The inerting pressure is very low, slightly higher than atmospheric, and is controlled by a tank blanketing valve which is often of sanitary design when used in food and biopharmaceutical processes. Sanitary tank blanketing valves can be made with USP Class VI materials or FDA approved materials depending on the process. An Equilibar FDO back pressure regulator (BPR) is a good fit for a sanitary tank blanketing valve. The schematic below shows how the FDO BPR would be installed for the inerting process.
How an FDO sanitary valve works for tank blanketing
Nitrogen gas inside the tank will build pressure as the tank is filled with sanitary process media. The Equilibar back pressure regulator will relieve the tank pressure when it reaches the desired blanket pressure.
The Equilibar BPR is dome-loaded with pilot operation. This means that gas or air is fed into the top (dome) area of the regulator to provide the pressure setpoint for the process in a 1 to 1 ratio. The pressure of the gas in the dome is set by a secondary standard regulator called a pilot regulator. The pilot setpoint pressure determines the blanket pressure above the media.
During fermentation or other sanitary batch processing, the Equilibar sanitary BPR will maintain the precise blanket pressure and make adjustments if pressure changes due to temperature fluctuations. As the process medium is drawn down and moved to the next processing step, the Equilibar FDO valve adjusts instantaneously to allow nitrogen gas into the tank to maintain pressure at the precise setpoint given by the pilot setpoint regulator. Equilibar FDO back pressure regulators are easy to maintain and very precise at low pressures making them an excellent choice in this application. If the process does not require the use of sanitary valve, Equilibar has standard back pressure regulators equally as precise for tank blanket control.
Contact an Equilibar application engineer for more information.