Yokogawa Magnetic Flow Meter Selection Guide
Selecting a magnetic flow meter is not simply a matter of matching the pipe diameter to a product catalog. Electromagnetic flow measurement depends on the electrical and physical properties of the liquid, the expected velocity range, the materials in contact with the process, installation conditions and the accuracy or diagnostic capability required by the plant. Yokogawa’s ADMAG family covers applications from small process lines to very large water pipelines, but the correct configuration should be selected from the process data rather than from a model name alone. This guide explains the practical engineering questions to answer before choosing a Yokogawa magnetic flowmeter and shows where ADMAG AXG and AXW fit within the selection process.
SELECTION GUIDE
Request Yokogawa Magnetic Flowmeter Selection Support
01 TECHNOLOGY FIT
When Is a Magnetic Flow Meter the Right Technology?
A magnetic flowmeter uses Faraday’s law to determine volumetric flow as a conductive liquid passes through a magnetic field. Because the measurement does not require a mechanical obstruction in the flow path, magnetic meters are widely used for water, wastewater, corrosive liquids and many slurry or process applications. They are not the correct choice for gases, steam or non-conductive liquids such as many hydrocarbons. Conductivity must also meet the requirement of the selected meter, and that requirement can vary by model and size. This is why conductivity should be checked rather than assumed from the fluid name alone.
Magnetic measurement is especially attractive when pressure loss must be minimized, when the liquid contains solids, or when there is a need to avoid moving parts in contact with the process. However, a magmeter still needs a full pipe and a sound installation. Entrained gas, an empty pipe, poor grounding, severe coating, incorrect liner selection or a velocity range that is badly matched to the meter size can all affect measurement quality.
SUITABLE
Water, wastewater, corrosive liquids, conductive slurries, solids-bearing streams
NOT SUITABLE
Gases, steam, non-conductive liquids such as many hydrocarbons
02 SELECTION INPUTS
Key Information Required Before Selecting a Magnetic Flowmeter
Send your process dataProcess Medium and Conductivity
Start with the exact medium, not a generic description such as ‘water’ or ‘chemical’. Is it drinking water, demineralized water, brine, wastewater, acid, caustic, pulp stock or a mineral slurry? Does the composition change? What is the minimum expected conductivity? The answer determines whether electromagnetic measurement is suitable and influences electrode and liner selection. Yokogawa also provides diagnostic functions on ADMAG Total Insight products that can help identify conditions such as low conductivity, flow noise, electrode adhesion, empty pipe or wiring issues, depending on the configuration.
Pipe Size, Flow Range and Velocity
The line size should not automatically become the meter size. The min/normal/max flow must be checked against the useful velocity range so the meter performs well during normal operation and still covers turndown conditions. Oversizing can create very low velocity at minimum flow, while unnecessary downsizing increases velocity and may affect pressure, abrasion or installation. Yokogawa positions ADMAG AXG from 2.5 to 500 mm and AXW from 25 to 1,800 mm, so the size requirement is one of the first factors that separates the two families.
Liner and Electrode Materials
The liner isolates the meter body from the process, while the electrodes are directly exposed to the liquid. Both must be compatible with the fluid, temperature and abrasion level. AXG uses ceramic or PFA lining options and supports a broad choice of electrode materials for demanding process applications. AXW uses PTFE and rubber-based liner options and is positioned strongly for general industrial, water and wastewater duties, including very large line sizes. Material selection should be based on chemical compatibility and operating conditions rather than price alone.
Pressure, Temperature and Process Connection
Normal and design pressure and temperature affect the allowable meter construction, liner, flange rating and installation. The specification should also define the required process connection and applicable piping standard. If the installation is in a hazardous area, the relevant protection approval must be confirmed for the exact model and market. Remote or integral transmitter arrangements should be considered according to access, ambient conditions and maintenance requirements.
Accuracy, Diagnostics and Communication
Yokogawa lists standard ADMAG AXG accuracy at ±0.3% of rate, with high-accuracy AXG configurations available down to ±0.15% for applicable sizes; AXW is listed at ±0.35% of rate. The specification should use the accuracy actually required by the application rather than automatically selecting the highest option. Communication is another design decision: ADMAG Total Insight supports industrial protocols such as HART, BRAIN, Modbus, FOUNDATION Fieldbus, PROFIBUS PA and, for applicable AXG configurations, EtherNet/IP. The required protocol should match the plant’s control and asset-management architecture.
03 PRODUCT FAMILY
ADMAG AXG or AXW?
| SELECTION FACTOR | ADMAG AXG | ADMAG AXW |
|---|---|---|
| Typical positioning | Process industries; demanding chemical, slurry, food/beverage, metals/mining applications | General industrial, water and wastewater; large pipelines |
| Nominal size range | 2.5 to 500 mm | 25 to 1,800 mm |
| Typical liner families | Ceramic, PFA | PTFE, polyurethane rubber, natural hard/soft rubber |
| Published standard accuracy | ±0.3% of rate; high-accuracy option available for applicable sizes | ±0.35% of rate |
| Strong selection driver | Process performance, material options, diagnostics, smaller process sizes | Large diameters and water/general industrial applications |
The table is a starting point, not an automatic model-selection rule. An AXW can be the better engineering choice even when an AXG size exists, and an AXG can be preferable where a more demanding process, material requirement or diagnostic need justifies it. For detailed AXG product information, see Tomarok’s ADMAG AXG page. When the main question is whether magnetic technology is appropriate at all, compare it with ROTAMASS Coriolis and Yokogawa vortex flowmeters before finalizing the specification.
04 ALTERNATIVES
When Should You Consider Another Flow Technology?
A magnetic flowmeter should not be forced into an application simply because it has low pressure loss and no moving parts. If the fluid is non-conductive, magnetic measurement is not appropriate. If the process requires direct mass flow and density, ROTAMASS Coriolis may offer a more direct measurement. If the service is steam or a suitable gas, Yokogawa vortex flowmeters are usually more relevant. A good selection process therefore begins with the fluid and measurement objective, then chooses the measurement principle, and only then selects the product family and model.
05 CHECKLIST
Magnetic Flowmeter Selection Checklist
Fourteen data points that let Tomarok narrow the measurement principle and configuration before quotation.
- Measured liquid and full composition
- Minimum expected conductivity
- Min/normal/max flow rate
- Pipe size and schedule
- Normal and design pressure
- Normal and design temperature
- Solids, abrasion, coating or entrained-gas conditions
- Required wetted materials, liner and electrodes
- Process connection and flange standard
- Required accuracy and turndown
- Hazardous-area classification and certificates
- Output signal and communication protocol
- Integral or remote transmitter preference
- Existing model code and installation dimensions for replacement projects
Request Yokogawa Magnetic Flowmeter Selection Support
If you are comparing ADMAG AXG, AXW or another flow technology, send Tomarok the process data before requesting a final model. The most useful information is the medium, conductivity, flow range, line size, pressure, temperature, material requirements, area classification and required communication. Tomarok can use this information to narrow the suitable Yokogawa measurement principle and configuration and then link the recommendation to the relevant product documentation and quotation process.
