The practical advantage this gives weirs and flumes is the ability to maintain high accuracy of
flow measurement at very low flow rates – something a fixed-orifice element simply cannot do. It
is commonly understood in industry that traditional orifice plate flowmeters do not maintain good
measurement accuracy much below a third of their full-range flow (a rangeability or turndown of
3:1), whereas weirs (especially the V-notch design) can achieve far greater turndown (up to 500:1
according to some sources