The standard throttling device includes orifice plate, nozzle and venture. And the orifice plate is the most wildly used flow meter.
|Standard orifice plate||Standard Nozzle||Standard Venturi|
Here we will have the brief introduction about the orifice plate flow meter.
The structure of the orifice plate
Standard orifice plate is a circular metal plate with the hole in the middle part, the edge of the hole is very sharp and concentric with the pipe axis. The standard orifice plate for different pipe diameter, its structure is always the geometric similarities. The standard orifice plate is rotationally symmetrical, and the connection between any two points on the end plate of the upstream orifice plate should be perpendicular to the axis.
The use condition of the orifice plate
(1) The measured medium should be filled with all the pipe sections and continuously flowing.
(2) The flow (flow state) within the pipe should be stable.
(3) The measured medium should not undergo phase change when passing through the orifice (e.g. the liquid should not evaporate and the gas dissolved in the liquid should not be released) while it is present as a single phase. For complex media, it can use only if its properties are similar to those of a single component.
(4) Condensate or dust precipitated during the measurement of the gas (vapor) flow rate, or gas or sediment precipitated during the measurement of the liquid flow rate shall neither accumulate in the vicinity of the orifice plate in the pipe nor accumulate in the connecting pipe.
(5) The orifice plate should be regularly cleaned when measured media which can cause clogging of the orifice.
(6) On the inner surface of the pipe leaving both the front and rear faces 2D of the orifice plate, there is no protrusion or any visible roughness and unevenness on the pipe. And it can apply to the standard nozzles and standard venturi tubes.
The orifice plate is easy to install, and the cost is low because of the simple manufacturing process, so it is widely used. And we should pay special attention when using it. Especially when measuring the corrosive medium and the medium containing dust, we should observe the accuracy of the measurement. To prevent excessive measurement errors caused by corrosion and blockage of the pressure intake. Or the phenomenon that cannot be measured at all. The cleaning of the orifice plate should be carried out on a regular basis. When it is found that the corrosion is serious, a new orifice plate should be replaced immediately.