Maritime Questions › Enclosed Space Entry

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

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.

Q: What is the maximum validity period for an Enclosed Space Entry Permit under MSC.581(110)?

8 hours — it should never be exceeded Para. 5.2 introduces a defined validity period for the Entry Permit that must never exceed 8 hours, requiring SMS procedures to be updated and Responsible Persons trained to enforce this limit.

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

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

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

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

What is the maximum validity period for an Enclosed Space Entry Permit under MSC.581(110)?

A. 8 hours — it should never be exceeded

B. 24 hours, renewable once

C. The duration of the voyage leg

D. There is no defined maximum; it is left to the Responsible Person's discretion

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