The IMO (International Maritime Organisation) regulatory update provides for the adoption of the Resolution MSC.581(110), updating the recommendations for entry into the enclosed spaces (enclosed spaces) on board ships. These recommendations were approved by the IMO Assembly and entered into force on 3 December 2025, replacing and revoking Resolution A.1050(27).
The aim of the revised recommendations is to reduce deaths and serious injuries associated with entering enclosed spaces. Indeed, these working environments are still among the most dangerous on board ships. There are often oxygen-deficient or oxygen-enriched atmospheres, as well as the possible presence of flammable or toxic gases.
The main new features of the IMO regulatory update
For atmospheric testing prior to entry into enclosed spaces, hand-held detectors must now be able to measure at least 5 gases, including mandatory CO₂ (carbon dioxide).
Consequently, the traditional 4-gas detectors are no longer sufficient to meet the new IMO recommendations on enclosed spaces.
Minimum required configuration (“5 gas”)
Hand-held detectors must allow the measurement of:
- Oxygen (O2).
- Flammable gases or vapours (LEL).
- Carbon monoxide (CO).
- Carbon dioxide (CO2), the new requirement.
- Other toxic gases identified by the risk assessment (typically H2S).
Criteria for entry into the enclosed spaces
Entry into enclosed spaces on board ships is only permitted when atmospheric measurements confirm that all parameters are within acceptable limits:
- O₂ ≥ 20.9% by volume.
- CO₂ < 0.5% by volume (5,000 ppm).
- Flammable gases/vapours < 1% of LFL.
- Toxic gases/vapours < 50% of the applicable occupational exposure limit (OEL).
Implications for shipowners and operators
The revised recommendations define new operational methods for managing entry into enclosed spaces, with implications for ship owners and operators, including:
- Upgrade or replacement of existing portable detectors.
- Adaptation of confined space entry procedures.
- Updating the Safety Management System (SMS).
- Calibration, maintenance and crew training.
Ventis Pro5 from Industrial Scientific
With the entry into force of Resolution MSC.581(110), it becomes essential to have portable detectors 5-gas with CO2. The most suitable solution is Ventis Pro5 from Industrial Scientific.
- Customised configuration optionsIt allows the configuration of sensors (standard and non-standard 4-gas, 5-gas and methane IR sensors) and alarms for the detection of up to five gases among LEL (Methane), LEL (Pentane), Cl₂, CO, CO₂, H₂S, HCN, NO₂, NH₃, O₂, PH₃, SO₂ and VOC.
- IP68 degree of protectionIt withstands the most extreme conditions thanks to its IP68 protection rating, backed by a Guaranteed for Life™ warranty.
- iNet Now wireless connectivityIt ensures connectivity between all workers, sharing real-time data on gas readings, location and man-down alarms, so everyone can know who is in danger and why.
- Reducing human error: reinforces safe behaviour with programmable alarm action messages such as “EVACUATE” or “VENTILATE” depending on the alarm level.
- Risk reductionIt reduces the risks and costs associated with using several gas detectors by using one detector for all needs, from personal monitoring to entry into enclosed spaces.
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Contact us to find out about our portable gas detectors and how to comply with regulations. Trust our experts, awarded at the Industrial Scientific EMEA Conference 2026 with the “Largest iNet Launch Award 2025” by Industrial Scientific. This recognition strengthens Irbema's role as a strategic partner of Industrial Scientific in Italy.
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