Which gas detector complies with current maritime regulations?

A gas detector complies with current maritime regulations when it meets the requirements set by SOLAS XI-1/7, the relevant IMO resolutions, and the certification standards of recognized classification societies. As of 2026, the adoption of IMO Resolution MSC 581(110) has raised the bar significantly: standard 4-gas monitors are no longer sufficient for all situations, and CO2 detection at parts-per-million resolution is now a mandatory parameter for enclosed space entry on many vessel types. Below, we answer the most common questions fleet engineers ask when selecting or replacing a compliant marine gas detector.

What regulations govern gas detection on ships?

Gas detection on ships is governed primarily by SOLAS (Safety of Life at Sea), supplemented by IMO resolutions and classification society rules. SOLAS XI-1/7 requires ships to carry portable atmospheric testing instruments for enclosed space entry. IMO Resolution MSC 581(110), endorsed in December 2025, now supersedes the older Resolution A 1050(27) and sets a stricter, more technically detailed framework for confined space safety.

MSC 581(110) is not a routine administrative update. It introduces a “Closed-Loop Management” philosophy, meaning safety must be verifiable, continuously monitored, and backed by a documented rescue framework. Key changes include:

CO2 detection is now a mandatory pre-entry testing parameter alongside O2, flammable gases, and CO
Entry is only permitted when CO2 levels are confirmed below 0.5% (5,000 ppm)
Connected and adjacent spaces must be independently assessed and ventilated
A vessel-specific Enclosed Space Register must be maintained on board and synchronized with the shore-side office in real time
A dedicated Enclosed Space Emergency Response Plan is required before any entry permit is issued

RightShip RiSQ version 3.2 has already integrated these requirements into its inspection scope, so Port State Control inspections now reflect the new standard. For fleet engineers, this means the gas detection equipment you carried in 2024 may not satisfy an inspection today.

What types of gas detectors are required on different vessel types?

The type of gas detector required depends on the cargo carried, the spaces being entered, and the vessel’s specific risk profile. All ships subject to SOLAS must carry portable multi-gas detectors capable of measuring oxygen (O2), flammable gases (LEL), and toxic gases. Under MSC 581(110), CO2 detection at ppm resolution is now mandatory for any vessel where cargo or structural conditions can deplete oxygen or generate CO2.

Here is a practical overview of detection requirements by situation:

General cargo and bulk carriers: Full 5-gas capability (O2, LEL, CO, H2S, CO2 at ppm level) is now the benchmark, particularly because damp iron cargo such as scrap metal can cause rapid oxygen depletion through oxidation
Tankers: Combustible gas detection (LEL) and O2 monitoring are standard; CO and H2S sensors are also required depending on the product carried
Vessels with enclosed cargo holds: CO2 ppm monitoring is specifically triggered by MSC 581(110) for spaces where rusting or organic cargo can generate hazardous atmospheres
All vessel types: Portable detectors must be able to test connected and adjacent spaces independently, not just the primary entry point

The key practical shift is that legacy 4-in-1 detectors measuring LEL, O2, CO, and H2S are no longer sufficient for full compliance on vessels where CO2 is a credible hazard. Non-Dispersive Infrared (NDIR) sensor technology is now the benchmark for CO2 detection because it provides the high-resolution ppm monitoring that traditional electrochemical sensors cannot deliver.

What certifications must a compliant marine gas detector carry?

A compliant marine gas detector must carry type approval from a recognized classification society, such as DNV, Lloyd’s Register, Bureau Veritas, or another society accepted by the flag state. For detectors used in hazardous areas on tankers or gas carriers, additional ATEX or IECEx certification for intrinsic safety is required. Detectors used for enclosed space entry must also meet the sensor performance thresholds defined by MSC 581(110).

When evaluating certifications, check for the following:

Classification society type approval: Confirms the detector meets the technical standards recognized by SOLAS and port state authorities
ATEX / IECEx certification: Required for use in potentially explosive atmospheres, such as cargo holds or pump rooms on tankers
CO2 sensor resolution: The detector must be capable of accurately measuring CO2 down to the 5,000 ppm regulatory limit; standard percent-range sensors do not meet this requirement
Calibration records: Port State Control inspectors treat an unrecorded or uncalibrated test as a test that did not occur; current calibration documentation is part of compliance

It is worth checking whether the detector you are considering is compatible with your existing onboard equipment and inspection records. A detector that carries the right certifications but cannot be calibrated in your port of call creates practical problems that are just as serious as a certification gap. Our fire and gas detection systems are selected with exactly this compatibility question in mind.

What’s the difference between fixed and portable gas detectors for maritime use?

Fixed gas detectors are permanently installed in specific locations on a vessel, continuously monitoring the atmosphere in high-risk areas such as engine rooms, pump rooms, or cargo holds. Portable gas detectors are handheld instruments carried by crew members and used for pre-entry atmospheric testing of enclosed spaces. Both types are required under maritime regulations, but they serve fundamentally different purposes.

Fixed gas detection systems

Fixed systems provide continuous, real-time monitoring of designated spaces and are connected to alarm panels that alert the bridge or engine control room when thresholds are breached. They are required in spaces where a gas hazard can develop without a crew member being present, such as battery rooms, CO2 flooding system spaces, and cargo pump rooms. Fixed systems must be type-approved and integrated with the vessel’s fire and gas alarm infrastructure.

Portable gas detectors

Portable detectors are the instruments used by crew before and during enclosed space entry. Under MSC 581(110), these instruments must now be capable of detecting all five parameters: O2, LEL, CO, H2S, and CO2 at ppm resolution. The portable detector must be used to test not only the primary entry space but also all connected and adjacent spaces before any permit is issued. Entry permits carry a maximum validity of 8 hours, and if ventilation stops or the team takes a break, the atmosphere must be re-tested and the results officially recorded.

For fleet engineers managing older vessels, one practical consideration is whether your existing fixed system is still compatible with current alarm panels and monitoring infrastructure. If you are sourcing a replacement portable detector, verify that it integrates with your existing documentation and calibration procedures.

How do you verify a gas detector is still compliant after regulations change?

To verify compliance after a regulatory change, compare your detector’s sensor capabilities and certification status against the updated requirements. For MSC 581(110), the most direct check is whether your portable detector can measure CO2 at ppm resolution using NDIR technology. If it cannot, the detector does not meet the new enclosed space entry standard regardless of its other certifications.

A structured compliance check should cover the following steps:

Review the updated regulation: Identify which specific parameters, thresholds, or procedures have changed and how they apply to your vessel type and trading routes
Audit your current detector specifications: Confirm the sensor types, detection ranges, and resolution against the new requirements
Check calibration and service records: Ensure records are current and that calibration has been carried out by a qualified technician using certified reference gases
Verify classification society acceptance: Confirm that the detector’s type approval is still recognized by your vessel’s classification society under the revised framework
Assess compatibility with existing systems: If a replacement is needed, check that the new unit works with your existing alarm panels, documentation procedures, and spare parts inventory

Enclosed space drills under MSC 581(110) must now be conducted at least once every two months and must include practical use of atmospheric testing instruments. These drills are also an opportunity to identify whether your current detectors perform reliably under operational conditions, not just on paper. Our service and repair team can support calibration, inspection, and assessment of your existing gas detection equipment.

How Lavastica helps with maritime gas detector compliance

Keeping your gas detection equipment compliant with evolving regulations is something we deal with every day. At Lavastica, we supply portable and fixed gas detection systems that meet current maritime standards, including the updated requirements under MSC 581(110). We also help when your existing installation is the starting point, not a blank slate.

Supply of compliant portable gas detectors with CO2 ppm detection (NDIR technology) for enclosed space entry
Advice on compatible replacements for older or obsolete detectors that no longer meet current standards
Support for fixed gas detection systems that integrate with your existing alarm panels and onboard infrastructure
In-house calibration, repair, and overhaul to keep your instruments inspection-ready
Fast worldwide delivery to minimize port days when a replacement is urgent

Whether you need a single replacement unit or a broader compliance review of your gas detection setup, we are ready to help. Learn more about us or get in touch directly and we will make sure you get the right answer quickly.

Phone: +31 (0) 10 265 5070
Email: info@lavastica.com