A Coriolis meter is a mass flow meter that measures flow directly - not by inferring it from velocity or pressure drop, but by sensing the tiny twisting force that mass in motion exerts on a vibrating tube. As a bonus it measures fluid density at the same time. Its high accuracy and direct mass reading make it a favorite for custody transfer of crude, NGLs, and other liquids.
Coriolis Meter in one line: A Coriolis meter measures mass flow directly by vibrating a tube and detecting the phase shift, or twist, that flowing mass induces in it; the vibration frequency also gives fluid density, so it reports mass, density, and inferred volume together.
The meter continuously vibrates one or two flow tubes at their resonant frequency. When fluid flows through a vibrating tube, the Coriolis effect makes the inlet and outlet halves of the tube twist slightly out of phase with each other - the faster the mass flow, the greater the phase shift. Sensors at each end measure that phase difference, which is directly proportional to mass flow rate. No flow profile assumptions, no pressure/temperature compensation for the flow measurement itself.
Separately, the natural resonant frequency of the vibrating tube depends on the total mass of tube plus fluid, so the meter derives fluid density from the vibration frequency. Knowing mass flow and density, it can also compute volumetric flow. This is why a Coriolis meter is so useful: one device reports mass flow, density, and volume, and density is exactly what a crude LACT unit or NGL measurement point needs to characterize the fluid.
Direct mass measurement sidesteps the biggest error sources in inferential meters. Because flow does not depend on the velocity profile, a Coriolis meter is far less sensitive to upstream piping and needs little or no straight run, and because it reads mass, it is immune to the density swings from pressure and temperature that complicate volumetric metering. It handles a very wide turndown with high accuracy, which is why it is common in LACT units, NGL and product custody, and chemical injection.
The trade-offs are cost, size and pressure drop on large lines, and sensitivity to entrained gas or two-phase flow, which disturbs the tube vibration. In service, the meter is verified or proved to confirm its calibration for custody use. A Coriolis transmitter reports mass flow, density, temperature, volume, and drive/diagnostic data - almost always over Modbus - so a cloud SCADA platform can poll those values to trend production, watch density as a quality indicator, and alarm on the tube-drive diagnostics that reveal entrained gas or a coating problem.
It measures mass flow rate directly, from the phase shift a flowing mass induces in a vibrating tube, and it measures fluid density from the tube's resonant frequency. From those two it can also report volumetric flow and, with temperature, additional derived values - all from a single meter.
Because it reads mass directly, it avoids the velocity-profile and density-correction errors that limit inferential meters, is insensitive to upstream piping, handles wide turndown accurately, and simultaneously reports density for fluid characterization. That combination makes it well suited to LACT units and liquid custody points, where it is proved for legal-for-trade accuracy.
It is more expensive than an orifice or turbine meter, gets bulky and adds pressure drop on large lines, and its accuracy suffers with entrained gas or two-phase flow, which disrupts the tube vibration. For clean single-phase liquid measurement, though, its accuracy and built-in density reading usually justify the cost.
This page references the protocol specifications published by the organizations below. Editions, product capabilities, and documentation change over time - confirm current requirements and specifications directly with the source.
Last reviewed: July 27, 2026. Merobix is not affiliated with, endorsed by, or sponsored by these organizations; their names are used only to identify the standards and products discussed.
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