مرور کلی بر فلو متری های کوریولیس (Coriolis)
The French mathematician Gustave Coriolis formulated the principle that underlies Coriolis flowmeters. Coriolis showed in 1835 that an inertial force needs to be taken into account when the motion of bodies in a rotating frame of reference is described. The earth is often used as an example of the Coriolis force. A hypothetical object thrown from the North Pole to the equator appears to vary from its intended path, due to the earth’s rotation.
Coriolis flowmeters contain one or more vibrating tubes. These tubes are usually bent, although straight-tube meters are also available. The fluid to be measured passes through the vibrating tubes. It accelerates as it flows toward the maximum vibration point, and slows down as it leaves that point. This causes the tubes to twist. The amount of twisting is directly proportional to mass flow. Position sensors detect tube positions.
While the roots of today’s Coriolis flowmeters can be traced back to the 1950s, it was not until 1977 that Micro Motion introduced a commercially viable Coriolis flowmeter for industrial applications. Since that time, a number of other suppliers have entered the market, including Endress+Hauser and Krohne. Coriolis suppliers have introduced a wide variety of models and types of Coriolis flowmeters in the past 35 years.
Coriolis suppliers differentiate themselves in a number of ways. One is by the proprietary design of the bent tubes in their Coriolis flowmeters. Another is by the different types of straight tube Coriolis flowmeters that are offered. Suppliers also compete by bringing out Coriolis flowmeters for particular industries and applications, such as food & beverage and pharmaceutical. Accuracy and other performance specifications are other areas of supplier differentiation.
While Coriolis flowmeters are loved by many end-users, price is often an issue. Coriolis flowmeters are the most expensive meter made, in terms of average selling price. The average selling price of Coriolis flowmeters are between $5,000 and $6,000. Some suppliers have introduced low-cost Coriolis flowmeters in the $3,000 range. Performance specifications for the lower-cost flowmeters are not at the same level as those of the higher-priced meters. However, these lower-cost meters can help satisfy the needs of users who want the essential benefits of Coriolis technology but prefer not to pay the higher price.