Outlet weir design standard

1. Type of outlet weir

There are three common types of outlet weirs: triangular weir, trapezoidal weir, and rectangular weir.

There are two types of triangular weirs: right-angled triangular weirs and acute-angled triangular weirs. Rectangular weirs are divided into non-submersible rectangular weirs and submerged rectangular weirs. This standard focuses on introducing triangular weirs and trapezoidal weirs commonly found in sewage.

Second, the triangular weir

2.1 Basic structure

Triangular outlet weir is abbreviated as triangular weir, which is mainly composed of two parts: weir plate and weir mouth. The common type is 90° triangle weir, namely right-angle triangle weir, its cross section is shown in Figure 1.

Figure 1: Partial cross-sectional view of the right-angled triangular weir

The meaning of each symbol in the figure is as follows:

a: length of weir;

b: Static distance between weirs;

c: Reserved length at the end of the weir;

d: height of weir mouth, its value is equal to 0.5a;

h: water depth across the weir;

H: Weir height;