ASME MFC-11-2006 pdf free download.Measurement of Fluid Flow byMeans of Coriolis Mass Flowmeters.
tests of the meter, over longer (specified) periods of lime, or when test conditions may change (changes to be specified); such as the typical mcter.usage patterns a turning the meter off and then turning it back on. or testing it on successive days. Reproducibility can be quantified in terms of the standard deviation or the max/mm. differences In these results.
cl Resultant differences for reproducibility may be brgcr than their repeatahilities because of the lest conditions.
‘condari containment: housing designed to provide protection to the environment if the oscillating tube(s) fail.
transmitter: electronic system providing the drive and transforming the signals from the flow sensor to give output(s) of measured and inferred parameters; it also provides corrections derived from parameters such as temperature.
uncertainty (of measurement): the range within which the true value of the measured quantity can be expected to lie with a specified probability and confidence level.
zero stability: maximum expected magnitude of the Conotis flowmeter output at zero flow after the zero adjustment procedure has been completed, expressed by the manufacturer as an absolute value in mass per unit time.
2.2 Definitions Specific for This Document
conditions: specified conditions to which the measured mass of a fluid is converted to the volume of the fluid.
error: the difference between a measured value and the “true” value of a measurand.
NOTE: The “true’ value cannot usually be determined, In pracIke, a conventional recogn.ied “standard” or “reference” value is typically used instead.
installation effict: any difference in performance of a component or the measuring system arising between the calibration under ideal conditions and actual conditions of use. This difference may be caused by different flow conditions due to velocity profile, perturbations, or by different working regimes (pulsation, intermittent flow, alternating flow, vibrations, etc.).
linearity: the consistency of the change in the scaled output of a Coriolis Ilowmeter for a related scaled change in the input of the flowmeter.
master flowmeter: a flowmeter calibrated with a primary flow reference and used as a secondary or transfer reference to calibrate other flowmeters.
pig: a mechanical device, pressured through piping to clean the walls and/or remove construction debris. There is a type of smart pig that can identif record, and transmit the condition of the internal surface of the pipe and locations of the defect.
pressure loss: the difference between the inlet pressure and the outlet pressure of the Coriolis flowmeter.
Hence, we see that (direct or indirect) measurement of the Coriolis force on an oscillating tube can provide a determination of the mass flow rate. This is the basic principle of operation of the Coriolis flowmeter.
3.1.2 Coriolis flow Sensor. In commercial designs of Coriolis flowmeters, the generation of inertial forces through continuous rotary motion is not practical and instead the necessary forces are generated by oscillating the tube.
In one class of Coriolis flowrneters, the oscillating tube is anchored at two points and oscillated at a position between the two anchors, thus giving rise to opposite oscillatory rotations of the two halves of the tube. In another version, a section of tube is oscillated and a transverse Coriolis force is generated. Coriolis flowmeters have one or more oscillating tube(s) that are straight or curved.
The smallest driving force required to keep the tube in constant oscillation occurs when the frequency of oscillation is at, or close to, the resonant frequency of the filled oscillating tube.
The movement of the oscillating tube(s) is measured at various points. When flow is present, Coriolis forces act on the oscillating tube(s), causing a small displacement, deflection, or twist that may be observed as a phase difference between the sensing points.
Coriolis forces (and hence distortion of the oscillating tube) only exist when both axial flow and forced oscillation are present. When there is forced oscillation but no flow, or flow with no oscillation, no deflection will occur and the Coriolis flowmeter will show no output.
The flow sensor is characterized by flow calibration factors that are determined during manufacture and calibration. These values are unique for each sensor and should be recorded on a data plate secured to the sensor.