The PLAATO Valve connects between your fermenter and airlock and equalizes any negative pressure that might be present in the system. It eliminates suck-back during fermentation or cold crashing, and increases control if you want an oxygen-free atmosphere during fermentation.
Many brewers experiences suddenly empty airlocks, or water flowing from the blow-off vessel to the fermenter. This phenomena is due to temperature changes that in turn lead to negative pressure in the fermenter. This is seen the moment a fermenter is placed in a temperature controlled room after pitching of yeast, or during cold crash. To offset this negative pressure, the fermenter will either suck in water from an airlock, or suck in air, or in some rare cases implode under the forces of this pressure. In most cases air will be introduced in the fermenter in the hours before the fermentation starts, and during cold crash.
The PLAATO Valve is made out of FDA-approved food grade PP and has an incorporated umbrella silicon valve as working principle. It comes ready with optional 65PPI activated carbon filters for the inlet (16pcs), and fits most airlocks and fermenters.
As stated above, rapid changes in temperature will always introduce air, water or partial implosion into the fermenter. In order to obtain a non-oxidizing atmosphere, the headspace in the fermenter must therefore be flushed with CO2.
For cold-crash, the oxygen in the headspace is already replaced by CO2, so introduction of small amounts of oxygen is not a significant source of oxidation.
If you are aiming for an oxygen-free fermentation, the Plaato valve is designed to be connectable to a bag containing CO2/inert gas, maintaining a non-oxidizing atmosphere in the fermenter.