ASME MFC-12M:2006 pdf download Measurement of Fluid Flow in Closed Conduits Using Multiport Averaging Pitot Primary Elements
This Standard,provides information on the use ofmultiport averaging Pitot head-type devices used tomeasure liquids and gases. The Standard applies whenthe conduits are full and the flow
(a) has a fully developed profile
(b) remains subsonic throughout the measurementsection
(c) is steady or varies only slowly with time
(d) is considered single-phaseA differential pressure transmitter or other pressuremeasuring device, known as a secondary element, mustbe used with a multiport averaging Pitot primary element to produce a flow rate measurement.
Although multiport averaging Pitot primary elementsare sometimes used in noncircular conduits, such applications are beyond the scope of this Standard.
TERMS AND DEFINITIONS
The terminology and symbols (Table 1) used in thisStandard are in accordance with ASME MFC-1MSomeitems from ASME MFC-1M are listed in para. 2.2.1 foreasier reference.
Terminology not defined in ASME MFC-1M but usedin this Standard, are defined in para. 2.2.2
2.1 Symbols
See Table 1.
22 Definitions
2.2.1 Definitions Found in ASME MFC-1M
cavitation: the implosion of vapor bubbles formed afterflashing when the local pressure rises above the vaporpressure of the liquid. See also flashing.
differential pressure device: device inserted in a pipe tocreate a pressure differential whose measurementtogether with a knowledge of the fluid conditions andof the geometry of the device and the pipe, enables theflow rate to be calculated.
flashing: the formation of vapor bubbles in a liquid whenthe local pressure falls to or below the vapor pressureof the liquid, often due to local lowering of pressurebecause of an increase in the liquid velocity.See alsocavitation.
primary device (ofa differential pressure device): differentialpressure device with its pressure tappings.
rangeability: flowmeter rangeability is the ratio of themaximum to minimum flowrates or Reynolds numberin the range over which the primary element meets aspecified uncertainty (accuracy).
reproducibility: the closeness of agreement betweenresults obtained when the conditions of measurementdiffer; for example, with respect to different test appara-tus, operators, facilities, time intervals, etc.
Reynolds number: a dimensionless parameter expressingthe ratio between inertia and viscous forces. It is givenby the formula