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1. Introduction

2. Calculation

3. Pipe velocities recommendation

The fluid velocity in a pipe is a fundamental data to calculate to be able to characterize the flow in a pipe, thanks to the Reynolds number, and size a pipe circuit calculating the pressure drop expected for a certain flow.

When designing the pipe, it is necessary to **chose a fluid
velocity to have good compromise in between pressure drop and
economics, some recommendations are given below.**

With :

Q = Volumetric flowrate (m^{3}/s)

D = Pipe diameter (m)

u = Fluid velocity in pipe (m/s)

Note that the velocity will be constant for a non compressible fluid but will vary with a compressible fluid such as a gas. For a gas it is therefore necessary to slice the pipe layout in several sections in order to recalculate the velocity along the pipe.

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Fluid | Recommended velocity |
---|---|

Water |
1.5-2.5 m/s [1]1-2.5 m/s [2] |

Air |
10-30 m/s [1] 30 m/s [2] |

Steam |
20-40 m/s [1]HP : 45 m/s [2] LP : 30 m/s [2] |

Gas Process flows |
15-45 m/s |

Dry gas |
30 m/s [2] |

Wet gas |
18 m/s [2] |

In addition to the sources given below, one may also wish to consult

[1] Mecanique et Rheologies des fluides en Genie
Chimique, Midoux, Tec et Docs, 1993

[2] Rules of Thumbs for Chemical Engineers, Brannan,
Gulf, 2005