Difference between revisions of "Flow through perforated pipe"
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| − | Manufacturers of perforated pipe are often able to provide the open area | + | Manufacturers of perforated pipe are often able to provide the open area per meter length. |
<math>Q_{max, p}=B\times C_{d}\times A_{o}\sqrt{2\cdot g\cdot \sum d}</math> | <math>Q_{max, p}=B\times C_{d}\times A_{o}\sqrt{2\cdot g\cdot \sum d}</math> | ||
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*''g'' is acceleration due to gravity (m/s<sup>2</sup>) | *''g'' is acceleration due to gravity (m/s<sup>2</sup>) | ||
*''Σ d'' is the total depth of bioretention components over the perforated pipe (mm) (e.g. ponding/[[mulch]]/[[filter media]]/[[choker layer]]), | *''Σ d'' is the total depth of bioretention components over the perforated pipe (mm) (e.g. ponding/[[mulch]]/[[filter media]]/[[choker layer]]), | ||
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| + | ===Example calculation=== | ||
| + | A part used roll of 100 mm diameter perforated pipe appears long enough to use for a stormwater planter project. Upon inspection the pipe is found to have perforations of 8 x 1.5 mm on six sides, repeated every 3 cm along the pipe. To calculate the maximum flow rate, first the open area per meter is calculated: | ||
| + | <math>\frac{0.008 m \times 0.0012 m\times6}{0.03 m }= m^{2}/m</math> | ||
Revision as of 03:23, 25 February 2018
Manufacturers of perforated pipe are often able to provide the open area per meter length.
Where:d is the coefficient of discharge (0.61 for a sharp edged orifice),
- B is the clogging factor (between 0.5 to calculate a for matured installation and 1 to calculate a new perfectly performing BMP),
- Cd is the coefficient of discharge (usually 0.61 for the sharp edge created by relatively thin pipe walls),
- Ao is the total open area per unit length of pipe (m2/m),
- g is acceleration due to gravity (m/s2)
- Σ d is the total depth of bioretention components over the perforated pipe (mm) (e.g. ponding/mulch/filter media/choker layer),
Example calculation[edit]
A part used roll of 100 mm diameter perforated pipe appears long enough to use for a stormwater planter project. Upon inspection the pipe is found to have perforations of 8 x 1.5 mm on six sides, repeated every 3 cm along the pipe. To calculate the maximum flow rate, first the open area per meter is calculated:
