Maritime Questions › Enclosed Space Entry

What is the principal hazard of testing a space using only a sample drawn through a long sample line lowered from the entrance, without also taking readings progressively as personnel descend?

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. A remote sample line can miss localised pockets and time-lag in the line can give a falsely reassuring average reading that does not reflect conditions at the point of entry

B. There is no hazard — a remote sample is always more accurate than readings taken while descending

C. Sample lines only work for oxygen, not for flammable or toxic gases

D. Sample lines are banned under COSWP and may not be used at all

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. 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

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