In most operations, the measurement of flow is a critical parameter. Knowing the correct fluid is in the correct place is important within an operation. In critical applications conducting accurate flow measurements ensure product quality. Health and safety are an incredibly important factor when working with liquids and gases. Measuring flow and pressure helps to provide a level of security to the operation and the personnel.
Flow rate, in most cases, is determined inferentially by measuring the fluids velocity or the change in kinetic energy. The liquids viscosity and density, and the friction of the liquid in contact with a pipe are also a factor to a liquids flow rate.
Direct Flow Measurement
The development of Direct Mass Flow measurement is an important innovation because it eliminates inaccuracies caused by the physical properties of the fluid. Mass is not affected by the change of temperature and pressure, which makes it an important method of fluid flow measurement. Volumetric remains a valid method of flow measurement if the process conditions and calibration reference conditions are followed.
The Coriolis Measuring Principle
The Coriolis measuring principle is evident in our everyday lives. An example of this is the earth’s rotation and its effect on the weather. The operating principle is simple but very effective. A fixed vibration energizes a tube. When the fluid passes through the mass flow momentum will cause a change in the vibration. The tube will then twist resulting in a phase shift. This can be measured and result in a linear output derived proportional to flow.
As this principle measures mass flow independent of what is within the tube it can be directly applied to any fluid flowing through it, liquid, or gas. In parallel with the phase shift in frequency between inlet and outlet, it is also possible to measure an actual change in natural frequency. This change is in direct proportion to the density of the fluid – and further signal output can be derived. When you have measured both the mass flow rate and the density it is, interestingly, possible to derive the volume flow rate.
Advantages of Coriolis Mass Flow Meters
The Coriolis mass flow meters offer significant features compared to other principles:
- No need for (re)calibration in the field – fluid independent flow measurement and control
- Gas and liquid can be measured with the same sensor
- Ability to measure undefined or variable mixture
- Multi parameters
The Coriolis principle, applied as a mass flow meter, therefore has its place within fluid measurement and control within the Process Industry.
Mini CORI-FLOW flowmeters and controllers
Bronkhorst realized a compact, cost-effective Coriolis Mass Flow Meter/Controller series for accurate measurement and control of (very) low flow rates called the mini CORI-FLOW series. These flow meters and flow controllers feature unsurpassed performance, even with changing operating conditions in pressure, temperature, density, conductivity and viscosity. Check them out!