Gas Detection: What is a 4-gas detector?

A confined space rescue drill required portable gas detection

4-Gas Detectors

Effective gas detection is one of the most important safety concerns in the shipping industry. A third of all dangerous incidents that happen offshore are gas related.
Fatalities among seafarers are still occurring despite attempts by regulatory bodies to prevent them.
 

Regulations

SOLAS Regulation XI/1-7 states that:

‘Every ship to which Chapter 1 applies shall carry an appropriate portable atmosphere testing instrument or instruments.
As a minimum, these shall be capable of measuring concentrations of oxygen, flammable gases or vapours, hydrogen sulphide and carbon monoxide.’
 
It’s these gases that a 4 gas detector is designed to monitor. They represent the biggest threat to crew members on vessels at sea or in port.
 
Oxygen (O2)
As well as being necessary to breathe, oxygen also supports combustion. So, monitoring its presence is vital in hazardous working environments on board ship.
 
Flammable gases (LEL)
LEL is short for ‘Lower Explosive Limit’.
LEL is the lowest concentration of a gas or vapour capable of producing fire in the presence of an ignition.
 
Concentrations lower than the LEL are too lean to burn, those above, too rich. The LEL is displayed as a percentage with 0% showing a combustible gas-free atmosphere and 100% when a gas is at its lower flammable limit.
The percentages will differ from gas to gas.
Methane, for example, is too lean to burn between 0% and 5% but is highly flammable between 5% and 17%. Over 17% and the atmosphere is too rich for methane to ignite.
 
Hydrogen Sulphide (H2S)
Known as ‘sewer gas’ or ‘swamp gas’, Hydrogen Sulphide is colourless and highly flammable.
It’s produced by industrial processes and/or decaying organic matter and has a characteristic odour of rotten eggs.
However, this may not be detected until it’s too late as exposure to the gas affects your sense of smell.
It’s heavier than air, so hydrogen sulphide accumulates in enclosed and poorly ventilated areas.
 
Inhalation produces extremely rapid unconsciousness and death.
 
Carbon Monoxide (CO)
CO is produced whenever a fossil fuel is burned and collects in poorly ventilated areas. CO displaces oxygen in the blood, depriving vital organs of oxygen causing victims to lose consciousness and suffocate.
 
Because it’s odourless and colourless and can overcome you in minutes, it kills thousands of people every year.
 

Fixed gas detectors

Fixed gas detection systems are a requirement for some vessels but are recommended for a much wider range of ships. These can be placed in vulnerable locations to monitor gases at all times, issuing alerts at the first sign of potential danger.
 
However, one gas detection system doesn’t necessarily suit all vessels. You have to make sure that you have the correct equipment for your vessel’s particular needs.
SOLAS guidance states:
It should be noted that, given a ship’s specific characteristics and operations, additional atmospheric hazards in enclosed spaces may be present that may not be detected by the instrument recommended to be selected by these Guidelines, and in such cases, if known, additional appropriate instruments should be carried.’
 
That’s why at Martek, we have a team of expert engineers. They build our fixed detection systems in-house so that we can ensure that the equipment is tailored to your specific requirements.
 
Our MM2000 system tests for toxic and flammable gases in a wide variety of situations and is guaranteed to be SOLAS and ISGOTT compliant.
 

Portable gas detectors

Worn by seafarers entering spaces where dangerous gases may be present.
This equipment should be as versatile and easy to use as possible so that all crew members are protected.
 
We have a range of the best portable gas detection equipment designed to cover a variety of requirements, including:
 

A robust and accurate portable gas detector, the Marine 4™ provides unrivalled protection in confined space applications with audible and visual alarms in the event of exposure to flammable or toxic gases.

Detecting and displaying up to 4 gases simultaneously, it is suitable for a host of applications in a variety of industries. The Marine 4™ can be configured to detect a combination of:

    • Methane
    • Oxygen
    • Carbon Monoxide
    • Hydrogen Sulphidea
  • and other flammable gases.

MGC Simple+

NO CALIBRATION. NO CHARGING. NO COSTS.

A WORLD FIRST IN PORTABLE GAS DETECTION.

From Zone 0 to inert atmospheres – with the Marine Triple-C you’re always good to go.

Innovative 3-year battery life and cutting-edge infrared technology remove the need to calibrate, meaning no unproductive maintenance breaks and no expensive sensor replacement.

This all-in-one solution guarantees compliance and reduces risk whilst saving time and money – all at the touch of a single button.

 

Discover how we can help to keep your crew safe on board ship.