Space velocity (chemistry)

The space velocity is a term which is of significance in industrial chemistry. She sits by forming the quotient a volume flow - usually a gas, but also for liquids - with a spatial volume V - eg a catalyst or adsorbent bed - according to the formula

In relationship. Space velocity represents the inverse of the retention time the more frequently used

If the flow rate based on the hour, the unit is given by:

In catalysts, the volume refers to the macroscopic catalyst volume, the volume flow is independent of the shape or internal structure of the catalyst.


  • In heterogeneous catalysis can be calculated for the conversion of a known volume flow in this way the catalyst volume required.
  • In the ad- or absorption thus can the required amount of ad / determine absorber volume to treat a given flow rate.