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In general pipeline fluid measurement, flow meters can only measure fluid flowing in one direction; if the direction of the fluid changes, measurement becomes impossible. There are few flowmeters that can measure bidirectional flow; the ones we are familiar with include electromagnetic flowmeters and ultrasonic flowmeters. The direction of flow for electromagnetic flowmeters can be set accordingly. When installed horizontally, flow selection provides considerable convenience on-site. However, when installed vertically, the fluid can only flow through the flow meter from bottom to top. Electromagnetic flowmeters have strict requirements regarding a full pipe condition; when the fluid flowing through the flowmeter does not meet this requirement, the meter will issue an empty pipe alarm, and the display will indicate no flow. During operation, electromagnetic flowmeters often experience an empty tube alarm. This alarm indicates whether the sensor’s measurement tube is filled with fluid. To determine the cause of this alarm, we can short-circuit the signal input terminal of the converter to ground using a wire; if the measurement shows that the tube goes from empty to full, it means the converter is functioning properly. The possible causes of the problem could be a low conductivity of the fluid being measured or an incorrect setting for the empty tube threshold. Furthermore, if there is a problem with the electrodes of the electromagnetic flowmeter, an empty tube alarm may also occur. The air traffic control alarm threshold is often used in conjunction with air traffic control alarms. The alarm threshold for empty tubes is usually set at 500%. The alarm related to empty tubes is a relative value that is directly related to both the state of the tube when it is full and the conductivity of the medium. The value of this alarm threshold determines the sensitivity of the alarm for empty tubes. Before determining this threshold, it is necessary to measure the conductivity of the medium in question, as well as its resistance value when the tube is full. Then, by considering factors such as the time it takes for the fluid to adhere to the wall, an appropriate alarm response time can be set; therefore, the threshold for air tube alarms should be an adjustable parameter. In practical use, the resistivity value of the fluid when the pipe is full is defined as 100%; that is, when the pipe is full, the measurement value for an empty pipe is calibrated to 100% using the \"empty pipe alarm threshold\". When the fluid level in the pipe is below the measuring electrode, the relative resistivity increases; when it exceeds the empty pipe alarm threshold, the instrument will display an empty pipe alarm signal. Theoretically, if the air traffic control alarm threshold is set at 900%, an air traffic control alarm will be displayed when air traffic control is active. The lower the air traffic control alarm threshold, the more sensitive the air traffic control alarms are. Each is set according to on-site requirements. Methods for dealing with an empty tube alarm in an electromagnetic flowmeter: 1. Check whether the fluid fills the measurement tube; 2. Short-circuit the converter’s signal terminals SIG1, SIG2, and SIGGDN using wires. If the “empty tube” warning disappears, it indicates that the converter is functioning properly; the issue may be due to low conductivity of the fluid being measured, or incorrect settings for the empty tube threshold and range; 3. Verify that the signal lines are connected correctly; 4. Check whether the sensor electrodes are in good condition; 5. Set the flow rate to zero and ensure that the displayed conductivity ratio is less than 100%; 6. With current flowing, measure the resistance at terminals SIG1, SIG2, and SIGGDN – it should be less than 50kΩ. 7. The DC voltage between DS1 and DS2, as measured with a multimeter, should be less than 1V; otherwise, it indicates that the sensor electrodes are contaminated and need to be cleaned. The air control alarm is likely indicating that the tube isn’t fully filled. It’s not full but there is flow, which occurs in horizontally placed pipes. Installing the sensor on the riser should resolve this issue. For more information, please visit the company’s official website at http://www.yb1518.com/. Please retain this link when reproducing the content!