subsequent transmit pulses of each sequence are caused to start by the arrival of its predecessor at the detector end of the measuring tube. A first transmit pulse calculates a delay (110) to a zero crossing which is used to identify a particular zero crossing at which the arrival of each pulse in the sequence is determined.