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Notch and Weir, definition, classification, types, difference.

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. 



Notch and Weir, definition, classification, types, difference.

Notch and Weir, definition, classification, types, difference.

Notch and Weir, definition, classification, types, difference.

Notch and Weir, definition, classification, types, difference.

Notch and Weir, definition, classification, types, difference.



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