Orifice plate flowmeter.

DN10mm to DN500mm
Measuring range: available from 0.08 to 2500m3/h (water); 0.8 to 24000 Nm3/h (air)
Temperature limit: 0°C to 60°C (PVC); 0°C to 120°C (SS304)
Accuracy: ±2.5%
Maximum working pressure: 1.0MPa