The attached plot shows 2 pumpdowns of the HAM6 chamber. The first is in April and the second in July.

In both cases the duration with rotating pumps is about 8 days. In an attempt to speed the crossover to the ion pump a larger power supply was used in the July pumpdown - this did allow an earlier transition to the ion pump. However, the vent time was longer and perhaps accounted for the same overall time on the turbo pump.