How does a Coriolis Flow Meter work?

Monday, January 30, 2023

Firstly, what is ‘Coriolis’?

Let’s start with the word Coriolis, if we look at Earth and the weather as a starting point. The Coriolis effect can be described in terms of movement around the Earth. We can look at hurricanes, typhoons, and tornadoes rotating above the Earth for the Coriolis effect. The observed movement of these is the result of the Coriolis effect.

The Earth rotates faster at the equator than at the poles, these hurricanes rotate in opposite directions in the northern and southern hemispheres. That’s as deep as I will go at this stage. At the bottom of this article are two videos that explain this.

Using the Coriolis Effect in Metering flows

This Coriolis effect can be used in Metering flows. The past 20 years have seen a rapid rise in the use of Coriolis Meters being used to measure flow of Liquids or gases. (View our range of Coriolis Flow Meters)

The fluid (Liquid or Gas) will travel through a tube when the starting point is at a higher pressure than the end point. To measure this flow at a certain point in a system is crucial for many processes. Using a Coriolis meter in the system at the desired point gives valuable data.

The Coriolis meters are of variable diameters, shapes materials of construction, depending on the flow rate, fluid flowing and the specific design of the manufacture. All these Coriolis meters have in common is that the meter is a tube, they have an applied force on the tube and a measuring device to observe the movement in the tube.

How does a Coriolis Flow Meter work?

Typically, a vibration is applied to the tube by way of an actuator, the tube will vibrate at the applied frequency. When the tube is full of the fluid and in a no-flow situation the tube simply vibrates. When the fluid starts to move (Flow) the tube will not only vibrate but the tube twists, the measurement of the twist is a direct measurement of the flow.

Coriolis mass flow measurement

Diagram explanation: In the Image above we can see that the actuator that creates the vibration at a specific frequency is a Magnetic Oscillator. The measurement of the movement - or Twist on the sensing tube is by way of the Detectors as shown on the side of the image, these are often optical sensers that are capable of measuring the high frequency tiny movements of the tube.

Can Coriolis Flow Meters measure any Liquid or Gas?

The Coriolis Meters are suitable for any Liquid or any Gas as long as the Materials of construction are safe to do so. Alicat Coriolis can be used to measure either Gas or Liquid, dual phase (gas and liquid together example a bubbly liquid) is not possible.

The Coriolis Meter therefore lends itself to be able to measure the flow of an unknown fluid: liquid, gas, or even an unknown liquid or gas mixture.

What readings can a Coriolis Flow Meter output?

As well as a Volumetric or Mass Flow reading many including the Alicat Coda will also give the user the Density and Fluid temperature readings.

How do you set up a Coriolis Meter?

• Connect to the system typically using VCR Fittings for excellent leak tightness.
• Turn on the device, often best to leave devices to warm up prior to using for the most accurate results.
• Allow flow of the specific fluid through the device.
• Shut off the fluid to allow a no flow situation, by using shut off valves.
• Zero the device for the specific fluid.
• Open the shut off valves and measure the flow with the device!

If you change fluid repeat the above steps to zero the device for a new fluid.

We can help with your Flow Metering requirements

Premier Control Technologies offer Alicat and Rheonik Coriolis Meters. With the Alicat we can add a valve and using the onboard PID controller to control the flow of Liquids and Gases. Please note the valve must be selected for the correct fluids, flow rate and Pressures in advance.

Alicat CODA Coriolis Standard Accuracy Flow Meter

Suitable for high accuracy flow measurement for both liquids and gases

Rheonik RHM 30 Medium Coriolis Flow Meter

Suitable for high temperature liquids and viscous fluids

Where the user has no pressure supply on the inlet Alicat can help you! Simply combining a pump directly connected to the Alicat Coriolis Meter, the user would send the signal to the meter for their desire flow rate, the Meter communicates with the pump to apply the signal to rotate the gears on a micro-gear pump. The meter constantly monitors and adjusts the signal to the pump for a perfectly controlled accurate Flow Rate.

If you want a demonstration or more information, please contact Premier Control Technologies the UK’s sole distributor for Alicat Scientific Inc part of one of UK largest companies The Halma Group.

Helpful video resources:

Here are the two videos we mentioned earlier; they explain the Coriolis Effect very well!

Related articles

• Introducing a Mini Coriolis solution for Liquid Flow Control - read more about adjusting the flow to meet the demanding high accuracy specifications of a dosing system.
• Overcoming Peristaltic Pump Limitations with a Flow Meter-Pump System - Read about the key benefits of a flow meter-pump system.

Posted by Paul Burroughs, National Sales Manager