Electromagnetic Flow Meters - Complete Selection Guide
Dirksen DKS-EMF Series intelligent electromagnetic flow meters (magmeters) operate on Faraday Law of electromagnetic induction for precise conductive liquid flow measurement. Full range DN10~DN3000. Suitable for chemical, power, water treatment, food and pharma, pulp and paper, and oil and gas industries worldwide.
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1. Working Principle
Electromagnetic flow meters are based on Faraday Law of Electromagnetic Induction: when conductive liquid flows through a magnetic field, it generates induced voltage proportional to flow velocity. Formula: E = kBVD. Key advantages: no pressure loss, wide turndown ratio (1:20), fast response, high accuracy.
2. Technical Specifications
| Parameter | Specification | Notes |
|---|
| Nominal Diameter | DN10~DN3000 | Custom sizes available |
| Accuracy | 0.5% (std) / 0.2% (opt) | JJG 1033-2007 |
| Liner Material | PTFE / PFA / Neoprene / Polyurethane | See selection table |
| Electrode Material | 316L / HC / HB / Ti / Ta / Pt | See selection table |
| Min. Conductivity | 5 uS/cm (20 for remote) | |
| Output Signal | 4-20mA + HART + RS485 + Pulse | Profibus-DP optional |
| Power Supply | 220VAC / 24VDC | Battery optional |
| Protection Rating | IP65 / IP68 | Remote sensor IP68 rated |
| Media Temperature | -25~180 deg C | Liner dependent |
| Working Pressure | PN0.6~PN4.0MPa | Size dependent |
| Mounting Type | Integral / Remote / Insertion | |
| Communication | HART, Modbus RTU, Profibus-DP | DCS/PLC/SCADA ready |
3. Liner Selection Guide
| Liner | Suitable Media | Temp | Application |
|---|
| PTFE (Teflon) | Strong acids/bases, solvents, high temp | -40~180C | Chemical, H2SO4/HCl/NaOH |
| PFA | High-purity, food-grade | -40~180C | Pharma CIP, food, ultrapure water |
| Neoprene | Water, wastewater, seawater | -25~80C | Municipal water, WWTP |
| Polyurethane | Slurries, pulps, particle-laden | -25~80C | Paper pulp, mining slurry |
4. Electrode Selection Guide
| Electrode | Suitable Media | Corrosion |
|---|
| 316L SS | Water, wastewater, weak acids/bases | General |
| Hastelloy B (HC) | HCl, HF, non-oxidizing acids | Strong |
| Hastelloy C (HB) | HNO3, H2SO4, H3PO4 | Strong |
| Titanium (Ti) | Chlorides, seawater, brine | Very Strong |
| Tantalum (Ta) | Conc. HCl, conc. H2SO4 | Excellent |
| Pt-Ir Alloy | Almost all acids/bases/salts | Excellent |
5. Product Models
| Model | Type | Application |
|---|
| DKS-EMF-I | Integral EMF | Normal conditions |
| DKS-EMF-R | Remote EMF | High temp, IP68, EMI |
| DKS-EMF-INS | Insertion EMF | Large pipes >DN800 |
| DKS-EMF-S | Sanitary EMF | Food/pharma CIP/SIP |
| DKS-EMF-B | Battery EMF | Remote sites, irrigation |
| DKS-EMF-EX | Ex-proof EMF | Hazardous areas |
6. Industry Applications
Chemical
H2SO4, HCl, NaOH, solvents. Recommend: Ta + PTFE/PFA
Water Treatment
Water supply, wastewater, reuse. Neoprene + 316L
Food and Pharma
CIP cleaning, batching, sanitary piping. PFA + 316L
Pulp and Paper
Pulp stock, black liquor, white water. Polyurethane + 316L/HC
Mining and Metals
Slurry transport, reagent dosing. Polyurethane + HC/HB
Power Generation
FGD slurry, cooling water, boiler feed. Neoprene + 316L
7. Installation Requirements
Key Points:
1. Sensor must be in full pipe - vertical mount (flow upward) or pipe lowest point
2. Straight pipe: upstream >= 10DN, downstream >= 5DN. With disturbance: upstream >= 20DN
3. Proper grounding: sensor ground <= 10 Ohm, converter separately grounded
4. Avoid installation near pumps, valves, elbows
5. Remote signal cable in metal conduit, separate from power cables
6. Keep away from large motors, VFDs, welders (EMI sources)
8. Frequently Asked Questions
Q1: What fluids can EMFs measure?
Only conductive liquids (conductivity >= 5 uS/cm). Industrial aqueous solutions, acids, bases, salt solutions. NOT for pure water, oils or gases.
Q2: Integral vs remote type?
Integral: normal temp/pressure, easy access. Remote: high temp (>60C), submerged IP68, strong EMI, hard-to-reach. Max cable 100m.
Q3: Straight pipe requirements?
Standard: upstream >= 10DN, downstream >= 5DN. With disturbance: upstream >= 20DN. Space-constrained: >= 5DN.
Q4: EMF vs Vortex?
EMF: high accuracy (0.5%) for liquids, zero pressure loss, DN10~3000. Vortex: measures gas/steam/liquid, has pressure loss. Liquids = EMF, steam/gas = Vortex.
Q5: Must pipe be completely full?
Yes. Non-full pipe causes electrodes to lose liquid contact. Install vertically (upward flow) or use ultrasonic meter if full pipe is impossible.
Q6: How often to calibrate?
Every 1-2 years recommended. Factory calibration certificate included. On-site verification via portable ultrasonic meter.
Q7: Why is grounding critical?
EMF measures microvolt signals susceptible to EMI. Grounding (<= 10 Ohm) suppresses common-mode interference. Non-metallic/lined pipes need grounding rings.
Q8: Insertion-type accuracy?
Typically 1.0~2.5% (vs 0.5% full-bore). Ideal for large pipes (>DN800) with hot-tap installation and significant cost savings.
9. Information for Quotation
Please provide:
1. Fluid name and concentration
2. Temperature (deg C) and pressure (MPa)
3. Pipe diameter (DN)
4. Flow range (normal/max/min)
5. Mounting: integral or remote?
6. Hazardous area classification?
7. Power supply: 220VAC or 24VDC?
8. Output signals? (4-20mA / RS485 / HART / Pulse)
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