tracks and even causing rivers to dig their beds deeper on one side.
Turbine meters are very accurate with the lighter hydrocarbons like gasoline, diesel fuels, and distillates; however, wear and tear affects this type of meter, just as it does any other. If the rotor or blades are damaged or worn, they do not perform as well as they did when new; hence, just as with any other type of meter, the difference between the registered volume and the true volume must be verified or proved on a regular schedule. 6.4 Coriolis Meter In addition to the Displacement and Turbine Meters many other types of meters have been introduced, such as, Coriolis and ultra sonic. These are sometimes referred to as ‘micro - motion’ devices because they rely on measuring very small movements or changes in movement.
scientist, in 1835. When an object is moving in a rotating coordinate system, the path of the object appears to deviate due to the Coriolis Effect. If you are in the moving coordinate system, this deviation makes it look like a force is acting upon the object (due to Newton’s laws of motion), but in reality, there is no real force acting on the object, only an apparent one. The effect is due to rotation associated with an acceleration of the coordinate system itself. A similar effect, from a moving frame of reference, is the centrifugal force. In a rotating frame of reference such as the earth, the apparent force is a function of the mass and velocity of the object in motion and the angular velocity of the coordinate system. Subsequently, the force will be proportional to the velocity of the object and the rotation of the coordinate system. Additionally, the force will be in a direction perpendicular to the velocity. If an object is travelling on earth in the northern hemisphere, the Coriolis force will deflect the object to the right. In the southern hemisphere the reverse is true, while at the equator the horizontal component of the force is zero for horizontal motions. Although the Coriolis force is relatively small it does have an observable influence on small systems such as the whirlpool of a draining bathtub and can have a more visible effect over large amounts of time, causing uneven wear on railroad
6.4.2 Mass Flow Meters
A practical application of the Coriolis force is the mass flow meter, which is an instrument that measures the mass flow rate of a fluid through a tube. Turbine and positive displacement flow meters measure volume flow rate, which is proportional to mass flow rate only when the density of the fluid is constant. If the fluid has varying density, or contains bubbles, then the volume flow rate multiplied by the density is not an accurate measure of the mass flow rate. The Coriolis mass flow meter works by applying a vibrating force to a curved tube through which the fluid passes. The Coriolis Effect creates a force on the tube perpendicular to both the direction of vibration and the direction of flow. This force is measured to give the mass flow rate. Coriolis flow meters can also be used with non- Newtonian fluids, which tend to give inaccurate results with volume flow meters. The same instrument can be used to measure the density of the fluid, since this affects the resonant frequency of the vibrating tube. A further advantage of this instrument is that the fluid is contained in a smooth tube, with no moving parts that would need to be cleaned and
They have few or no moving parts, which is very beneficial from a maintenance perspective.
The Coriolis meter is one that measures mass and is a type of meter that is gaining significantly in popularity. To understand how a Coriolis meter works, you must first understand what is meant by the Coriolis Effect. 6.4.1 Coriolis Effect The Coriolis Effect is an internal force first described by Gaspard-Gustave Coriolis, a French
41
Made with FlippingBook Annual report maker