Static Pressure Error and Correction Method in Differential Pressure Flow Meter

Abstract: The static pressure error and correction method information in the differential pressure flow meter are provided by the excellent flow meter and flow meter manufacturers and quotation manufacturers. The differential pressure scale of the differential pressure transmitter is usually calibrated under the condition that the negative pressure chamber is open to the atmosphere. When it is installed to the site and the actual static pressure calibration is used, it is often found that the zero output and the negative pressure chamber are open to the atmosphere for calibration. When the zero output is inconsistent. This positive and negative pressure chamber access. For more flowmeter manufacturers to select models and price quotations, you are welcome to inquire. The following is the details of the static pressure error and correction method in the differential pressure flowmeter. The differential pressure scale of the differential pressure transmitter is usually calibrated under the condition that the negative pressure chamber is open to the atmosphere. When it is installed to the site and the actual static pressure calibration is used, it is often found that the zero output and the negative pressure chamber are open to the atmosphere for calibration. When the zero output is inconsistent. The zero position output obtained when the positive and negative pressure chambers are connected to the same static pressure is called the static pressure error. If the static pressure error of the differential pressure transmitter is not corrected, it will bring errors to the flow measurement, and the impact is more considerable when the relative flow is small. For example, there is a DDZ-Ⅲ differential pressure transmitter and a throttling device together to form a differential pressure flowmeter. Under normal pressure conditions, its static pressure error is 0.5% FS. Because the static pressure error is not adjusted, it is put into operation. , then when the actual flow rate is zero, the flow indication value of the meter may reach 7.1% FS. Although the small-signal cut-off function covers up this contradiction, its influence exists objectively, and it is within the full scale range.±A differential pressure deviation of 0.5% FS is always in play. The static pressure error of the differential pressure transmitter is caused by the unequal effective area of ​​the positive and negative pressure chamber diaphragms. In the DDZ-Ⅲ differential pressure transmitter, the static pressure error can be as high as±0.5%FS. In the intelligent differential pressure transmitter, because the static pressure sensor is installed, and the deviation value of the zero position output is measured by the experimental method when the static pressure changes within the specified range, and then the static pressure is measured in the single-chip microcomputer in the table. pressure error is corrected. After the differential pressure transmitter has been corrected online for the static pressure error, the residual static pressure error can generally be reduced to±0.1% or less, so that its performance is significantly improved. Some differential pressure transmitters have square root function and small signal cut-off function. When checking static pressure error, the small-signal cut-off function should be temporarily released to observe the real zero position. The output of the differential pressure transmitter can also be read out in the flow display instrument or DCS. In order to read out the real zero position output, the small signal cut-off function also needs to be temporarily released. Combine the differential pressure transmitter with the flow display instrument to check the zero position output. If there is a deviation in the zero position, the possible reasons are as follows: 1. The installation position of the differential pressure transmitter deviates from the correct position, causing the zero point offset. 2. Flow display instrument zero deviation. 3. Differential pressure transmitter static pressure error. After the differential pressure flowmeter has undergone the above-mentioned static pressure error and zero point inspection and calibration, the balance valve can be closed, the high and low pressure valves can be fully opened and put into operation. The algebraic sum of this deviation is not very large, and it is finally eliminated by zero calibration of the differential pressure transmitter. Therefore, the inspection and calibration link before the instrument is put into operation is an important part of the operation of opening the meter. The above is the whole content of this article. You are welcome to inquire about the flowmeter selection and quotation of our factory. 'Static pressure error and correction method in differential pressure flow meter'

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