Coriolis meters

The Coriolis meter (Figure 6.28) contains a sensor consisting of one or more tubes which are vibrated at their resonant frequency by electromagnetic drivers, and their harmonic vibrations impart an angular motion to the fluid as it passes through the tubes which,... 

Velocity meters measure the velocity v of fluid flow in a pipe of known cross section, thus yielding a signal linearly proportional to the volume flow rate Q. Mass meters provide signals directly proportional to the mass flow rate m = pQ, where p is the mass density. Coriolis meters, which are true mass meters, can be used only for liquids. Thermal-type flow meters use a heating element and determine the rate of heat transfer, which is proportional to the mass flow rate. This type of device is used mostly for gas measurements, but liquid flow designs are also available. 

Density Nuclear gauges are the norm for density measurement. Nuclear density instruments require nuclear handling permits in most countries. Note that there are now some types that use very low level sources that do not require nuclear licensing. Density gauges should be recalibrated regularly as they are subject to drifting. Small flow applications may be able to use a coriolis meter to measure both mass and percent solids with one instrument. 

Figure 10. Schematic of Coriolis Meter flowpath. Foxboro, Mass.)...

CORIOLIS METERS. An object moving in a rotating system experiences a Coriolis force proportional to its mass and forward velocity and to the angular velocity of the system. This force is perpendicular to the object s direction of travel and to the direction of the angular velocity of the system. In a Coriolis meter (Fig. 8.26) the fluid is passed through two U-shaped curved tubes that are vibrated at their... 

Coriolis meters are highly accurate and directly measure the mass flow rate. Used mostly with small pipes, they are costly to install and operate. Consequently their applications are generally limited to difficult fluids or to situations where their high accuracy justifies their higher cost. 

The Coriolis meter is commonly used to measure liquid flow rates. The coriolis meter utilizes the coriolis effect to directly measure the mass flow rate of liquids. The meter is equipped with a specially shaped vibrating tube through with the liquid flows. When a fluid flows through the tube it alters the manner in which the tube vibrates. The mass flow rate of the fluid is then... 

The types of instruments used in an industrial setting are often different from those used in the laboratory. The most common high precision laboratory instrument is the mass flow controller and rotameters are frequent for applications for both gases and liquids but are much less accurate. In industry, obstruction flow meters, Coriolis meters, and vortex shedders are more standard. 

Coriolis-meters oscillating pipework which is flowed through. Resonant frequency and phase shift enable the determination of density and mass flow, thus of the volume flow, at the same time. 

Thermal mass flow sensors have also found wide application for pure media, such as metering of N2, compressed air, or oils because of their compact design, precise detection, and lower cost than comparable Coriolis meters. Their handicap is the... 

---