What happens if gas detection systems fail a PSC inspection?

If gas detection systems fail a PSC inspection, the ship can receive a formal deficiency notice and, in serious cases, be detained in port until the issue is resolved. This means the vessel cannot sail until inspectors are satisfied that the equipment meets the required standards. The financial and operational consequences of a detention are significant, which is why gas detection compliance deserves serious attention before any scheduled port call. Below, we answer the most common questions fleet engineers ask when facing this situation.

What deficiencies do PSC inspectors record for gas detection systems?

PSC inspectors record deficiencies related to gas detection systems when equipment is missing, non-functional, incorrectly calibrated, or unable to measure the gases required by current regulations. The most common findings include expired calibration certificates, sensors that are out of specification, and portable detectors that cannot measure all mandatory parameters.

Since IMO Resolution MSC.581(110) entered into force on 3 December 2025, carbon dioxide (CO₂) is now a mandatory measurement parameter for enclosed space entry. This means traditional four-gas detectors measuring only O₂, LEL, CO, and H₂S are no longer sufficient. Inspectors checking compliance with the revised recommendations will flag any vessel whose portable detectors cannot measure CO₂ at the required ppm resolution.

Other commonly recorded deficiencies include:

Portable gas detectors with missing or expired calibration records
Detectors that lack a dedicated CO₂ sensor with ppm-level resolution (standard percent-range sensors are not adequate)
No documented Enclosed Space Register on board
Missing or incomplete Enclosed Space Emergency Response Plan
Permit-to-Work records that are incomplete, unsigned, or older than the 8-hour maximum validity period
Entrances to enclosed spaces without the required SAFE or UNSAFE markings
EEBD equipment that is not properly maintained or is stored incorrectly

Inspectors treat an unrecorded atmospheric test the same as a test that never happened. If the logbook does not show the result, the deficiency stands regardless of what the crew says.

Can a ship be detained because of a gas detection failure?

Yes, a ship can be detained because of a gas detection failure. Detention is the most serious outcome of a PSC inspection and occurs when deficiencies are considered a direct risk to safety, the crew, or the environment. Gas detection failures that prevent safe enclosed space entry are strong grounds for detention because they relate directly to SOLAS requirements.

Not every gas detection deficiency automatically results in detention. Inspectors assess the severity and combination of findings. A single expired calibration certificate may result in a deficiency notice with a deadline for correction. However, if a vessel has no functioning CO₂-capable detector on board, no Enclosed Space Register, and incomplete Permit-to-Work records, the cumulative picture presents a serious safety risk that inspectors are likely to treat as grounds for detention.

It is also worth noting that RightShip RiSQ version 3.2 has already integrated the MSC.581(110) requirements into its inspection scope. This means vetting inspections, not just PSC, now look for these same compliance markers. A poor vetting result can affect commercial opportunities for the vessel even without a formal PSC detention.

How long does it take to resolve a gas detection deficiency in port?

Resolving a gas detection deficiency in port typically takes anywhere from a few hours to several days, depending on the type of deficiency and the availability of replacement equipment. Simple issues like recalibration or paperwork corrections can often be resolved within the same port call. Equipment replacement takes longer and depends entirely on local supply availability.

The fastest resolutions involve documentation deficiencies: updating the Enclosed Space Register, completing the Emergency Response Plan, or correcting Permit-to-Work records. These can be done on board without waiting for external parts or services.

Equipment deficiencies take longer. If a vessel’s portable gas detectors lack a CO₂ sensor and need to be replaced or supplemented with a dedicated standalone CO₂ detector, the timeline depends on:

Stock availability at a nearby supplier or warehouse
Port location and the logistics involved in getting equipment on board
Calibration requirements for new equipment before it can be used
PSC inspector availability for a follow-up check to lift the deficiency

Working with a supplier who maintains a large ready stock and can arrange fast worldwide delivery is the most effective way to minimize the time a vessel spends waiting in port. Our fire and gas detection systems are held in stock in Rotterdam for exactly this reason, and we regularly support vessels that need urgent replacement equipment during a port call.

What documentation must be onboard for gas detection systems?

Ships must carry several key documents related to gas detection systems to satisfy PSC inspectors. These include calibration certificates for all portable gas detectors, a vessel-specific Enclosed Space Register, an Enclosed Space Emergency Response Plan, and completed Permit-to-Work records for any recent enclosed space entries.

Under MSC.581(110), the documentation requirements have become more detailed. Here is a practical overview of what inspectors expect to find on board:

Calibration certificates for each portable gas detector, showing the date of last calibration and the gases tested
Enclosed Space Register, maintained as a live document that lists every enclosed space on the vessel, its hazard source, ventilation method, gas testing points, and estimated gas exchange times. This register must be synchronized with the shore-side office in real time and updated whenever cargo or the purpose of a space changes
Enclosed Space Emergency Response Plan, a ship-specific document that includes a mapped rescue route, pre-determined communication channels, and clear evacuation signals for every listed space
Permit-to-Work records, including the atmospheric test results recorded at entry. Permits have a maximum validity of 8 hours; if work stops or ventilation is interrupted, the permit is void and a new one must be issued with a fresh atmospheric test
Updated Safety Management System (SMS) procedures that reflect the requirements of MSC.581(110), including revised risk assessment forms for enclosed space entry
Drill records showing that enclosed space drills have been conducted at least once every two months, covering practical use of atmospheric testing instruments

A common mistake is treating the Enclosed Space Register as a static list. Inspectors now expect it to be a dynamic, up-to-date document. If cargo has changed since the last update, that alone can be flagged as a deficiency.

How can ships prepare gas detection systems before a PSC inspection?

Ships can prepare gas detection systems before a PSC inspection by conducting a thorough internal audit of all portable detectors, calibration records, and onboard documentation. The goal is to identify and correct any gaps before an inspector does. A structured pre-inspection checklist makes this process reliable and repeatable.

Here is a practical preparation plan that fleet engineers can follow before any scheduled port call or PSC inspection:

Audit all portable gas detectors. Confirm that every unit can measure at least five gases: O₂, LEL, CO, CO₂, and at least one additional toxic gas such as H₂S. Detectors that cannot measure CO₂ at ppm resolution need to be supplemented with a dedicated standalone CO₂ detector. Non-Dispersive Infrared (NDIR) technology is now the benchmark for CO₂ compliance.
Check calibration certificates. Verify that all certificates are current and that the gases tested match the required parameters. Arrange recalibration for any detector that is out of date. Our service and repair team can support calibration and overhaul remotely or on-site.
Review the Enclosed Space Register. Confirm it is up to date, accounts for any recent cargo changes, and includes all connected and adjacent spaces with their specific ventilation requirements and gas testing points.
Verify the Enclosed Space Emergency Response Plan. Check that it exists for every vessel in the fleet, is ship-specific, and includes a mapped rescue route, communication channels, and evacuation signals.
Check Permit-to-Work records. Ensure recent permits are properly completed, signed, and include recorded atmospheric test results. Any permit older than 8 hours that was still active during work is a red flag.
Confirm SMS alignment. Revise the Safety Management System to ensure shipboard procedures and risk assessment forms reflect the requirements of MSC.581(110).
Conduct a drill. Run an enclosed space drill that includes practical use of atmospheric testing instruments. Document the drill with a record that inspectors can review.

The atmospheric limits to confirm before entry and before an inspection are: O₂ at or above 20.9%, CO₂ below 0.5% (5,000 ppm), flammable gases below 1% of the Lower Explosive Limit, and toxic gases below 50% of the applicable Occupational Exposure Limit. Any detector that cannot confirm these values with sufficient resolution is a compliance risk.

How Lavastica helps with gas detection compliance

We understand that a gas detection deficiency during a PSC inspection can stop a vessel from sailing and cost a significant amount per day in port. That is why we keep a large stock of compliant gas detection systems and components in our warehouse in Rotterdam, ready for fast worldwide delivery.

Here is how we can help:

Supply of compliant gas detectors, including 5-gas units with dedicated CO₂ sensors and NDIR technology that meet the requirements of MSC.581(110)
Standalone CO₂ detectors to supplement existing 4-in-1 units without requiring a full fleet replacement
Calibration and repair services through our in-house workshop, with emergency service available for urgent situations
Technical advice on compatibility, so that any new equipment integrates with your existing onboard installation without requiring a full system overhaul
Support with obsolete equipment, including replacement parts and reconditioned units for older systems that are no longer in production

Whether you need a single replacement detector before a port call or a fleet-wide compliance review, we are ready to help. Learn more about who we are or get in touch with our team directly. You can reach us by phone at +31 (0) 10 265 5070 or by email at [email protected]. We respond fast, because we know every hour in port counts.