How to Prepare Magnetic flowmeters Data Sheets: Step-by-Step with Field-Wise Explanation

In the world of industrial instrumentation, magnetic flowmeters—commonly known as magmeters—are widely used for accurate and reliable flow measurement of conductive liquids. Whether you’re designing a new process system, troubleshooting an existing one, or replacing a failed flowmeter, understanding the instrument datasheet is crucial.

A well-prepared datasheet encapsulates everything about the magnetic flowmeter’s construction, application, performance specifications, installation requirements, and compatibility with your process. But for many, interpreting this document can be overwhelming.

This blog post is your complete guide to decoding a magnetic flowmeter datasheet, ideal for instrumentation engineers, designers, and procurement teams working in the oil & gas, chemical, water treatment, power, and food & beverage industries.

Table of Contents

  1. What is a Magnetic Flowmeter?
  2. Structure of a Magmeter Datasheet
  3. Key Parameters Explained
    • Tag Number and Service
    • Flow Range and Units
    • Pipe Size and Liner Material
    • Electrode Material
    • Accuracy and Repeatability
    • Process Pressure and Temperature
    • Conductivity Range
    • Output Signal and Protocol
    • Power Supply
    • Installation Configuration
    • Protection Class (IP/ NEMA Rating)
    • Hazardous Area Certification
    • Approvals and Standards
  4. Special Features and Accessories
  5. Practical Example: Sample Datasheet Breakdown
  6. Common Pitfalls and Tips
  7. Conclusion
  1. What is a Magnetic Flowmeter?

A magnetic flowmeter measures flow by using Faraday’s Law of Electromagnetic Induction. It works only for electrically conductive liquids (typically > 5 µS/cm), such as water, slurries, and corrosive chemicals.

Key Advantages:

  1. Structure of a Magmeter Datasheet

A typical datasheet is divided into the following sections:

Understanding each of these sections helps ensure proper specification, procurement, and operation.

  1. Key Parameters Explained
  2. Tag Number and Service

This identifies the instrument’s function in your plant.

👉 Tip: Ensure tag matches the P&ID and IO list.

  1. Flow Range and Units

Defined based on process needs. Typically given in:

Example:

👉 Note: The specified flow range should fall within the 0.2–10 m/s velocity range for optimum magmeter performance.

  1. Pipe Size and Liner Material

👉 Liner is critical for corrosion and abrasion resistance. PTFE is widely used for aggressive chemicals.

  1. Electrode Material

Common options:

👉 Match electrode with fluid chemical compatibility.

  1. Accuracy and Repeatability

Accuracy defines how close to the true value; repeatability defines the meter’s ability to produce consistent readings.

👉 Check if the accuracy includes or excludes zero stability.

  1. Process Pressure and Temperature

👉 Ensure compatibility with process line rating. Also, consider liner temperature limits.

  1. Conductivity Range

Minimum conductivity required:

👉 Deionized water, hydrocarbons, and gases are not measurable by magmeters.

  1. Output Signal and Protocol

👉 Choose based on DCS/PLC interface. HART is widely adopted.

  1. Power Supply

👉 Choose based on site power availability and safety.

  1. Installation Configuration

👉 Flow direction arrow must match the actual process flow.

  1. Protection Class (IP/NEMA Rating)

For outdoor and submersible installations, higher protection is essential.

  1. Hazardous Area Certification

For flammable/explosive environments:

👉 Ensure certification matches plant classification.

  1. Approvals and Standards

Check for:

👉 SIL compliance is critical in shutdown loops.

  1. Special Features and Accessories

Modern magmeters come with several value-adding features:

  1. Practical Example: Sample Datasheet Breakdown

Let’s consider a sample datasheet for a magmeter:

Parameter Specification
Tag No. FT-105
Service Treated Effluent
Line Size 6″ (150 mm)
Flow Range 20 – 600 m³/h
Accuracy ±0.5% of reading
Electrode Material Hastelloy C
Liner PTFE
Process Pressure 10 barg
Temp Range 0 – 100°C
Min Conductivity ≥ 20 µS/cm
Output 4-20 mA + HART
Mounting Flanged ANSI 150#
Enclosure Rating IP67
Certification ATEX II 2G Ex d IIC T4 Gb
Display Local display with keypad
Power Supply 24 VDC
Diagnostics Empty pipe, electrode coating

Analysis:

  1. Common Pitfalls and Tips
Pitfall Solution/Tip
Specifying for non-conductive liquids Magmeters need conductivity >5 µS/cm
Ignoring grounding requirements Always use grounding rings for insulated pipes
Wrong liner/electrode selection Cross-check with chemical compatibility chart
No straight run provision Ensure enough straight pipe to avoid flow distortion
Overestimating accuracy Check if zero stability is included
  1. Conclusion

A magnetic flowmeter is an excellent flow measurement solution—but only when correctly specified and applied. The datasheet is the bridge between process needs and instrumentation capability. As an engineer, your ability to decode the datasheet ensures:

Understanding the datasheet is not just about reading numbers—it’s about visualizing how the flowmeter will perform in the field. By applying the concepts discussed in this guide, you’ll gain confidence and precision in selecting the right magmeter for your application.

 

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