ASME MFC-11-2006 pdf download
ASME MFC-11-2006 pdf download.Measurement of Fluid Flow by Means of Coriolis Mass Flowmeters.
Most manufacturers calibrate their Coriolis flowmeters using water and gravimetric weigh scales or transfer standards directly traceable to scales. Water and gravimetric scales or transfer standards are generally used to calibrate flowmeters that are to be used in either liquid or gas applications because they are available with lower uncertainties than those of gas labs. The calibration factors determined by this procedure should be noted on the flow sensor data plate and calibration certificates for the Coriolis flowmeter should be available.
Test data in the public domain substantiates that a Coriolis flowmeter factor is independent of fluid used during calibration within the uncertainty of the calibration references.
As the Coriolis flowmeter is a mass flow device, it is preferable to perform the calibration against a mass- traceable reference. Calibration against a volume-traceable reference combined with a density-traceable reference may be used where applicable. Master flowmeters, like turbine flowmeters, sonic nozzles, or Coriolis flow- meters, may be used to calibrate Coriolis flowmeters. Calibration of the master flowmeters must be traceable to recognized standards.
Detailed calibration information including calibration intervals, suggested procedures, calibration levels, and an example of a calibration certificate are included in Nonmandatory Appendix A.
4 CORIOLIS FLOWMETER SELECTION AND APPLICATION GUIDELINES
4.1 Coriolis Flowmeter Selection Considerations
(a) The major consideration when selecting and sizing a Coriolis flowmeter is the tradeoff between pressure loss and flowmeter performance (accuracy). The following information is used to select and size a Coriolis
flowmeter:
(1) flow rate range
(2) pressure range
(3) temperature range
(4) available pressure drop
(5) liquid density
(6) liquid viscosity
(7,) gas composition or flowing density at minimum operating pressure and maximum operating temper- a ture
(8) required flowmeter performance (accuracy)
(b) Properly selecting a Coriolis flowmeter consists of choosing a flowmeter size that optimizes the tradeoff between measurement error at (see para. 4.1.1) and pressure loss at qmax (see para. 4.1.2), at acceptable velocities through the flowmeter oscillating tube(s). At a given flow rate
(2) pressure drop and velocity are higher through a smaller diameter Coriolis flowmeter but potential measurement error at the lowest flow rates is generally reduced and useable turndown ratio is typically increased.
(2) pressure drop and velocity are lower when a larger diameter Coriolis flowmeter is chosen but measurement error at low flow rates will increase and turndown ratio will decrease.
4.1.1 Minimum Flow Rate (q,J. The minimum flow rate, (mass or volume) of a Coriolis flowmeter is determined by the maximum permissible measurement error.
NOTE: The measurement error of a Coriolis flowmeter is determined from the flowmeter’s zero stability (ZS) and the manufacturer’s published accuracy equation. Once qmjn is determined in base units (mass or volume) for a particular gas or liquid mixture, it will remain constant over the range of temperature, pressure, and flow velocity. Only a change in gas composition or base conditions will cause the value of qmjn to change.
4.1.2 Maximum Flow Rate (qmax). The maximum flow rate, qmax, (mass or volume) of a Coriolis flowmeter is determined by the maximum acceptable pressure drop (Pc) across the flowmeter.
4.1.3 Coriolis Flowmeter Pressure Loss (Pc). Correct sizing of the Coriolis flowmeter will optimize the flowmeter performance over the flow rate range with a pressure drop that is acceptable for the application. If maintaining a low pressure drop is a priority, flowmeter selection will be made to provide the lowest possible pressure drop at maximum flow while maintaining an acceptable measurement performance at minimum flow rates.
(ja) Figures 4.1.3-1 and 4.1.3-2 show examples of the relationship between pressure drop and Coriolis flow- meter performance in gas applications at 70 bar (1,000 psig) and 35 bar (500 psig) for several typical sizes of Coriolis flowmeters.
(b) Figure 4.1.3-3 shows examples of the relationship between pressure drop and Coriolis flowmeter performance in liquid application over a wide turndown for several typical sizes of Coriolis flowmeters.
(c) Figure 4.1.3-4 shows examples of Coriolis flow- meter performance in a liquid application at q11 for several typical sizes of Coriolis flowmeters.
NOTE: Check with the manufacturer for similar data on Coriolis flowmeters being considered for your applications.
Pressure drop is determined by a constant called the pressure loss coefficient, K, and is defined as.
