ASME MFC-7 pdf download.Measurement of Gas Flow by Means of Critical Flow Venturis and Critical Flow Nozzles.
ASME MFC-7 applies only to the steady flow of single-phase gases through critical flow venturis (CFV) of shapes specified herein lalso sometimes referred to as critical flow nozzles (CFN), sonic nozzles, or critical flow venturi nozzlesj. This Standard applies to CFVs with diverging sections on the downstream side of the throat. When a CFN (no diverging section) is discussed, it is explicitly noted. This Standard specifies the method of usc (installation and operating conditions) of CFVs. This Standard also gives information necessary for calculating the mass flow of 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 mass flow through the CFV is the maximum possible for the existing upstream conditions. At critical flow or choked conditions, 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 he assumed that there is a large volume upstream of the CFV or upstream of a set of CFVs mounted in a parallel flow arrangement (in a common plenum), thereby achieving higher flow; or
(ii) the pipeline upstream of the CFV is of circular cross section with throat to pipe diameter ratio equal to or less 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 Venturi
ASME I’TC 19.5, Flow Measurement
Publisher: The American Society of Mechanical Engineers (ASME), Two Park Avenue, New York, NY 10016-5990 (www.iisme.org)
ISO 9300:2005, Measurement of gas flow by means of critical flow Venturi nozzles
ISO/IEC Guide 98-3:2008, Uncertainty of measurement—Part 3: Guide to the expression of uncertainty in measurement
Publisher: International Organization for Standardization (ISO) Central Secretariat, Chemin de Blandonnet 8, Case l’ostale 401, 1214 Vernier, Geneva, Switzerland (www.iso.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, Gaithersburg, MD 20899 (www.nist.gov)
3 SYMBOLS AND DEFINITIONS
3.1 Symbols and Nomenclature
See Table 3.1-1.
3.2 DefInitions
3.2.1 Temperature Measurement
measured gas temperature: temperature of the gas after being irreversibly brought to rest against the temperature probe.
ASME MFC-7 pdf download
