Consultation outcome report on the MGN 657 on requirements for fixed aerosol fire extinguishing systems for use in small vessel machinery spaces
Updated 17 May 2023
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Section 1: Introduction
1.1 The Maritime and Coastguard Agency (MCA), an Executive Agency of the Department for Transport (DfT), carried out a public consultation on the draft Marine Guidance Note MGN 657 (M+F) Requirements for Fixed Aerosol Fire Extinguishing Systems for use in Small Vessel Machinery Spaces, which ran from 5 August to 10 October 2022.
1.2 Aerosol fire extinguishing systems involve the release of a chemical agent to extinguish a fire by interruption of the process of the fire. The MCA has previously approved aerosol fixed fire suppression systems for use in small vessel machinery spaces through approval certificates based on the MCA’s MSF 1814 forms issued to suppliers of aerosol suppression systems. These certificates required the MCA approval of tests to show the safe and effective operation of the systems by live fire testing. This MGN now formalises the process by publishing the test requirements for future approvals and to require the tests are witnessed by an Approved Body appointed by the MCA.
1.3 The consultation generated some very detailed and technical responses especially from the manufacturers. The detailed responses offering constructive feedback are welcomed and through our engagement with stakeholders as part of this consultation and through other meetings we have made significant changes to the guidance.
1.4 This Report gives a high-level outline of the comments received from respondents. It does not seek to cover every individual comment received, but all comments received have been taken into consideration.
Section 2: Consultation
2.1 This consultation was carried out between 5 August to 10 October 2022. It can be found at: https://www.gov.uk/government/consultations/mgn-657-requirements-for-fixed-aerosol-fire-extinguishing-systems-for-use-in-small-vessel-machinery-spaces
2.2 Whilst the consultation was promulgated on GOV.UK for anyone who wished to read it and/or respond to it, and triggered notifications for anyone who is subscribed to receive such government notifications, all persons and organisations who had specifically requested notification were included.
Section 3: Consultation outcome
Questions posed
3.1 The government’s proposals were described in the consultation document, which then posed seven generic questions and offered a free comment box for respondents to provide detail and other thoughts they had on the content of the proposed guidance. A total of five responses were received, three from manufacturers of aerosol fire suppression systems (representing all the equipment suppliers currently approved by the MCA), one from the Isle of Man government and one from the Royal Yacht Association.
3.2.1 Isle of Man Response
The Isle of Man responded that they support the guidance and found it to be proportional with no major omissions. Some minor comments and corrections around the wording and presentation.
3.2.2 MCA comments
The MCA welcomes the response from the Isle of Man and has made corrections to the guidance in line with the proposed amendments by the Isle of Man.
3.3.1 Royal Yacht Association Response
The Royal Yacht Association (RYA) made two technical comments related to the guidance. The first related to the use of automatic fixed firefighting systems (FFS) in small enclosures pointing out the need for automatic detection and raising concerns over the unintended activation of the FFS in hot and dusty engine enclosures. The second concern was over the use of isolation switches and concerns over the risks of these systems being accidentally left isolated removing the ability to operate the FFS when required.
3.3.2 MCA comments
The MCA welcomes the response from the RYA and the concerns that it raises are valid.
The fitting of an automatic or manual system is at the discretion of the owner (within the parameters detailed in MGN 657) and the use of an automatic deployment should only be considered where it is a practical measure. The use of an aerosol FFS should not interfere with the continued operation of the engine, or any secondary engines within the space. Whilst the RYA concerns are valid, these can be resolved with correct design of the system and as such the MCA will continue to allow automatic activation in certain circumstances.
The RYA concerns over the misuse of isolation switches was well founded, especially over the risk of inadvertent isolation interfering with an intended activation in event of fire. The comment around a visual indication being required at the control station is now addressed in Section 5.6 of the MGN.
3.4.1 Manufacturers Responses
Responses to the consultation were received from the three manufacturers of aerosol systems that are currently approved by the MCA for installation in vessels under 24m. While the manufacturers generally welcomed the new guidance and testing requirements, they did have concerns over the proportionality, technical requirements and recognition of the testing.
3.4.1.1 Open Ventilation during testing
All three manufacturers took issue with the requirement in Appendix 1, Article 3.4 of MGN 657 which required “The container should have some permanently open ventilation in the ceiling measuring at least 6% of the ceiling area.” They pointed out that the requirement does not exist in other testing standards and would result in a significant increase in the aerosol concentration required to extinguish fires. It was also noted that this was contradictory to the requirement in 5.4 which requires that “The space to be protected should be provided with means to close all openings which may admit air to the protected space. All openings should be closed before the system is discharged.”
3.4.1.2 Scaling of testing volume
All the manufacturers raised concerns over the introduction of a limit on the acceptable volume of the protected space the FFS was installed in to two times the tested volume. They noted that the 20ft ISO container that the test is based on would have a volume of approximately 33m3 and that this would limit installation to spaces up to 66m3 which is significantly smaller than the existing allowable limit of 256m3. They state that “condensed aerosol systems are operating on the total-flooding principle“ and this is acknowledged by standard bodies such as International Standards Organisation (ISO), European Committee for Standardization (CEN), British Standards Institute (BSI), Kiwa, Underwriters Laboratories (UL), National Fire Protection Association (NFPA) and more and is the basis of the standards these bodies have issued for this type of system. Essentially that no limit should be applied to the scaling of testing as this is not applied in land-based approvals for these systems.
3.4.1.3 Use of existing test requirements
One manufacturer proposed aligning entirely with the testing requirements of BS EN 15276-1:2019 removing the testing requirements from this MGN and instead relying entirely on the requirements contained within the ISO standard to remove the need for repeated testing.
3.4.1.4 Removal of Wood Crib Class A Fire Test
One manufacturer requested that the wood crib test was removed from the testing requirements and a second manufacturer requested that if the wood crib test is not removed it is aligned with the requirements in BS EN 15276-1:2019 especially with respect to the pre burn time. This was requested on the basis that section 5.5 of the MGN states that “Class A fire materials such as wood, paper, plastics, rubber, or textiles are to be stored outside the protected space. Regular inspection and control of Class A materials present shall be undertaken in the protected space”.
3.4.1.5 Approval, recognition, and equivalence
One manufacturer raised questions around the approvals that would be awarded following the completion of satisfactory testing and if this would be deemed as equivalent to the requirements of MSC Circ 1270 for IMO and MED/UKCA approval. They also wanted to know if this would be covered by the UK and US Coastguard (USCG) Mutual Recognition Agreement.
3.4.1.6 Maintenance requirements and the difference between dispersed and condensed aerosols
One manufacturer raised concerns over the proportionality of the maintenance requirements, claiming that the maintenance requirements for condensed aerosol systems (those that are pyrotechnically released) are much lower than those for dispersed aerosol systems (those that are stored under pressure).
3.4.2 MCA comments
The MCA welcomes the comments from the manufacturers and thanks them for their technical responses. These have been taken onboard where appropriate and the MGN updated accordingly.
3.4.2.1 MCA comments on Open Ventilation during testing
On review of the requirements and in alignment with other standards the MCA agrees with the comments raised by the manufacturers and has removed the open ventilation equivalent to 6% of ceiling area from the testing standard. This has been removed in the updated MGN and will not be required in any testing.
3.4.2.2 MCA comments on Scaling of testing volume
The scaling factor was introduced to the test requirements in MGN 657 to replicate the requirements in the IMO testing for aerosol FFS on convention vessels. Upon review of the testing standards used in the land-based applications of these systems including BS EN 15276-1:2019, NFPA 2010 Standard for Fixed Aerosol Fire-Extinguishing Systems and UL: 2775 and from experience gained during the 20 years that these systems have been approved by the MCA for use in small vessels that this scaling factor can be removed from the testing requirements. The 20ft ISO container test as described within MGN 657 will be sufficient for machinery space volumes up to the maximum size of 64m2 floor area and 4m height.
3.4.2.3 MCA comments on Use of existing test requirements
The test standard in MGN 657 is based on the MCA’s existing approval from when these aerosol FFS’ were first approved for use in the marine environment. It is designed to best replicate the fire type and general properties of a small vessel’s machinery space including placing the pool fire under a metal box to replicate a leak from an engine. It is the MCA’s view that this test should remain the basis for approval of these systems in small vessels in the UK. The MCA has taken the feedback from the manufacturer and aligned with BS EN 15276-1:2019 where practical for requirements such as pre-burn times, discharge rates and measurement distances.
3.4.2.4 MCA comments on Removal of Wood Crib Class A Fire Test
The MCA acknowledges that the guidance recommends that Class A fire materials are restricted within the machinery space, however it will be very difficult to enforce this requirement and the risk of Class A materials such as wood and cardboard being present in the compartment will always remain. As this risk will continue to exist the testing requirements should include a limited Class A fire test. The pre-burn, moisture content and other requirements related to the wood crib test are now aligned with BS EN 15276-1:2019.
3.4.2.5 MCA comments on Approval, recognition, and equivalence
The approval status is unchanged based on the new testing. Completion of testing in MGN 657 is only for the approval of the system for use on the vessels noted on its approval certificate. The approved body will approve the testing on behalf of the MCA and will take responsibility for the testing being undertaken to the appropriate standard. It is the decision of other maritime administrations if they wish to accept this testing as equivalent. This testing is not an equivalent to the testing in MSC Circ. 1270 and its completion will not satisfy the requirements of MSN 1874 UK 3.46 for use in convention vessels. The MCA are exploring the possibility of including an additional standard in MSN 1874 to allow aerosol FFS which have been tested to and installed per the instructions contained in MGN 657 for use on UK domestic passenger ships under 21.34m load line length.
3.4.2.6 MCA comments on Maintenance requirements and the difference between dispersed and condensed aerosols
The MCA appreciates the difference in the maintenance requirements for condensed and dispersed aerosol systems. While dispersed aerosols are not largely commercially available at this time this MGN is developed to be neutral in its approach to the delivery method as far as is reasonably practical. Where the maintenance instructions clearly do not apply (such as pressure checks for condensed aerosol systems) these would be marked as not applicable in the ships maintenance record, however the frequency of maintenance activities should not be reduced. Visual inspection that the system is installed correctly and has not moved or that wiring has not become damaged or corroded is a proportional requirement and will remain within MGN 657.
3.5 Summary
There was engagement in the responses across all areas of the guidance. The responses were generally supportive with all respondents approving of the overall plan to introduce formal guidance and to have the testing approved by a third party.
While not all comments have been included with in the revised MGN they have all been fully considered. The MGN has been updated accordingly and will be published after final review by the MCA.
Section 4: Next steps
4.1 The government will finalise the guidance with a view to publishing by Summer 2023.