The objective of this phase is to eliminate the air in the chamber fast and pre-heat the
load. For achieve that, system makes vacuum in chamber till for example 20.0 kPa
(removing the 80% of chamber air), and then reaches again the atmospheric value but
introducing pure steam in chamber for this. Repeating this process few times, nearly
100% of chamber air is removed.
Vacuum pulses are making vacuum into the chamber till the selected vacuum (P3a) and
intake steam till selected pressure (P3b) as times as required by the user (N3).