Work out oxygen deficiency risk instantly with clear inputs, formula shown and shareable results.
Any gas released into a confined space displaces air and dilutes oxygen in proportion to the volume added: predicted oxygen is measured oxygen times space volume over the total volume after release. Below 19.5 percent entry is prohibited without supplied air, and below 16 percent judgement is impaired before the victim recognises the problem.
Dilution
Predicted O2 = measured O2 x volume / (volume + inert gas released)
Restoration
Fresh air required = volume x (20.9 - predicted) / predicted
Preliminary estimate only. Confined space entry requires a permit system, calibrated continuous gas monitoring, forced ventilation and trained rescue arrangements.
Predicted O2 = measured O2 x volume / (volume + inert gas released). Any gas released into a confined space displaces air and dilutes oxygen in proportion to the volume added: predicted oxygen is measured oxygen times space volume over the total volume after release.
There is no smell or irritation, and the first symptom is impaired judgement, so the victim does not recognise the danger. It remains the leading cause of confined space fatalities.
This calculator takes 3 inputs: Measured oxygen, Space volume, Inert gas released into the space. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.