This standard specifies the face-to-face dimensions for flanged vortex flowmeters of size up to 12 inches (DN 300)@ of rating up to ANSI Class 600 (PN 100).
ISA 97.00.01-2014 history
2014ISA 97.00.01-2014 Face-to-face Dimensions of Flanged Vortex Flowmeters