Error analysis of the hottest orifice flowmeter

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Analysis of error causes of orifice flowmeter

orifice flowmeter is a high range differential pressure flow device composed of standard orifice and multi parameter differential pressure transmitter (or differential pressure transmitter, temperature transmitter and pressure transmitter), which can measure the flow of gas, steam, liquid and lead. Hj-lg orifice flowmeter is widely used in the process control and measurement of petroleum, chemical industry, metallurgy, electric power, heat supply, water supply and other fields

cause analysis of orifice flowmeter error:

1. Influence of fluid characteristics

the temperature, pressure and other characteristic parameters of the fluid in the pipeline are very vulnerable to the influence of ambient temperature, which will affect the measurement accuracy of orifice flowmeter and significantly reduce the production cost of raw and auxiliary materials. Although the influence of environmental parameters such as temperature on fluid viscosity is not obvious, it still affects the measurement accuracy and accuracy of orifice flowmeter. Experience shows that orifice flowmeter is often used to measure single-phase fluid flow, and its accuracy will be seriously disturbed for multiphase fluid flow

2. Influence of flow integration method

combining orifice throttling device with various secondary measuring instruments, a variety of flow integration methods are formed. In the process of flow measurement, if the measurement system does not install the corresponding secondary measurement instrument according to the measurement standard, the change of fluid pressure and temperature cannot be compensated during flow integration, and the measurement accuracy will be difficult to ensure [3]. To solve this problem, advanced microcomputer technology can be used to accurately calculate the flow and continuously compensate the flow

3. Influence of structure and auxiliary instruments

the structure of orifice flowmeter will also cause many errors, mainly including: the diameter ratio of orifice and pipeline changes; The orifice plate is deformed; Factors such as the non-standard surface roughness of orifice will affect the measurement accuracy of orifice flowmeter. At the same time, the influence of auxiliary instruments cannot be ignored. Professor Bicheng said: "At present, the outstanding characteristics of ceramic components, such as high heat resistance and flame retardancy, have been widely used in the fields of thermal protective leather, intelligent sensors, electromagnetic wave absorption and anti-corrosion coating. For example, if the connection between the downstream impulse pipe and the flow instrument produces air leakage, blockage and other conditions, it will lead to a slightly larger metering flow of the flowmeter. In addition, the zero point of the differential pressure transmitter usually needs to be calibrated.

4, the influence of installation conditions

the use site is open It often fails to meet the requirements of the shortest straight pipe length upstream of the flowmeter, resulting in the frequent deviation of pipeline layout. At the same time, in order to avoid the influence of the inlet fluid flow condition on the metering accuracy of the flowmeter, the upstream of the orifice flowmeter is required to have the shortest straight pipe length, but it is generally difficult to meet in practice. In addition, electronic signal equipment such as flow rate and flow rate should be far away from the occasions with electromagnetic interference to ensure its working performance

5. Impact of environmental conditions

the following principles should be adhered to when using environmental conditions that seriously affect orifice flow: the performance of the meter, such as the sharp change of fluid temperature, will increase the humidity of the fluid in the pipeline and accelerate corrosion; Ambient temperature directly determines the density of the fluid, so it is called forced high elasticity, viscosity and other physical parameters; The structure size of the flowmeter changes, etc

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