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Quick Answer: Mag flow meters measure conductive liquid volume without moving parts or inline obstruction. Silver Automation Instruments supplies these meters for water, wastewater, chemicals, food, and marine lines from DN15 to DN3000. Send your pipe size, flow range, fluid conductivity, temperature, and pressure for a matched model and price.
Mag flow meters rely on electromagnetic induction. The flow tube generates a magnetic field. Two electrodes measure the voltage created by the moving conductive fluid. That voltage is proportional to volumetric flow. There is no orifice, no gear, and no turbine inside the pipe. This is why engineers call it an obstructionless electromagnetic volumetric measurement method.
In practice, the meter works best with water, acids, slurries, and any fluid with conductivity above 5 µS/cm. Oils, solvents, deionized water, and most gases do not work with this technology. So we ask about conductivity early in the selection process. It saves time and avoids a wrong quote.
Magflow elements are the parts that make the measurement repeatable. The key elements are the flow tube, liner, electrodes, excitation coils, and the transmitter. The flow tube can be carbon steel or stainless steel. The liner protects the tube from corrosion. Common liner materials are PTFE, hard rubber, and polyurethane. Electrodes pick up the induced voltage. Electrode materials include 316L stainless steel, Hastelloy C, titanium, tantalum, and platinum iridium.
The excitation coils create the magnetic field. The transmitter converts the electrode signal into a 4-20 mA HART output, a pulse output, or a Modbus RTU signal. Most engineers skip this part during initial sizing. But the liner and electrode material selection decides the meter life in aggressive fluids. We have seen this on customer sites many times. A cheap natural rubber liner fails fast in hot caustic, while PTFE works fine up to 150 °C.
A desalination plant in Saudi Arabia uses DN500 rubber lined mag flow meters on the seawater feed line. The meters run at 2.1 m/s and send 4-20 mA signals to the control room. There is no pressure drop across the meter. For reverse osmosis brine, the plant uses Hastelloy C electrodes and PTFE liners. Brine conductivity is above 50,000 µS/cm, so signal strength is excellent.
A water treatment contractor in Surabaya, Indonesia installed DN300 mag flow meters for raw water intake. The specification was simple. Accuracy is 0.5 percent of reading. Electrodes are 316L. Liner is hard rubber. The transmitter is remote mounted with IP68 protection. The line pressure was 6 bar. The meter body had no moving parts. Maintenance was limited to annual electrode cleaning.
For chemical dosing in a paint plant in Binh Duong, Vietnam, we supplied DN15 and DN25 mag flow meters with PTFE liners and tantalum electrodes. The fluid was a water based titanium dioxide slurry. Flow range was 0.3 to 3.0 m/s. The customer wanted a fast batch pulse output. We configured the transmitter for 100 pulses per liter. That made batching easy for the PLC.
Silver Instruments offers two common mag flow configurations. The SA-MAG 2100 is a compact electromagnetic flow meter for water, wastewater, and utility lines. It suits DN15 to DN600. Accuracy is 0.5 percent of rate. Liner options include hard rubber and PTFE. Electrode options include 316L and Hastelloy C. Process temperature can reach 120 °C for hard rubber and 180 °C for PTFE.
The SA-MAG 4100 is a remote transmitter model for harsh or hard to reach installations. It covers DN15 to DN3000. It supports 4-20 mA HART, pulse, RS485 Modbus, and optional Profibus DP. The remote version works well for buried water mains, hot chemical lines, and ATEX Zone 1 areas. For seawater, choose PTFE or polyurethane liner with Hastelloy C or titanium electrodes. For food grade, choose PTFE liner with stainless steel sanitary connections.
Mag flow meters need a full pipe. Mount the sensor in a location where the pipe always stays flooded. For horizontal lines, do not install the meter at the top of a high point where air can collect. For DN50 and smaller, a straight run of 5 diameters upstream and 3 diameters downstream is enough. For larger meters, 10 diameters upstream gives better profile stability. Use grounding rings when the liner is PTFE or when the pipe is non conductive.
Most procurement delays come from missing fluid data. When you send an inquiry, include pipe size in DN, flow range in m3/h or L/h, fluid name, conductivity, process temperature, pressure, and output signal. For example, a customer in Chile sent us one line. DN80, clean water, 10 to 60 m3/h, 20 °C, 4 bar, 4-20 mA HART. We quoted the same day with a delivery date to Santiago.
For pricing and delivery, contact Silver Automation Instruments. Tel: +86-25-68650347. WhatsApp: +86-25-52155837. WeChat: +86 15365082610. You can also visit flow-meter.com.au for the full electromagnetic flow meter range.
Q: What is the minimum conductivity for a mag flow meter?
A: Most Silver Instruments mag flow meters need at least 5 µS/cm. Some high end transmitters can read down to 1 µS/cm, but the signal becomes sensitive to cable noise. For raw industrial water, conductivity is rarely a problem.
Q: Does a mag flow meter create pressure drop?
A: No. The flow tube is the same diameter as the pipe. There is no obstruction. Pressure loss equals the friction of a straight pipe section of similar length.
Q: Can a mag flow meter measure sludge or slurry?
A: Yes. Hard rubber and polyurethane liners handle abrasive slurries. Use 316L or tungsten carbide electrodes for abrasive service. Avoid gas slugs because the meter reads only the conductive liquid phase.
Q: Which liner is best for a seawater flow meter for desalination plant duty?
A: PTFE or polyurethane with Hastelloy C or titanium electrodes. A seawater flow meter for desalination plant duty must resist chlorides. PTFE handles cleaning chemicals. Titanium electrodes resist seawater corrosion well. For brine, Hastelloy C is often more cost effective.
Q: What output signals can I get from these meters?
A: Standard outputs include 4-20 mA HART, pulse, and RS485 Modbus. Optional Profibus DP and Foundation Fieldbus are available for the SA-MAG 4100. Tell us which PLC or RTU you are using. We set the output at the factory.
Send us your pipe size in DN, flow range in m3/h, fluid conductivity in µS/cm, temperature in °C, and pressure in bar. We will return a specific model, liner, electrode, and price within one business day.
