Are throttle orifice plates and flow-limiting orifice plates the same thing?

Their uses are completely different; throttling is used in situations where pressure reduction is required, with the enthalpy values before and after remaining unchanged, based on the principles of thermodynamics. But the flow control plate is only used to limit the flow rate.

Structurally, they are the same; it’s just the application that differs. Throttle orifice plates are generally used, together with temperature, pressure, and pressure difference sensing elements, to measure flow rate in orifice plate flow meters. Throttle orifice plates can limit flow rate, and they can also be used in pressure reduction processes where high precision is not required

I. Throttle orifice plate: The orifice plate throttle device is a primary component in differential pressure flow measurement systems; it consists of an orifice plate, pressure tapping devices, straight sections before and after the orifice plate, as well as connection flanges. Used in conjunction with differential pressure transmitters, it enables the measurement of the flow rate of various single-phase, homogeneous liquids, gases, and vapors in pipes. Manufacturing standards: GB2624-93, ISO5167-91. Measurement principle: When the fluid filling the pipeline flows through the orifice plate, a local contraction occurs, causing the flow to concentrate and the flow velocity to increase, while the static pressure decreases. As a result, a static pressure difference is created before and after the orifice plate. This pressure difference has a certain functional relationship with the flow rate; the greater the flow rate, the greater the pressure difference. The differential pressure signal is transmitted to the differential pressure transmitter via a pressure guiding tube, where it is converted into a 4–20 mA.DC standard signal; through the flow display instrument, the instantaneous and cumulative flow rates within the pipeline are shown. 　There are three common pressure tapping methods for orifice plate throttling devices: corner tapping (annular chamber, drilled hole) and flange tapping. Standards: GB/T 2624-1993; Throttling devices for flow measurement – Measurement of fluid flow in circular pipes using orifice plates, nozzles, and Venturi tubes. GB/T 18215.1-2000; Flow measurement in main pipelines for urban artificial gas – Part 1: Method using standard orifice plate throttling devices. SY/T 6143-2004; Measurement of natural gas flow using standard orifice plate flow meters. II. Flow-limiting orifice plates: (HG/T 20570–95 Technical Specifications for the Design of Process System Engineering) 1.0.1 Flow-limiting orifice plates are installed in pipelines to restrict the flow rate of fluids or reduce their pressure. Throttling orifice plates are used in the following areas: 1.0 .1.1 when the process material requires pressure reduction and low precision is sufficient. 1.0 .1.2 When a significant pressure drop is required upstream and downstream of a valve in a pipeline, in order to reduce fluid erosion on the valve, an orifice plate can be connected in series upstream of the valve, provided that throttling through the orifice plate does not result in the formation of a gas phase. 1.0 .1.3 Places where the fluid needs to flow in small amounts and continuously, such as the flushing pipes of pumps, the bypass pipes of hot standby pumps (low-flow protection pipes), analysis sampling pipes, etc. 1.0 .1.4 Places where voltage reduction is needed to reduce noise or wear, such as vent systems. 1.0.2 Unless otherwise specified, all pressures in these regulations are absolute pressures.

I thought it was the same person’s stuff too

Great discussion, and thanks to the person on floor 7 for the explanation; I learned a lot

1. Throttling orifice plates for pipelines are used in the following areas: A throttling orifice plate is a concentric sharp-orifice plate designed to limit the flow rate of a fluid or reduce its pressure. A pressure drop occurs as fluid passes through the orifice plate, and the flow rate through the orifice plate increases as this pressure drop increases. However, when the pressure drop exceeds a certain value, that is, beyond the critical pressure drop, regardless of how much the outlet pressure decreases, the flow rate will remain at a constant level and will not increase any further. A flow control orifice plate is used based on this principle to limit the flow rate of a fluid or reduce its pressure. Throttling orifice plates are classified into single-orifice plates and multi-orifice plates based on the number of openings on the plate ； Based on the number of plates, they can be divided into single-plate and multi-plate types. 2 Key selection criteria: 2.1 Gas, steam – To avoid flow blockage in pipelines using orifice plates, the pressure behind the orifice plate (P2) must not be less than 55% of the pressure before the plate (P1), that is, P2≥0.55P1. Therefore, when P2