What is a rectangular weir?
[rek′taŋ·gyə·lər ′wer] (civil engineering) A weir with a rectangular notch at top for measurement of water flow in open channels; it is simple, easy to make, accurate, and popular.
How do you size a weir?
The Length is the bottom width of the weir. The height is measured from the bottom of the weir opening to the top of the water level ponded behind the weir (not the water level right as it leaves the weir).
How do you calculate rectangular weir?
The equation recommended by the Bureau of Reclamation in their Water Measurement Manual, for use with a suppressed rectangular weir is: Q = 3.33 B H3/2, where Q is the water flow rate in ft3/sec, B is the length of the weir (and the channel width) in ft, and H is the head over the weir in ft.
What is weir height?
The height of the weir from the bottom of the channel to the crest should be at least 2 times the maximum expected head of liquid above the crest. This is necessary to lower the velocity of approach. The weir height should never be less than 1 foot (0.3 m).
What is suppressed rectangular weir?
Standard Suppressed Rectangular Weir. A standard suppressed rectangular weir has a horizontal crest that crosses the full channel width. The elevation of the crest is high enough to assure full bottom crest contraction of the nappe.
Is the standard shape of a weir?
Explanation: Rectangular is the standard shape of a weir. Triangular and trapezoidal weirs are modifications of it. They are generally suitable for larger flowing channels.
What is pond level in weir?
(vii) Pond Level: The weir stores water on its upstream side in front of a head regulator to create a still pond. The canal gets water from this pond through the head regulator . The pond level determines the crest level and the height of the shutters to be provided.
How many types of weir are?
How many types of weirs are there based on the shape of the crest? Explanation: The four types are sharp-crested, broad-crested, narrow-crested and ogee-shaped weir.
What is the head over the rectangular weir?
The head over the rectangular weir is measured and correlated with the water flow rate through the open channel (and over the weir). A rectangular weir equation gives water flow rate as a function of head over the rectangular weir.
What is the formula for a fully contracted rectangular weir?
Contracted Rectangular Weir Equation. For S.I units the fully contracted rectangular weir equation is: Q = 1.84(L – 0.2H)H 3/2, where Q is the water flow rate in m 3 /sec, and H is in m. This weir equation is subject to the same conditions given above.
What is a sharp crested rectangular weir?
A sharp crested, rectangular weir is simply a flat plate obstruction in an open channel flow path, with a straight, level opening to allow water flow over the weir, as shown in the pictures and diagrams in the rest of this article.
What is a suppressed rectangular weir used for?
The suppressed rectangular weir in the picture at the left is being used to meter flow of water in an open channel. The equation recommended by the Bureau of Reclamation in their Water Measurement Manual, for use with a suppressed rectangular weir is: