Interpreting Orifice Flow Meter Accuracy-

The orifice flow meter is a differential pressure generating device for measuring flow. It is used in conjunction with various differential pressure gauges or differential pressure transmitters to measure liquid, vapor and gas flow. It is widely used in petroleum, chemical, metallurgy, electric power, light industry and other departments. So, how to ensure the accuracy of the orifice flow meter?

1. Fixed Reynolds number. There is a definite relationship between the flow coefficient of the orifice flow meter and the Reynolds number. When the mass flow changes, the Reynolds number changes proportionally, thus causing a change in the flow coefficient.

2. The orifice flowmeter is calibrated one by one. As we all know, as long as the standard orifice plate is designed and manufactured according to relevant standards, it can be used directly without flow calibration.t real. Because the output coefficient can be directly calculated by the software, but the computer calculated installation is ultimately ideal, and there is still a certain difference with the on-site environment. Therefore, in order to ensure the accuracy of the measurement, it is recommended to perform an actual flow calibration for each flow meter and the calibrated flow. The coefficients are compared with the results of the calculation, and the difference is calculated and corrected.

3. The influence of temperature on the orifice flowmeter and its correction. The change in temperature of the fluid causes the change in density, which causes the relationship between differential pressure and flow rate to change. Second, the temperature change causes the inner diameter of the pipe and the opening of the orifice plate The correction of the temperature change is to take the temperature instrument to measure the temperature on site, and then to the entrer in the secondary instrument to correct the error caused by the temperature change.

4. Calculation of mass flow rate of steam, orifice flow meter
When measuring steam, first obtain the flow rate value from the differential pressure signal, then obtain the density from the steam temperature and pressure chart to calculate steam traffic quality. 5. Correction of swelling ability. When the orifice flowmeter measures the flow of steam and gas, the expansion of the fluid must be corrected. For the specific correction coefficient, please refer to the throttling device design manual.

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