Notch:-
- A notch is an opening in the side of a tank or a vessel in such away that the liquid surface is below the top edge of the opening.
- In other words, it is a device used to measure the rate of a liquid through a tank or a small channel.
- Mitch is a very thin structure, usually made of a metallic plate.
Weir:-
- A weir I'd an obstruction constructed over the channel, which causes the upstream level to rise until the flow across.
- In other words, a weir is a concrete or masonry structure across a stream or an open channel over which the liquid flow across.
- A weir is a notch on a large scale.
- It has a substantial breadth in the direction of flow.
* The terms related to notch and weir are:-
Nappe or Vein:-
The sheet of water flowing through a notch or weir is known as nappe or vein.
Crest or Sill:-
The bottom edge of a notch or the top edge of a weir over a which water flows is known as Crest or sill.
☆ Classification of Notches and Weirs:-
1. Notches:-
Notches are classified as:-
i. On the basis of their shape of opening:-
a. Rectangular notch
b. Triangular notch ( V- Notch)
c. Trapezoidal notch
d. Stepped notch.
ii. On the basis of effect of the sides of notch on the napple:-
a. Notch with end contraction.
b. Suppressed notch that is Notch without abby end contraction.
Must read:- Measurement of pressure, Absolute, Atmospheric and vaccum gauge.
2. Weirs:-
Weir's are classified as:-
i. On ther basis of shape:-
a. Rectangular weir
b. Triangular weir
c. Trapezoidal weir
ii. On the basis of shape of Crest:-
a. Narrow crested weir
b. Broad crested weir
c. Sharp crested weir
d. Ogee shaped weir
iii. On the basis of effect of sides of weir on the nappel:-
a. Contacted weir
b. Suppressed weir
iv. On the basis of discharge condition:-
a. Ordinary weir
b. Drowned or submerged weir.
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