Application failure of metal tube flowmeter of electronic measuring instrument

　　1. Slight pointer jitter: generally caused by medium fluctuations. This can be overcome by increasing damping.

　　2. Moderate pointer jitter: generally caused by the flow state of the medium. For gas, it is generally caused by unstable medium operating pressure. A pressure stabilizing or flow stabilizing device can be used to overcome or increase the gas damping of the float flowmeter.

　　3. Severe pointer jitter: mainly due to medium pulsation, unstable air pressure or the pressure, temperature and flow rate of the gas operating state given by the user do not match the actual state of the float flowmeter. There is a large difference causing the float flowmeter to over-range.

　　2. The main reason why the pointer stops at a certain position and does not move is that the float of the float flowmeter is stuck.

　　Generally, when the metal tube float flowmeter is used, the valve is opened too quickly, causing the float to quickly impact the stopper, causing the stopper to deform and jam the float. However, it is not ruled out that the float is jammed due to the non-concentricity of the float guide rod and the stop ring.

　　When handling, the instrument can be disassembled, the deformed stopper can be removed and reshaped, and check whether it is concentric with the guide rod. If not, it can be corrected. Then the float can be installed and the float can be pushed by hand until it feels that the float can move up and down smoothly without obstruction. In addition, the float flowmeter must be installed vertically or horizontally and cannot be tilted, otherwise it will easily cause the meter to get stuck and bring errors to the measurement.

　　3. Large measurement error

　　1. Installation does not meet the requirements. For vertically installed metal tube float flowmeters, they must be kept vertical, with an inclination of no more than 20 degrees. For horizontally installed float flowmeters, they must be kept horizontal, with an inclination of no more than 20 degrees. There must be no ferromagnetic objects in the 100mm space around the float flowmeter. The installation location should be far away from the valve reducer, pump outlet, process pipeline bend, etc. The straight pipe section requirement of 5D in front and 250mm in the back should be maintained.

　　2. Large changes in the density of liquid media are also a reason for large errors. Before calibration, the instrument converts the medium into the density given by the user and converts it into the water flow rate under the 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 measured by the flowmeter by the coefficient to convert it into the actual flow.

　　3. Since gas media are greatly affected by temperature and pressure, it is recommended to use temperature and pressure compensation to obtain the actual flow rate.

　　4. Due to long-term use and pipeline vibration and other factors, the active parts of the metal tube float flowmeter such as the sensor magnet, pointer, counterweight, rotating magnet, etc. are loose, resulting in large errors. Solution: You can first verify by pushing the pointer by hand. First, press the pointer at the RP position to see if the output is 4mA and the flow display is 0%, and then verify according to the scale. If it is found to be inconsistent, the position of the component can be adjusted. Generally, professional personnel are required to adjust, otherwise the position will be lost and it needs to be returned to the manufacturer for correction.

　　4. No current output

　　1. First check whether the wiring is correct.

　　2. Check whether the LCD has any display. If there is display but no output, it is probably that the output tube is broken and the circuit board needs to be replaced.

　　3. Loss of calibration value. Due to E2PROM failure, the calibration data of the instrument is lost, which will also cause no output current, and the current will remain unchanged. Solution: You can use the data recovery operation. If it does not work, you can first set the data in password 2000, and then set the data in password 4011. The method is to use the hand-pushing pointer to calibrate the data from RP to 100%.

　　5. 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 for loose contact.

　　4. For multi-wire power supply mode, check whether terminals 12 and 13 are connected to an ammeter or short-circuited.

　　6. The on-site LCD always displays 0 or full scale

　　1. Check the range and zero parameters set in the password 2000. It is required that ZERO should be smaller than SPAN and the two values ​​cannot be equal.

　　2. Check whether the sampling data is coming up, push the pointer by hand to see the sampling value change. If there is no change, it is generally due to a circuit board sampling circuit failure, and the circuit board needs to be replaced.

　　7. Incorrect alarm

　　1. Check that the deviation setting d value is not too large.

　　2. In the FUN function, is the logic function correct? HA-A indicates upper limit positive logic. LA-A indicates lower limit positive logic.

　　3. Check the alarm value setting in SU.

　　4. If the LCD barcode indication is correct and the output has no action, check the external power supply and whether the negative pole of the external power supply is connected to the negative pole of the instrument power supply.

　　5. The circuit board is faulty, please replace it.

　　8. The cumulative pulse output is incorrect

　　1. Check whether the alarm value of the channel that selects the cumulative pulse output is set to zero.

　　2. The circuit board is faulty, please replace it.