Method for judging the quality of electromagnetic flowmeter

The electromagnetic flowmeter is a flowmeter that measures flow and has certain applications in many industries. The electromagnetic flowmeter has many advantages such as small pressure loss, wide measuring range, good stability and high measurement accuracy. When we use electromagnetic flowmeters, how do we know the quality of electromagnetic flowmeters? Today, Huaheng Instrument will give you a detailed introduction to the method of judging the quality of the electromagnetic flowmeter. I hope that it will help you in the future.

1. Measure the resistance value of the excitation coil, mainly to judge whether the excitation coil has a short circuit between turns. The resistance value of the excitation coil should be 30 ohms to 170 ohms under normal conditions. If the resistance value is the same as the factory record, then we consider the coil to be good, and indirectly evaluate the magnetic field strength of the electromagnetic flowmeter sensor.
2. Measure the insulation resistance of the excitation coil to ground (measurement line number "1" and "7" or "8") to determine whether the sensor is damp. The resistance value should be greater than 20 megohms.
3. Measure the contact resistance between the electrode and the liquid, and indirectly evaluate the condition of the surface of the electrode and the lining layer in the component. For example, whether the electrode surface and the lining layer have an attached deposition layer, whether the deposited layer is electrically conductive or insulative. The resistance value between them should be 1 kohm to 1 megohm, and the resistance values ​​of the line numbers "1" and "2" and "1" and "3" must be symmetrical.
4. Close the valve on the pipeline and check the zero point of the electromagnetic flowmeter in the absence of liquid flow, remember to be from full liquid.
5. Use GS8 calibration instrument to detect the output current of the converter. When the given flow rate is 0, the output current of the flowmeter should be: 4.00mA; when 100% flow is given, the output current should be: 20.00mA. The error of the output current value should be guaranteed to be around 1.5%.
6. Between the “7” and “8” terminals of the excitation current value converter, the positive and negative values ​​of the excitation current should be within the range of 137 (5%) mA. In the detection, pay attention to the influence of the external environment of the electromagnetic flowmeter on the detection result: if the excitation line and the signal line are laid in the same pipeline, the excitation line and the signal line are parallel with the high-voltage cable, and there are large transformers or motors around the electromagnetic flowmeter. The impact of the operation accuracy is evaluated. This evaluation mainly uses the visual method to observe whether the electromagnetic flowmeter in operation has sudden or fluctuating conditions. It is generally judged whether the electromagnetic flowmeter is interfered by electromagnetic waves or other stray waves or whether there is any  bubble presence in the pipeline.

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