Negative pressure source device, gas meter verification gas path system and verification method

Abstract

The invention relates to a negative pressure source device, a gas meter verification gas path system and verification method. The negative pressure source device includes a pressure reducing valve, a sealed box, a pressure gauge and an external vacuum extraction device; the pressure reducing valve is installed in the sealed box; the two ends of the pressure reducing valve are respectively connected to a gas inlet port and a gas outlet port; the gas inlet port and the gas outlet port pass through the box wall of the sealed box and are placed outside the sealed box; the pressure gauge is placed outside the sealed box to detect the gas pressure inside the sealed box; and a side of the sealed box is further provided with a negative pressure port, and the negative pressure port is connected to the external vacuum extraction device. The gas meter verification gas path system includes a positive pressure test gas path, a normal pressure test gas path, a negative pressure test gas path and a vacuum pump; and the negative pressure test gas path includes the above-mentioned negative pressure source device. After test and measurement, the negative pressure verification test gas path installed with the negative pressure source device has a good effect in an actual detection process, and the output pressure does not change with the change of the verification flow rate.

Description

technical field [0001] The invention relates to the technical field of gas meter verification, in particular to a negative pressure source device, a gas meter verification gas circuit system and a verification method. Background technique [0002] At present, most of the gas meter verification devices in my country are negative pressure gas flow standard devices using critical flow Venturi nozzles as standard meters. Multiple gas meters to be tested and standards are connected in series in the same pipeline system. In the front, the standard (nozzle) is in the back, the front of the tested meter is directly connected to the atmosphere, and the nozzle is connected to a high-vacuum vacuum pump. The work of the vacuum pump makes the nozzle form a critical pressure ratio and makes the test medium (atmosphere) in the pipeline. In the middle, a constant flow rate flows through the tested meter and the standard device, and the error of the tested meter is obtained by comparing the in...

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Problems solved by technology

Normal pressure or positive pressure gas source is relatively easy to obtain, normal pressure gas source can directly use the atmosphere; positive pressure gas source can use dried compressed air to obtain a stable gas source of specified pressure after the first and second stages of pressure regulation; The pressure source generally needs to use a pressure reducing valve, and all pressure reducing valves can only decompress the high-pressure gas to a pressure higher than the local atmospheric pressure, and it is impossible to decompress the high-pressure gas to a pressure lower than the atmospheric pressure, for example, the local atmospheric pressure is 100kPa pressure, the gauge pressure is 0), and the medium pressure requirement at the tested meter of the verification device is 80kPa (absolute pressure, the gauge pressure is -20kPa), which cannot be achieved with a general pressure reducing valve, so it is necessary to design a Negative pressure source device for verification medium gas source lower than atmospheric pressure, gas meter verification gas circuit system and verification method with the negative pressure source device installed

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