A Cyclic Self-Calibration Method Based on a High-Precision Piston and Standard-Meter Water Flow Prover

The standard meter water flow prover is widely used due to its mature technology and high work efficiency. However, the process of sending the standard meter for calibration is not only time-consuming and laborious but also introduces deviations due to differences in installation and operating conditions. Therefore, by leveraging the high precision, convenient adjustment, and simple traceability of the piston prover, as well as the good repeatability of the standard meter, this paper proposed a cyclic self-calibration method, which iteratively transmits the calibrated piston value to different flow points of the standard meter through the standard meter itself and the transition flow meter, so as to realize the in situ transmission of the value from the high-precision piston to the wide range of standard meter. The water flow standard device and the cyclic self-calibration method, combining the standard meter and the transfer meter in series and parallel, were introduced; the uncertainty transfer chain was analyzed based on the error transfer theory; and experimental validation was conducted. The results show that the proposed self-calibration method is feasible, that the (0.005~4) m³/h high-precision flow rate of the piston can be extended to the (4~1250) m³/h of standard meters through multiple self-calibration value transfers, and that the expanded uncertainty of the water flow standard device is better than 0.20% (k = 2).