Maritime Questions › Enclosed Space Entry

Which of the following is NOT, by itself, a reliable indicator that a space is safe to enter?

Q: Under MSC.581(110), what is the maximum acceptable CO2 reading (by volume) before an enclosed space can be considered safe for entry?

Less than 0.5% by volume (5,000 ppm) Para. 7.4 sets the CO2 exposure limit at below 0.5% by volume (5,000 ppm) before entry; if this is not achieved, the space remains unsafe. CO2 is now explicitly addressed as a major asphyxiation hazard alongside oxygen depletion.

A. The space was tested and found safe several hours ago, before it was closed up again

B. A current, correctly calibrated atmosphere test taken from multiple levels showing acceptable readings

C. Continuous monitoring throughout the entry confirming the atmosphere remains acceptable

D. A valid, signed permit covering the current entry

Under MSC.581(110), what is the maximum acceptable CO2 reading (by volume) before an enclosed space can be considered safe for entry?

A. Less than 0.5% by volume (5,000 ppm)

B. Less than 2% by volume

C. Less than 21% by volume

D. There is no specific CO2 limit, only an oxygen limit

Under the revised recommendations, is single-person entry into an enclosed space ever permitted?

A. Yes, provided the person carries a personal gas detector

B. No — the company must ensure single-person entry into an enclosed space is not permitted

C. Yes, for spaces that have previously tested safe within the last 24 hours

D. Yes, but only for spaces below 5 metres in depth

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