Flowmeter for custody transfer

Salaam

My understanding for the above is as follows:
The meter minimum performance (accuracy & repeatability) criteria for a gas custody transfer application is defined in relevant insternational measurement standards.
The inherent accuracy of a meter is often published in the manufacturer’s specification, and may be expressed as repeatability and/or linearity. In other words,
accuracy is based on how repeatable and how linear the meter can stay within the manufacturer’s performance specifications.
Manufacturers’ specifications are based on meter operation
within recommended flow ranges, within a narrow
range of pressures, temperatures, and fluid viscosities. For
custody transfer applications, meters with the highest inherent
accuracy should be used and should be proved (mostly for liquid applications)on site .
The meters should operate within the manufacturer’s specifications.