A Weir Box is a simply fabricated box or vault into which a weir plate has been installed to measure the flow of piped water. The water being measured cannot be under pressure and the pipe should generally not flow full prior to the attachment of the weir box to the pipe.
Weir Boxes can incorporate several different weir plate types:
- V-notch
- 22-1/2º, 30º, 45º, 60º, 90º
- 120º notches can be incorporated, but the loss of flow resolution and the larger box width general preclude their use
- Cipoletti
- 12-inch or 18-inch are most common
- Rectangular
- With our without end contractions
