Compact water meter calibration bench

摘要

A calibration bench was developed and constructed to calibrate domestic water meters, especially for the needs of the water distribution companies. The bench could calibrate up to 6 water meters at the same time in the present version. It was designed to work with water and in normal operation with two reservoirs and a battery of working standards, electromagnetic flowmeters of special grade. The mag meters assure an uncertainty of less than 0,3%, because they are calibrated on the spot: there is an electronic scale in the circuit of the bench that can be used at any time to calibrate the secondary standards or the meters under test. With this, this bench is almost a "primary" laboratory. A centrifugal pump feeds the constant head level tank and the water in excess turns back to the lower reservoir, assuring that there is no influence of the level of water, or of its oscillation due to the pump movement, in the calibration of the meter. For the highest flow rates, the pump is used in direct connection to the meters under test, with no passage through the upper reservoir. The range of operation is from 2 L/h up to 7500 L/h. The control is totally automated using a PLC and data is stored in an electronic data sheet.