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APPENDIX听MCA Fire Test Approval Procedures -听Fixed Aerosol Fire Extinguishing Systems听for Small Vessel Machinery Spaces听

1. Definitions听

1.1.1 Aerosol听is a fire-extinguishing medium consisting of finely divided solid particles of chemicals released into a protected space as either condensed aerosol听(pyrotechnic charge)听or dispersed aerosol听(compressed carrier gas).听

1.1.2 Generator听is a device for creating a听condensed听aerosol fire extinguishing medium by pyrotechnical means.听

1.1.3 Test Density (g/m3)听is the mass of a听solid听aerosol forming composition per cubic metre of the enclosure volume听required听to extinguish a specific type of fire as听determined听by听the听testing听regime听described below.听

1.1.4 Design Density (g/m3)听is the mass of a听solid听aerosol forming composition per cubic metre of the machinery space onboard provided to extinguish a specific type of fire, which is equal to the test density听increased by听safety factor of 1.3.听

1.1.5 Medium 鈥撎齮he听aerosol product听containing听both the active fire suppressant and the听by products听of the combustion process which generated the aerosol stream.听

1.1.6 Agent听- medium for the purpose of these guidelines, these words are interchangeable.听

1.1.7 听Casing听鈥撎齌he听casing of the condensed aerosol generator, that is the metal outer part of the generator.听听

2. Test Enclosures听

2.1 Figures (1) and (2) are for a small machinery space mock-up, constructed within a 20-foot ISO steel container. The container is one听option; other enclosures may also be used for the test听subject to approval by the Approved Body and with agreement of the MCA. A mock-up of an engine shall be created in the test enclosure to听represent听the expected fire scenarios more accurately than for an empty container with no obstructions to the seat of the fire. Figure (2) provides details for this mock up.听听听

2.2 IMO MSC.1/Circular 1270 鈥淩evised Guidelines for the Approval of Fixed Aerosol Fire-Extinguishing Systems for Machinery Spaces test methods鈥� is used as the basis for these tests, with a smaller test enclosure volume and fire sizes to听more accurately represent the small machinery spaces听being approved.听

2.3 The test enclosure volume should be at least equal to that of a standard 20-foot ISO container.听听

2.4 Tray A is placed in the听enclosure away from obstructions including the mock听engine.听A simulated听bilge system is created by plating-in close to the sides of the engine听mockup,听with a fuel tray (Tray B) placed underneath the听mock 鈥榚ngine鈥櫶齮o simulate fuel accumulation听from a leak. A fuel-spray is situated at the forward end of the engine mock-up, aiming across the engine and hidden by a plate听placed听over听it. Also, in the four corners of the enclosure, small cans听with 0.3 litres of heptane听are placed听at floor level in the four corners of the test enclosure听to check the distribution of the extinguishing agent.听The fire in all four cans shall be extinguished.听

2.5 The Wood Crib should be made of kiln spruce and consist of four layers,听each layer being made up of three members; the size of each member being 38 mm x 38 mm x 260 mm. Ignition of the crib is achieved by burning听1.5 litres of听heptane听on a 12.5 litre layer of water听in a听500 mm x 500 mm x 100mm听square pan听with steel walls of 6mm thickness听located underneath the crib. The bottom of the crib should be 140 mm above the floor. The members should be placed in 4 alternate layers at right angles to one another. Members should be evenly spaced forming a square structure.听The pre-burn time for the wood crib听is 2听minutes.听The wood crib shall be听located听between trays A and B in Figure 1 below.听

3. Required Fire Tests听

3.1 A series of eight tests should be conducted as follows:听

3.1.1 Open pool听(Tray A)听fire - diesel fuel听(Diesel听Fuel means light diesel or commercial fuel oil).听

3.1.2 Hidden spray fire - diesel fuel.听

3.1.3 Hidden pool fire听(Tray B)听- lubricating oil听(Lube oil meaning 15W-40 heavy duty diesel engine oil, or similar).听

3.1.4 Combined open pool听(Tray A)听/听hidden spray听-听diesel听fuel.听

3.1.5 Combined open pool听(Tray A)听/听hidden pool听(Tray B) -听diesel听fuel听/听lube oil.听

3.1.6 Combined hidden pool听(Tray B)听/听hidden spray - lube oil听/听diesel听fuel.听

3.1.7 Combined open pool听(Tray A)听/听hidden pool听(Tray B)听/ hidden spray听/ heptane filled cans -听diesel听fuel听/听lube oil听/听diesel听fuel / heptane.听 3.1.8 Wood Crib (Class A fire)听

Note:听听3.1.1 to听3.1.7 are for Class B fires.听Combined tests can be used to听validate听the effectiveness of single tests at the discretion of the approved body.听

3.2 With reference to the Figures 1 and 2, Tray A should听contain听10 litres of diesel fuel; Tray B should听contain听5 litres of lubricating oil and 5 litres of diesel fuel.听When required for the relevant fire test,听trays should have a water base and may be started using heptane as an accelerant.听听

3.3 The hidden spray should provide a flow of 1听litre per听minuteat听3 bar pressure. The fuel spray should be听shut-off听15 seconds after extinguishment. At the end of the听15 minute听hold-time听after the end of the aerosol discharge during which the test enclosure听remains听closed, the fuel spray should be restarted for 15 seconds prior to reopening the door and there should be no re-ignition.听

Figure 1: Test enclosure听(Plan View all Dimensions in听millimetres)听

Table 1:听 Fire听scenarios听

Ref.	Constituents	Quantity	Container type	Container size
Tray A	Diesel fuel oil	10听L听diesel fuel	Steel tray	1.20 m x 0.80 m = 0,96听m2
Tray B	Engine lube oil and diesel fuel	5听L听lube oil and 5听L听diesel fuel	Steel tray	1.00 m x 0.50 m =0.50 m2
Spray C	Hidden spray fire听	听	听	听
(Diesel fuel oil)	1听L/min	Pressurized听container at 3 bar pressure	-	听
Cans 1-4	Heptane	0.3听L/can	Open tin approx. 100听mm听diameter	100 mm internal diameter and 100 m in height
Wood Crib	Kiln dried spruce or fir limber members. (Allowable moisture 9 % to13 %)	12 of听38 x 38 x 260 mm	-	The members are to be placed in 4 alternate layers of three at right angles to one another. Members are to be evenly spaced forming a square structure (spacing approx. 50 mm).听The wood crib should be听located听where Tray A would be placed.

Figure 2: Engine mock-up (all Dimensions in听millimetres)听

3.4 A pre-burn time of 2 minutes for the tray fires, and 5 seconds for the spray fire should be allowed before the fire extinguishing system is activated. The doors to the test enclosures should be closed just prior to system release to ensure Oxygen levels are not听reduced significantly听pre-test. Times to extinguishment and re-ignition, if any, should be noted, together with other details.听听

3.5 A continuous measure at a sampling rate of at least 1听Hz should be made from temperature thermocouples听located听above each tray and spray fire. Pressure readings, flow rates and duration of the discharge time should also be recorded听when dispersed aerosol systems are being tested. The extinguishing system should be installed in the test enclosure according to the manufacturer鈥檚 design and installation instructions.听The thermocouple should be听located听between 30 mm and 100 mm above the fire source.听Additional听thermocouples should be co-located at each generator unit in the discharge stream at听a distance of 100听mm to 300 mm from the generator unit outlet. Measurement devices should be appropriately calibrated to a relevant standard agreed by the approved body with traceability accounted for and recorded.听

3.6 An overall restriction is imposed to the effect that the system is only considered suitable for installation in the machinery spaces of small vessels of less than 24 metre load line length.听The maximum height of the protected space is 4m and the听maximum听floor area (including any areas covered by permanent installations like engines).听

3.7 Please note that this test method has been agreed by the MCA for UK operation and may听or may听not be accepted听by other maritime administrations.听

3.8 The test arrangement should be representative of the expected arrangement in a ship鈥檚 machinery space, for example the distance between generators and the seat of the fire should be similar.听听

3.9 The release of an extinguishing agent may produce significant over or under pressurization in the protected space. Measures to limit the induced pressures to acceptable limits may have to be provided.听

4. Principal Requirements听

4.1 The components to be tested should be supplied by the manufacturer together with design and installation criteria, operational instructions, drawings,听technical data, certificate of conformity听and manufacturing location听sufficient for the identification of the components.听

4.2 The test procedure is intended for the determination of the effectiveness of different aerosol agent extinguishing systems against Class A fires and Class B spray听and听pool fires.听

4.3 For aerosol systems, the discharge time should not exceed听60听seconds to achieve 85 % of the design density. Systems may need to discharge in a shorter time for reasons other than for fire-extinguishing performance.听This can be done by weighing of generator units before and after discharge to听determine听the quantity of aerosol released and by using the readings from the thermocouples co-located with the generator units to听determine听discharge start and end times.听

4.4 The quantity of extinguishing agent for the protected space should be calculated at the minimum expected ambient temperature using the design density based on the net volume of the protected space.听

4.5 The听gross听volume of a protected space is听calculated from the dimensions of the space.听听

4.6 The听net听volume of the space听is听determined听by removing the volume of the machinery in the space from the gross volume.听The objects that occupy volume in the protected space include, but are not necessarily limited to auxiliary machinery, boilers, condensers, evaporators, main engines, reduction gears,听tanks听and enclosed trunks.听

4.7 When calculating the net volume of a protected space, the volumes of the听bilges,听or the fire extinguishing system听itself should not be removed from the gross volume.听听

4.8 The volume of free air contained in air receivers that听in the event of听a fire may be released into the protected space听also has to be considered and will add to the net volume.听

4.8.1 The volume of air in air receivers is the volume of air that would be released听in the event of听a fire to the protected space ambient pressure and temperature. For example, a听10 litre听air receiver at 10 bar pressure would have an equivalent volume of 100 litres when released to the protected space which is at a nominal 1 bar pressure.听

4.9 Subsequent听modifications to the protected space that alter the net volume of the space should require the quantity of extinguishing agent to be adjusted to meet the requirements.听

4.10 No fire suppression system should be used which is carcinogenic,听mutagenic听or teratogenic at concentrations expected during use. The discharge of aerosol systems to extinguish a fire could create a hazard to personnel from the natural form of the aerosol, or from certain products of aerosol generation (including combustion products and trace gases from condensed aerosols). Other potential hazards that should be considered for individual systems are the following: noise from discharge, turbulence, cold temperature of vaporizing liquid, reduced visibility, potential toxicity, thermal hazard and potential toxicity from the aerosol generators, and eye irritation from direct contact with aerosol particles. Unnecessary exposure to aerosol media, even at concentrations below an adverse effect level, and to their decomposition products should be avoided. All aerosols used in fire-extinguishing systems should have non-ozone depleting characteristics.听

4.11 All systems should employ two separate control听actions听for releasing the extinguishing medium into a protected space, such as lift cover and听turn key听or similar. Means should be provided for automatically giving audible warning of the release of fire-extinguishing medium into any space in which personnel normally work or to which they have access. The alarm should听operate听for a suitable period, (at least 20 seconds)听before the medium is released. Exposure to aerosol media, even at concentrations below an adverse effect level, should be avoided, proper the use of the isolation switch will avoid inadvertent exposures.听

4.12 Fixed听aerosol听fire听extinguishing听systems听are only听for use in听not normally occupied spaces.听However, IMO circular听1270 鈥淩evised Guidelines for the Approval of Fixed Aerosol Fire-Extinguishing Systems Equivalent to Fixed Gas Fire-Extinguishing Systems, as听referred to in SOLAS 74, for Machinery Spaces鈥� (4 June 2008) contains further requirements for听normally occupied spaces听related to the听No Observable Adverse Effect Levels (NOAEL)听for aerosol systems and their by-products (such as Carbon Monoxide). Compliance with these requirements does not need to be听demonstrated听for systems to be used in听not normally occupied spaces,听however as the spaces are occasionally occupied, the MCA will review manufacturer鈥檚 evidence of aerosol and by-products toxicity before approving any systems for use in听not normally occupied spaces.听

4.13 In no case should a dispersed aerosol system be used with halocarbon carrier gas concentrations above the 鈥淟owest Observed Adverse Effect Level (LOAEL) nor the 鈥淎pproximate Lethal Concentration (ALC)鈥�.听 Nor should a dispersed aerosol system be used with an inert gas carrier at gas concentrations above 52 %听calculated on the net volume of the protected space at the maximum expected ambient temperature, without the use of controls.听

4.14 The system and its components should be suitably designed to withstand ambient temperature changes, vibration, humidity, shock, impact, clogging, electromagnetic听compatibility听and corrosion normally听encountered听in machinery spaces. Generators in condensed aerosol systems should be designed to prevent self-activation at a temperature below 250 掳C.听This can be听demonstrated听through existing test reports or through new testing to the satisfaction of the approved body.听

4.15 The system and its components should be designed,听manufactured听and installed听in accordance with听standards acceptable to the International Maritime Organisation (IMO) and the National Authority (MCA). As a minimum, the design and installation standards should cover the following elements:听

4.15.1 Safety:

• Toxicity.听

• Noise - Generator/Nozzle discharge.听

• Decomposition products.听

• Obscuration.听

4.15.2 Storage container design and arrangement strength requirements:听

• Maximum听/听minimum听fill density,听operating, temperature range.听

• Pressure & weight听indication.听

• Pressure relief.听

• Agent identification, production date, installation date & hazard classification.听

4.15.3 Agent supply, quantity, quality standards, shelf life & service听life of an agent and igniter.听

4.15.4 Handling & disposal of generator after service life.听

4.15.5 Pipes and fittings:听

• Strength, material properties, fire听resistance听and cleaning requirements.听

4.15.6 Valves: 听

• Testing requirements; and听

• Elastomer compatibility.听

4.15.7 Generators/Nozzles:听

• Height & testing requirements; and听

• Elevated temperature resistance.听

4.15.8 Actuation & Control Systems:听

• Testing requirements; and听

• Backup power requirements.听

4.15.9 Alarms & Indicators:听

• Predischarge alarm, agent discharge alarms & time delays.听

• Supervisory Circuit requirements.听

• Warning signs, audible & visual alarms.听

• Annunciation of faults (fault warning).听

4.15.10 Enclosure integrity & leakage requirements:听

• Enclosure leakage.听

• Openings.听

• Mechanical ventilation interlocks.听

4.15.11 Design听and test听density requirements, total flooding quantity.听

4.15.12 Agent flow calculation:听

• Verification & approval of design calculation method.听

• Fitting losses and/or equivalent length.听

4.15.13 Inspection, maintenance,听service听and testing requirements.听

4.15.14 Handling & storage requirements for pyrotechnical components.听

4.16 Agent containers may be stored within a protected machinery space if the containers are distributed throughout the space. The arrangements of generators, containers, electrical circuits & piping essential for the release of any system should be such that in the event of damage to any one power release line through fire or explosion in the protected space (i.e. a single fault concept), at least the听test听density of the fire-extinguishing charge as required in paragraph听4.15.11 above can still be discharged having regard to the requirement for uniform distribution of medium throughout the space.听

4.17 For all ships, the fire-extinguishing system design manual should address recommended procedures for the control of products of agent decomposition. The decomposition products should not be discharged in the vicinity of assembly spaces.听

4.18 Spare parts and听operating听& maintenance instructions for the system should be provided as recommended by the manufacturer.听

5. Success Criteria:听听

5.1 鈥�鈥�鈥疌lass B fires should be extinguished within 30 s of the end of discharge. At the end of the hold period there should be no re-ignition upon opening the enclosure.听

5.2 鈥�鈥疶he fuel spray should be shut off 15 s after extinguishments. At the end of the hold time, the fuel spray should be restarted for 15 s prior to reopening the door and there should be no re-ignition.听

5.3 鈥�鈥疶he ends of the test fuel trays should听contain听sufficient fuel to cover the bottom of the tray.听

5.4 鈥�鈥疶he wood crib weight loss should be no more than 30% during the 2 min pre-burn test.听

5.5 鈥�鈥�鈥疉 re-ignition test should be conducted after the successful extinguishments of the tell-tale fires in test 1 (Fire A) within 30 s after completion of discharge. The test should involve the attempted ignition of two of the tell-tale fire containers. One container should be at the floor level and the other at the ceiling level at the diagonally opposite corner. At 10 min after extinguishment of the fires, a remotely听operated听electrical ignition source should be energized for at least 10 s at each container. The test should be repeated at 2 min intervals two more times, the last at 14 min after extinguishment. Sustained burning for 30 s or longer of any of these ignition attempts constitutes a re-ignition test failure.听

6. Test Report:听听

6.1 The test report should include the following information:听

6.1.1 Name and Address of the Test Laboratory.听

6.1.2 Date and Identification Number of the Test Report.听

6.1.3 Name and Address of Client.听

6.1.4 Purpose of the Test.听

6.1.5 Method of Sampling System Components.听

6.1.6 Name and Address of Manufacturer or Supplier of the Product.听

6.1.7 Name or other Identification Marks of the Product听(for example serial numbers, date of manufacture, expiry date etc.).听

6.1.8 Description of the Tested Product:听

6.1.8.1 Drawings.听

6.1.8.2 Descriptions.听

6.1.8.3 Assembly Instructions.听

6.1.8.4 Specification of included Materials.听

6.1.8.5 Detailed Drawing of Test Set-up.听

6.1.9 Date of Supply of the Product.听

6.1.10 Date of Test.听

6.1.11 Test method.听

6.1.12 Drawing of each test configuration.听

6.1.13 Identification of the Test Equipment and Instruments used.听

6.1.14 Conclusions.听

6.1.15 Deviations from the Test Method, if any.听

6.1.16 Test Results including measurements and observations during and after the test.听

6.1.17 Date, Name and Signature of qualified person听witnessing听the test.听

7. Certificate:听听

7.1 On successful completion of the eight tests mentioned in paragraph 1.6 a Certificate of Inspection and Tests will be issued and the Aerosol system听/听product will be considered suitable for installation in normally unoccupied spaces containing fuel having a flash point of not less than 43听掳C (closed cup test), of vessels of less than 24 metres load line length, where the space to be protected does not exceed a deck height of 4 metres, or听deck听area greater than 64 square metres听equal to 256 m3, this volume is the maximum permitted volume for approvals under this MGN.听The certificate will听state听that the system/product is acceptable for the purpose of听complying with听the requirements of:听

7.1.1 MGN 280 - Small Vessels in Commercial Use for Sport or Pleasure, Workboats and Pilot Boats - Alternative Construction Standards.听As Amended.听

7.1.2 The Codes of Practice for the Safety of Small Commercial Motor or Sailing Vessels of up to 24 metres Load Line length.听As amended.听

7.1.3 鈥淭he Safety of Small Workboats and Pilot Boats听-听A Code of Practice. As amended.听听

7.1.4 MSN 1871 (F) The Code of Practice for the Safety of Small Fishing Vessels of less than 15m Length Overall.听As amended.听

7.1.5 MSN 1872 The Code of Safe Working Practice for the construction and use of fishing vessels of 15m length overall to less than 24m registered length.听As amended听

7.1.6 The Codes of Practice for Police Boats.听As amended.听听

7.1.7 听Non-Category A Machinery Spaces in domestic passenger ships of Class III to VI(A) where the听requirement听was听introduced by the Merchant Shipping (Safety听Standards for Passenger Ships on Domestic Voyages) (Miscellaneous amendments) Regulations 2022.听

8. References:听

(a) International Maritime Organization听听 MSC.1/Circ.1270听of听4 June 2008听

鈥淩evised Guidelines for the Approval of Fixed Aerosol Fire Extinguishing Systems Equivalent to Fixed Gas Fire Extinguishing Systems, as referred to in SOLAS 74, for Machinery Spaces.听

(b) International Maritime Organization MSC/Circ. 668 of 30 December 1994 鈥淎lternative arrangements for Halon Fire Extinguishing Systems in Machinery Spaces and Pump Rooms鈥�.听

(c) IMO 2010 FTP Code. International Code for Application of Fire Test Procedures, 2010 ISBN听 978 92 801 1548 2 (International Maritime Organization).