Your Ship’s Gas Detectors May No Longer Be Legal

Your Ship's Gas Detectors May No Longer Be Legal. Here's What IMO MSC.581(110) Requires.

Ten crew members died. Nineteen were hospitalised. Not because the ship’s fire suppression system failed, but because it worked exactly as designed.

The accidental activation of the CO₂ fire suppression system onboard the bulk carrier MV Jin Hai Xiang exposed a gap that maritime safety procedures had long overlooked: CO₂ can become lethal even when oxygen readings appear completely normal. Standard gas detection was not watching for it.

That incident is part of the reason the International Maritime Organization introduced MSC.581(110), which came into force in December 2025. For ship operators, safety managers, and procurement teams, this regulation is not just a policy update. It is a direct question about whether your current gas detection equipment is still fit for purpose.

Here is what changed, what it means for your fleet, and what you need to do before your next port inspection.

Why CO₂ Became Impossible to Ignore

CO₂ does not behave like other atmospheric hazards. It has no colour. No smell. And critically, it does not displace oxygen quickly enough to trigger a conventional O₂ alarm before incapacitating the person breathing it.

Data submitted to the IMO by InterManager confirms the scale of the problem. Casualties in enclosed spaces doubled between 2022 and 2023. Sixty-six percent of fatalities involved senior officers. Reporting delays and inconsistent atmospheric testing continued to place crews at risk.

In a separate incident, three stevedores died after exposure to dangerously high CO₂ concentrations emitted by organic cargo. In each case, the atmospheric testing conducted before entry was not equipped to detect what killed.

What MSC.581(110) Now Requires

The new regulation replaces A.1050(27) and fundamentally expands what vessel operators must test before authorising entry into any enclosed space, including cargo holds, ballast tanks, pump rooms, bilge spaces, chain lockers, and engine crankcases.

Under MSC.581(110), all vessels must ensure:

Mandatory CO₂ monitoring before enclosed space entry
Multi-gas detection capability across all vessel types
Enhanced atmospheric testing for adjacent and connected spaces
Stricter calibration accuracy and detector compliance standards

The regulation also establishes new atmospheric thresholds that must be confirmed before entry is permitted:

Oxygen (O₂): 20.9%
Carbon dioxide (CO₂): Below 0.5% (5,000 ppm)
Flammable gases: Below 1% LFL/LEL
Toxic gases: Below 50% of Occupational Exposure Limits (OELs)

On minimum detector requirements: vessels must carry at least two calibrated personal gas detectors. Those carrying hazardous cargoes or requiring frequent cargo-space entry must carry a minimum of four devices.

The Compliance Gap Most Fleets Are Now Facing

Most legacy portable gas detectors do not include a CO₂ sensor.

For years, confined space entry testing focused on oxygen, flammable gases, carbon monoxide, and hydrogen sulphide. CO₂ was not a standard requirement, and detectors were procured accordingly. MSC.581(110) changes that entirely.

Vessels carrying detectors without CO₂ sensing capability are operating outside the new regulatory standard. Port State Control inspectors are equipped to identify this gap, and the consequences of non-compliance range from operational delays to vessel detention.

What Compliant Gas Detection Looks Like

To meet MSC.581(110), your gas detection equipment must be capable of:

Detecting CO₂ accurately at concentrations approaching the 0.5% / 5,000 ppm threshold
Monitoring multiple gases simultaneously in a single pumped unit
Delivering fast sensor response times suitable for pre-entry atmospheric testing
Supporting accurate calibration with the correct span gas mixtures
Performing reliably in the humidity and temperature conditions typical of marine environments

The MSA ALTAIR 5X Multigas Detector meets each of these requirements. It detects up to five gases simultaneously in a single pumped unit, including CO₂, and includes InstantAlert, a manual emergency alarm function that gives crew members an additional layer of protection during confined space entry.

Why Supply Is a Real Concern Right Now

Across the maritime industry, demand for CO₂-capable gas detectors has surged since MSC.581(110) came into force. Many suppliers cannot keep pace.

MSA Safety manufactures its own CO₂ sensors. In anticipation of this regulatory shift, MSA increased production capacity ahead of the market demand curve. As PSA Africa’s supply partner, that means we can currently supply ALTAIR 5X units fitted with CO₂ sensors, fully compliant with MSC.581(110), without the lead times operators are encountering elsewhere.

The Calibration Step Operators Cannot Afford to Skip

Several investigations into enclosed space fatalities identified a consistent failure: detectors calibrated with incorrect span gas mixtures, producing unreliable readings that gave crews false confidence before entry.

MSC.581(110) places increased emphasis on calibration accuracy. Compliant CO₂ detection is only as reliable as the calibration process behind it. PSA Africa provides calibration services, bump testing support, and access to the correct calibration gas for ALTAIR 5X units operating in marine environments.

Steps to Take Before Your Next Inspection

Audit your current gas detection inventory against MSC.581(110) requirements
Identify which detectors lack CO₂ sensing capability
Determine the minimum number of compliant devices required for your vessel type and cargo profile
Confirm calibration records are current and that correct span gas mixtures are in use
Replace or supplement non-compliant units before your next Port State Control inspection

PSA Africa has supported maritime and industrial operators across Africa for more than 25 years. We can help you assess your current compliance position and source detection equipment that is in stock and ready to deploy.

Confined Space