5.5 Gas detection
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - Resolutions - Maritime Safety Committee - Resolution MSC.285(86) – Interim Guidelines on Safety for Natural Gas-Fuelled Engine Installations in Ships – (Adopted on 1 June 2009) - Annex – Interim Guidelines on Safety for Natural Gas-fuelled Engine Installations in Ships - Chapter 5 – Control, Monitoring and Safety Systems - 5.5 Gas detection

5.5 Gas detection

  5.5.1 Permanently installed gas detectors should be fitted in the tank room, in all ducts around gas pipes, in machinery spaces of the ESD-protected type, compressor rooms and other enclosed spaces containing gas piping or other gas equipment without ducting. In each ESD-protected machinery space, two independent gas detector systems should be required.

  5.5.2 The number of detectors in each space should be considered taking size, layout and ventilation of the space into account.

  5.5.3 The detection equipment should be located where gas may accumulate and/or in the ventilation outlets. Gas dispersal analysis or a physical smoke test should be used to find the best arrangement.

  5.5.4 An audible and visible alarm should be activated before the vapour concentration reaches 20% of the lower explosion limit (LEL). For ventilated ducts around gas pipes in the machinery spaces containing gas-fuelled engines, the alarm limit can be set to 30% LEL. The protective system should be activated at a LEL of 40%.

  5.5.5 Audible and visible alarms from the gas detection equipment should be located on the bridge and in the engine control room.

  5.5.6 Gas detection for gas pipe ducts and machinery spaces containing gas-fuelled engines should be continuous without delay.


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