Enclosed Space Ventilation, Gas-Freeing, Detector & Rescue Readiness Tool
MSC.581(110) • SOLAS XI-1/7 • SOLAS III/19 • Ventilation Dilution • Atmosphere Testing • Permit • Detector • SCBA • Rescue
Enclosed Space Ventilation, Gas-Freeing, Detector & Rescue Readiness Tool
Estimate theoretical ventilation time, screen the actual pre-entry atmosphere against current IMO recommendations, verify permit and control readiness, and use Advanced to model multiple spaces, detector sampling, gas-freeing, rescue breathing-air endurance and retrieval capacity. No calculator result authorizes enclosed-space entry.
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Need much more depth? Click Advanced above.Advanced adds individual gas dilution times, multiple enclosed spaces, detector/sampling hose checks, calibration, isolation/attendant/communications controls, rescue-drill status, SCBA endurance, retrieval SWL and ventilation-upgrade economics.Fast10 primary inputs
Core answerAtmosphere + entry-control screen
Never authorizesShip SMS and responsible person control
Fast Pre-Entry Screen
Enter the stable atmosphere actually measured after ventilation has been stopped and the space has stabilized. Calculated ventilation time never replaces gas testing.
m³ after major internal obstructions.
m³/h actually reaching/mixing through the space.
% volume.
% of LFL.
ppm.
% of that gas's applicable OEL.
minutes. MSC.581 example permit notes about 10 minutes.
hours. Current recommendation: never over 8 hours.
Space & Hazard Basis
Current IMO principle: a connected space should be treated as containing a hazardous atmosphere until testing proves otherwise. Risk assessment, the Enclosed Space Register and the actual entry procedure remain ship-specific.
Advanced Enclosed-Space Register
Each space is screened independently. Space names stay on screen only and are not transmitted through Tool Data.
| Space | Volume m³ | Effective flow m³/h | O₂ % | LFL % | CO₂ ppm | Toxic ppm | Toxic OEL ppm | Continuous vent |
|---|
Forced Ventilation & Gas-Freeing Model
m³/h.
% of rated blower flow delivered.
% after dead zones / poor distribution.
% volume.
ppm.
% for theoretical dilution math only. Actual pre-entry recommendation remains 20.9%.
% added to theoretical gas-freeing time.
Initial Atmosphere for Gas-Freeing Model
% volume.
% LFL.
ppm.
ppm.
ppm.
ppm.
ppm. Enter applicable national/company OEL.
ppm.
ppm.
% of applicable OEL.
Actual Pre-Entry Atmosphere Test
These stable readings control the atmosphere screen. The gas-freeing calculation above never authorizes entry.
% volume.
% LFL.
ppm.
ppm.
ppm.
ppm.
percentage points. Tool screening tolerance, not an IMO replacement threshold.
minutes.
Gas Detector & Sampling Readiness
MSC.581 recommends at least two sets on all ships.
days, maker/SMS basis.
m.
L/min.
mm. Used only for hose-volume purge estimate.
Permit, Isolation & Entry Controls
hours. MSC.581 recommends never more than 8 hours.
Single-person entry should not be permitted.
SOLAS III/19 requires at least every two months; the tool uses a conservative 60-day planning screen.
SCBA & Rescue-Team Endurance
L.
bar.
% of nominal cylinder free-air volume used for planning.
L/min per rescuer under workload.
min.
min.
m.
m/min.
kg.
kg.
Ventilation Upgrade / Delay Economics
m³/h before same duct/mixing derates.
selected currency/day.
selected currency/hour.
%.
Life-safety limitation: this tool does not declare an enclosed space safe and must never be used instead of the ship's SMS, Enclosed Space Register, risk assessment, permit, responsible person, competent atmosphere testing, cargo-specific guidance, flag requirements or staged rescue plan. Gas pockets, stratification, corrosion, biological oxygen depletion, continuing gas generation, cargo residues, fumigants, leaks and blocked ventilation paths can invalidate theoretical dilution calculations.