What is the difference between PA and MC on a water meter? And what is the meaning of Q?=() and R=() on the water meter?

Water surface plate symbols should be: CPA and CMC

CPA: CPA logo is a measuring instrument type approval certificate of the special sign. Imported measuring instruments need to be measured by the State Council administrative department authorized by the technical agencies to carry out stereotypes identification, stereotypes identification of the results of the technical institutions to undertake identification of the State Council measurement of the administrative department for review. Qualified by the audit, measured by the State Council administrative department to the applicant issued a "Chinese People's *** and the State of imported measuring instruments type approval certificate" and granted in the corresponding measuring instruments and packaging on the use of Chinese People's *** and the State of imported measuring instruments type approval of the CPA special sign and number.

CMC: "Chinese People's **** and the State manufacturing measuring instruments license" logo, the acronym "China Metrology Certification", meaning that China's manufacturing measuring instruments license. Obtain a license to manufacture measuring instruments, enterprises can be marked on the production of measuring instruments CMC logo. The logo indicates: measuring instruments manufacturing enterprises have the ability to produce measuring instruments.

Q?: water surface plate Q? refers to the common flow rate of the water meter, for example: DN15 water meter, Q? = 2.5, means that the common flow rate of DN15 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 measurement range of the water meter), for example: DN15 water meter, Q?=2.5, R=100, means: DN15 water meter, the common flow rate of 2.5m?/h, the range ratio of 100:1, i.e.: the minimum flow rate of 2.5 ÷ 100=0.025m?/h. Then the effective measurement range of the meter is 0.025~0.025m?/h. Measuring range is 0.025~2.5m?/h.