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technical article
Measures to prevent metal rotor flowmeters
2011-12-30 10:40:39

适用于小口径和低流速介质流量测量;工作可靠,维护量小,寿命长;对于直管段要求不高;较宽的流量比10:1;双行大液晶显示,可选现场 Metal rotor flowmeter is suitable for small-diameter and low-velocity medium flow measurement; reliable operation, low maintenance and long life; low requirements for straight pipe sections; wide flow ratio of 10: 1; dual-line large liquid crystal display, optional field

Instantaneous / cumulative flow display, with single-axis sensitive indication of backlight; non-contact magnetic coupling transmission; metal rotor flowmeter full metal structure, suitable for high temperature, high pressure and strong corrosive media; can be used in flammable and explosive hazardous situations; can be Choose two-wire system,

Battery, AC power supply mode; multi-parameter calibration function; metal rotor flow meter with data recovery, data backup and power failure protection functions.

另一件是置于锥形管中且可以沿管的中心线上下自由移动的转子。 The metal rotor flowmeter consists of two parts. One of the rotor flowmeter is a tapered tube that gradually expands from bottom to top; the other is a rotor flowmeter that is placed in a conical tube and can move freely up and down along the centerline of the tube. Rotor. Rotameter

When measuring the flow of fluid, the measured fluid flows in from the lower end of the conical tube, and the flow of the fluid impacts the rotor and generates a force on it.


常见故障原因对策 Common failure causes of metal rotor flowmeter and countermeasures


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 rotor flow meter gas damping.


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 state of the rotor flowmeter, and there are large differences that cause the rotor flowmeter to exceed the range.


Second, the pointer stops at a certain position

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

Generally, the rotor flowmeter opens the valve too quickly when it is used, causing the rotor to impact the stopper quickly, causing the stopper to deform and the rotor to be stuck. However, it is not excluded that the rotor is stuck due to the concentricity between the rotor guide rod and the stop ring.

When processing, you can remove the instrument, remove the deformed stopper, and check whether it is concentric with the guide rod. If the concentricity can be corrected, then install the rotor, push the rotor by hand, and feel that the rotor is smooth and unobstructed. Yes, in addition,

When the rotor flowmeter is installed, it must be installed vertically or horizontally, and it cannot be tilted, otherwise it may easily cause a card meter and bring errors to the measurement.


Large measurement error


1. Installation does not meet requirements


For vertical installation of the rotor flowmeter, keep it vertical, and the inclination angle should not be greater than 20 degrees


For horizontal installation of the rotor flowmeter, keep it horizontal and the inclination angle is not greater than 20 degrees


There must be no ferromagnetic objects in the 100mm space around the rotor flowmeter.


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. The large change in the density of the liquid medium is also a cause of the larger 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 the calibration state for calibration. Therefore, if the medium density

Large changes can cause large errors 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.


4. Due to long-term use and pipeline vibration and other factors, the rotor flowmeter 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 the pointer

Press 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 can be performed by pushing the pointer by hand to calibrate the data from RP to 100%.


V. No on-site display


1. Check that the wiring is correct.


2. Check whether the power supply is correct.

3. Reinstall the LCD module, and check that 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.


Six, the field LCD always displays 0 or full scale


1. Check the set range and zero parameters. 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, it is usually the circuit board sampling circuit failure that needs to be replaced.


Seven, the alarm is incorrect


1. Check that the deviation setting d cannot be too large.


2. Is the logic function correct?

3. Check the alarm value setting size.


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.


Eight, the cumulative pulse output is incorrect


1. Check whether the alarm value of the accumulated pulse output is set to zero.


2. The circuit board is faulty. Replace the circuit board.