AIR & WATER

MONITORING NEWSLETTER  

March 2013
No. 401

Coriolis Mass Flow Meters Have Advantages for Bulk Measurement

Accurate measurement of liquids is important for all oil and gas industry production or consumption sites. This is especially true for bulk transfer devices where large volumes of products are being moved and must be monitored, including crude oil pipelines, depots, gasoline and jet fuel tank farms, refineries and even cruise line terminals. Andrew Verdone, writing in Pipeline & Gas Journal, analyzed the technology.

In the past, mass transfer was measured in batches with weigh scales or load cells. However, installation, calibration and maintenance activities of a scale or load cell are costly, difficult to do, time consuming and don’t work for continuous processes. For these processes, such methods as orifice plates and magnetic flow tubes can measure volumetric flow, but additional instruments are needed to measure temperature and pressure to compensate for fluid density changes. Introducing additional instruments also introduces errors, which can result in an overall measurement error rate as high as 3 percent.

Now, several measurement standards are moving toward use of Coriolis mass flow meters, which can measure mass flow directly at the same time as they measure temperature and density. What’s more, transfer measurement by mass is the most accurate method, since mass is independent of, and unaffected by, changing process fluid characteristics, including pressure, temperature, viscosity, conductivity and gravity.

Among the Coriolis devices available, the straight tube design is being hailed as the most accurate and easiest to install and maintain. Especially for measurement skids, widely used in the oil and gas industry, the straight tube Coriolis meter can be a factor in minimizing skid size.

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