Coriolis Mass Flowmeters Principle

Coriolis Principle





The Coriolis principle refers to the effect that a moving mass has on a body in a rotating frame of reference. The moving mass exerts an apparent force on the body, causing a deformation of the body. This force is called the Coriolis force. It does not act directly on the body, but on the motion of the body. This principle is used in Coriolis flowmeters.


A Coriolis flowmeter consists of two parallel tubes that are made to oscillate using a magnet. These oscillations are recorded by sensors fitted at the inlet and outlet of each tube. In a no-flow state, the oscillations are synchronised, i.e. in phase with each other, since there is no mass exerting any force on the tubes. On the other hand, any fluid or gas flowing through the tubes generates Coriolis forces, causing the tubes to twist in proportion to the mass flow rate of the medium. The magnitude of this twisting is measured by the sensors as a phase shift between the inlet and outlet of the tubes. And this phase shift is used to measure the mass flow rate of the medium. The tubes also oscillate at their own resonant frequency in proportion to the density of the medium through the tubes. This effect is used to derive the density of the medium. Knowing the mass flow rate and the density, it is then possible to calculate the volume flow rate of the medium. A Coriolis flowmeter is thus used to simultaneously measure the mass flow rate, density and temperature of any fluid or gas flowing through a pipe.
 

1. U-shaped Flowmeters	These flowmeters comprise two tubes that are arranged in the shape of the letter ‘U’, a magnet and coil assembly, and sensors at the inlet and outlet of the tubes. Coriolis forces exerted by the flow medium are used to determine the mass flow rate and density of the medium.
2. Micro-bend Flowmeters	These flowmeters comprise two U-shaped tubes in a casing with a considerably smaller radius than conventional U-shaped Coriolis flowmeters. The smaller radius ensures a more compact instrument with significantly lower pressure differential values compared to other flowmeters.
3. Triangular-shaped Flowmeters	The triangular flowmeter is the most compact in our range of Coriolis mass flowmeters, designed specifically to provide optimum performance in low-flow applications. It comprises a single flow tube which is considerably smaller in size than the conventional U-shaped tube.
4. Super-bend Flowmeters	The super-bend coriolis mass flowmeter is used in a wide range of applications to accurately measure the flow media. It consists of a loop-powered dual tube system, capable of withstanding pressures of up to 1450 psi. It is also more cost-efficient compared to conventional flowmeters.