Commonly asked questions about Magnetic Flow Meters.
Insertion Magmeters
Insertion type meters offered by Omega have a standard 2 NPT or fit into a specific size fitting. The FMG-550 Series are designed for 2” to 48” in size with a flow rate of 0.05 to 10 m/sec (0.15 to 33 ft/sec). The FMG-550 Series offers an analog output with an integral display for flow rate and totalization. The FMG3000 series offers corrosion resistant materials for pipes from 0.5 to 8”. These insertion type flow meters are ideal for large pipe applications.
Minimum Conductivity
5 to 20 microSiemens/cm
Installation Considerations
Select a location for the sensor where the flow profile is fully developed and not affected by any disturbances. A minimum of 10 pipe diameters of straight run upstream and 5 diameters downstream is recommended. Some situations may require 20 pipe diameters or more upstream to ensure a fully developed turbulent flow profile. The insertion magmeter is sensitive to air bubbles at the electrodes. If there is any question that the pipe is absolutely full, mount the sensor at a 45 to 135 degree angle.
Grounding Requirements
For many years, sensors used in high-reliability applications, such as those used in aerospace and military applications, relied upon connectors such as the Mil-C-5015 or MIL-C-38999 connectors that provided high reliability and secure connections but at a high price. With the expanded use of industrial automation systems, however, the number of sensors used have increased dramatically, driving the need for a reliable, cost effective connection system for these sensors.
In-Line Magmeters
The In-Line type magnetic flow meters offer a higher accuracy. They can be as accurate as 0.5% of the flow rate. The insertion styles offer a 0.5 to 1% accuracy. OMEGA’s FMG-600 series In-Line flange and wafer style meters offer higher flow rates of 1 to 10 m/sec. These In-Line meters are offered in pipe sizes up to 12”.
Installation Considerations
In-Line flow meters do not require as much straight pipe as the insertion styles. A minimum of 5 to 10 pipe diameters of straight run upstream and 1 to 2 diameters downstream is recommended. In vertical pipe runs, flow should always run up and not down. These flow meters are very sensitive to air bubbles. The magmeter cannot distinguish entrained air from the process fluid; therefore, air bubbles will cause the magmeter to read high.
Low Flow Magmeters
These low flow mag flow meters are also In-Line and offer 3/8 to ½ NPT connections. The FMG200 series offer flow rates down to 0.38 LPM (.1 GPM). A digital display with relay and analog outputs are standard.
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