Facing the Challenges in Vaccine Upstream Bioprocessing * rAAV Production in Suspension CAP GT® Cells in BioBLU® 3c and 10c Single-Use Vessels Power number The impeller power number is a dimensionless number associated with different types of impellers. The impeller power number is used to calculate P/V using the following equation: P/V = (Np x ρ x N³ x d5)/V with Np being the impeller power number, ρ being the density of water (1000 kg/m³), N being the agitation speed (rps), d being the impeller outer diameter (m), and V being the full working volume (m³). To calculate P/V, the bioprocess engineers at Cevec used impeller power numbers which were experimentally determined in the Eppendorf applications laboratory. Experimental determination of power numbers using a rotational torque sensor requires a direct drive motor. To be able to measure the power numbers for BioBLU SingleUse Vessels-which have a magnetic drive-, the Eppendorf application scientists modified the vessels to remove the magnet from the magnetic drive coupling. They then connected the torque sensor directly to the impeller shaft. 26 | GENengnews.com Figure 2. Power numbers of BioBLU c Single-Use Vessels with one impeller were determined according to [1] and [2]. Power numbers were measured at tip speeds between 0.3 and 1 m/s and then the average was calculated. For the BioBLU 3c the mean was 2.98 and for the BioBLU 10c the mean was 3.33 (Figure 2).http://www.GENengnews.com