ASME MFC-7 pdf download

ASME MFC-7 pdf download Measurement of Gas Flow by Means of Critical Flow Venturis and Critical Flow Nozzles
SCOPE AND FIELD OF APPLICATION
This Standard applies only to the steady flow of single-phase gases through critical flow venturis (CFV) of shapesspecified herein also sometimes referred to as critical flow nozzles (CFN), sonic nozzles, or critical flow venturinozzles). This Standard applies to CFVs with diverging sections on the downstream side of the throat. When aCFN (no diverging section) is discussed, it is explicitly noted. This Standard specifies the method of use (installationand operating conditions) of CFVs. This Standard also gives information necessary for calculating the mass flowof the gas and its associated uncertainty.
This Standard applies only to CFVs and CFNs in which the flow is critical. Critical flow exists when the massflow through the CFV is the maximum possible for the existing upstream conditions. At critical flow or chokedconditions, the average gas velocity at the CFV throat closely approximates the local sonic velocity.This Standard specifically applies to cases in which(a) it can be assumed that there is a large volume upstream of the CFV or upstream of a set of CFVs mountedin a parallel flow arrangement (in a common plenum), thereby achieving higher flow; or(b) the pipeline upstream of the CFV is of circular cross section with throat to pipe diameter ratio equal to orless than 0.25
2 REFERENCES
The following publications are referenced in this Standard. The latest edition of ASME publications should be used.ASME MFC-3M, Measurement of Fluid Flow in Pipes Using Orifice, Nozzle, and VenturiASME PTC 19.5,Flow MeasurementPublisher: The American Society of Mechanical Engineers (ASME), Two Park Avenue, New York, NY 10016-5990(www.asme.org)
ISO 9300:2005, Measurement of gas flow by means of critical flow Venturi nozzlesISO/IEC Guide 98-3:2008, Uncertainty of measurement-Part 3: Guide to the expression of uncertainty inmeasurementPublisher: International Organization for Standardization (1SO) Central Secretariat, Chemin de Blandonnet 8, CasePostale 401.1214 Vernier, Geneva, Switzerland (wwwiso.org)
NIST Standard Reference Database 23, NIST Reference Fluid Thermodynamic and Transport Properties Database(REFPROP): Version 9.1
Publisher: National Institute of Standards and Technology (NIST), 100 Bureau Drive, Stop 1070, GaithersburgMD 20899 (www.nist.gov)
3SYMBOLS AND DEFINITIONS
3.1 Symbols and Nomenclature
See Table 3.1-1.
32 Definitions3.2.1 Temperature Measurementmeasured gas temperature: temperature of the gas after being irreversibly brought to rest against the temperatureprobe recovery factor: parameter used to correct the temperature of the gas after being irreversibly brought to rest against the temperature probe.