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Section summary |
---|

1. Definition of
the solids load ratio in pneumatic conveying systems |

2. Calculation of solid-loading ratio
in pneumatic conveying |

3. Usual values for dilute and dense
phase conveying solid to air ratio |

The solids load ratio is defined as the ratio of the mass of solids transported over the mass of air - or other gas - transporting the solids. Along with the air conveying velocity, the solids load ratio is very important parameter to characterize the flow of the solids in the conveying pipe and classify it as dilute phase, dense phase or intermediary.

The solids loading ratio is calculated by divided the mass flowrate of solids by the mass flowrate of conveying air.

**Equation 1 : calculation of solids loading ratio
**

With :

- m- m

**Note the following :** the litterature is giving various
formula for the solids load ratio to cope with different units. The
equation above is the most simplest way to calculate the ratio,
although you may have to make intermediary calculations to be able
to determine the air mass rate. It is important **to have both air
mass flowrate and material mass flow rate in the same units**.

Every conveying line is unique and will have its specific product air ratio, however, some orders of magnitudes can be given for both dilute and dense phase. Some of the ranges given overlap as at a same loading ratio in the intermediary zone some materials will behave in denser phase than others.

**Table 1 : Reference solids load ratio for dilute and dense phase
conveying**

Type of conveying | Material / air ratio |
---|---|

Dilute phase |
5-15 |

Intermediary |
10-30 |

Dense phase |
> 30 |

Generally speaking, the higher the solid-air ratio is, the higher the
pressure drop in the conveying pipe will be.