Functionality and target color gradient

When using an adsorber on a hydraulic tank, gearbox, storage tank as well as barrels and IBCs, the ambient air drawn in will flow into the adsorber from below (see figure). In the process, the desiccant silica gel absorbs the water from the air and changes color. In most adsorbers, the color changes from orange to a dark blue-green.
If the adsorber has valves, only the air sucked in will flow into the granulate and be dried by it. Without valves, the dry granulate is exposed to permanent loading by diffusion.

Maximum load

With increasing loading of the silica gel, the color change moves from the bottom to the top of the adsorber. In the process, the entire body acquires a very dark hue. Once the color change is complete, the silica gel must be replaced, as it no longer absorbs water and becomes ineffective.

Cause – Adsorber discolors from above

If the adsorber discolors from above, this indicates moisture escaping from the system. The adsorber is designed as an aerator and deaerator. Thus, incoming air is dried and this dry air is used to regenerate the silica gel as it flows down through the adsorber from the top.

However, if the air present in the tank, or even the liquid, have a certain amount of water, the adsorber will absorb this moisture – the color will change from the top. This will always be the case if an aeration dryer is installed right from the beginning, but only after several months (or years).

Solution and procedure

Due to this effect, the plant is continuously dried in the interior and the operating conditions are significantly improved. At the beginning of the use of an adsorber, the loading from the top can take place very quickly. However, this cycle will slow down with each silica gel exchange until loading only takes place from below and thus only the ambient air dries before it flows in.

Picture 1: Loading starts from the top. Plant is dried and protected from moisture

Picture 2: Loading from the top slows down and also starts from the bottom. Plant is effectively protected.

Picture 3: Loading only takes place from below. Plant interior is dry and no new moisture flows in