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Impact Factor Analysis of Orifice Flowmeters - Focus on Microfluidic Control Technology

Influence Factor Analysis of Influence on Orifice Plate Flowmeter
At present, there are various flow measuring instruments for different purposes, and the accuracy of their measurement is widely recognized by people. The accuracy of the orifice flowmeter is determined by its structure, measurement principle, the nature of the fluid being tested, the environmental conditions of use, and the level of manufacturing process. However, many objective factors in the verification process and in the process of use will also affect the accuracy of the orifice flowmeter, and even greatly reduce the accuracy of the orifice flowmeter, affecting the normal use of the orifice flowmeter, and deviating from the original intention. The main influencing factors are the following.

A: The actual use accuracy of the flow standard device
Orifice flowmeters must be properly sized for use in all conditions. The actual use accuracy of the verification ground flow standard device is higher than the accuracy of the orifice flowmeter. For the inspection instrument, it is necessary to ask whether the equipment, method and accuracy of the verification meet the requirements.

Two: the measured fluid flow condition
Fluid flowing in a pipe or in an open channel has different flow conditions such as laminar flow, turbulent flow, pulsating flow, uneven flow, and the like. In particular, the use of Bernoulli's theorem to develop ground orifice flowmeters requires constant flow and uniform flow velocity distribution, such as orifice flowmeters. If there are obstacles in the pipeline, it will cause a drastic change in the flow, resulting in a non-negligible error in the measurement results of the orifice flowmeter. When the orifice flowmeter is installed, the requirements of the straight pipe section are generally the first 10 and the last 5, and it is required to minimize the use of bends, valves, and the like.

Three: The physical properties of the measured medium
As of now, each orifice flowmeter is in normal use under specific conditions, and no orifice flowmeter can measure any media flow under any conditions. Flow measurement is a relatively complex measurement. When the orifice flowmeter measures the flow rate, it is not suitable to measure the viscosity of the large earth fluid flow. When measuring the steam, the pressure and temperature signals should be collected in the flow meter for correction. Ultrasonic orifice flowmeters cannot measure gas. When the measurement fluid contains large and more solid particles, the measurement accuracy will be greatly affected. Therefore, when the accuracy of the orifice flowmeter decreases, it should be noted whether the physical properties of the fluid being measured have changed.

IV: Properly Install and Use Orifice Flow Meters
Many orifice flow meters are installed and used in close proximity to their measurement accuracy, especially those orifice plates where the sensing element is located directly in the flowing fluid. If the orifice plate in the orifice flowmeter is not concentric with the pipe, an error will occur, and the error will be 100% in severe cases. Therefore, depending on the degree of requirements for installation conditions, various orifice flowmeters must be strictly differentiated. Only installation in compliance with installation conditions can ensure the accuracy of orifice flowmeters.
The accuracy of the orifice flowmeter is 0.5, 1 and the actual accuracy is 1.5 or 2. Orifice plate is affected by the straight pipe section before and after the impact, in addition to the installation requirements are relatively high, but also pay attention to the range ratio is not too large (usually 3:1). Because the fundamental reason that influences the accuracy of the orifice flowmeter measurement is whether the geometric shape and flow dynamics of the throttling device deviate from the design standards, the system must be regularly calibrated and maintained in the use process. For practical use, the pressure and temperature Changes in operating conditions and other parameters should be corrected in time. The full-compensation and local flow totalizer can be used to reduce the measurement error and ensure the measurement accuracy. The orifice flowmeter is a very strict instrument from design, manufacture to installation and use. Any mistake in the link will cause a large error. Therefore, if it is strictly in accordance with the standard, its accurate measurement is guaranteed. The repeatability of the orifice flowmeter is lower than that of other orifice flowmeters (vortex street orifice flowmeters, ultrasonic orifice flowmeters, and electromagnetic orifice flowmeters) because the output signal is susceptible to interference due to analog values. In particular, the differential pressure and pressure-inducing pipeline can easily cause interference fluctuations in the signal. It is precisely because the repeatability is not high, which affects its accuracy.

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