Cargo Tank Gas-Freeing & Ventilation Time Tool
SOLAS II-2/16.3 • Hydrocarbon Purge <2% vol • Air Gas-Freeing • %LFL • O₂ Recovery • Fan Capacity • Outlet Velocity • Multi-Tank Schedule
Cargo Tank Gas-Freeing & Ventilation Time Tool
Plan the atmospheric transition from hydrocarbon-rich or inert cargo-tank conditions to a measured gas-free state. Simple mode models the two-stage inert-gas purge and air-ventilation sequence. Advanced adds multiple tanks, sequential or parallel ventilation, fan availability, non-IG tanker outlet-velocity screening, 30% LFL deck-level transition and tank-by-tank atmosphere targets.
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This is a time-planning model, not a safe-entry certificate.Actual hydrocarbon, oxygen, H₂S, benzene and other toxic-gas measurements throughout the tank remain controlling.Phase 1IG purge to <2% HC
Phase 2Air ventilation to gas target
AtmosphereHC / %LFL / O₂ timeline
Tank Atmosphere
m³.
% by volume.
% by volume.
% hydrocarbon by volume. Enter cargo-specific value.
% of LFL, not vol%. 1% LFL is a conservative entry-reference target.
% by volume. Actual entry criteria require measurement, not model prediction.
Purging & Gas-Freeing
m³/h.
m³/h.
%.
%.
Vessel / Procedure Basis
% by volume.
% vol. Gas-freeing with air begins only after <2% on an IG-equipped tanker.
% of cargo LFL.
Inert Gas Delivery
m³/h.
Gas-Freeing Fan Register
Available fan capacity is summed. Parallel mode distributes available air in proportion to tank vapour volume; sequential mode gives full available air flow to one tank at a time.
| Use | Fan capacity m³/h | Available now? | Outlet area m² | Flame-protected outlet? |
|---|
Cargo Tank Register
| Use | Vapour volume m³ | Initial HC vol% | Initial O₂ % | Cargo LFL vol% |
|---|
Gas-Freeing Safety Checks
Entry warning: modeled concentration is never a substitute for atmosphere testing. Public OCIMF guidance for entry without breathing apparatus calls for testing throughout the space to confirm cargo vapour below 1% LFL, oxygen at 21% by volume, and absence of H₂S, benzene and other toxic gases as appropriate. Your vessel/company/flag enclosed-space entry criteria remain controlling.