The zero flow performance of a sing-around type flow meter

Design considerations were taken to correct for the speed of sound influences and reciprocity effect. The meter was tested using from 1000 to 20000 sing-around loops. To investigate averaging phenomena, 1-100 primary velocity values were averaged to form one velocity value. The temperature range tested was 2-45°C, with measurements at 5°C intervals. The measurements show a zero flow stability of better than ±0.6 mm/s (±1 l/h, φ 25-mm pipe) in the entire temperature range. The standard deviation at each temperature tested was less than 0.45 mm/s. This implies that flow velocities as low as 6 cm/s (100 l/h, φ 25-mm pipe) could be measured with an accuracy of better than ±1%. The tests were made with water as the medium