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Published on 17/12/2021

Gas Detection – Staying Safe At Sea

Stored or functional gases are a regular occurrence on board sea-going vessels. The use of gas is part and parcel of daily operations on board any vessel and often form an essential aspect of functionality both form a commercial and welfare perspective.

Despite an extensive history of gas use on board vessels of all shapes and sizes, exposure to hazardous gas still causes thousands of incidents at sea each year – and in many cases, resulting illness and fatalities were preventable.

With proper management and safety protocols, the risks posed by using, storing and transporting gases at sea can be greatly reduced. In this informative guide we explore the key points to consider when staying gas safe at sea – including some common pitfalls to be aware of and avoid to maintain optimal safety on board at all times.

What types of gases are commonly found on board sea-going vessels?

Gases found on board sea-going vessels can be roughly split into two categories – gases used on board or produced as a by-product of on-board processes, and gases that are stored or transported (such as those on cargo ships and cruise liners). Most vessels will have a combination of both types on board at any given time – and some fall into both categories, for example, hydrogen.

The gases themselves are not always immediately hazardous – but often pose a risk to health only when they are mismanaged or exposed to other external or environmental factors.

Some of the main gases that can pose a risk to health (and have potentially life-threatening consequences if left unchecked and improperly managed) include:

*Hydrogen Sulfide – Toxic, corrosive and highly flammable, H2S can cause headaches, skin and eye irritation, nausea and unconsciousness. H2S occurs naturally during the breakdown of organic matter such as sewage, waste water and foodstuffs.

Please see our guide showing an insight into the many dangers of Hydrogen.

*Liquid Propane (LPG) – Often used as fuel especially on smaller vessels, LPG can be extremely dangerous – heavier than air, it flows like water and can quickly accumulate in confined spaces posing risk of combustion and explosion.

*Carbon Monoxide (CO) – Often produced as a by-product of burning fuel and known as the ‘silent killer’, carbon monoxide is undetectable through the senses alone. Please see our guide to understanding carbon monoxide here.

Of course, each vessel will have a unique combination of gases on board – so it’s important to check your requirements and ensure the gas detection solutions you choose covered.

How do portable gas detectors work?

Portable gas detectors offer a first line of defence against unexpected (and otherwise undetectable) gas leaks on board. Through highly sensitive technology they can quickly identify the presence of gas and alert crew members to ensure a timely response that prevents illness or fatalities.

Portable gas detectors are carried or worn by the user and can be used to carry out tests at any time or location as and when needed. Unlike fixed gas detectors which permanently monitor a specific area, portable gas detectors provide pre-entry gas level checks keeping personnel safe at all times when on board.


Bump testing is an important (yet commonly overlooked) key component of safety when protecting against gas leaks on board. Although selecting high quality, reliable gas detector models offers peace of mind and optimal protection, a detector may not always respond as expected when exposed to gas for a number of reasons.

The proper function of gas detectors can be compromised through:

Improper calibration – failing to properly set up your gas detection device to cover the type and quantity of gases that could pose a risk on board will compromise safety function. This can also occur due to incorrect or expired calibration gas during the set-up stage

* Unusually high temperatures, pressure or humidity in the environment where a gas detector is stored or used (selecting specialist detectors specifically developed for the challenges faced within a marine environment is crucial)

Dirt and dust – failing to properly clean equipment or keep it in good working condition

Physical damage – such as dropping, crushing or submerging a detector in liquid

Using improper cleaning products – using wipes or solutions containing alcohol can damage electro-chemical sensors whilst silicone-based cleaning products can inactivate catalytic bead sensors which measure hydrocarbons such as methane, pentane and propane.

In many of the cases above the circuitry within the sensor would remain complete and the unit would appear to maintain a normal output – making the potential consequences of failing to bump test even more severe and possibly deadly.

Although precautions can be taken to ensure gas detectors are well maintained and function remains uncompromised, bump testing still provides a firm buffer should unexpected events occur that impact upon the accuracy and operational efficiency of a detector. The only way to be sure your gas detector is safe and compliant is to bump test at regular intervals, such as shift changeovers and the beginning or end of journeys. Ideally bump testing should be conducted at least daily for full protection and compliance.

With this in mind, regular and stringent bump testing should be part of every sea-going vessel’s safety schedule.


During a bump test, the sensors within your gas detector are briefly exposed to a concentration of gas higher than the alarm set points.

Each individual device has a slightly different bump testing protocol – but the easiest way to bump test is with a docking station. Docking stations can automatically bump test gas detectors on a set schedule, eliminating the possibility of missed bump tests through human error and addressing the issue of time constraints often present for crews on board.

It’s important to note that bump tests don’t check the accuracy of a reading – they simply confirm that alarms and sensors are fully operational.

Fixed and portable gas detection solutions from Martek Marine

At Martek Marine safety is our priority – having been at the forefront of the development of marine gas detectors for over twenty years, we’ve been able to devise solutions that are the most robust, reliable and simple to use on the market.

Our world-class portable gas detector range includes the Marine 4 Gas Monitor, Marine 5 and Triple-C, fitted with state-of-the-art smart sensor technology which can identify multiple hazardous gases commonly found on board sea-going vessels including carbon monoxide, oxygen and hydrogen at customisable levels.

You can find more detailed information on our range of fixed and portable gas detectors offering unrivalled protection against hazardous gases here on the Martek site – or speak to our team for personalised, professional guidance on gas detector selection.