Calculations
Input data
Flow
Output data
Minimum Parshall size
k minimum
n minimum
Velocity gradient of the minimum size
Intermediary Parshall size
k intermediary
n intermediary
Velocity gradient of the intermediary size
Maximum Parshall size
k maximum
n maximum
Velocity gradient of the maximum size
Description
Given the flow, selects the Parshall size. In some cases, it indicates up to three possibilities. It shows the values for k and n of the equation , for each case (metric units), as well as the corresponding velocity gradient.
Parshall dimensions table
| W (in or ft) | W (cm) | A | B | C | D | E | F | G | K | N |
|---|---|---|---|---|---|---|---|---|---|---|
| 1” | 2.5 | 36.3 | 35.6 | 9.3 | 16.8 | 22.9 | 7.6 | 20.3 | 1.9 | 2.9 |
| 3” | 7.6 | 46.6 | 45.7 | 17.8 | 25.9 | 38.1 | 15.2 | 30.5 | 2.5 | 5.7 |
| 6” | 15.2 | 62.1 | 61 | 39.4 | 40.3 | 45.7 | 30.5 | 61 | 7.6 | 11.4 |
| 9” | 22.9 | 88 | 86.4 | 38.1 | 57.5 | 61 | 30.5 | 45.7 | 7.6 | 11.4 |
| 1’ | 30.5 | 137.1 | 134.4 | 61 | 84.5 | 76.2 | 61 | 91.5 | 7.6 | 22.9 |
| 1,5’ | 45.7 | 144.8 | 142 | 76.2 | 102.6 | 91.5 | 61 | 91.5 | 7.6 | 22.9 |
| 2’ | 61 | 152.3 | 149.3 | 91.5 | 120.7 | 91.5 | 61 | 91.5 | 7.6 | 22.9 |
| 3’ | 91.5 | 167.5 | 164.2 | 122 | 157.2 | 91.5 | 61 | 91.5 | 7.6 | 22.9 |
| 4’ | 122 | 182.8 | 179.2 | 152.5 | 193.8 | 91.5 | 61 | 91.5 | 7.6 | 22.9 |
| 5’ | 152.5 | 198 | 194.1 | 183 | 230.3 | 91.5 | 61 | 91.5 | 7.6 | 22.9 |
| 6’ | 183 | 213.3 | 209 | 213.5 | 266.7 | 91.5 | 61 | 91.5 | 7.6 | 22.9 |
| 7’ | 213.5 | 228.6 | 224 | 244 | 303 | 91.5 | 61 | 91.5 | 7.6 | 22.9 |
| 8’ | 244 | 244 | 239 | 274,5 | 340 | 91.5 | 61 | 91.5 | 7.6 | 22.9 |
| 10’ | 305 | 274.5 | 260.8 | 366 | 475.9 | 122 | 91.5 | 183 | 15.3 | 34.3 |
Source: AZEVEDO NETTO, J. M. de; FERNANDEZ Y FERNANDEZ, Miguel. Manual de hidráulica, 9.ed. São Paulo: Blucher, 2015.
Note:
The value of velocity gradient must be verified through hydraulic calculations. It was obtained using the following expression::
Source: (Vianna, Marcos R. Hidráulica aplicada às estações de tratamento de água. 6. ed. Belo Horizonte: Bloom, 2019);
Get to Know Life Saneamento
Discover the innovative solutions from Life Saneamento in water and sewage treatment plants made of FRP (Fiber Reinforced Polyester) and Stainless Steel. Learn more at https://www.lifesaneamento.com.br/
References
- Parlatore, A. C. Mistura e floculação. In: CETESB. Técnica de abastecimento e tratamento de água. Vol. II. São Paulo:CETESB, 1974.