It is the most used flow measurement device in oil & gas plants. Accuracy and rangeability of orifice metering systems In evaluating the accuracy of orifice flow, first consider transmitter accuracy and rangeability
Flow Measurement technologies- Orifice Plate | PPT
Modern transmitters have a δp rangeability of up to 200:1, which equates to a flow range.
Turndown ratio (rangeability) can be used to compare flow measurement devices like orifices, venturi meters etc
An orifice plate meter has a practical turndown ratio of 3:1 This means that if an orifice meter with a design flow rate of 200,000 m³ per day is installed, the flow range that the meter can. However, orifice only allows 3:1 rangeability to maintain accuracy This means, if one wants to measure maximum flow of 10 mmscfd, then the minimum flow measurement that could be measured is only 3.3.
