The Coriolis Flow Meter
An interactive guide to the gold standard of direct mass flow measurement. Discover how fundamental physics is harnessed for unparalleled accuracy.
1. The Core Principle: Mass Flow from Phase Shift
This simulation demonstrates how a Coriolis meter measures mass flow. An exciter makes the tube vibrate. As fluid flows, its inertia creates a twisting force on the tube. Sensors detect this twist as a tiny time difference, or phase shift, between the inlet and outlet. This shift is directly proportional to the mass flow rate. Select a flow rate below to see this in action.
Mass Flow Rate
0.0 kg/s
Tube Twist
None
Phase Shift (Δt)
0 µs
2. The Second Trick: Density from Frequency
The same vibrating tube also acts like a high-tech tuning fork. The total mass of the system (tube + fluid) determines its natural vibration frequency. Denser fluids add more mass, causing the tube to vibrate slower. Less dense fluids result in a faster vibration. The meter measures this frequency to calculate density directly and independently of the flow rate. Select a fluid to observe this effect.
Vibration Frequency
100 Hz
Calculated Density
1000 kg/m³
3. Anatomy of a Meter
A Coriolis meter is a system of precision components working in concert. Explore the key parts of a typical dual-tube meter by clicking on the numbered hotspots below. Each component plays a critical role in inducing, controlling, and measuring the minute forces generated by the flowing fluid.
Flow Tube(s)
The central element where fluid flows. These precision-engineered tubes (often in a dual configuration for balance) are made of stainless steel or other alloys. Their geometry and material properties define the "spring" characteristics of the oscillating system.
4. Design Matters: Tube Geometries
There is no single "best" design; each geometry is an engineering trade-off tailored to specific applications. The choice between a curved or straight tube design significantly impacts performance characteristics like sensitivity, pressure drop, and cleanability.
Curved Tubes (U-Shape)
Designed to amplify the Coriolis effect, offering the highest sensitivity and accuracy.
- ✔High Sensitivity: Maximizes the twisting force, ideal for low flows and gases.
- ✔Highest Accuracy: Generally offers the best performance and turndown ratios.
- ✘Higher Pressure Drop: The winding path creates more flow resistance.
- ✘Harder to Clean: The shape can make it difficult to drain or clean completely.
Straight Tubes
Offers a direct, unobstructed flow path, prioritizing low pressure drop and ease of cleaning.
- ✔Low Pressure Drop: Minimizes impact on the process line.
- ✔Easy to Clean/Drain: Ideal for hygienic, high-viscosity, or slurry applications.
- ✘Lower Sensitivity: Produces a smaller Coriolis effect, less ideal for gases.
- ✘Reduced Turndown: Less accurate at very low flow rates compared to curved tubes.
5. Operational Challenges & Solutions
The meter's high sensitivity can also be a vulnerability. Certain process conditions can disrupt the measurement, but modern designs and advanced electronics provide effective solutions.
Problem: Two-Phase Flow (Gas in Liquid)
Gas bubbles disrupt the fluid's homogeneity, damping the tube's vibration and causing significant measurement errors. The meter may "stall" or report inaccurate values.
Solution: Advanced Signal Processing
Modern transmitters use powerful algorithms to detect entrained gas. They can apply correction factors, boost drive power to overcome damping, or hold the last known good value to ensure a stable output during upsets.
Problem: External Vibrations
Vibrations from nearby pumps or motors can be transmitted to the meter, interfering with the tiny flow-induced twist and corrupting the measurement signal.
Solution: Mechanical Balancing & Filtering
Dual-tube designs that vibrate in opposition are intrinsically balanced, cancelling out most external noise. Advanced digital filters in the transmitter are also used to isolate the true measurement frequency from interference.
6. How It Compares: Flow Technology Showdown
The Coriolis meter is a premium technology. See how it stacks up against other common industrial flow meters. Select a feature from the dropdown to compare their performance. This highlights why Coriolis is the top choice for applications demanding the highest accuracy and fluid compatibility.