# How do you calculate flow rate through a weir?

## How do you calculate flow rate through a weir?

Weirs to Measure Flow It works by raising the water level upstream of the weir, and then forcing the water to spill over. The more water is flowing over the weir, the deeper the water will be upstream of the weir. So measuring flow rate (CFS) can be done by simply measuring the depth of the water upstream.

## What is the Weir equation?

The Weir formula is a formula used in indirect calorimetry, relating metabolic rate to oxygen consumption and carbon dioxide production. According to original source, it says: Metabolic rate (kcal per day) = 1440 (3.9 VO2 + 1.1 VCO2)

**What is rectangular weir?**

Rectangular weirs and triangular or v-notch weirs are often used in water supply, wastewater and sewage systems. They consist of a sharp edged plate with a rectangular, triangular or v-notch profile for the water flow.

**What is Francis formula?**

Q = 2 3 × C d × L × 2 g [ H ] 3 2.

### What is flow over weirs?

Weirs are commonly used to measure or regulate flow in rivers, streams, irrigation canals, etc. Installing a weir in an open channel system causes critical depth to form over the weir. Since there is a unique relationship between the critical depth and discharge, a weir can be designed as a flow-measuring device.

### 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.

**What is weir flow?**

A flow measuring weir is simply a structure over which water flows in such a way that volumetric flow rate can be calculated…. it lets you know how much water is flowing. Many times a flow measuring weir is simply a thin plate across a flow stream, but weirs can also be broad, thick structures.

**How do you calculate weir discharge coefficient?**

The generalized weir equation can be written as Q = C D C V C S C P C b l g b h 1.5 where CD is a discharge coefficient, Cv is the velocity coefficient, both as defined before, Cs is a shape coefficient depending on the lateral shape of the crest (e.g. shallow ‘Vee’), Cp is a coefficient to take into account the height …

#### What is the weir coefficient?

The weir coefficient, since it is a function of the gravitational constant, is not dimensionless and therefore has different values depending on which unit system you are using. For example, a weir coefficient (C) of 3.00 in English Units would be 1.66 in SI units.

#### What is Francis formula for rectangular weir?

Q. | According to Francis formula, the discharge over a rectangular weir is (where n = Number of end contractions) |
---|---|

A. | (2/3) × Cd (L – nH) × |

B. | (2/3) × Cd (L – 0.1nH) × × H3/2 |

C. | (2/3) × Cd (L – nH) × × H² |

D. | (2/3) × Cd (L – nH) × × H5/2 |

**How is weir length calculated?**

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).

**What is weir coefficient?**