The UK Maritime and Coastguard Agency (UK MCA) has issued Amendment 1 to MGN 657 (M+F), updating the requirements for fixed aerosol fire-extinguishing systems used in small vessel machinery spaces.

Aerosol fixed fire extinguishing systems involve the release of an agent to extinguish a fire by interruption of the chemical process of fire. There are two methods considered for applying the aerosol agent to the protected space as defined by the IMO (see MSC Circular 1270) as:

• Condensed aerosols – created in pyrotechnic generators through the combustion of the agent charge.

• Dispersed aerosols – these are not pyrotechnically generated but are stored in compressed gas containers with carrier agents (such as inert or approved halocarbon gases) with the aerosol released into and distributed throughout the space through valves, pipes & nozzles.

Systems will be installed on the vessel based on the requirements in this MGN and the equipment approval certificate and accepted by the attending surveyor. Systems are to be installed in accordance with the requirements of each manufacturer’s design, operation, and maintenance manuals. Installation details including position of generators relative to entrances, exits and walkways and the concentration design calculation should be supplied along with a declaration from the competent installer that it complies with the MCA requirements and accepted by the vessel’s Certifying Authority before the system is installed.