Earth’s Coriolis effect is relied upon by Coriolis flow meters in order to make fluid mass flow rate measurements. Inside a Coriolis meter’s flow body, flow gets diverted to two sensor flow tubes that are parallel to one another. An energized drive coil vibrates them in opposition to each other. The phase shift of the mass flow meter, which the Hall Effect sensors measure and that are mounted at the inlets and outlets of the sensor tubes, is the result of the Coriolis effect. It is directly proportional to the media mass that is flowing through the tubes. Therefore, the Coriolis flow meter is a real mass flow meter.
The Coriolis Effect is a kind of natural phenomenon causing objects to seem to “curve” while they are moving across the Earth’s surface. Coriolis flow meters, which are referred to as Coriolis meters, are a type of flow meter which utilize the Coriolis Effect for directly measuring a process’s mass flow rate.
Coriolis flow meters, compared with other flow meter technologies, are fairly new and did not start to be widely used until the 1980s in industrial applications. There are several different designs of modern Coriolis meters that are available. A majority of configurations consist of one to two U-shaped flow tubes that have outlets on one side and inlets on the other side. Those tubes are enclosed within a sensor housing and connected with an electronic unit.
The standard Coriolis meter design has seen recent variations including double-looped single tubes as well as straight-through tubes that are used with abrasive and/or dirty liquids which could potentially clog U-shaped tubes.
When there is no flow, the tubes will vibrate. In addition, the sine waves outputs for each of the hall-effect transducers will be in phase. Whenever the flow is initiated, the fluid that flows through the tubes will induce a twist or rotation of the tube from the Coriolis Effect being accelerated. It operates in opposite directions on both sides of the applied force.
For instance, whenever the flow meter tube moves up during the cycle’s first half, the fluid that flows into the meter will resist being forced upward and will push down onto the tube. On the other hand, when the liquid flows out of the meter it resists its vertical motion being decreased through pushing up on the tube. The action results in the flow meter tube twisting. During the second part of the vibration cycle when moving downward, the tube will twist in the exact opposite direction. The twist results in there being a phase difference (or time lag) between the outlet and inlet sides. The mass that is passing through the tube directly affects the phase difference.
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