Common Fault Analysis of Metal Tube Float Flowmeter

First, the pointer jitter:

1. Slight pointer jitter: Generally caused by media fluctuations. It can be overcome by increasing the damping.

2. Moderate pointer jitter: Generally due to media flow conditions. Gases are generally caused by unstable media operating pressures. The regulator or steady current device can be used to overcome or increase the air damping of the float meter.

3. Violent pointer jitter: mainly due to medium pulsation, unstable air pressure or user-supplied gas operating state pressure, temperature, flow rate and the actual state of the float flowmeter, there is a large difference caused by the float flowmeter over-range.

Second, the pointer stops at a certain position and does not move

The main reason is that the float of the float flowmeter is stuck.

Generally, when the float flowmeter is used, the valve is opened too fast, so that the float quickly impacts the stopper upward, causing the stopper to deform and the float to be stuck. However, it is not excluded that the float is stuck due to the difference between the float guide rod and the stop ring. The instrument can be removed during processing, the deformed stopper is removed and shaped, and checked whether it is concentric with the guide rod. If it is different, the correction can be made, then the float is installed, and the float is pushed by hand, and the float is unobstructed. Yes, in addition, when the float flowmeter is installed, it must be installed vertically or horizontally, and it cannot be tilted. Otherwise, it may easily cause the card table and bring errors to the measurement.

Third, the measurement error is large

1. Installation does not meet the requirements

For vertical installation of the float flowmeter to maintain vertical, the inclination is not more than 20 degrees

For horizontal installation of the float flowmeter to maintain horizontal, the inclination is not more than 20 degrees

There shall be no ferromagnetic objects in the 100mm space around the float flowmeter.

Install the position away from the valve reducer, pump outlet, process line turn, etc. To maintain the requirements of the 250mm straight pipe section after the first 5D.

2. A large change in the density of the liquid medium is also a cause of large errors. Since the instrument is converted according to the density given by the user before the calibration, the flow rate of the water in the calibration state is calibrated. Therefore, if the density of the medium changes greatly, the measurement will cause a large error. The solution can bring the density of the medium after the change into the formula, convert it into the error correction coefficient, and then multiply the flow measured by the flow meter by the coefficient to replace the actual flow.

3. Since the gas medium is greatly affected by the temperature and pressure, it is recommended to use the temperature and pressure compensation method to obtain the true flow rate.

4. Due to many factors such as long-term use and pipeline vibration, the floating flowmeter senses magnetic steel, pointer, counterweight, rotating magnetic steel and other moving parts loose, resulting in large errors. Solution: You can verify by hand pushing the pointer first. First press the pointer to the RP position to see if the output is 4 mA, whether the flow display is 0%, and then verify according to the scale. If the discrepancies are found, the parts can be adjusted. Generally require professional adjustment, otherwise it will cause the position to be lost, need to return to the manufacturer for correction.

Fourth, no current output

1. First look at the wiring is correct.

2. Whether the LCD has a display, if there is no output on the display, the output tube is mostly broken, and the circuit board needs to be replaced.

3. Missing calibration value. Due to the E2PROM failure, the meter calibration data is lost, and there will be no output current, and the current will remain unchanged. Solution: Data recovery operation can be used. If it does not work, you can set the data in password 2000 first, and then set the data in password 4011 by pushing the pointer to calibrate the data from RP to 100%.

Five, no live display

1. Check that the wiring is correct.

2. Check if the power supply is correct.

3. Reinstall the LCD module and check that the contact is not correct.

4. Check whether the 12 and 13 terminals are connected to the ammeter or short circuit for the multi-wire power supply mode.

Sixth, the on-site LCD always shows 0 or full scale

1. Check the set range and zero point parameters in the 2000 password. ZERO is required to be less than the value of SPAN, and the two values ​​cannot be equal.

2. Check whether the sampled data is up, and push the pointer to see the sample value change. If there is no change, the circuit board sampling circuit is faulty and the circuit board needs to be replaced.

Seven, the alarm is incorrect

1. Check the deviation setting d value can not be too large.

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

3. Check the alarm value setting size in the SU.

4. If the LCD bar code indication is correct and the output is not active, check whether the negative pole of the external power supply and the external power supply is connected to the negative pole of the meter power supply.

5. The board is faulty and the board is replaced.

Eight, the cumulative pulse output is incorrect

1. Check if the alarm value of the selected cumulative pulse output is set to zero.

2. The board is faulty and the board is replaced.

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