Selection and installation considerations for metal tube float flowmeters

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1. High-temperature resistant, capable of reaching 450°C; metal tube float flow meter, Wilo flow meter. 2. Suitable for measuring the flow rates of gases, liquids, and steam with small diameters and low flow velocities. 3. Magnetic coupling principle: leak-free and high-pressure resistant. 4. Affected by a certain viscosity, it is not suitable for measuring high-viscosity media. 5. When the flow rate exceeds 100 m3/h, the pressure loss is high. 6. It is mainly used in instruments for process control; the desired accuracy is 1%, with 1.5% being typical, and the range ratio is 10:1. 7. Both intrinsically safe and flameproof types are available, suitable for hazardous environments. 8. The most suitable installation method is vertical installation with inlet at the bottom and outlet at the top. 9. There are various options available, including local pointer type, battery-powered type, two-wire type, and 220V AC powered type. 10. When measuring media at high and low temperatures (below -30°C), a jacketed type is preferred. 11. Not suitable for measuring media with large density changes. 12. Not suitable for measuring the flow rate of pulsating media (such as at the outlet of a metering pump). 13. For gases, there is no temperature and pressure compensation in this table, which requires separate consideration. 14. When multiple instruments are installed closely together, or when carbon steel process pipelines pass near the instruments, a distance of at least 100 mm should be maintained from the instruments to avoid magnetic field interference. 15. When measuring the flow rate of media containing a large number of ferromagnetic particles, a magnetic filter should be installed in front of the instrument, and it should be purged regularly. 16. If instruments are to be used in explosion-proof environments, round-shell M4 indicators should be selected. 17. Metal tube rotameters do not have high requirements regarding straight pipe sections; generally, 5D in front and 250 mm behind is sufficient. 18. The high and low flow alarms for flowmeters are generally implemented using an open-collector OC circuit; a relay is required to amplify the current. A relay-output type is also available, with contact ratings of 1A@30VDC or 0.25A@250VAC. Metal tube rotameters are being used more and more widely.