MSC.1/Circ.1271

GUIDELINES FOR THE APPROVAL OF HIGH-EXPANSION FOAM SYSTEMS USING INSIDE AIR FOR THE PROTECTION OF MACHINERY SPACES AND CARGO PUMP-ROOMS

(4 June 2008)

 

1. The Committee, at its eighty-fourth session (7 to 16 May 2008), having considered the proposal by the Sub-Committee on Fire Protection, at its fifty-second session, approved the Guidelines for the approval of high-expansion foam using inside air for the protection of machinery spaces and cargo pump-rooms, as set out in the annex.

 

2. Member Governments are invited to apply the annexed Guidelines when approving inside air foam systems for ships of which the building contract is placed on or after 1 July 2009 and bring them to the attention of ship designers, shipowners, equipment manufacturers, test laboratories and other parties concerned.

 

Annex.

GUIDELINES FOR THE APPROVAL OF HIGH-EXPANSION FOAM SYSTEMS USING INSIDE AIF FOR THE PROTECTION OF MACHINERY SPACES AND CARGO PUMP-ROOMS

 

1. General

 

These Guidelines apply to fixed high-expansion foam systems using inside air for the protection of machinery spaces in accordance with SOLAS regulation II-2/10.4.1.1, and cargo pump-rooms in accordance with SOLAS regulation II-2/10.9.1.2. These Guidelines do not apply to cargo pump-rooms of chemical tankers carrying liquid cargoes referred to in SOLAS regulation II-2/1.6.2. Fixed high-expansion foam fire-extinguishing systems using inside air should demonstrate by test that they have the capability of extinguishing a variety of fires, which may occur in a ship's engine-room. Systems complying with these Guidelines are not subject to the criteria stated in chapter 6 of the International Code for Fire Safety Systems (FSS Code).

 

2. Definitions

 

2.1 Foam is the extinguishing medium produced when foam solution passes through a foam generator and is mixed with air.

 

2.2 Foam solution is a solution of foam concentrate and water.

 

2.3 Foam concentrate is the liquid which, when mixed with water in the appropriate concentration forms a foam solution.

 

2.4 Foam mixing rate is the percentage of foam concentrate mixed with water forming the foam solution.

 

2.5 Foam generators are discharge devices or assemblies through which foam solution is aerated to form foam that is discharged directly into the protected space, typically consisting of a nozzle or set of nozzles and a casing. The casing is typically made of perforated steel / stainless steel plates shaped into a box that enclose the nozzle(s).

 

2.6 Inside air foam system is a fixed high-expansion foam fire-extinguishing system with foam generators located inside the protected space and drawing air from that space. A high-expansion foam system using inside air consists of both the foam generators and the foam concentrate.

 

2.7 Nominal flow rate is the foam solution flow rate expressed in l/min.

 

2.8 Nominal application rate is the nominal flow rate per area expressed in l/min/m².

 

2.9 Nominal foam expansion ratio is the ratio of the volume of foam to the volume of foam solution from which it was made.

 

2.10 Nominal foam production is the volume of foam produced per time unit, i.e., nominal flow rate times nominal foam expansion ratio, expressed in m³/min.

 

2.11 Nominal filling rate is the ratio of nominal foam production to the area, i.e., expressed in m/min.

 

2.12 Nominal filling time is the ratio of the height of the protected space to the nominal filling rate, i.e., expressed in minutes.

 

2.13 Design filling rate is the minimum filling used during the approval tests in accordance with appendix 2.

 

3. Principal requirements for the system

 

3.1 Principal performance:

 

.1 the system should be capable of manual release. Automatic release of the system should not be permitted unless appropriate operational measures or interlocks are provided to prevent the local application system from interfering with the effectiveness of the system;

 

.2 the system should be capable of fire extinction, and tested in accordance with appendix 2 to these Guidelines;

 

.3 the foam concentrates should be tested in accordance with MSC/Circ.670;

 

.4 the foam generators should be successfully tested in accordance with appendixes 1 and 3 to these Guidelines; and

 

.5 onboard procedures should be established to require personnel re-entering the protected space after a system discharge to wear breathing apparatus to protect them from oxygen deficient air and products of combustion entrained in the foam blanket.

 

3.2 Requirements for the system:

 

.1 the system should be supplied by both main and emergency sources of power and should be provided with an automatic change-over switch. The emergency power supply should be provided from outside the protected machinery space;

 

.2 the system and its components should be suitably designed to withstand ambient temperature changes, vibration, humidity, shock, clogging and corrosion normally encountered in machinery spaces or cargo pump-rooms in ships, and manufactured and tested to the satisfaction of the Administration in accordance with the requirements given in appendix 1 to these Guidelines. Piping, fittings and related components inside the protected spaces should be designed to withstand 925°C;

 

.3 system piping, components and pipe fittings in contact with the foam concentrate should be compatible with the foam concentrate and be constructed of corrosion resistant materials such as stainless steel, or equivalent. Other system piping and foam generators should be galvanized steel or equivalent;

 

.4 means for testing the operation of the system and assuring the required pressure and flow should be provided by pressure gauges at both inlets (water and foam liquid supply) and at the outlet of the foam proportioner. A test valve should be installed on the distribution piping downstream of the foam proportioner, along with orifices which reflect the calculated pressure drop of the system. All sections of piping should be provided with connections for flushing, draining and purging with air;

 

.5 the quantity of foam concentrate available should be sufficient to produce a volume of foam equal to at least five times the volume of the largest protected space at the nominal expansion ratio, but in any case not less than enough for 30 min of full operation for the largest protected space;

 

.6 means should be provided for the crew to safely check the quantity of foam concentrate and take periodic control samples for foam quality;

 

.7 operating instructions for the system should be displayed at each operating position;

 

.8 spare parts should be provided in accordance with the manufacturer's instruction;

 

.9 the design filling rate for the system should follow the results of the tests to be conducted in accordance with appendix 2 to these Guidelines, and should be adequate to completely fill the largest protected space in 10 min or less;

 

.10 if an internal combustion engine is used as a prime mover for the seawater pump for the system, the fuel oil tank to the prime mover should contain sufficient fuel to enable the pump to run on full load for at least 3 h and sufficient reserves of fuel should be available outside the machinery space of category A to enable the pump to be run on full load for an additional 15 h. If the fuel tank serves other internal combustion engines simultaneously, the total fuel tank capacity should be adequate for all connected engines;

 

.11 means should be provided for automatically giving audible and visual warning of the release of the system. The alarms should operate for the length of time needed to evacuate the space, but in no case less than 20 s;

 

.12 the arrangement of foam generators and piping in the protected space should not interfere with access to the installed machinery for routine maintenance activities;

 

.13 the system source of power supply, foam concentrate supply and means of controlling the system should be readily accessible and simple to operate, and should be arranged at positions outside the protected space not likely to be cut off by a fire in the protected space;

 

.14 the arrangement of foam generators should in general be designed based on the approval test results. The number of generators may be different, but the minimum design filling rate determined during approval testing should be provided by the system. A minimum of two generators should be installed in every space containing combustion engines, boilers, purifiers, and similar equipment. Small workshops and similar spaces may be covered with only one foam generator;

 

.15 foam generators should be uniformly distributed under the uppermost ceiling in the protected spaces including the engine casing. The number and location of foam generators should be adequate to ensure all high risk areas are protected in all parts and at all levels of the spaces. Extra foam generators may be required in obstructed locations. The foam generators should be arranged with at least 1 m free space in front of the foam outlets, unless tested with less clearance. The generators should be located behind main structures, and above and away from engines and boilers in positions where damage from an explosion is unlikely;

 

.16 the piping system should be sized in accordance with a hydraulic calculation technique* to ensure availability of flows and pressures required for correct performance of the system; and

_____________

* Where the Hazen-Williams method is used, the following values of the friction factor C for different pipe types which may be considered should apply:

 

Pipe type                          C

 

Black or galvanized mild steel    100

 

Copper or copper alloys           150

 

Stainless steel                   150

 

.17 for spaces greater than 500 m³, the arrangement of the protected spaces should be such that they may be ventilated as the space is being filled with foam. Procedures should be provided to ensure that upper level dampers, doors and other suitable openings are kept open in case of a fire.

 

3.3 Testing requirements:

 

.1 after installation, the pipes, valves, fittings and assembled systems should be tested to the satisfaction of the Administration, including functional testing of the power and control systems, water pumps, foam pumps, valves, remote and local release stations and alarms. Flow at the required pressure should be verified for each section using orifices fitted to the test line. In addition, all distribution piping should be blown through with air to ensure that the piping is free of obstructions; and

 

.2 functional tests of all foam proportioners or other foam mixing devices should be carried out to confirm that the mixing ratio tolerance is within + 30 to -0% of the nominal mixing ratio defined by the system approval. For foam proportioners using foam concentrates of Newtonian type with kinematic viscosity equal to or less than 100 cSt at 0ºC and density equal to or less than 1.1 kg/dm³, this test can be performed with water instead of foam concentrate. Other arrangements should be tested with the actual foam concentrate.

 

APPENDIX 1.

COMPONENT MANUFACTURING STANDARDS FOR INSIDE AIR FOAM SYSTEMS

 

1. Foam generator nozzles for inside foam systems should be tested in accordance with the following items stipulated in appendix A of MSC/Circ.1165:

 

3.1 Dimensions

 

3.4.1 Flow constant: the value of the flow constant K should be determined by measuring the flow at the maximum operational pressure, minimum operational pressure and the middle operational pressure.

 

3.11.1 Stress corrosion: a representative sample extracted from the generator may be used.

 

3.11.2 Sulphur dioxide corrosion: visual inspection only may be carried out.

 

3.11.3 Salt spray corrosion: the test may be carried out at NaCl concentration of 5%. Paragraph 3.14.2 in appendix A of MSC/Circ.668 need not be applied.

 

3.15 Resistance to heat: where the components are made of steel, this test need not be applied.

 

3.17 Impact test: only, the nozzles need to be tested.

 

3.22 Clogging test: where the diameter of the opening of the nozzle exceeds 1.5 mm, this test need not be applied.

 

2. Foam generators should also be tested in accordance with the following items stipulated in standard EN 13565-1:

 

.1 clause 4: General construction requirements (4.1 - connections, 4.5 - corrosion resistance of metal parts, 4.8 - heat and fire resistance);

 

.2 clause 5: Discharge coefficients;

 

.3 clause 6: Quality of foam (6.2 - High-expansion components); and

 

.4 clause 9: Components for medium and high-expansion foam systems.

 

Foam generators should also be able to withstand the effects of vibration without deterioration of their performance characteristics when tested in accordance with paragraph 4.16 of appendix A of MSC/Circ.1165. After the vibration test, the generators should show no visible deterioration and should meet the requirements of clauses 5 and 9 of standard EN13565-1.

 

Equivalent alternative testing standards may be used as determined by the Administration.

 

APPENDIX 2.

FIRE TEST METHOD FOR INSIDE AIR FOAM SYSTEMS

 

1. Scope

 

The test method is intended for evaluating the extinguishing performance of inside air high-expansion foam fire-fighting systems. System approval should be based on the nominal filling rate, water pressure and other conditions used during the specified tests.

 

2. Sampling

 

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

 

3. Fire tests

 

3.1 Test principles

 

This test procedure enables the determination of design criteria and the effectiveness of inside air high-expansion foam fire-extinguishing systems against spray and pool fires, which are obstructed by a simulated engine.

 

3.2 Test description

 

3.2.1 Test enclosure

 

3.2.1.1 The tests should be performed in a room having an ambient temperature of 20 ± 5ºC at the start of each test. Details of the test hall geometry, the ventilation conditions and environmental conditions should be given in the fire test report.

 

The fire-extinguishing tests of the system should be carried out using the following test compartments:

 

.1 Test compartment 1

 

The test should be performed in a 100 m² room with a 5 m ceiling height and ventilation through a 2 m x 2 m door opening according to figure 2. The engine mock-up should be designed according to figures 1 and 3. The door opening to the test compartment may be covered during the test at the same rate as the foam layer is building up in the compartment to avoid foam leakage through the door opening.

 

.2 Test compartment 2

 

The test should be performed in a test compartment having a volume greater than 1,200 m³, but not greater than 3,500 m³, and a ceiling height exceeding 7.5 m. The ventilation of the test compartment should be achieved by a 2 m x 2 m door opening at floor level (as in test compartment 1) combined with a 20 m² total ventilation area, distributed in the ceiling and/or along the walls, just below the ceiling. The foam generators should not be positioned near the openings. The door opening to the test compartment may be covered during the test at the same rate as the foam layer is building up in the compartment to avoid foam leakage through the door opening.

 

3.2.2 Simulated engine

 

The fire test should be performed in a test apparatus consisting of:

 

.1 a simulated engine of size (width x length x height) 1 m x 3 m x 3 m constructed of sheet steel with a nominal thickness of 5 mm. The simulated engine is fitted with two steel tubes of 0.3 m in diameter and 3 m in length, which simulate exhaust manifolds and a grating. At the top of the simulated engine a 3 m² tray is arranged (see figures 1 and 3); and

 

.2 a floor plate system of 4 m x 6 m and 0.5 m in height surrounding the simulated engine with a tray (4 m² in area), underneath (see figure 1).

 

3.2.3 Test programme

 

The fire test should be carried out using the following fire scenarios:

 

.1 combination of the following fire programmes (Test fuel: commercial fuel oil or light diesel oil):

 

.1 low-pressure spray on top of the simulated engine centred with nozzle angled upward at a 45° angle to strike a 12 to 15 mm diameter rod 1 m away; and

 

.2 fire in trays under (4 m²) and on top (3 m²) of the simulated engine;

 

.2 high-pressure horizontal spray fire on top of the simulated engine. (Test fuel: commercial fuel oil or light diesel oil);

 

.3 low pressure concealed horizontal spray fire on the side of the simulated engine with oil spray nozzle positioned 0.1 m in from the end of the simulated engine and 0.1 m² tray positioned 1.4 m in from the engine end at the inside of floor plate. (Test fuel: commercial fuel oil or light diesel oil); and

 

.4 flowing fire 0.25 kg/s from top of mock-up (Test fuel: heptane).

 

 

3.2.4 Installation requirements for tests

 

3.2.4.1 Foam generators should not be installed above the simulated engine in such a way that the foam flow directly hits the test fires. The generators should also not be located near ventilation openings.

 

3.2.4.2 Foam generators should be installed at the uppermost level of the space. The vertical distance between the generators and test ceiling and floor should be recorded and reflected in the manufacturer's design manual.

 

3.2.4.3 The number and spacing of foam generators should be in accordance with the manufacturer's system design and installation manual.

 

3.2.4.4 The inlet water supply pressure to the foam generators should be maintained within the acceptable range determined in paragraph 3.2.5 below, throughout the tests.

 

3.2.5 Foam generator test

 

Representative foam generators should be tested according to appendix 3 to these Guidelines. The results of the testing should be reflected in the manufacturer's design and installation manual.

 

4. Test procedure

 

4.1 Preparation

 

4.1.1 Combination fire (paragraph 3.2.3.1 above): the 4 m² fire tray below the engine mock-up should be filled with at least 50 mm fuel on a water base with a freeboard of 150 ± 10 mm. The 3 m² fire tray on top of the engine should be filled with at least 50 mm fuel on a water base with a freeboard of 40 ± 10 mm (this requires that the notch on the side of the 3 m² fire tray is blocked off by an appropriate means, e.g., steel plate).

 

4.1.2 Low pressure concealed fire and 0.1 m² tray fire (paragraph 3.2.3.3 above): the 0.1 m² tray should be filled with at least 50 mm fuel on a water base with a freeboard of 150 ± 10 mm.

 

4.1.3 Flowing fire (paragraph 3.2.3.4 above): the 4 m² fire tray below the engine mock-up should be filled with a 50 mm water base and the 3 m² fire tray on top of the engine mock-up should be filled with a 40 mm water base. The fuel should be ignited when flowing down the side of the mock-up, approximately 1 m below the notch. The pre-burn time should be measured from the ignition of