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2 Mag Flow Meter Sizing for Two Inch Conductive Liquid Electromagnetic Spools
Quick Answer: A two inch Silver Instruments electromagnetic flow meter is a DN50 spool piece built for conductive liquids with a conductivity of 5 µS/cm or higher. You need to match the liner, electrode material, flow range, pressure rating, and ground connection to the application. Send us your liquid type, flow range, pressure, and temperature to get a DN50 model and price.
Two Inch Spool Means DN50
In pipe size, 2 inch equals DN50. The electromagnetic flow meter spool uses the same inside diameter as the process pipe. Most two inch flanged spools have face-to-face length around 200 mm. Flange options include ANSI 150, ANSI 300, PN16, and PN40. Because the flow tube has no moving parts, pressure drop is almost zero for a straight DN50 run.
Conductive Liquid Rules
Magnetic flow meters need conductive liquid to generate a signal. Silver Automation Instruments standard two inch meters work with liquids at 5 µS/cm or more. Some low cost units need 20 µS/cm. Water, wastewater, acids, caustic, and slurries are fine. Deionized water, oils, and hydrocarbons are not measurable because their conductivity is too low.
Here is the thing. Many engineers check only pipe size and forget the conductivity value. We have seen a condensate line in Malaysia with 2 µS/cm water. The reading drifted and would not stabilize. The plant changed to a different meter principle for that line.
Liner and Electrode Selection for DN50
Liner material matters for chemical resistance and temperature. Hard rubber liner handles water, wastewater, and mild slurries from 0 to 80 °C. PTFE liner handles acids, alkalis, and solvents from -20 to 120 °C. PFA liner extends temperature up to 180 °C for aggressive chemicals. Electrode material also depends on the fluid. 316L works for potable water and cooling water. Hastelloy C suits acidic streams. Titanium is standard for seawater and brine. Tantalum handles strong acids.
In practice, a desalination plant in Oman operates DN50 spools with PTFE liners and titanium electrodes on seawater. A paint manufacturer in Indonesia uses 316L electrodes with PTFE liner for water based paint. Both cases run stable because the liquid conductivity is above 500 µS/cm.
Grounding rings or a grounding electrode are required when the process pipe is plastic, lined, or protected by cathodic protection. Without a good ground, the signal can be noisy.
Flow Range and Sizing for Two Inch
DN50 is not just a pipe size. You need to check flow velocity. For a two inch tube, the cross section is about 0.00196 m². At 0.5 m/s, flow is about 1.8 m³/h. At 1 m/s, flow is about 7 m³/h. At 5 m/s, flow is about 35 m³/h. At 10 m/s, flow is about 70 m³/h. Most liquid applications run best between 0.5 and 5 m/s.
Most engineers skip this part. They select DN50 because the pipe is DN50. If your normal flow is 0.4 m³/h, the meter will be oversized and accuracy may drop. If your flow is 80 m³/h, pressure drop may climb and you should consider DN80. We have seen a food batching line in Thailand with 3 m³/h on a DN50 spool. That gave about 0.43 m/s. The meter performed well because the flow was steady and the pipe stayed full.
>Installation Notes for Two Inch Mag Spools
The tube must stay full of liquid. Do not install a magnetic flow meter at the highest point or in a free falling discharge line. Mount the spool in a low point or in a vertical pipe with upward flow. Keep the meter away from pump suction. Air bubbles cause unstable readings. Straight run is also necessary. Five diameters upstream and two diameters downstream is enough for many clean water lines. After a pump, elbow, or valve, use ten diameters upstream for stable signal.
Keep the signal cable away from VFD cables and high power lines. Use shielded twisted pair cable for remote installations. Grounding must follow the installation drawing.
Output and Power Options
Silver Instruments electromagnetic flow meters can be ordered with 4-20 mA HART, pulse, or RS485 Modbus output. Standard power is 24 VDC. Optional power is 85 to 265 VAC. Sensor protection can be IP67 or IP68 for flooded pits. Accuracy is typically 0.5% of reading. Some clean water applications can specify 0.2% of reading. For batching, the pulse output connects to a PLC. For remote monitoring, 4-20 mA HART works with most control systems.
Typical Model for a Vietnam Wastewater Plant
Last year a customer in Vietnam needed a two inch electromagnetic flow meter for raw wastewater at a small treatment plant. Average flow was 22 m³/h, pressure 3 bar, temperature 30 °C, conductivity about 900 µS/cm. We supplied a DN50 spool with hard rubber liner, 316L electrodes, PN16 flanges, 4-20 mA HART, and IP67 enclosure. The meter has run without maintenance since installation.
FAQ
What is the minimum conductivity for a two inch magnetic flow meter?
Most Silver Instruments standard DN50 meters need 5 µS/cm or more. Budget models may need 20 µS/cm. Check the datasheet before ordering.
Can a two inch electromagnetic flow meter measure deionized water?
No. Deionized water conductivity is usually below 1 µS/cm. A standard magnetic flow meter cannot produce a stable signal. Choose another principle for deionized water or ultra pure water.
Which liner and electrode are best for seawater in a DN50 pipe?
Use a hard rubber or PTFE liner with titanium electrodes. 316L can pit in seawater over time. Grounding rings are also required if the pipe is non conductive.
How much straight run does a DN50 electromagnetic flow meter need?
Five diameters upstream and two diameters downstream is enough for many applications. After a pump or elbow, use ten diameters upstream for stable readings.
What flow range can a two inch magnetic flow meter handle?
In water service, about 2 to 70 m³/h depending on velocity. Normal design range is often 5 to 40 m³/h. If your flow is below 1 m³/h, consider DN25 or DN15.
For a two inch electromagnetic flow meter price, send your fluid type, conductivity, flow range, pressure, temperature, and pipe specification to Silver Automation Instruments. Tel: +86-25-68650347, Whatsapp: +86-25-52155837, WeChat: +86 15365082610. You can find technical data at flow-meter.com.au and silverinstruments.com. Our application engineers will reply with a model recommendation and quote within one working day.