CPA:CPA mark is a special mark of type approval certificate of measuring instruments. Imported measuring instruments need to be appraised by a technical organization authorized by the metrological administrative department of the State Council, and the appraisal results shall be reported to the metrological administrative department of the State Council for review. After passing the examination, the metrological administrative department of the State Council will issue the Certificate of Approval for the Type of Measuring Instruments Imported from People's Republic of China (PRC) to the applicant, and allow the use of the special marks and numbers of certified public accountants approved by the type of measuring instruments imported from People's Republic of China (PRC) on the corresponding measuring instruments and packages.
CMC: The symbol of "License for Manufacturing Measuring Instruments of the People's Republic of China", referred to as "China Metrology Certification", refers to the license for manufacturing measuring instruments in China. An enterprise that has obtained a manufacturing license for measuring instruments may mark CMC marks on the measuring instruments it produces. This sign shows that the measuring instrument manufacturer has the ability to produce measuring instruments.
q？ Ask on the surface plate? Refers to the common water meter flow, such as DN 15 water meter, Q? =2.5, that is to say, the common flow of DN 15 water meter is 2.5m? /h (2.5 cubic meters per hour).
R: R on the water surface plate refers to the range ratio of the water meter (the effective range of the water meter), for example: DN 15 water meter, Q? =2.5, R= 100, that is to say: DN 15 water meter, ordinary flow of 2.5m? /h, the range ratio is 100: 1, that is, the minimum flow is 2.5÷ 100=0.025m? /H. So, the effective range of this water meter is 0.025~2.5m? /h .