Metal tube float flowmeter is also known as metal rotor flowmeter. Widely used for measuring small and medium flow rates and micro flow rates. The measuring medium is generally relatively clean and difficult to crystallize and solidify. The viscosity of liquids, gases, and vapors is low, and it is necessary to slowly change the flow rate of the medium. The correct installation of the instrument is the foundation for ensuring its subsequent stable operation. The correctness of instrument installation is an important indicator for technical personnel testing instrument installation. Introduce to friends the following factors that should be noted when installing metal tube float flow meters in response to various influencing factors encountered during installation:
Installation of metal tube float flowmeter.
1、 Instrument installation direction.
Most float flow meters must be installed vertically on non vibrating pipelines without significant inclination. The fluid flows through the instrument from the bottom to the top, which is said to be an example of a pipeline connection, with a bypass pipeline used for continuous flow maintenance. The angle between the centerline of the float flowmeter and the plumb line is generally not greater than 5 degrees, and high-precision instruments (above level 1.5)θ Up to 20 degrees. If θ = 12, will result in an additional error of 1%. There is no strict length requirement for the upstream straight pipe section of the instrument, but the manufacturer also requires (2-5) size length, which is not actually required.
Secondly, for dirty fluids.
The filter should be installed upstream of the instrument. When a metal tube float flowmeter with magnetic coupling is used for fluids that may contain iron and magnetic impurities, a magnetic filter should be installed in front of the flowmeter.
Floats and cones should be kept clean, especially for small diameter instruments. The cleanliness of the float will significantly affect the measured values. For example, a glass float flowmeter with a diameter of 6mm looks like clean water when measured in the laboratory. The flow rate is 2.5 liters per hour. After running for 24 hours, the traffic indicator increased by several percentage points. There are foreign objects on the surface of the float that cannot be observed by the naked eye. Remove the float and wipe it with gauze to restore the original flow indicator value. If necessary, a flushing pipe can be arranged as shown in Figure 7 for routine flushing.
Thirdly, install pulsating flow.
Used for pulsating flow itself, if there is a reciprocating pump or regulating valve upstream of the instrument installation location, or there is a significant load change downstream. Changing the measurement position or repairing and improving the pipeline system, such as installing buffer tanks; If the instrument itself oscillates, such as when the air pressure is too low during measurement, the upstream valve of the instrument is not fully opened, and the regulating valve is not installed downstream of the instrument. Targeted improvements should be made to overcome or select instruments with damping devices.
Fourthly, expand the installation scope.
If the required flow range for measurement is very wide, exceeding 10, usually two or more glass tube float flowmeters with different flow ranges will be connected in parallel. Select one or more series instruments based on the measurement results. The values of low flow range instruments are read at low flow rates, while the values of high flow instruments are read at high flow rates. The series method is simpler than the parallel method. The valve does not need to open and close frequently, but the pressure loss is large. Two floats of different shapes and weights can be placed within one meter. When the flow rate is low, a float reading can be obtained. When the float reaches the top, a larger float reading can be obtained. The range can be expanded to 50-100.
Angular metal float flow meters with inlet and outlet not in a straight line should be completely emptied. When used for liquids, attention should be paid to whether air remains in the extended sleeve, so that the float can be discharged outward and must be completely discharged. If the liquid contains small bubbles that can easily accumulate in the casing during flow, it should be discharged regularly. This is more important for small caliber instruments, otherwise the flow indication will be significantly affected.
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