You can first ask what caliber the Jiangsu Provincial Technical Supervision Bureau can inspect. If not, go to the calibration station of Shanghai Instrument and Control Research Institute for calibration. The maximum diameter is 500mm and a provincial certificate will be issued. You can also go to the East China National Metrology Institute. The maximum diameter is 300mm and a national certificate will be issued. If it still doesn't work, send it to Kaifeng Instrument Factory's National Water Flow Calibration Station, which can mark it to 1600mm.