orifice meter 
It is the most popular flow meter which widely used in many field.The throttling element of standard orifice-plate is strictly following the international standard for design, manufacture, installation and operation. It doesn't require real-calibration for flow rate measuring or estimating the inaccuracy. It made up the standard orifice flow meter with pressure transmitter and display device.
Taking pressure mode :corner joint(ring chamber or drill hole alone)taking pressure,flange taking pressure,D-D/2 taking pressure.Nominal pressure : ≤32MPa (≥20MPa ,it can use high pressure lens orifice plate welding type )
Caliber: 50~2200mm;Accuracy(indeterminacy ): ±1.0%;Range of application: open hole diameter rateβ:0.1≤β≤0.75;
Reynolds number range ReD:0.1 ≤β≤ 0.75