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I. Overview of Mine-Use Explosion-Proof Electromagnetic Flow Meters Mine-use explosion-proof electromagnetic flow meters offer advantages such as no pressure loss, no clogging, significant energy savings, high accuracy, and strong pressure resistance. Therefore, they are widely used in the water supply and drainage systems of coal mines, playing a crucial role in hydrological monitoring and safe production in these facilities. II. Principle of measurement: When the pipe diameter is constant, the cross-sectional area remains fixed, and thus the flow velocity is directly proportional to the flow rate (the volume per unit time). When fluid flows through the flow meter, the meter generates an induced electromotive force. By amplifying and processing this signal, a voltage value that is proportional to the flow rate is obtained. Through analog-to-digital conversion, this voltage value is transformed into a numerical value; thus, the numerical value represents the instantaneous data. In practice, we have found that due to variations in hardware such as the excitation coil, when the medium being measured is relatively stationary, the instantaneous values (reading values) obtained by the flow meter are not exactly \"0\"; there is a slight offset. This reading value at such times is usually referred to as the zero point value. The relationship between Q in equation (1), the standard flow rate Qs, and the coefficient K is given by: Q = c – ZN * k, where Q represents the measured flow rate ； c —— Actual measured value of the flow meter ； z —— The zero setting value of the flow meter ； N — Constant for flowmeter conversion ； K —— the coefficient of the flow meter ； III. Methods to improve accuracy 3.1 Segmented calculation method. This is because mining explosion-proof electromagnetic flowmeters have a very wide measurement range. For example, the typical measurement range of the standard type is from 0.3 m/s to 10 m/s. To meet the measurement accuracy for each point, a segmentation coefficient can be introduced, employing a segmented calculation approach. Relationship between the segmented metering coefficient and flow rate in Equation (2): Qf = Q * kf, where kf is the segmented metering coefficient ； Qf—the flow rate value displayed after segmented measurement ； During measurement, the entire flow range is divided into several segmented ranges, with a corresponding segment-specific measurement coefficient kf for each range, in order to ensure the accuracy of each range. When the flow rate is calculated using equation (3) to obtain the value Q, this value is analyzed; by comparing it with the predefined range categories, the appropriate category is identified. For example, the range from 14.13 m3/h to 28.26 m3/h is one such category, and the corresponding coefficient kfn for this range is 1.012. If an instantaneous flow meter measures a flow rate of Q = 10.00 m3/h, which falls within this range, then the final displayed flow rate will be Qf = Q * kfn = 10.12 m3/h. It can be seen that during the calibration process, it is possible to adjust the segmental measurement coefficients for each range, thereby ensuring more accurate measurements. 3.2 Fine-tuning zero-point method. During the calibration of a flowmeter, the static zero value is set only after calibration at the beginning; in subsequent calibration processes, the default zero value is taken as the standard value. However, in reality, there are slight variations in the offset of the zero value each time it is set. Therefore, in the methods for determining the zero point, there can be a discrepancy between the set zero point value and the actual zero point value. One method is the fine-tuning of the zero point, which involves performing calculations and adjustments to make the set zero point value more close to the actual one. As can be seen from Equation (1), when the count value remains constant, there are two factors that affect the display of the instantaneous flow rate: the zero-point value z and the flow meter coefficient K. At different flow rates, that is, when the count value varies, the influence of these two factors changes. If a flow meter has a zero point value of 50 and a coefficient of 80.0%, then when this coefficient k changes by 0.5%, the corresponding change in the zero point for different measurement values is as follows: when the measured value is 6000, the zero point offset ZP = (6000 – 50) × 0.5% = 29.75. When the measured value is 1000, the zero offset ZP = (1000 – 50) × 0.5% = 4.75. It can be seen that when the instantaneous flow rate Q is high, the value of C is also high; among the values of z and the coefficient k, it is the flow meter coefficient k that has the greatest impact on the flow rate. When the instantaneous flow rate Q is very low, the value of C is also small; among the values of z and the coefficient k, it is the zero point value of the flow meter, z, that has the greatest impact on the flow rate. Therefore, fine-tuning this zero point value during the calibration process helps to ensure accuracy. 3.3 Calculation of the zero-point adjustment value: Zp = C – z×E ； zp——Fine-tuned zero value ； c —— Actual measured value of the flow meter ； z —— The zero setting value of the flow meter ； E ——the error value of the calibration. During the calibration process, if the flow readings are normal at higher flow rates, but there is a slight deviation at lower flow rates, the zero-point adjustment method can be used. It should be noted, however, that although the impact of the zero-point value on higher flow rates is small, it cannot be ignored. Therefore, when adjusting the zero point, it is necessary to take into account the effect of such adjustments on other flow rates. Generally, the adjusted zero-point value should not exceed 1% of the measured flow rate value; if there is a greater deviation, recalibration is required to ensure the accuracy of the flow meter. IV. Conclusion: The calibration of mine-used flameproof electromagnetic flowmeters allows for the combined use of various methods, enabling targeted correction of the main factors that affect accuracy. This ensures precise measurement at each point, thereby improving the overall performance of the flowmeter as well as the efficiency of the calibration process.