A Guide to Ship Air Con Gas Detection
A Guide to Ship Accommodation Air Conditioning Gas Detection
The fifth edition of ISGOTT advises of the advantage of fitting flammable gas detection at accommodation air conditioning inlets:
24.2 Central Air Conditioning and Ventilation Systems
On ships with central air conditioning units, it is essential that the accommodation is kept under positive pressure to prevent the entry of hydrocarbon vapours. Intakes for air conditioning units are usually positioned in a safe area and vapours will not be drawn into the accommodation under normal conditions. A positive pressure will be maintained only if the air conditioning system is operating with its air intakes open and if all access doors are kept closed, except for momentary entry or exit.
The system should not be operated with the intakes fully closed, that is in 100% recirculation mode, because the operation of extraction fans in galley and sanitary spaces will reduce the atmospheric pressure in the accommodation to less than that of the ambient pressure outside.
There is a benefit from having a gas detection and/or alarm system fitted to air conditioning intakes.
In the event that hydrocarbon vapours are present at the inlets, the ventilation system should be shut down and transfer of cargo suspended until such time as the surrounding atmosphere is free of hydrocarbon vapours.
The same principles of positive pressure and gas detection apply to ships that have alternative air conditioning systems or where additional units have been fitted. The overriding consideration in all cases is that hydrocarbon vapours must not be permitted to enter the accommodation.
Externally located air conditioning units, such as window or split air conditioning types, should not be operated during any of the operations listed in Section 24.1 unless they are either located in safe areas or are certified as safe for use in the presence of flammable vapours.
On ships that depend on natural ventilation, ventilators should be kept trimmed to prevent the entry of petroleum gas. If ventilators are located so that petroleum gas can enter regardless of the direction in which they are trimmed, they should be covered, plugged or closed.
MM2000® – Addressable Gas Detection
The MM2000® system is fully Type Approved and is already proven on over 1000 ships worldwide.
Because the MM2000® system is addressable, gas detectors are run on a 4-core loop cable. This means that installation costs are vastly reduced compared to conventional systems running several independent field sensor cables.
In total the system can monitor 32 individual gas detectors, allowing multiple inlets and to be monitored in addition to hydrogen sulphide/hydrocarbon gas detection in the cargo pump room, all serviced by one compact control panel.
