We usually install a safety valve on top of the fermenter when we design a fermenter. The safety valve, also known as a two-way pressure relief valve, is a device that automatically regulates the pressure inside the tank. When the pressure inside the fermenter is overpressure, it will trigger its switch and open automatically to release the pressure; or when there is negative pressure inside the fermenter, it can allow air to enter.

Some customers may wonder if the safety valve on the fermenter is effective in safeguarding the fermenter from damage when the beer is pumped from the fermenter to the keg.

In fact, safety valves mainly guard against overpressure/vacuum situations that occur slowly. If the change is large and sudden, the small hole of the safety valve cannot allow too fast gas flow. Second, whether the pressure inside the fermenter is overpressure can be easily read from the pressure gauge, but the pressure gauge cannot reflect the vacuum pressure inside the tank. So avoid sudden and large pressure fluctuation events as much as possible.

The inside of the fermenter is usually pressurized (1bar-2bar): when recirculating the beer with a pump, CO2 may escape from the beer and fill the fermenter without creating a vacuum pressure. Therefore CO2 back pressure or N2 back pressure is necessary to avoid foam and vacuum pressure when the beer level is getting low. It is important to note that to pump beer, use a diaphragm pump rather than a centrifugal pump, which is gentle and safe for the fermenter. No pressure (or very low pressure) inside the fermenter: open the CO2 drain / CIP drain slightly to avoid sudden vacuum pressure.