Fire suppression system

Abstract

A panel (10) for use as a fire suppressing system which comprises a substrate (12) and an exothermic gas producing charge (14) wherein the exothermic gas producing charge (14) is integral with the substrate.

Claims

1. A fire suppression panel, the panel comprising: a polymeric foam substrate; and an exothermic gas producing charge, wherein the exothermic gas producing charge is integral with the polymeric foam substrate.

2. The panel according to claim 1, wherein the polymeric foam substrate comprises an open cell foam.

3. The panel according to claim 1, wherein the polymeric foam substrate has a tensile strength in the range of about 80 to about 100 kg/m.sup.3.

4. The panel according to claim 1, wherein the polymeric foam substrate further includes one or more of zeolites, porous titania material, ceramic material, sintered metals and silicon carbide.

5. The panel according to claim 1, wherein the polymeric foam substrate comprises a phenolic resin.

6. The panel according to claim 1, wherein the exothermic gas producing charge comprises potassium nitrate.

7. The panel according to claim 1, wherein the exothermic gas producing charge comprises at least one of: a binder, burn rate modifier, flame inhibition chemical and an additional oxidizing agent.

8. The panel according to claim 1, wherein the exothermic gas producing charge is positioned within a void formed in the polymeric foam substrate, and wherein the void is a substantially enclosed cavity or chamber within the polymeric foam substrate of the panel.

9. The panel according to claim 8, wherein the polymeric foam substrate comprises a plurality of voids, and wherein one or more of the plurality of voids contains the exothermic gas producing charge.

10. The panel according to claim 9, wherein the voids are distributed in a two-dimensional array in a direction perpendicular to the panel thickness.

11. The panel according to claim 8, wherein an internal surface of the void comprises a heat resistant material selected from at least one member of a group consisting of: rock wool, gypsum, perlite, vermiculite, alumina, aluminum hydroxide, magnesium hydroxide, and calcium silicate.

12. The panel according to claim 1, wherein the panel comprises at least one channel such that gas produced by the exothermic gas producing charge can be ejected from the panel.

13. The panel according to claim 12, wherein at least one nozzle is used to provide the at least one channel within the polymeric foam substrate.

14. The panel according to claim 12, wherein at least one nozzle is used in addition to the at least one channel within the polymeric foam substrate.

15. The panel according to claim 14, wherein the at least one channel is positioned so as to direct gas produced by the exothermic gas producing charge in a particular direction.

16. The panel according to claim 14, wherein the at least one channel is shaped so as to control the pressure of gas produced by the exothermic gas producing charge.

17. The panel according to claim 12, wherein the at least one channel is offset from the exothermic gas producing charge.

18. The panel according to claim 1, wherein the panel is sealed to prevent unwanted ejection of gas from the exothermic gas producing charge.

19. The panel according to claim 1, wherein the panel is substantially coated in a skin, wherein the skin is formed from sheet-form polymeric material of gypsum.

20. The panel according to claim 1, further comprising at least one reinforcing layer.

21. The panel according to claim 20, wherein the at least one reinforcing layer is located within a skin which substantially coats the panel.

22. The panel according to claim 1, wherein at least one face of the panel has a profiled surface.

23. The panel according to claim 1, wherein an outer surface of the panel is bonded to a surface effect material, wherein the surface effect material is selected from a simulated stone surface, a simulated brick surface, a simulated wood surface, a wood laminate surface, a material of high thermal conductivity (a cool touch surface) and a reflective surface.

24. The panel according to claim 1, further comprising an absorbent material to remove at least one member of a group consisting of: toxic substances produced by combustion of the exothermic gas producing charge or corrosive substances produced by combustion of the exothermic gas producing charge.

25. The panel according to claim 1, further comprising a filter positioned to filter gas produced by the exothermic gas producing charge.

26. The panel according to claim 1, further comprising an igniter for igniting the exothermic gas producing charge.

27. The panel according to claim 1, further comprising a fan.

28. The panel according to claim 1, wherein the panel is modular.

29. A fire suppression system comprising a panel according to claim 1, the system further comprising: a fire detection system connected to the panel, the fire detection system comprises a sensor and means for activating the panel.

30. A shield for use in fire suppression comprising a panel according to claim 1.

31. A method of preparing a panel in accordance with claim 1, comprising the steps of: (i) providing a polymeric foam substrate; (ii) forming a void therein; and (iii) positioning an exothermic gas producing charge within the void.

32. The method according to claim 31, further comprising the step of providing at least one further substrate.

33. The method according to claim 32, wherein the at least one further substrate has a void therein which is complementary to the void in the substrate.

34. The method according to claim 31, wherein the exothermic gas producing charge is positioned whilst in the form of a powder, paste or solid.

35. A method for producing a fire suppression system comprising the steps of: (i) providing a panel as described in claim 1; (ii) providing a detector and means for activating the panel; and (iii) connecting the panel to the detector and means for activating the panel.

Description

(1) The present invention will now be described by way of example and with reference to the accompanying drawings in which:

(2) FIG. 1 is a diagrammatic cross-section though a panel in accordance with the present invention;

(3) FIG. 2 is a diagrammatic cross-section though a further panel in accordance with the present invention;

(4) FIG. 3 is a diagrammatic cross-section though a panel in accordance with the present invention wherein the panel has channels on opposite sides;

(5) FIG. 4 is a diagrammatic view of a room comprising panels such as described in FIG. 3

(6) FIG. 5 is a diagrammatic view of a fire suppression system for use with a panel in accordance with the present invention;

(7) FIG. 6 is an exploded diagrammatic view of a panel in accordance with the present invention;

(8) FIG. 7 is a diagrammatic cross-section through a further panel, having channels on opposite sides, in accordance with the present invention;

(9) FIG. 8 is a diagrammatic cross-section through a panel in accordance with the present invention, showing an alternative embodiment of pressure chamber;

(10) FIG. 9 is a diagrammatic cross-section through a panel in accordance with the present invention, showing the use of a reinforcing casing;

(11) FIG. 10 is a diagrammatic cross-section through a panel in accordance with the present invention, showing use of a further type of reinforcing casing;

(12) FIG. 11 is schematic diagram showing the approximate position of discharge units installed in a test room;

(13) FIG. 12 is a graph showing a typical profile of the temperature measured at one of the discharge outlets on each of the units during testing;

(14) FIG. 13 is a graph showing an increase in temperature of a test room during testing; and

(15) FIG. 14 is a graph showing a decrease in oxygen concentration in a test room during testing.

(16) Looking at FIG. 1, there is provided a panel (10) for use as a fire suppressing system comprising a substrate (12) and an exothermic gas producing charge (14).

(17) In the present example, the substrate (12) is a foamed phenolic resin which is porous in nature.

(18) The substrate (12) defines a void (16) in which exothermic gas producing charge is retained. The void (16) in FIG. 1 is defined by a substrate formed from two parts (18 and 20both of which are foamed phenolic resins).

(19) The panel (10) further comprises channels (22) and (24) which are in fluid communication with the void (16) and permit, in use, gas to be ejected out of the panel (10). It will be noted that the channels (22) and (24) are offset from the exothermic gas producing charge (14).

(20) Plugs (26) and (28) are located in the channels (22) and (24) respectively so as to prevent the ingress of any moisture and/or dust.

(21) The panel (10) is covered in a web (30) of carbon fibres so as to provide additional strength to the panel structure. It will be appreciated that the fibres could be general fibres such as chopped strand, continuous filament, woven fabrics such as glass fibres, carbon fibres or even metal filaments so as to provide additional strength to the panel structure.

(22) In addition to the web (30), a skin (32) has been provided on the outer surfaces of the substrate (12) which forms the panel (10).

(23) Further, the part (20) of the substrate (10) comprises a region (34) located in proximity to the exothermic gas producing charge (14). The region (34) comprises suitable substances for removing toxic and/or corrosive substances produced by the exothermic gas producing charge (14). In the example of FIG. 1, the substances are located within the pores of the substrate material.

(24) An igniter (36) is also provided for activation of the exothermic gas producing charge (14).

(25) When activated by the igniter (36), the exothermic gas producing charge (14) rapidly combusts producing a fire surpassing gas (38) shown by the arrows in FIG. 1. The void (16) under such conditions forms a pressure chamber (40) thereby increasing the pressure under which the gas (38) is ejected from the panel (10).

(26) As shown in FIG. 1 the gas (38) produced moves essentially in the direction of the arrows (38) towards the region (34). The region (34) is able to at least partially remove unwanted particulate matter within the gas and/or any removing toxic and/or corrosive substances in the gas.

(27) The gas (38) is ejected from the panel (10) by way of the channels (22 and 24) allowing suppression of a fire (not shown).

(28) FIG. 2 illustrates a further panel (10) in accordance with the present invention. Similar to the embodiment of FIG. 1, the panel (10) comprises a substrate (12) and an exothermic gas producing charge (14). The substrate (12) is a foamed phenolic resin which is porous in nature. The substrate (12) defines a void (16) in which exothermic gas producing charge is retained. The void (16) in FIG. 2 is defined by a substrate formed from two parts (18 and 20both of which are foamed phenolic resins).

(29) In this embodiment, the exothermic gas producing charge (14) is in the form of a powder, and is retained within an envelope (42) constructed of suitable material.

(30) The panel (10) further comprises channels (44) and (46) which are in fluid communication with the void (16) and permit, in use, gas to be ejected out of the panel (10). It will be noted that the channels (44) and (46) are offset from the exothermic gas producing charge (14).

(31) The channel (44) is tapered such that the channel narrows in a direction away from the void (16). The taper is used as a means of increasing the pressure of the gas produced by the exothermic gas producing charge upon combustion, and thereby increase the distance that the gas will travel on ejection from the panel (10)

(32) The channel (46) is formed from a nozzle (48). The nozzle (48) may be used to direct gas produced by the exothermic gas producing charge upon combustion upon ejection from the panel (10). This allows for directing the fire suppressing gas to particular areas, for example the floor, and/or to improve visibility during the evacuation of a room.

(33) In the embodiment of FIG. 2, the web (30) of carbon fibres is located within the skin (32) on the outer surfaces of the substrate (12) which forms the panel (10) so as to create an impregnated structure (50).

(34) Further, the part (20) of the substrate (10) comprises a region (34) located in proximity to the exothermic gas producing charge (14). The region (34) comprises a separate porous substrate (52) upon which the suitable substances for removing toxic and/or corrosive substances produced by the exothermic gas producing charge (14) have been positioned. In the example of FIG. 1, the substances are located within the pores of the separate substrate (52).

(35) FIG. 3 shows a panel (100) in accordance with the present invention, which would be suitable for use, for example, within a hung ceiling.

(36) The panel is based on the structure of the panel (10) in FIG. 1, as reflected by the numbering of the structures within FIG. 3.

(37) In contrast to FIG. 1, the embodiment of FIG. 3 comprises two voids (16), two regions (34) and two sets of channels (22 and 24; and 22 and 24 respectively). Whilst only a single exothermic gas producing charge (14) is present, it will be appreciated that at least two or more could be present.

(38) In the embodiment of FIG. 3, the igniter (36) may be used to combust the exothermic gas producing charge (14) in such a way that gas is produced on opposite sides (60 and 62) of the charge.

(39) In this way gas (as shown by the arrows 60 and 62) is ejected from opposite sides (64 and 66) of the panel (100) through the two sets of channels (22 and 24; and 22 and 24 respectively).

(40) It will be appreciated that such an embodiment is particularly applicable for use with a hung-ceiling, where it may be necessary to suppress fires both below and above (i.e. in the ceiling space) the ceiling.

(41) The panel (100) further comprises fans (82) adjacent to the nozzles (22 and 24). The use of fans (82) helps to force the fire suppressant gas generally towards a particular point, for example, the floor to increase visibility for persons in the event of an evacuation. By forcing the initial gas produced towards a lower level, any persons within a room following activation of the panel (100) will have extra time to locate an exit before their view is blocked by the gas.

(42) A power supply (not shown) for the fans (82) may be the detector (not shown) wherein the power supply is maintained only during use of the panel (100).

(43) FIG. 4 illustrates the use of a fire suppression panel (100) within a room wherein the fire suppressing panels (100) emit the fire suppressant gas both above (62) and below (60) the panels (100).

(44) As shown, the panels further comprises the fans (82) which to help retain the fire suppressant gas generally towards the floor, preferably below eye level.

(45) FIG. 5 depicts a fire detection system (102) which includes a fire detector system (104) connected to at least one fire detector (106) in each of rooms A and B, a fire alerting system (108), a fire control panel (110) and a fire suppression activating system (112) connected to fire suppression panels (10, 100) directed at the interior of rooms A and B.

(46) The fire detectors (106) detect the presence of smoke, gas or a temperature high than desired in rooms A and B. The fire detector system (102) monitors information received from the fire detectors (104) and determines whether a potential and/or existing condition exists that may indicate a fire and were that fire may be.

(47) The fire detector system (102) communicates with the fire control panel (110). The fire detector system (102) sends the status of each of the fire detectors (104) to the fire control panel (110). The fire control panel (110) is located where it may be monitored by maintenance personnel in a location separate from rooms A and B. The fire control panel (110) controls the fire alerting system (108) and the fire suppression activating system (112).

(48) If the fire detector system (102) determines that a potential and/or existing condition exists that may indicate a fire then the fire control panel (110) emits, via the fire alerting system (108), an audible and/or visual signal indicating a potential and or existing fire. The fire alerting system is connected to speakers (not shown) in the rooms A and B to alert the occupants. Also, the fire control panel (110), via the fire activating system (112), activates the fire suppressing panels (10, 100) where that potential or existing fire may be.

(49) Independent of whether the fire detector system (102) detects a potential and/or existing fire condition, the fire control panel (110) uses fire detector data to display the temperature in rooms A and B on the fire alerting system (108).

(50) Connections between the fire detector system (102), the fire detectors (106), fire alerting system (108), fire control panel (110) and fire suppression activating system (112) may be hardwired and/or via a wireless link.

(51) Power supplies (not shown) to lighting, air conditioning, mains power sockets etc. in each of rooms A and B pass via the fire control panel (110). In the event of a potential and/or existing fire condition, the fire control, the fire control panel isolates these power supplies from the relevant room. This helps to avoid spread of any fire.

(52) Maintenance personnel may manually activate the fire suppression system (112) with controls located on the fire control panel (110). This is for the purpose of testing. The fire control panel (110) is connected to fire alarm buttons (not shown) in rooms A and B for manual activation of the fire suppression activating system (112) in the event a fire is detected by occupants before the fire detection system (102).

(53) The fire suppressing panels (10, 100), shown in FIG. 4, are those described above. Two such panels are shown in each of rooms A and B. Optionally, the panels could be used to construct rooms A and B. Optionally, extra fire suppressing panels (10, 100) may be located in the wall, the ceiling and/or the floor.

(54) The fire suppressing panels (10, 100) are configured to refrain from release of gas into a room while supplied by power and deactivated by the fire suppression activating system (112) (under the control of the control panel (110)). The fire suppressing panels (10, 100) release gas when activated by the fire suppression activating system (112) or, as a fail-safe feature, when power supply is cut.

(55) FIG. 6 shows an exploded view of a fire suppression panel (120), which may be used to form, for example, a door.

(56) The panel (120) comprises substrates (18 and 20) which comprise external skins (122 and 124) which are moulded to resemble the external appearance of, for example, a door.

(57) In the present example, the substrate (18) comprises channels (not shown), through which fire suppressant gas may be released. The substrate (18) defines a void (16) into which the exothermic gas producing charge (14) is placed. A region (34) is also provided and contains suitable substances for removing toxic and/or corrosive substances produced by the exothermic gas producing charge (14).

(58) The panel (120) is formed by bonding of the substrates (18) and (20) such as by use of an adhesive and pressure. Bonding of the substrates is used to create an air-tight seal.

(59) FIG. 7 illustrates an alternative embodiment of a panel (100) in accordance with the present invention, which would be suitable for use, for example, as a hung ceiling. Similar to the embodiment disclosed in FIG. 3, the panel (100) comprises two sets of channels (22 and 24; and 22 and 24 respectively) and two regions (34).

(60) The panel (100) further comprises a foamed phenolic resin substrate (18) which comprises two sections (126) which are shaped to retain exothermic gas producing charge (14). In the present embodiment there are two separate charges (14).

(61) As can be clearly seen, once activated, the fire suppressing gas produced (128), as shown by the arrows, flows into the void (16) within the panel (100). Under such conditions the void (16), formed from by the substrates (18 and 20), becomes a pressure chamber (130).

(62) The fire suppressing gas (128) which builds up within the void (16) is dispersed through the channels (22, 24 and 22, 24).

(63) As before, the phenolic resin (20) further comprises a region (34) wherein particulate, toxic and/or corrosive matter produced through the exothermic reaction of the charge (14) can be at least partially removed from the fire suppressing gas before it is ejected from the panel (100).

(64) An advantage of the embodiment of FIG. 7 is that the exothermic gas producing charge (14) is retained in place substantially throughout its combustion.

(65) FIG. 8 discloses an alternative panel (10) in accordance with the present invention.

(66) The panel (10) is similar in structure to the embodiment of FIG. 1 wherein corresponding features have been provided with the same numbering above, for example, the panel (10) comprises a substrate (12) and an exothermic gas producing charge (14).

(67) The substrate (12) is preferably a foamed phenolic resin comprising two parts (18 and 20). The parts (18 and 20) are both shaped such that they cooperatively define a void (16).

(68) The exothermic gas producing charge (14) is retained within pores of the foamed phenolic resin forming the substrate.

(69) As can be clearly seen, the cooperating parts (18 and 20) form a substantially enclosed chamber (132).

(70) Upon combustion of the exothermic gas producing charge (14), the chamber (132) fills with gas (not shown), and due to its shape, reaches temperatures in excess of 850 C.

(71) Gas is ejected in a manner similar to the other embodiments of the present invention.

(72) FIG. 9, discloses an embodiment of a further panel (10) in accordance with the present invention. The panel (10) is similar to the panel exemplified in FIG. 8.

(73) The panel (10) comprises a substrate (12) and an exothermic gas producing charge (14). The substrate (12) preferably comprises a foamed phenolic resin.

(74) The panel further comprises a metal casing (134). The casing (134) is positioned and shaped so as to substantially surround the chamber (132).

(75) When the chamber is positioned within the substrate, it will be appreciated that there is substrate material both inside and outside the casing (134) as shown in FIG. 9.

(76) The metal casing (134) is used to provide additional reinforcing means to the panel (10) due to the high pressures created during combustion of the exothermic gas producing charge (14) within the chamber (132).

(77) The panel (10) of FIG. 9 comprises a single channel (136) wherein the channel is tapered to increase the pressure of the fire suppressing gas and therefore increase the ejection distance achieved.

(78) The panel (10) also comprises fixing clips (138) which are used to provide a means for attachment when the panel (10) is in use.

(79) FIG. 10, discloses yet another example of a panel (10) in accordance with the present invention. The panel (10) is similar to that described in FIG. 9.

(80) Similar to FIG. 9, the panel (10) comprises a substrate (12), an exothermic gas producing charge (14) and a metal casing (134).

(81) In this example, the metal casing (134) comprises two metal casings (140 and 142). The casing (140) is located within the casing (142). More specifically, the casing (140) substantially surrounds the chamber (132) so as to provide reinforcing means.

(82) The casing (142) surrounds the casing (140) so as to provide yet further reinforcing means to the pressure chamber.

(83) In addition, the casings (140 and 142) define channels (22, 24) through which fire suppressing gas can travel. As shown in FIG. 10, the channels are defined by inner walls of the casing (142) and outer walls of the casing (140).

(84) In use, the fire suppressing gas flows through the two channels (22 and 24) defined by the metal casings (140 and 142).

EXAMPLE

(85) A extinguishing system was subjected to a series of tests in accordance with certain specific provisions of the International Standard for condensed aerosol fire extinguishing systems, ISO 15779, Condensed aerosol fire extinguishing systemsRequirements and test methods for components and system design, installation and maintenanceGeneral requirements, 2011. The fire extinguishing performance of the system was assessed against selected fire testing provisions of the standard, as follows: Wood crib Class A fire (clause D.6.1) Heptane pan Class B fire (clause D.6.2) Polymethyl methacrylate (PMMA) polymeric Class A fire (clause D.6.3) Polypropylene (PP) polymeric Class A fire (clause D.6.3) Acrylonitrile-butadiene-styrene polymer (ABS) polymeric Class A fire (clause D.6.3) Class A compatible wood crib Class A fire test (clause D.6.4)

(86) The system for the testing incorporated a nominal 1.41.6 m spacing of discharge units.

(87) The Gas Testing Facility

(88) The enclosure used for the evaluation of the extinguishing systems had internal dimensions of 8.1 m long by 4.1 m wide and 3.6 m high. The total internal volume was approximately 120 m.sup.3. The test enclosure was a steel framed structure raised 0.5 m above the floor constructed in 6 mm steel and having calcium silicate board lining the internal walls and ceiling. Over pressure protection vents were also present in the enclosure.

(89) Instrumentation was added to the test facility in accordance with the specifications of ISO 15779 Annex D, as follows: Paramagnetic oxygen analysers at 0.1H, 1 m and 0.9H for measurement of oxygen concentration (where H is the height of the test room)referred to herein as the low, medium and high analysers, respectively. 0-2000 Pascal differential pressure transducer in the test room. K-type thermocouples to measure the temperature 100 mm above the test object height and at 0.9H. K-type thermocouple to measure the enclosure temperature at half the room height 1 m from the centre of the floor. K-type thermocouples to measure the temperatures of a discharge outlet of each of the aerosol generators.

(90) Additional instrumentation was added as follows: Carbon monoxide and carbon dioxide concentration monitoring at mid room height. Additional temperature measurements in the room and above the fire location. Pressure and temperature in the exhaust duct. The fuel load mass (loss) during fire testing.

(91) All measurement readings were continuously recorded on a data logging system for the duration of each test.

(92) Extinguishing System Arrangements

(93) A schematic diagram showing the approximate position of the discharge units installed in the test room is shown in FIG. 11.

(94) The discharge units included a solid foam base used as a bed for the exothermic gas producing charge, which was in the form of a powder. For ease of testing, discharge outlets were provided in a metal plate located proximate to the exothermic gas producing charge. Electrical igniters were provided to initiate a combustion process in the powder. The igniters comprised a small fusehead providing an explosive charge when an electrical current was applied to the connecting wires. Alarm cable wiring connected the electrical igniters cable and batteries. Up to 15 of the discharge units were used in each test.

(95) Test Programme

(96) The test programme consisted of the following fire tests: ISO polymeric sheet Acrylonitrile-Butadiene-Styrene (ABS) extinguishing concentration test ISO heptane pan extinguishing concentration test ISO compatible wood crib extinguishing concentration test ISO wood crib extinguishing concentration test ISO polymeric sheet polymethyl methacrylate (PMMA) extinguishing concentration test ISO polymeric sheet polypropylene (PP) extinguishing concentration test

(97) All tests were undertaken to the specific relevant requirements of ISO 15779 Annex D as appropriate. After discharge of the system there was a 10 minute hold time where the contents of the room remained sealed before forced ventilation of the space was commenced.

(98) The calculation of agent concentration was determined from the mass of powder installed in each discharge unit, using the following formula:
Agent concentration(g/m.sup.3)=total mass of powder inserted into all activated units(g)/room volume(m.sup.3)

(99) Testing to ISO 15779 requires that the discharge of aerosol be a maximum of 90 seconds. Thermocouple measurements were used to determine approximate discharge times.

(100) ISO 15779 specifies that jet energy from the discharge outlets shall not influence the development of the fire. Therefore, the discharge outlets shall be directed away from the fires. For unbaffled fires (the wood crib and heptane pan) the discharge unit directly above the centrally positioned fire was therefore removed from the system.

(101) The wood crib pre-burn inside the test room was carried out as per the specification in the most recent version of ISO 14520 as of 6 Mar. 2012, rather than the earlier version of ISO 14520, the text of which was adapted in ISO 15779. It was necessary to open a large over pressure protection vent in the test room ceiling to maintain the oxygen concentration during the pre-burn period, therefore, it was not possible to install a discharge unit in Location 15 (see FIG. 11) for the test.

(102) Findings

(103) A total of 7 fire tests were carried out. Table 1 provides a summary of the results.

(104) TABLE-US-00001 TABLE 1 No. of units discharged Max room Min Max carbon Extinguishing Concentration and quantity pressure oxygen monoxide time.sup.1 of aerosol.sup.2 Test Scenario (grams) (Pa) (%) (ppm) (s) (g/m.sup.3) 1 Polymeric 9 @ 145 72 18.49 >3000 Not 10.9 sheet (ABS) extinguished 2 Polymeric 13 @ 500 370 20.45 1239 ~10 54.2 sheet (ABS) 3 Heptane pan.sup.3 10 @ 500 320 19.44 1391 ~36 41.7 4 Compatible 13 @ 500 432 20.05 1474 ~20 54.2 wood crib.sup.4 5 Wood crib 11 @ 500 313 19.33 >3000 Not 45.8 extinguished 6 Polymeric 13 @ 500 437 20.50 1229 ~20 54.2 sheet (PMMA) 7 Polymeric 12 @ 500 374 20.58 1050 ~10 50.0 sheet (PP) .sup.1Extinguishing times stated have been measured from the start of system operation. The times are based on thermocouple measurements taken directly above (or in) the test fires. .sup.2The stated concentration (for successfully extinguished tests) is the extinguishing concentration for the relevant fuel. According to ISO 15779, this should be subject to verification by means of 3 successful test results for each fire scenario. .sup.3Four heptane test cans positioned in the corners of the room (two at high level, two at low level) were all extinguished within approximately 10 s of the onset of activation of the system. .sup.4ISO 15779 clause D.6.4 Class A compatible wood crib test specifies two wood crib fires. One of the wood cribs is to be placed behind a baffle installed between the floor and ceiling the baffle is to be perpendicular to the direction of nozzle discharge. Due to the multiple discharge outlet design of the system, it was not appropriate to include this crib in the test (the crib would have been exposed to direct application from discharge units above).

(105) It can be seen from Table 1 that the discharge units successfully extinguished the fires in the heptane pan, compatible wood crib, PMMA and PP tests. The fire in the ABS test was successfully extinguished when the amount of material discharged was increased. The wood crib was not successfully extinguished in test 5. It is worth noting that the discharge unit directly above the centrally positioned fire was removed for this testhad this unit been present then the fire extinguishing performance of the system would have likely been enhanced.

(106) Further observations from the tests are discussed in the following sections: Discharge times The effective discharge time of aerosol from the units was difficult to determine accurately. Due to the obscuration caused by the discharge it was not possible to define the discharge time from visual or video records. Measurement of temperature at the discharge outlet of the units indicated peak temperatures in excess of 1000 C. approximately 5 seconds after discharge was initiated. Temperatures began to decline quickly after approximately 8 seconds and had reached a level below 400 C. after about 25-30 seconds. A typical profile of the temperature measured at one of the discharge outlets on each of the units is shown in FIG. 12. The temperatures measured at the discharge outlets of the units were in the region of 150 C. 10 minutes after activation. Room temperatures As the test room was flooded with the aerosol an increase in the room temperatures was observed. This is illustrated in FIG. 13. Thermocouples were located in a quarter position in the room and spaced from the floor (RT1) up to the ceiling (RT8) in 0.5 m intervals. As an example, in Test 7, the average temperature in the room prior to activation of the system was 14.9 C.; this was increased to 43.4 C. one minute after discharge (a 28.5 C. temperature increase). The increase in room temperature resulted in a buoyant aerosol within the room which was observed to rise out of the door when ventilation of the space was commenced 10 minutes after discharge. Discharge aerosol energy, fire baffling and unit array Upon activation of the discharge units the aerosol was discharged directly downwards to floor level with sufficient force that when it hit the floor (or another obstruction) the momentum of the aerosol discharge was deflected and bounced up which quickly resulted in mixing and complete coverage of the entire test room. The rapid room coverage was aided by the multiple discharge points. The design also meant that there was no position in the room (or for a fire to be located) that was more than 1.5 m from an aerosol discharge point. The ISO 15779 standard states that measures shall be taken to avoid effects of blowing out the fire and the jet energy from the discharge outlets shall not influence the development of the fire. This was difficult to verify, or otherwise, in the tests conducted. However, any such similar discharge design (employing the same spacing of units for a protected space) in an actual system would of course benefit from aerosol discharge in the vicinity of a fire, wherever located. FIG. 14 shows how the oxygen concentration in the room varied during the ABS test in which a greater amount of material was used, as measured using the low, medium and high analysers. The graph shows that oxygen concentration dropped with discharge. The greatest reduction in concentration is observed at the high analyser, presumably due to its proximity to the discharge units. However, over the course of the discharge, a comparable concentration was observed at the medium analyser, and a noticeable drop was observed at the low analyser. This shows that the aerosol used in the experiment spreads through the room to provide coverage at all analyser heights. Room pressure on system discharge The measured peak room over pressure in the test room upon activation of the system ranged from 72 Pascals to 437 Pascals. A small under pressure (less than 25 Pascals) was observed in some tests approximately 15 seconds after initiation of the discharge. Aerosol was recorded discharging through an over pressure protection vent installed in the door. Obscuration/visibility Video recordings taken from inside the room during the test programme showed that complete obscuration resulted a few seconds after the onset of discharge. Visibility from the camera was reduced to a short distance and total whiteout was observed. Visibility from the camera (at a height of approximately 1 m from the floor) did not improve significantly until after ventilation of the space was commenced 10 minutes after discharge.