Nitrogen overpressure

In nitrogen overpressure, a process space is pressurized with nitrogen. The pressure is above the ambient pressure. The goal is to achieve a low-oxygen or oxygen-free atmosphere.

Oxygen mole fraction in the gas phase: x_O2 = n_O2 / n_total

• x_O2 = mole fraction (or concentration in terms of share) of oxygen in the gas phase (dimensionless)
• n_O2 = amount of substance of oxygen in the gas phase (mol)
• n_total = total amount of substance of all gas components combined (mol)

Overpressure share of nitrogen: p_N2,over = p_system − p_ambient

• p_N2,over = "overpressure" contribution attributed here to nitrogen (e.g., bar or Pa)
• p_system = pressure in the system (e.g., in the vessel)
• p_ambient = ambient pressure (e.g., atmospheric pressure)

Nitrogen overpressure is used to prevent oxidation, moisture absorption, and microbial growth. It is also used for inerting in the case of dust-explosive or flammable substances. Typical areas of application are mixers, silos, reactors, filters, and conveying lines.