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1. Can the displayed flow rate of an electromagnetic flowmeter be reduced by closing the valve?
The displayed flow rate of an electromagnetic flowmeter cannot be reduced by closing the valve of a flushing balance. Instead, abnormal fluctuations or even errors in the displayed flow rate may occur due to the valve being closed too small. 1. The core principle of the electromagnetic flowmeter is to calculate the flow rate by measuring the induced electromotive force generated by the cutting of magnetic induction lines by a conductive liquid in a magnetic field. The displayed flow rate directly corresponds to the actual fluid flow velocity and flow cross-sectional area in the pipeline. When the valve is closed, the flow cross-sectional area of the pipeline decreases. Under the condition of constant upstream pressure, the fluid flow velocity in the pipeline will increase, but the actual volumetric flow rate flowing through the sensor will change due to increased resistance in the main pipeline and limitations in the systems supply capacity. If it is a constant pressure water supply system, the total flow rate of the system will decrease after closing the valve, but the flow velocity in the sensor section of the flowmeter will increase, and the displayed flow rate will first increase and then fall back to the new equilibrium value; -If it is a constant flow system, closing the valve will cause an increase in the pressure difference before and after the flowmeter, and some of the static pressure compensation parameters of the flowmeter will be abnormal, resulting in display flow jump and out of range alarm
2. Correct adjustment of the displayed flow. If it is necessary to adjust the display value of the electro
1. Calibration: Contact the manufacturer or measuring institution, use a standard flow device to calibrate the flowmeter for real flow, correct the sensor coefficient, and adjust the display reading to the standard value
2. Parameter modification: Within the authorized authority of the flowmeter, modify the built-in parameters such as fluid density, sensor coefficient, damping time, etc., but only correct system errors and cannot arbitrarily tamper with the display value to deviate from the actual flow.
3 Replacing sensor caliber: If it is necessary to adapt to different flow ranges for a long time, replace the electromagnetic flowmeter sensor with a matching range. 3. Risk of unauthorized operation. Adjusting the displayed flow rate through a small valve is a form of measurement cheating, which can cause distortion of measurement data and violate relevant regulations of the Measurement Law. At the same time, it can also cause damage to the flowmeter itself: the throttling impact caused by the valve closing can accelerate the erosion and wear of the sensor lining, and may also cause cavitation and negative pressure in the pipeline, damaging the internal circuit and electrodes of the flowmeter.
2. How to prevent cheating of water pipe flow meters and prevent the meter from moving
I specialize in flow meters. In fact, flow measurement is a difficult problem to solve. For those who understand the industry, there are too many channels to prevent it. It is unrealistic to truly achieve 100% fairness and accuracy and block loopholes. The cost is too high, and it requires technology and manpower.
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