This standard specifies the structure form and technical requirements of standard orifice; the pressure tapping mode, usage method, installation and operation condition and inspection requirements of throttle device; the calculation method of the volume flow and ernery flow, quality flow and the uncertainty measurement of natural gas under the standard reference condition. The required data such as calculated flow and relevant uncertainlty are also supplied meanwhile.
This Standard is universal for the throttle device with flange pressure tapping and corner pressure tapping as the pressure tapping mode: standard orifice has been employed for the measurement of the mixed gas flow with the methane as the substantial ingredient produced from gas or oil fields.
This standard is not applicable to occasion with the opeing diameter of orifice less than 12.5mm, the inner diameter of measurement tube less than 50mm and greater than 1000mm, the diameter ratio less than 0.1 and greater than 0.75, the Reynolds number of caliber less than 5000.
The metering system rebuilt or newly built shall meet the requirements of this Standard. This Standard does not emphasize the updating of the existing metering system. If the metering system doesn't meet the requirements of this Standard, there may be additional errors of metering system due to the inadaption between the flow condition and the upstream straight pipe segment.
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