Compare Venturi meters and orifice plates for flow measurement.

Venturi meter: gradual converging section and diffuser for pressure recovery, permanent loss only 10-20% of measured dP, higher accuracy (Cd ~0.98), but expensive and requires more space. Orifice plate: simple, inexpensive, easy to install and replace, but permanent loss 40-80% of measured dP, lower accuracy (Cd ~0.6), susceptible to edge wear. Venturi preferred for large flows where pumping cost is significant; orifice for lower flows, cost-sensitive applications, or when frequent changes are needed.