According to the June 2023 document of the General Office of the State Administration for Market Regulation, the General Office of the State Administration for Market Regulation (2023) No. 56 "Notice of the General Office of the State Administration for Market Regulation on Issuing the 2023 National Metrology Technical Specification Project Revision, Revision and Publicity Plan", JJG577 "Membrane Gas Meter" and JJF1354 "Membrane Gas Meter Type Evaluation Outline" The drafting task was assigned to the MTC3 of the National Flow Measurement Technical Committee, and in accordance with the requirements of the National Flow Measurement Technical Committee, two drafts of technical specifications have been completed and are now open for comments.
"Regulations for the Verification of Membrane Gas Meters".
The gas meter is a volumetric gas flow meter, which adopts the measurement principle of flexible diaphragm metering chamber. The gas enters the metering room alternately through the distribution valve, and under the action of the pressure difference, the flexible diaphragm in the metering room is promoted to reciprocate the motion, and the circulating process of filling and exhausting is converted into a corresponding certain amount of gas through the conversion mechanism, and then transmitted to the counter through the transmission mechanism to complete the gas metering function.
The gas meter is mainly composed of the shell, the diaphragm metering room, the distribution valve, the connecting rod mechanism, the anti-reversal device, the transmission mechanism and the counter. It is mainly used to measure the cumulative volume flow of gas, and is generally used in civil, industrial and commercial gas metering occasions.
This regulation is based on the national standard GB T 6968-2019 "Membrane Gas Meter" and the international recommendation R137-1&2:2012 "Gas Meters" of the International Legal Metrology Organization (OIML), combined with the current situation of the membrane gas meter industry in China, and revised the JJG577-2012 version of the "Membrane Gas Meter". Compared with the JJG577-2012 version, the main technical changes in this regulation are as follows, except for editorial modifications:
The requirements for the verification environment have been revised.
Adjusted some of the description of the verification cycle;
Some non-metering checks have been eliminated
Modify the format of the inner page of the verification result notification of the verification certificate.
This procedure is applicable to the first verification, subsequent verification and in-use inspection of membrane gas meters with a maximum working pressure of no more than 50 kpa and a maximum flow rate of no more than 160 m3 h.
"Outline of Type Evaluation of Membrane Gas Meter".
The gas meter is a volumetric gas flow meter, which adopts the measurement principle of flexible diaphragm metering chamber. The gas enters the metering room alternately through the distribution valve, and under the action of the pressure difference, the flexible diaphragm in the metering room is promoted to reciprocate the motion, and the circulating process of filling and exhausting is converted into a corresponding certain amount of gas through the conversion mechanism, and then transmitted to the counter through the transmission mechanism to complete the gas metering function.
The gas meter consists of a shell, a diaphragm metering chamber, a valve seat and a bonnet, a reversal prevention device, a transmission mechanism and a counter. Additional devices such as prepaid devices, pulse generators, and secondary devices can be installed on the base meter, but the metering performance of the gas meter cannot be affected. It is mainly used to measure the cumulative volume flow of gas, and is widely used in gas metering occasions for domestic and industrial and commercial use.
This specification is drafted in accordance with JJF 1015 "General Specification for Type Evaluation of Measuring Instruments" and JJF 1016 "Guidelines for the Preparation of Outline for Type Evaluation of Measuring Instruments", and is applicable to the type evaluation of membrane gas meters.
This specification is based on the national standard GB T 6968-2019 "Membrane Gas Meters" and the R137-1&2:2012 "Gas Meters" of the International Organization for Legal Metrology (OIML), combined with the revision of the industry status of membrane gas meters in China.
Compared with the JJF1354-2012 version of the "Type Evaluation Outline", the main technical changes of this specification are as follows:
Revised the description of the technical requirements for counters;
Modifications improve the technical requirements for temperature adaptability;
Added a list of key components and materials;
Added naming requirements for gas meters;
Supplemented with requirements for electronic gas meter software;
Added a reference format for type evaluation reports (refer to R137);
Added temperature and pressure correction for gas meters.
This type evaluation outline is applicable to the type evaluation of membrane gas meters with a classification code of 12220500 and a maximum working pressure of no more than 50 kpa.