There should be a straight pipe section with a length greater than 5 times the pipe diameter at the entrance of the flowmeter, and a straight pipe section with a length of 250 mm at the exit.
The metal tube float flowmeter should be provided with a bypass, which is convenient for troubleshooting and does not affect production during purging;
The medium contains solid impurities, so a filter should be installed between the valve and the straight pipe section;
If the medium contains ferromagnetic substances, a magnetic filter should be installed;
When the measured medium temperature is higher than 220℃ or the fluid temperature is too low, it is easy to crystallize. When thermal insulation protection measures are needed, the jacket type for cooling or thermal insulation should be selected.
When used for gas measurement, ensure that the pipeline pressure is not less than 5 times of the pressure loss of the flowmeter, so that the float can work stably;
The standards of pipeline flanges, fasteners and gaskets are the same as those of flowmeter flanges, so that the instrument can be installed and operated normally;
Generally, the flowmeter does not need maintenance after the normal operation of the device, and the faults mostly occur when the device is just started. Because the pipeline was not cleaned, the float was stuck by solid particles, and the indicator pointer stopped at one position. At this time, the valves on both sides of the flowmeter should be closed first, then the upper flange should be removed, the float should be taken out for cleaning, and then reinstalled. Pay attention to the balanced tightening of the hexagon nut with flange and pad the washer;
In order to avoid the deformation of flowmeter caused by pipeline, the flange of process pipeline must be coaxial and parallel to the flange of flowmeter, and the pipeline should be properly supported to avoid pipeline vibration and reduce the axial load of flowmeter. The control valve in the measuring system shall be installed downstream of the flowmeter:
The instrument for measuring gas is calibrated at a specific pressure. If the gas is directly discharged into the atmosphere at the instrument outlet, it will produce pressure drop at the float, resulting in data distortion. If this is the case, a valve should be installed at the instrument outlet;
Because the instrument transmits signals through magnetic coupling, in order to ensure the performance of the instrument, ferromagnetic substances are not allowed to exist at least 10cm around the installation; When installing instruments with LCD, try to avoid direct sunlight on the display, so as not to reduce the service life of LCD.
When installing instruments powered by lithium batteries, direct sunlight and high temperature environment (≥65℃) should be avoided as far as possible to avoid reducing the capacity and life of lithium batteries.
Metal tube float flowmeter should be especially careful when installing PTFE-lined instruments. Due to the deformation of PTFE under uneven pressure, the hexagonal nut with flange is tightened evenly and symmetrically;
Treatment method of pointer blockage of metal tube float flowmeter
One: The pointer is stuck.
When the metal tube float flowmeter is used for the first time, the valve is opened too fast, so that the float quickly touches the plug, causing the plug to deform and jam the float. However, it does not rule out that the float is stuck because the float guide rod is not concentric with the stop ring. When handling, you can take out the instrument, take out the deformed stopper for shaping, and check whether it is concentric with the guide rod. If you don't agree, you can correct it. Then, install the float, push it by hand, and feel the float go up and down smoothly. In addition, when installing the metal tube float flowmeter, it must be installed vertically or horizontally, and it cannot be tilted, otherwise it will easily cause meter jamming and bring errors to the measurement.
Second, the pointer jitter:
1. Slight jitter of metal tube float flowmeter pointer: generally caused by medium fluctuation. It can be overcome by increasing damping.
2. Moderate pointer jitter: generally caused by the flowing state of the medium. For gas, it is generally caused by the unstable working pressure of the medium. Pressure stabilizing or flow stabilizing devices can be used to overcome or increase the air damping of the float flowmeter.
3. The pointer jitter is serious: the over-range of the float flowmeter is mainly due to medium pulsation, unstable air pressure or the pressure, temperature and flow rate of the gas operation state given by the user are different from the actual state of the metal tube float flowmeter.