3 Method of test
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC/Circular.848 – Revised Guidelines for the Approval of Equivalent Fixed Gas Fire-Extinguishing Systems, as Referred to in SOLAS 74, for Machinery Spaces and Cargo Pump-Rooms – (Adopted on 8 June 1998)Amended by MSC.1/Circular.1267 - Annex - Revised Guidelines for the Approval of Equivalent Fixed Gas Fire-Extinguishing Systems, as Referred to in SOLAS 74, for Machinery Spaces and Cargo Pump-Rooms - Appendix - Test Method for Fire Testing of Fixed Gas Fire-Extinguishing Systems - 3 Method of test

3 Method of test

Parent topic: Appendix - Test Method for Fire Testing of Fixed Gas Fire-Extinguishing Systems

3.1 Principle

 This test procedure enables the determination of the effectiveness of different gaseous agent extinguishing systems against spray fires, pool fires and class A fires.

3.2 Apparatus

  3.2.1 Test room

The tests should be performed in 100 m2 room, with no horizontal dimension less than 8 m, with a ceiling height of 5 m. The test room should be provided with a closable access door measuring approximately 4 m2 in area. In addition, closable ventilation hatches measuring at least 6 m2 in total area should be located in the ceiling.

  3.2.2 Integrity of test enclosure

The test enclosure is to be nominally leak tight when doors and hatches are closed. The integrity of seals on doors, hatches, and other penetrations (e.g., instrumentation access ports) must be verified before each test.

  3.2.3 Engine mock-up

  • .1 An engine mock-up of size (width x length x height) 1 m x 3 m x 3 m should be constructed of sheet steel with a nominal thickness of 5 mm. The mock-up should be fitted with two steel tubes diameter 0.3 m and 3 m length that simulate exhaust manifolds and a solid steel plate. At the top of the mock-up a 3 m2 tray should be arranged. See figures 1, 2 and 3.

  • .2 A floor plate system 4 m x 6 m x 0.75 m high shall surround the mock-up. Provision shall be made for placement of the fuel trays, described in table 1, and located as described in table 2.

Figure 1

Figure 2

Figure 3

  3.2.4 Instrumentation

Instrumentation for the continuous measurement and recording of test conditions should be employed. The following measurements should be made:

  • .1 temperature at three vertical positions (e.g., 1, 2.5, and 4.5 m)

  • .2 enclosure pressure

  • .3 gas sampling and analysis, at mid-room height, for oxygen, carbon dioxide, carbon monoxide, and relevant halogen acid products, e.g., hydrogen iodide, hydrofluoric acid, hydrochloric acid

  • .4 means of determining flame-out indicators

  • .5 fuel nozzle pressure in the case of spray fire

  • .6 fuel flow rate in the case of spray fires

  • .7 discharge nozzle pressure

  3.2.5 Nozzles

  • 3.2.5.1 For test purposes, nozzles should be located within 1 m of the ceiling.

  • 3.2.5.2 If more than one nozzle is used they should be symmetrically located.

  3.2.6 Enclosure temperature

The ambient temperature of the test enclosure at the start of the test should be noted and serve as the basis for calculating the concentration that the agent would be expected to achieve at that temperature and with that agent weight applied in the test volume.

3.3 Test fires and programme

  3.3.1 Fire types

The test programme, as described in table 3, should employ test fires as described in table 1.

 Achieve ignition of the crib by burning commercial grade heptane in a square steel tray 0.25 m2 in area. During the pre-burn period the crib should be placed centrally above the top of the tray a distance of 300 to 600 mm.

Table 1 Parameters of Test Fires

Parameters of Test Fires
Fire Type Fuel Fire Size, MW Remarks
A 76–100 mm ID can Heptane 0.0012 to 0.002 Tell tale
B 0.25 m² Tray Heptane 0.35  
C 2 m² Tray Diesel/Fuel Oil 3  
D 4 m² Tray Diesel/Fuel Oil 6  
E Low pressure spray Heptane 0.16 ± 0.01 kg/s 5.8  
F Low pressure, low flow spray Heptane 0.03 ± 0.005 kg/s 1.1  
G High pressure spray Diesel/Fuel Oil 0.05 ± 0.002 kg/s 1.8  
H Wood crib Spruce or Fir 0.3 See Note 2
I 0.10 m² Tray Heptane 0.14  
Notes to Table 1:    
1 Diesel/Fuel Oil means light diesel or commercial fuel oil.
2 The wood crib should be substantially the same as described in ISO/TC21/SC 5/WG 8 ISO Draft International Standard, Gaseous fire extinguishing systems, Part 1: General Requirements. The crib should consist of six, trade size 50 mm x 50 mm by 450 mm long, kiln dried spruce or fir lumber having a moisture content between 9% and 13%. The members should be placed in 4 alternate layers at right angles to one another. Members should be evenly spaced forming a square structure.
 
 

  3.3.2 Test programme

The fire test programme should employ test fires singly or in combination, as outlined in table 3.

  • 3.3.2.1 All applicable tests of table 3 should be conducted for every new fire extinguishant gas, or mixture of gases.

  • 3.3.2.2 Only Test 1 is required to evaluate new nozzles and related distribution system equipment (hardware) for systems employing fire extinguishants that have successfully completed the requirements of 3.3.2.1. Test 1 should be conducted to establish and verify the manufacturer's minimum nozzle design pressure.

Table 2 Spray fire test parameters

Spray fire test parameters
Fire Type Low Pressure (E) Low pressure, Low flow (F) High pressure
Spray nozzle Wide spray angle (120 to 125°) full cone type Wide spray angle (80°) full cone type Standard angle (at 6 Bar) full cone type
Nominal fuel pressure 8 Bar 8.5 Bar 150 Bar
Fuel flow 0.16 ± 0.01 kg/s 0.03 ± 0.005 kg/s 0.050 ± 0.002 kg/s
Fuel temperature 20 ± 5°C 20 ± 5°C 20 ± 5°C
Nominal heat release rate 5.8 ± 0.6 MW 1.1 ± 0.1 MW 1.8 ± 0.2 MW

Table 3 Test Programme

Test Programme
Test No. Fire Combinations (See Table 1)
1 A: Tell tales, 8 corners. See note 1.
2–a B: 0.25 m² heptane tray under engine mock up
  E: Horizontal LP spray directed at 15–25 mm rod 0.5 m away
See Note 2 G: HP diesel fuel oil spray on top of engine mock up
    Total Fire Load: 0.49 MW
2–b B: 0.25 m² heptane tray under mock up
  I: 0.10 m² heptane tray on deck plate located below sold steel
See Note 2   obstruction plate.
    Total Fire Load: 0.49 MW
3 C: 2 m² diesel/fuel oil tray on deck plate located below sold steel obstruction plate
  H: Wood crib positioned as in Figure 1
  F: Low pressure, low flow horizontal spray — concealed — with impingement on inside of engine mock-up wall.
    Total Fire Load: 4.4 MW
4 D: 4 m² Diesel tray under engine mock-up
    Total Fire Load: 6 MW
Notes to table 3:  
1 Tell-tale fire cans should be located as follows:
  (a) in upper corners of enclosure 150 mm below ceiling and 50 nn from each wall;
  (b) in corners on floors 50mm from walls.
2 Test 2–a is for use in evaluating extinguishing systems having discharge times of 10 seconds or less.
  Test 2–b is for use in evaluating extinguishing systems having discharge times greater than 10 seconds.

3.4 Extinguishing system

  3.4.1 System installation

The extinguishing system should be installed according to the manufacturer's design and installation instructions. The maximum vertical distance should be limited to 5 m.

  3.4.2 Agent

  • 3.4.2.1 Design concentration

    The agent design concentration is that concentration (in volume per cent) required by the system designer for the fire protection application.

  • 3.4.2.2 Test concentration

    The concentration of agent to be used in the fire extinguishing tests should be the design concentration specified by the extinguishing system manufacturer, except for Test 1 which should be conducted at 77% of the manufacturer's recommended design concentration but in no case at less than the cup burner extinguishing concentration.

  • 3.4.2.3 Quantity of agent

    The quantity of agent to be used should be determined as follows:

    • 3.4.2.3.1 Halogenated agents

      W = (V/S) • C/(100 - C)
      where:
      W = agent mass, kg
      V = volume of test enclosure, m3
      S = agent vapour specific volume at temperature and pressure of the test enclosure, kg/m3
      C = gaseous agent concentration, volume per cent.

    • 3.4.2.3.2 Inert gas agents

      Q = V [294/(273 + T)] • (P /1.013) • 1n[100/(100 - C)]
      where
      Q = volume of inert gas, measured at 294 K and 1.013 bar, discharged, m3
      V = volume of test enclosure, m3
      T = test enclosure temperature, Celsius
      P = test enclosure pressure, bar
      C = gaseous agent concentration, volume per cent.

3.5 Procedure

  3.5.1 Fuel levels in trays

The trays used in the test should be filled with at least 30 mm fuel on a water base. Freeboard should be 150 ± 10 mm.

  3.5.2 Fuel flow and pressure measurements

For spray fires, the fuel flow and pressure should be measured before and during each test.

  3.5.3 Ventilation

  • 3.5.3.1 Pre-burn period

    During the pre-burn period the test enclosure should be well ventilated. The oxygen concentration, as measured at mid-room height, shall not be less than 20 volume per cent at the time of system discharge.

  • 3.5.3.2 End of pre-burn period

    Doors, ceiling hatches, and other ventilation openings should be closed at the end of the pre-burn period.

  3.5.4 Duration of test

  • 3.5.4.1 Pre-burn time

    Fires should be ignited such that the following burning times occur before the start of agent discharge:

    • .1 sprays - 5 to 15 s

    • .2 trays - 2 min

    • .3 crib - 6 min

  • 3.5.4.2 Discharge time

    • .1 halogenated agents should be discharged at a rate sufficient to achieve delivery of 95% of the minimum design quantity in 10 s or less.

    • .2 inert gas agents should be discharged at a rate sufficient to achieve 85% of the minimum design quantity in 120 s or less.

  • 3.5.4.3 Soak time

    After the end of agent discharge the test enclosure should be kept closed for 15 min.

  3.5.5 Measurements and observations

  • 3.5.5.1 Before test

    • .1 temperature of test enclosure, fuel and engine mock-up

    • .2 initial weights of agent containers

    • .3 verification of integrity agent distribution system and nozzles

    • .4 initial weight of wood crib.

  • 3.5.5.2 During test

    • .1 start of the ignition procedure

    • .2 start of the test (ignition)

    • .3 time when ventilating openings are closed

    • .4 time when the extinguishing system is activated

    • .5 time from end of agent discharge

    • .6 time when the fuel flow for the spray fire is shut off

    • .7 time when all fires are extinguished

    • .8 time of re-ignition, if any, during soak period

    • .9 time at end of soak period

    • .10 at the start of test initiate continuous monitoring as per 3.2.4.

  3.5.6 Tolerances

Unless otherwise stated, the following tolerances should apply:

.1 length ±2 % of value
.2 volume ±5 % of value
.3 pressure ±3 % of value
.4 temperature ±5 % of value
.5 concentration ±5 % of value.

 These tolerances are in accordance with ISO standard 6182/1, February 1994 edition [4].

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