The Earth’s Coriolis effect is used by Coriolis flow meters to determine the fluid mass flow rates. Flow is diverted through two sensor flow tubes in the Coriolis meter. These tubes are vibrated using an energized drive coil. The Hall Effect sensors are mounted to the inlet and outlets of the sensor tubes and measures the mass flow meter’s phase shift. This measurement is proportional to the mass flowing through the tubes using the Coriolis effect. This type of flow meter is considered a true mass flow meter.
The Coriolis effect is a phenomenon which makes object “curve” as they travel across the Earth’s surface. Coriolis meters use the Coriolis effect to determine a process’s mass flow rate.
When a Coriolis flow meter is compared to other types of flow meters, the use of the application in the industrial setting is not widely used. This is because a Coriolis flow meter did not make an appearance till the 1980s. Today’s Coriolis meters come in a wide variety of designs. Most configurations consist of either one or two U-shaped flow tubes. These tubes have an inlet on one side and an outlet on the other side. Each tube is enclosed in a housing sensor that is connected to an electronic unit.
There have been variations to the Coriolis meter design, such as straight through single tubes or double looped single tubes. These are used for abrasive or dirty liquids that can clog traditional U-shaped tubes.
When a flow is not present in the tubes, the tubes will vibrate and produce sine wave outputs in the phase. When a flow is initiated, the liquid flowing through the tubes causes the tube to twist or rotated due to the Coriolis Effect. This effect operates in the opposite direction of the applied force.
For example, if the flow in the meter tube is moving upwardly during the first half of the process, the fluid being forced into the meter resists the upward force and pushes the tube downward. Conversely, the liquid that is flowing out of the meter resists the decrease in vertical movement and pushes up on the tube, causing the flow meter tubes to twist. During the second half, the flow will move downwardly and cause the tube to twist in the opposite direction. This creates a phase difference, or time lag, between the inlet sides and outlet sides. The phase difference is affected directly by the mass that is passing through the tubes.
The SmartMeasurementTM, ALCM family of Coriolis mass and density flowmeters features three of the most successful flow tube shapes in the industry. The ALCM employs the original yet robust U tube our ALCMUT for standard applications, as well as a better pressure drop features of our Microbend shaped in the ALCMMB, and our ALCMDT, the delta tube which is excellent for low flows and small sizes. The ALCM family of Coriolis mass/density measurement manufactured by SmartMeasurementTM offers a smart solution for many Coriolis flow applications.