ASME MFC-18M-2001 (R2016) PDF
This Standard describes the common variable area flowmeter. This Standard does not attempt to standardize dimensions because the commercial products differ too widely.
The variable area meter is manufactured in a variety of designs. This Standard addresses only those meters based on a vertical tapered tube of round or a modified round cross section. Specifically not addressed are the various vane type meters, meters with horizontal flow, or meters which use a spring deflection to oppose flow forces.