Introduction to flow limiting orifice plate:
At present, the application of flow limiting orifice plates in domestic process devices is still insufficient, and there is a gap compared to foreign countries. In places where it is necessary to limit flow or reduce pressure, regulating circuits are mostly used to achieve this. In some places, the flow rate of the fluid only needs to be limited within a specified range without adjustment, and the accuracy of its flow rate is not high, so a flow limiting orifice plate can be used instead. Therefore, it is necessary to fully understand the advantages of flow limiting orifice plates and attach importance to their application in the design of process equipment. The flow limiting orifice plate is designed and manufactured according to national standards such as GB2624, HG/T 20570, GD2000, GD87, etc.
Measurement principle:
The limiting orifice plate can be used as a flow measuring element to measure flow, or as a throttling element to limit flow and reduce pressure. When there is a certain pressure difference before and after the orifice plate, the fluid flows through the orifice plate. For a certain aperture, the flow rate through the orifice plate increases with the increase of pressure difference. But when the pressure difference exceeds a certain value (referred to as the critical pressure difference), the flow velocity of the fluid through the orifice plate reaches the sound speed. At this time, no matter how the pressure difference increases, as long as the pressure upstream of the orifice plate remains constant, the flow rate passing through the orifice plate will remain at a certain value and no longer increase. The flow limiting orifice is based on this principle to limit the flow rate of fluid and reduce pressure.
The flow limiting orifice plate is divided into single orifice plate and porous plate according to the number of openings on the orifice plate; According to the number of orifice plates, it can be divided into single level and multi-level.
Purpose:
1. Places where process materials need to be depressurized.
2. When there is a need for a significant pressure drop upstream and downstream of the valve in the pipeline, in order to reduce fluid erosion on the valve, orifice plates can be connected in series upstream of the valve when there is no gas phase generated through throttling through the orifice plate.
3. Places where fluid requires low flow and continuous flow, such as the flushing pipeline of the pump, the bypass pipeline of the hot standby pump (low flow protection pipeline), and the analysis sampling pipeline.
4. Places that require depressurization to reduce noise or wear, such as vent systems.
