Requirements of Vortex Flow Meter for Measured Media: A Complete Guide

Vortex flow meters are widely used in industrial applications due to their simple structure, high stability, and broad turndown ratio. These meters are suitable for measuring the flow of liquids, gases, and steam. However, the accuracy and reliability of vortex flow meters highly depend on the characteristics of the measured medium. If the medium does not meet certain criteria, it can lead to significant measurement errors or even damage to the instrument.

In this article, we will break down the key media requirements for vortex flow meters to help you make informed decisions during selection and installation.
 

1. Media State Requirements

● Single-phase Flow Only

Vortex flow meters operate on the Kármán vortex street principle, which requires a homogeneous, single-phase flow. Mixed-phase media such as wet steam, gas-liquid mixtures, or solid-liquid slurries can interfere with vortex shedding and lead to unreliable readings.

● Fully Developed Turbulent Flow

The medium must be in a turbulent state with a Reynolds number greater than 10,000 (Re > 10⁴). In laminar flow conditions (caused by low velocity or high viscosity), vortex formation becomes weak or unstable, resulting in low or no signal.
 

2. Physical Properties of the Medium

● Viscosity Limits

• Liquids: Viscosity should generally be below 30 mPa·s. High-viscosity fluids such as asphalt or heavy oil dampen vortex formation and reduce accuracy.

• Gases/Steam: Less affected by viscosity, but low-density gases (e.g., hydrogen) may produce weak signals.

● Purity and Cleanliness

• Avoid media with solid particles, fibers, or crystals, which can clog or damage the sensor.

• For corrosive fluids, select meters made with materials like Hastelloy or PTFE lining.

• Install filters upstream if contamination is expected.

● Temperature and Pressure

• Temperature Range: Typically -40°C to 400°C. For extreme conditions, select models with cooling fins or thermal isolators.

• Pressure Range: Standard vortex flow meters handle up to 4 MPa. For higher pressure systems, use custom or reinforced designs.

3. Flow Characteristics

● Velocity Range

• Liquids: Recommended 0.5 – 7 m/s.

• Gases/Steam: Recommended 4 – 60 m/s.

  • Low velocities may result in unstable signals.

  • Excessively high speeds can cause noise or damage to the vortex shedder bar.

● Full Pipe Condition

• The pipe must be completely filled with liquid during measurement.

• Gas or steam flows should avoid liquid droplet contamination.

• Vertical installation should follow best practices:

  • Gas/Steam: Flow from bottom to top.

  • Liquids: Flow from top to bottom.

4. Unsuitable Media Examples

Some media are inherently incompatible with vortex flow measurement unless special precautions are taken:

• High-viscosity liquids (e.g., honey, glue)

• Two-phase flows (e.g., bubbly water, wet steam)

• Highly corrosive chemicals (e.g., strong acids and bases unless specialized materials are used)

• Dirty fluids with solids (e.g., sludge, sewage)

For such applications, consider alternative flow meter types, such as magnetic flow meters or Coriolis mass flow meters.
 

5. Selection Tips and Installation Best Practices

To ensure optimal performance and long service life of your vortex flow meter:

• Understand media parameters: Density, viscosity, temperature, pressure, and purity.

• Address special conditions: Use filters, flow conditioners, or remote sensors for harsh environments.

• Follow installation guidelines:

  • Maintain straight pipe lengths (minimum 10D upstream, 5D downstream, where D = pipe diameter).

  • Avoid vibration and electromagnetic interference.

For more on proper installation, check our related guide:
➡️ How to Install a Vortex Flow Meter Properly
 

Conclusion

A vortex flow meter offers a reliable and cost-effective solution for flow measurement only when the medium meets certain requirements. By ensuring your media falls within the recommended parameters for state, viscosity, purity, temperature, and pressure, you can achieve accurate and stable measurements.

Always consult with flow meter specialists and consider your specific application environment before selecting a vortex flow meter. Click for help.