Matters Needing Attention to Ensure the Normal Operation of Metal Rotameter

 In order to ensure the normal operation of the metal tube rotameter and achieve the required measurement accuracy, the following points should generally be noted:

•The metal rotor flowmeter must be installed vertically, the fluid flows through the flowmeter from bottom to top, and the verticality is better than 2°, and the horizontal angle is better than 2° when installed horizontally;

•The metal tube float flowmeter installed on the process pipeline should be bypassed, so as to deal with the failure or not affect the production when purging;

•The entrance of the metal rotor flowmeter should have a straight pipe section of more than 5 times the pipe diameter, and the outlet should have a straight pipe section of 250mm to ensure the measurement accuracy of the instrument;

•If the medium contains ferromagnetic substances, a magnetic filter should be installed;

•If the medium contains solid impurities, consider installing a filter between the valve and the straight pipe section;

•When used for gas measurement, ensure that the pipeline pressure is not less than 5 times the pressure loss of the flowmeter to make the float work stably;

•If the temperature of the measured medium is higher than 220°C or the fluid temperature is too low, crystallization is likely to occur, and when heat insulation protection measures are required, the jacket type should be selected for cooling or heat preservation;

•The pipe flanges, fasteners, gaskets and the flow meter flange standards are the same to make the meter install and run normally;

• Generally, the product does not need maintenance after the normal operation of the device. Faults usually occur when the device is just started, and the float is stuck by the solid particles due to the uncleanness of the pipeline. At this time, the pointer of the indicator stops at a position. At this time should first close the valve on both sides of the flowmeter, and then remove the upper flange, take out the float for cleaning, and then reinstall. Pay attention to tighten the flange nut evenly and fill the washer well;

• In order to avoid flowmeter deformation caused by the pipeline, the flange of the process pipeline must be coaxial and parallel to the flange of the flowmeter, and the pipeline should be supported appropriately to avoid pipeline vibration and reduce the axial load of the flowmeter. In the measurement system The control valve should be installed downstream of the flow meter;

•Because the meter transmits signals through magnetic coupling, in order to ensure the performance of the meter, at least 250px around the installation, no ferromagnetic substances are allowed;

•The meter for measuring gas is calibrated under a specific pressure. If the gas is directly discharged to the atmosphere at the outlet of the meter, it will cause a pressure drop at the float and cause data distortion. If this is the working condition, a valve should be installed at the outlet of the instrument;

•Be careful when installing PTFE-lined meters. As the PTFE will deform under the action of uneven pressure, the flange nuts are tightened evenly and symmetrically;

•For instruments with liquid crystal display, avoid direct sunlight on the display when installing, so as not to reduce the service life of the liquid crystal;

•For meters with lithium battery power supply, try to avoid direct sunlight and high temperature environment (≥65℃) when installing to avoid reducing the capacity and life of the lithium battery.

The above information is provided by flow instrument manufacturer.

Mass Flow Meter Installation Process

The mass flow meter is the most accurate meter with the lowest installation requirements in the existing industrial production. Because it can directly detect the quality, density, and temperature of the medium flowing through the measuring tube inside the meter, there is no strict layer on the flow state of the medium. Flow requirements, so there is no requirement for straight pipe sections for the pipelines before and after the flowmeter during the installation process. Just like the regulating valve, it can be installed arbitrarily, which greatly facilitates on-site construction and installation.

Various shapes of mass flow meters

Mass flow meters have various shapes, but their internal structures are almost the same. They basically consist of two U-shaped measuring tubes. Three coils are installed at the bottom and left and right sides between the two measuring tubes. The bottom coil is an excitation coil. The two coils on the left and right measure the mass and the density. In addition, a thermal resistance is buried inside the measuring tube to detect the temperature of the medium.

Details of the installation process

Since the mass flowmeter can detect the density of the medium in real time, without artificially setting a constant density of the medium, the detection value of the mass flowmeter is accurate and reliable, and the construction and installation are simple and convenient.

1. Although the mass flowmeter has no requirements for the pipes before and after the flowmeter during construction and installation, some details should be paid attention to during the installation process;

2. It is necessary to ensure that the front and back process flanges of the flowmeter are welded concentrically, so as to eliminate the additional torque caused by the flanges not being concentric during the installation process, and reduce the use error of the mass flowmeter;

3. Also pay attention to some supporting construction process, especially the influence of eccentric torsion and additional stress on the operation of the flowmeter during the laying of heating wire;

4. Although the mass flowmeter measures the tube inside the shell, the external stress can still generate additional errors that cannot be measured, such as the fixed wire with hot wire in the figure, and deformation caused by the influence of temperature during recovery operation, resulting in a random change of stress superposition;

5. The laying of the heating wire should also be separated from the mass flow meter to prevent the asymmetric stress caused by the thermal expansion of the heating wire and the excessive conductive heat from affecting the medium temperature detection of the mass flow meter.

The above information is provided by flow instrument factory.

Common Failures and Maintenance of Mass Flow Meters

 In liquid chemical production such as petroleum refining, the incoming and outgoing materials of the device are mainly steam, gas energy, and liquid raw materials and products. These materials require high-precision metering instruments. Therefore, the production workshop has very strict requirements on the metering instruments for the incoming and outgoing materials of the device. .

Common failures and analysis of mass flow meters

Failures in the use of mass flowmeters are generally divided into measurement failures caused by process reasons and failures caused by damage to the flowmeter itself.

Measurement faults caused by process reasons:

The most common is the phenomenon of two-phase flow in the measured fluid. Specific to the measurement of liquid, the main reason is that the measured liquid is not filled with the flow meter measuring tube or the upper part of the measuring tube accumulated gas, or solid impurities enter the measuring tube to be stuck in the main body, which causes the mass flowmeter to alarm.

Treatment method: Ensure that the fluid measured by the mass flow meter is one-way flow by changing the installation method of the exhaust gas, and take measures to remove the solid impurities in the measuring tube.

Damage to the mass flowmeter itself causes flowmeter failure:

The most common faults in use are water in the flow meter junction box or loose wiring that causes short circuits and signal loss.

Treatment method: In addition to strictly standardizing on-site installation, daily detailed inspection and maintenance are also required to prevent more serious failures such as the sensor coil burned out due to untimely handling.

The transmitter circuit board is damaged. The most common fault is the damage of the transmitter's power supply board and signal processing output board.

Solution: In addition to strictly standardizing the cable signal wiring, it is also necessary to take measures to prevent lightning and grounding. Use an independent stabilized power supply to ensure the reliability of the power supply and prevent large fluctuations in the power supply voltage from burning the device.

Maintenance of mass flowmeter

As long as you pay attention to some details during the installation process, the mass flowmeter is almost maintenance-free after it is put into operation, and the probability of failure is very small. As long as it is ensured that the medium is not in a two-phase flow state during the flow process, stable operation can be achieved.

Perform some simple settings during the first commissioning of the mass flowmeter, such as the form of the output signal, the various coefficients of the flowmeter itself, the density of the medium in use, the upper and lower temperature limits, etc., basically before commissioning No need to change after setting.

The above information is provided by flow instrument manufacturer.