CEN/TR 15281:2022

Inerting Calculations

Explosion prevention through oxygen concentration reduction

Swing Inerting Flow-Through Purging Vent / Manhole Diffusion

Combined Swing Inerting — Annex A

Enter a lower and an upper swing pressure. Typically the lower pressure is a vacuum and the upper is an overpressure, but either may be atmospheric for a pure pressure- or vacuum-swing process. CEN/TR 15281:2022 §4.3.3.1 permits combining both methods.

Oxygen limits

LOC — Limiting Oxygen Concentration [%v/v] From EN 1839 (gases/vapours) or EN 14034-4 (dusts). Optional — used to derive MAOC.

Oxygen monitoring

Continuous Periodic

Determines the MAOC safety margin (§4.4.5.3.1).

Target O₂ concentration C_n [%v/v] Should be ≤ MAOC.

Gas concentrations

Initial O₂ C₀ [%v/v] 21 % for air; editable.

O₂ in inert gas C_i [%v/v] 200 ppm N₂ = 0.02 %; up to 3 % for some sources.

Swing pressures

Lower pressure P₁ (typically vacuum)

Default unit: bar absolute. Pure pressure swing → set this to atmospheric (≈1.013 bara).

Upper pressure P₂ (typically overpressure)

Pure vacuum swing → set this to atmospheric (≈1.013 bara). Overpressure is often given in barg.

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Equipment / tag

Prepared by

Enter the parameters and click Calculate.

Formula A.1 (CEN/TR 15281:2022 Annex A):
C_n = C_i + (C₀ − C_i) × (P₁/P₂)ⁿ

Formula A.2 — cycles required:
n = log[(C_n − C_i) / (C₀ − C_i)] / log(P₁/P₂)