Maritime Questions › Enclosed Space Entry

What should the attendant/standby person do if they lose communication with the entrant and cannot re-establish contact within a short, pre-agreed time?

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. Wait a further 15-20 minutes before doing anything, in case it is just a radio fault

B. Shout down the access and, if no answer, assume the entrant has simply moved out of hearing range and continue waiting

C. Raise the alarm immediately and initiate the emergency rescue plan — they must NOT enter the space themselves to investigate

D. Enter the space immediately to check on the entrant

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

+45 more Enclosed Space Entry questions available

Create a free account to practise all 48 questions, track your accuracy, and build your Reputation Score.

Create Free Account