The Development Of The DN350- DN400 Gas Flow Standard Device

Gas flow measurement is widely used in various fields of national economy, and plays an important role in the field of metrology. Ensure the accuracy and reliability of gas flow measurement is playing an important role in the product quality assurance, improving the science and technology progress and the protection of the interests of both the supply and demand. In order to ensure the gas meter in the value transfer and traceability of the accuracy, we need to establish a gas flow standard device. The research and application of flow standard device is an important link in the development of flow measurement and testing technology, and it has been paid more and more attention. In recent years, great progress has been made in the research and establishment of flow standard device. But with natural gas in common use, large caliber flowmeter is increasing, as the highest legal institute of metrology in Hebei Province, The original gas flow standard device in Measurement supervision and Inspection Institute of Hebei Province has been far from meeting the requirements of gas flow meter calibration and calibration in this province. Therefore, it is necessary to establish a set of pipe diameter and flow of gas flow standard device to meet the amount of gas flow meter value transfer and traceability requirements.This topic is the research and design of DN350-DN400 gas flow standard device. Through analysis of the characteristics of the existing gas flow standard device, combined with the operation of economic considerations, the design selection of nozzle method and standard table method combined by negative pressure method, with air as the medium to achieve on all gas flowmeter metrological verification, calibration, inspection and type of the evaluation work of the overall design scheme.According to the international standard and verification regulation of gas flow standard device, this paper gives the design specification. The whole set of device is composed of the sonic nozzle method gas flow standard device and the standard meter method gas flow standard device. An important part of the two sets of devices including hardware and software standards for sonic nozzle, turbine, centrifugal blower, vacuum pump, instrument calibration pipeline, computer control system, data acquisition system. These are discussed in detail in this paper.In this paper, the two sets of devices are considered for the treatment of humidity and the uncertainty analysis of the ideal state. In this paper, the influence factors of the two sets of devices are analyzed, the size of the uncertain component is determined quantitatively, and the extended uncertainty of mass flow and volume flow is given.At last, the functions of the two sets of devices were tested, the calibration and testing capabilities of the device were verified, and the results were satisfied with the design requirements of the device. Among them, the critical flow Venturi nozzle flow uncertain degree of 0.30% k = 2, the standard table flow method of uncertain degree 0.33%, k = 2.They passed the General Administration of quality supervision, inspection and quarantine, Hebei provincial quality and Technical Supervision Bureau of the assessment, and became the highest standards of measurement and social utility measurement standards of Hebei province.