The height of fluid above a weir increases as the flow rate increases, therefore
a measurement of height gives an indication of flow rate. This is one of the
most fundamental methods known for measuring the rate of flow of liquids.
Weirs are used for open c h a ~ efllo w measurement, "V" notch weirs being
especially suitable for low flow rates.
This experiment illustrates the use of a "V" notch weir in the measurement of
flow.