Differential pressure flowmeters are widely used. All kinds of objects are applied in the flow measurement of closed pipes. Such as fluid: single-phase, miscible, clean, dirty, viscous flow; working conditions: atmospheric pressure, high pressure, vacuum, normal temperature, high temperature, low temperature; pipe diameter: from several m m to several m; flow conditions: subsonic, sonic, pulsating flow and so on. It accounts for about 1/4 to 1/3 of the total amount of flowmeters used in various industrial sectors.
1. Commonly used standard throttling devices (orifice plate), (nozzle), (Venturi tube).
2. Commonly used non-standard throttling devices are (double orifice plate), (circular orifice plate), (1/4 circular nozzle) and (Venturi nozzle).
3. The common pressure-taking methods of orifice plate are (angular connection pressure), (flange pressure). Other methods are (theoretical pressure), (diameter distance pressure) and (pipe connection pressure).
4. Standard orifice plate flange pressure method, upstream and downstream pressure hole center distance from the orifice plate front and rear end face are (25.4 + 0.8) mm, also known as 1 inch flange pressure.