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Industry Information
Obstacle analysis of metal tube float flowmeter
2012-2-27 13:20:33


1. Pointer jitter:
1. Slight pointer shake: Generally caused by media fluctuations. This can be overcome by increasing damping.
2. Moderate pointer jitter: Generally caused by the state of media flow. For gas, it is generally caused by the unstable operating pressure of the medium. Can use voltage stabilization or flow stabilization device to overcome or increase the air flow damping of the float flowmeter.
3. Vigorous pointer jitter: Mainly due to the pulsation of the medium, the unstable air pressure, or the pressure, temperature, and flow rate of the gas operating state given by the user do not match the actual status of the float flowmeter, and there are large differences that cause the float flowmeter to exceed the range.
2. The main reason why the pointer stops at a certain position is that the float of the float flowmeter is stuck.
使用时开启阀门过快,使得浮子飞快向上冲击止动器,造成止动器变形而将浮子卡死。 Generally, because the metal tube float flowmeter opens the valve too fast when it is used, the float quickly hits the stopper upwards, causing the stopper to deform and the floater stuck. However, it is not ruled out that the float is stuck because the float guide rod and the stop ring are not concentric. During processing, the instrument can be removed, the deformed stopper can be removed and reshaped, and check whether it is concentric with the guide rod. If not, you can correct it, then install the float, push the float by hand, and feel that the float is smooth. Yes, in addition, the float flowmeter must be installed vertically or horizontally, and cannot be tilted, otherwise it will easily cause card meters and bring errors to the measurement.
Third, the measurement error is large 1. The installation does not meet the requirements;
要保持垂直,倾角不大于20度; For vertical installation of metal tube float flowmeter to maintain vertical, the inclination angle is not greater than 20 degrees;
For the horizontal installation of the float flowmeter to maintain the level, the inclination angle is not greater than 20 degrees;
There must be no ferromagnetic objects in the 100mm space around the float meter;
The installation position should be far away from the valve reducer, the pump outlet, and the turning point of the process pipeline. To maintain the requirements of the first 5D after 250mm straight pipe section.
2. Large density change of liquid medium is also a cause of large error. Before the instrument is calibrated, the medium is converted according to the density given by the user, and converted to the water flow under calibration state for calibration. Therefore, if the medium density changes greatly, it will cause a large error in the measurement. The solution is to bring the changed medium density into the formula, convert it into an error correction coefficient, and then multiply the flow rate measured by the flow meter by the coefficient to replace the real flow rate.
3. Since the gas medium is greatly affected by temperature and pressure, it is recommended to use the temperature and pressure compensation method to obtain the true flow rate.
传感磁钢、指针、配重、旋转磁钢等活动部件松动,造成误差较大。 4. Due to long-term use and pipeline vibration and other factors, the metal tube float flowmeter's sensing magnetic steel, pointer, counterweight, rotating magnetic steel and other moving parts are loose, causing large errors. Solution: first push the pointer by hand to verify. First press the pointer at the RP position to see if the output is 4mA and whether the flow rate display is 0%, and then verify according to the scale. If a discrepancy is found, the position of the component can be adjusted. Generally requires professional adjustment, otherwise the position will be lost, and it needs to be returned to the factory for correction.
Fourth, no current output 1. First see if the wiring is correct.
2. Whether the LCD has a display, if there is no output, the output tube is mostly broken, and the circuit board needs to be replaced.
3. Lost calibration value. Due to the failure of E2PROM, the calibration data of the instrument is lost, and no output current will be caused, and the current will remain unchanged. Solution: The data recovery operation is available. If it does not work, you can set the data in password 2000 and then the data in password 4011. The method is to push the pointer to calibrate the data from RP to 100%.
V. No on-site display 1. Check whether the wiring is correct.
2. Check whether the power supply is correct.
3. Reinstall the LCD module, and check the contact is not correct.
4. For multi-wire power supply mode, check whether terminals 12 and 13 are connected to ammeter or short circuit.
VI. On-site LCD always displays 0 or full scale 1. Check the range and zero parameters set in the 2000 password. ZERO is required to be less than the value of SPAN, and the two values cannot be equal.
2. Check if the sampling data comes up, push the pointer with your hand to see the sampling value change. If there is no change, the sampling circuit of the circuit board is generally faulty and the circuit board needs to be replaced.
Seven, the alarm is incorrect 1. Check that the deviation setting d value cannot be too large.
2. Whether the logic function is correct in the FUN function. HA-A stands for positive upper logic. LA-A means lower limit positive logic.
3. Check the alarm value setting size in SU.
4. If the LCD bar code is correct and the output has no action, you can check whether the external power source and the negative pole of the external power source are connected to the negative pole of the instrument.
5. The circuit board is faulty. Replace the circuit board.
8. Accumulative pulse output is incorrect 1. Check whether the alarm value of the channel that selects cumulative pulse output is set to zero.
2. The circuit board is faulty. Replace the circuit board.