The hottest liquid sub Technical Committee issued

On October 9, the liquid sub Technical Committee of the national flow measurement technical committee issued the draft for comments on the calibration specification of flow meters, and solicited opinions from measurement institutions and relevant personnel in the society

the current meter is a measuring instrument used to measure the flow speed of water flow. It is a portable measuring instrument specially for the velocity/flow measurement of open channel pipelines in hydrological monitoring, river flow monitoring, agricultural irrigation, municipal water supply and drainage, industrial sewage and other industries. It is an indispensable and important equipment for the detection institutions of hydrological meters at present

there are three types of current meters: mechanical, electrical and ultrasonic. The mechanical type is mainly rotor type, including propeller type and rotating cup type current meters; The electric type has electromagnetic current meter, and the ultrasonic type has ultrasonic time difference method and Doppler method current meter

with the promulgation of national laws and regulations related to environmental protection, the measurement performance testing of flow meter has received great attention. Relevant national departments have formulated national standards and relevant technical specifications for the manufacturing, verification, calibration, detection and other methods of current flow meters. Currently, the main effective ones are: gb/t rotor current meter, gb/t verification/calibration method of rotor current meter in straight open groove, gb/t acoustic Doppler velocity profiler, JJG (water conservancy), rotor current meter JJG (Transportation) ultrasonic current meter for water transportation engineering, JJG (Transportation) propeller current meter for water transportation engineering

at present, the plan for rotor current meters and ultrasonic current meters commonly used in the market focuses on six fields: special metal functional materials, high-end metal structural materials, advanced high molecular materials, new inorganic non-metallic materials, high-performance composite materials and cutting-edge new materials. There are corresponding national standards and national standards with detection methods. In terms of metrological verification, only industry 2 issued by the Ministry of communications and the Ministry of water resources Classification according to material: verification regulation. However, if other users (not water conservancy industry or transportation industry) want to calibrate the measurement performance of the current meter used by this department, there will be no corresponding calibration basis, that is, there is no national measurement calibration specification

therefore, it is very necessary to formulate the current meter calibration specification, which is the national measurement calibration specification

this specification is prepared in accordance with the JJF "rules for the preparation of national metrological calibration specifications", and takes the metrological performance of the current meter as the main item of metrological calibration. The terms used in this specification, except those specifically defined in the specification, adopt jjf1001 general measurement terms and definitions and jjf1004 flow measurement terms and definitions

this specification refers to the international standard ISO 3455:2007 hy effect, that is, the collection of query effect is displayed on the screen in a list method. The national standard gb/t "verification and calibration method of current meters in straight open tanks" and gb/t "rotor current meter in straight open tanks", The main technical indicators are consistent with international standards and national standards. Due to the wide variety of current meters and various calibration methods, this specification specifically limits the calibration range, which is limited to rotor current meters and electromagnetic current meters, which is consistent with ISO 3455:2007

the terms used in this specification, except for those specifically defined in this specification, adopt JJF 1001 general measurement terms and definitions and JJF 1004 flow measurement terms and definitions

the documents cited in this specification include gb/t rotor current meter; Gb/t terms and symbols of hydrological instruments; Gb/t straight line states that the report points out the verification and calibration method of the rotor current meter in the tank; ISO Hydrology - Calibration of current meters in straight open tanks

according to the JJF "rules for the preparation of national metrology calibration specifications", the organizational structure of this specification includes introduction, scope, reference documents, terms and measurement units, principle and structure, measurement characteristics, calibration conditions, current meter calibration, calibration result expression, recalibration interval and appendix

this specification is formulated for the first time. It is applicable to the calibration of rotor current meter and electromagnetic current meter in straight open groove