On the one hand, protection of the freeze-drying system can be achieved by the admission of nitrogen and the exclusion of air. However, this variant is very costly and requires a constant availability of nitrogen. A simpler and less expensive option is to use an adsorber to dry the drawn-in air. Since the air pendulum volume is very small, this solution is suitable.
An adsorber with valves designed for the particular plant, for example of the VV-DV series, offers a long maintenance interval and provides the silicone oil with lasting protection against atmospheric moisture. Condensate and the resulting damage are avoided.
Moreover, maintenance is very simple. If the the silica gel, which is orange at the beginning, turns into a dark green (see illustration on the right), the entire cartridge must be replaced. There are no specific guidelines to be observed and the disposal can be done in the normal household waste.