Coriolis Flow Meters

Coriolis Flow Meters

Also known as mass flow meters or inertial flow meters, coriolis flow meters function to measure the mass per unit time, or the force of acceleration, that is flowing through the tube. The mass per unit time, also referred to as the mass flow rate, is a calculation of the mass of the fluid as it travels past a fixed point per unit time. This type of flow meter is dubbed the coriolis because it utilizes the Coriolis effect, an inertial force that is caused by the Earth's rotation, in order to obtain a highly accurate measurement of mass flow as well as the density of the fluid. A relatively new type of flowmeter, coriolis flow meters began being used in industrial applications in the early 1980's. Additional applications of coriolis flow meters include continuous blending, combustion control, fermentation, fueling, vial filling, bottling and concentration measurements. As a result, coriolis flow meters are not only useful in the industrial manufacturing industry, but in a wide range of industries including petrochemical, food and chemical processing, automotive and pharmaceutical.

Coriolis flow meters are typically constructed from a u-shaped flow tube (which is filled with fluid but has not flow), a driving unit and displacement sensors, with an inlet and an outlet to allow for flow. To begin, the flow is guided into the flow tube from the inlet, from which point an oscillating excitation force is applied to the tube in order to cause vibration. Once the vibration is achieved, the flow of the fluid will cause a rotation of the tube caused by the Coriolis effect. This effect causes rotation because it causes acceleration on one side of the tube (the inlet) and deceleration on the other side of the tube (the outlet). As a result, the inlet is able to register the flow before the outlet is able to, which results in a time delay. This time delay is directly proportional to the mass flow rate of the fluid or gas. Coriolis flow meters are able to measure the mass flow rates of a broad spectrum of fluids and gases including hydrogen gas, bitumen, natural gas and water. Since some of the fluids or gases are corrosive, coriolis flow meters are often constructed from such corrosion-resistant materials as stainless steel and hastelloy.