On-line Calibration Method and Process of Magnetic Flowmeter

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How to calibrate a magnetic flowmeter? This online guide will tell you the fastest and most effective way to calibrate magnetic flowmeters.

How to calibrate a magnetic flowmeter? This online guide will tell you the fastest and most effective way to calibrate magnetic flowmeters.

(1) At present, there are two mainstream solutions for online calibration of electromagnetic flowmeters: one is the excitation coil inspection method, which is also called the "dry standard" method of electromagnetic flowmeters, and the other is the external clamp-on ultrasonic flowmeter calibration. Method, also known as "non-contact measurement method". However, in the "dry standard" method, since the standard coil is directly designed into the meter body of the flowmeter, the performance of its resistance and other indicators cannot be traced regularly, which makes it impossible to determine whether the measurement characteristics of the standard coil have changed after a period of time, so " "Dry standard" is difficult to effectively realize the traceability of the value. Compared with the detection of the "dry standard" method, the detection of the vortex flow meter has the advantages of on-site calibration such as non-stop flow, no pipe cutting, and no influence of the temperature, pressure, and density of the measured fluid.

(2) The external ultrasonic flowmeter calibration method. During on-site calibration, the inspector should first check whether the key parameters that affect the accuracy of measurement built in the flowmeter converter are input correctly, ask the staff about the daily flow rate, and observe and calculate the flowmeter for a period of time. According to the big data of the standard table in the laboratory standard device comparison, enter the calibration coefficient of the standard table and the pipe diameter and flow rate of the tested flow meter. The parameters such as outer diameter and wall thickness are based on the flowmeter online operation instructions. Field measurement input. When calculating the indication error, the cumulative flow method is used, and the cumulative value of the flow of the standard meter and the tested meter for a certain period of time is read in three times as the standard value of the measurement standard meter and the displayed value of the tested flow meter. Each measurement time is 30min, conditions Three flow points with obvious differences can be measured when the flow rate changes significantly within a day or permitted.

(3) Calibration method: non-contact measurement method, that is, the external ultrasonic flowmeter is clamped on the pipeline of the measured flow meter, and the measurement characteristics of the measured flowmeter are determined by comparing the cumulative flow error of the two flowmeters.

(4) Calibration item: the indication error of the cumulative flow of the electromagnetic flowmeter.

(5) Measurement basis: JJG1033-2007 "Verification Regulations for Electromagnetic Flowmeters".

(6) Environmental conditions: temperature: (0~45)℃, relative humidity: (40%~90%)RH, the external magnetic field, vibration and noise should be so small that the influence on the standard meter and the tested meter is negligible.

(7) Working medium: single-phase fluid filled with closed pipeline.

(8) The measuring equipment is shown in Table 1.