Abstract:
The present invention relates to a fire extinguishing system comprising a fire extinguishing medium container ( 3 ), a first ( 5 ) and second ( 7 ) fire extinguishing sub-systems, and a valve assembly ( 9 ) fluidly connecting the fire extinguishing medium container ( 3 ) to each of the first ( 5 ) and second ( 7 ) fire extinguishing sub-systems. The fire extinguishing system ( 1 ) further comprises a first and a second detection conduit arrangement ( 19, 21 ) connected to the valve assembly ( 9 ) and arranged to activate the fire extinguishing system ( 1 ), wherein the valve assembly ( 9 ) comprises a valve chamber ( 33 ), a valve member ( 35 ) being movably arranged in the valve chamber ( 33 ), the valve member ( 35 ) having: i) a first force receiving surface ( 45 ) arranged to be subjected to a first force (F 1 ) exerted by a force applicator of the first detection conduit arrangement ( 19 ), and ii) a second force receiving surface ( 47 ) arranged to be subjected to a second force (F 2 ) exerted by a second force application arrangement of the second detection conduit arrangement ( 21 ).

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a fire extinguishing system comprising a fire extinguishing medium container, a first and a second fire extinguishing sub-system, and a valve assembly fluidly connecting the fire extinguishing medium container to each of the first and second fire extinguishing sub-systems and arranged for selectively distributing fire extinguishing medium from the fire extinguishing medium container to the first or to the second fire extinguishing sub-system upon activation of the fire extinguishing system. 
       BACKGROUND OF THE INVENTION 
       [0002]    A fire extinguishing system of this type may be used where fire may occur at different locations and the space is limited, such as, e.g., in vehicles. 
         [0003]    EP 2 462 993 discloses a fire extinguishing system for vehicles. The system comprises a fire suppressant source, a distributor valve, a distribution system and a control system. The divert valve is movable between an initial first position which communicates extinguishing agent into a first distribution network and a second position which communicates extinguishing agent into a second distribution network. 
         [0004]    This fire extinguishing system has the drawback that the reliability may be regarded as relatively poor. Furthermore, the system may be regarded as complex. 
       SUMMARY OF THE INVENTION 
       [0005]    It is an object of the present invention to overcome the above described drawback, and to provide an improved fire extinguishing system. 
         [0006]    This and other objects that will be apparent from the following summary and description are achieved by a fire extinguishing system according to the appended claims. 
         [0007]    According to one aspect of the present disclosure there is provided a fire extinguishing system comprising a fire extinguishing medium container, a first and a second fire extinguishing sub-system, and a valve assembly fluidly connecting the fire extinguishing medium container to each of the first and second fire extinguishing sub-systems and arranged for selectively distributing fire extinguishing medium from the fire extinguishing medium container to the first or to the second fire extinguishing sub-system upon activation of the fire extinguishing system, wherein the fire extinguishing system further comprising a first and a second detection conduit arrangement connected to the valve assembly and arranged to activate the fire extinguishing system, wherein the valve assembly comprises a valve chamber, a valve member being movably arranged in the valve chamber and a fluid passage portion being arranged in at least one of the valve member and the valve chamber, the valve member having a first force receiving surface arranged to be subjected to a first force exerted by a force applicator of the first detection conduit arrangement and for moving the valve member to a first position, in which said fluid passage portion is aligned for distribution of fire extinguishing medium to the second fire extinguishing sub-system, and a second force receiving surface arranged to be subjected to a second force exerted by a force applicator of the second detection conduit arrangement and for moving the valve member to a second position, in which said fluid passage portion is aligned for distribution of fire extinguishing medium to the first fire extinguishing sub-system. 
         [0008]    The fluid passage portion thus allows fire extinguishing medium, such as e.g. water under high pressure, to be supplied from a common storage to one of the first and second fire extinguishing sub-systems. One single fire extinguishing medium container may thus supply fire extinguishing medium to one of two separate fire extinguishing sub-systems. Such a fire extinguishing system may be installed in applications where the space is limited and there is a need for separate extinguishing lines. Furthermore, a cost-efficient system may be provided since one single fire extinguishing medium container is needed. 
         [0009]    Furthermore, this fire extinguishing system may be fully automatic since e.g. pressurized detection conduits or electrical detection arrangements may be connected to the valve assembly. Hence, a very robust and reliable fire extinguishing system may be provided. Also, the system does not need to be powered by electricity if pressurized detection conduits are used. 
         [0010]    According to one embodiment at least one of said force applicators comprises pressurized fluid. Preferably each of said force applicators comprises pressurized fluid. Such a force applicator may thus comprise pressurized fluid or a device, such as a pyrotechnical charge, capable of generating pressurized fluid in the form of pressurized gas. 
         [0011]    According to one embodiment at least one of said force applicators comprises pressurized liquid. Preferably each of said force applicators comprises pressurized liquid. 
         [0012]    According to one embodiment said valve member is arranged to move along a linear path along the valve chamber. 
         [0013]    According to one embodiment said first and second force receiving surfaces are opposed to each other. 
         [0014]    According to one embodiment said valve member is a valve plunger. 
         [0015]    According to one embodiment said valve plunger is cylindrical. 
         [0016]    According to one embodiment said fluid passage portion is arranged in said valve member. 
         [0017]    According to one embodiment the fluid passage portion is formed by a recess in the valve member. 
         [0018]    According to one embodiment the first said valve member comprises at least a first blocking portion which is arranged to prevent distribution of fire extinguishing medium to the first or to the second fire extinguishing sub-system. 
         [0019]    According to one embodiment at least one of the first and second detection conduit arrangement comprises a liquid-filled detection conduit. This is advantageous since a liquid-filled detection conduit may be installed in a compartment where the normal operating temperature is relatively high. 
         [0020]    According to one embodiment at least one of the first and second detection conduit arrangement comprises a detection conduit formed from a thermoplastic material, such as a thermoplastic fluoropolymer. This has the advantage that the detection conduit may resist relatively high temperatures which is advantageous in applications where the normal operating temperature is relatively high. 
         [0021]    According to one embodiment at least one of said force applicators is a linear actuator. 
         [0022]    According to one embodiment said linear actuator is a pyrotechnical actuator. 
         [0023]    According to one embodiment the linear actuator comprises a piston. 
         [0024]    According to one embodiment at least one of the first and second detection conduit arrangement comprises an electrical detection cable. 
         [0025]    These and other aspects of the invention will be apparent from and elucidated with reference to the claims and the embodiments described hereinafter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    The invention will now be described in more detail with reference to the appended drawings in which: 
           [0027]      FIG. 1  is a schematic perspective view of a fire extinguishing system according to an embodiment of the present disclosure. 
           [0028]      FIG. 2 a    is a schematic section view of a valve assembly of the fire extinguishing system shown in  FIG. 1 . 
           [0029]      FIG. 2 b    is a schematic section view of a valve assembly of the fire extinguishing system shown in  FIG. 1 . 
           [0030]      FIG. 4  is a schematic perspective view of a fire extinguishing system according to a second embodiment of the present disclosure. 
           [0031]      FIGS. 5 a - c    are section views and illustrate the function of the fire extinguishing system shown in  FIG. 4 . 
           [0032]      FIGS. 6 a - c    are section views and illustrate the function of a fire extinguishing system according to a third embodiment of the present disclosure. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0033]      FIG. 1  illustrates a fire extinguishing system  1  according to an embodiment of the present disclosure. The fire extinguishing system  1  may e.g. be installed in a vehicle, or in a building, with several compartments. On release of the extinguishing system  1  extinguishing liquid in the form of atomised mist is sprayed in the compartment where a fire has been detected to cool and extinguish the fire. 
         [0034]    The fire extinguishing system  1  comprises a fire detection system, a container  3  for fire extinguishing medium, a first fire extinguishing sub-system  5 , a second fire extinguishing sub-system  7  and a valve assembly  9  for distribution of fire extinguishing medium to the first or to the second fire extinguishing sub-system  5 ,  7 . Each of the first and second fire extinguishing sub-systems  5 ,  7  comprises several nozzles  11 ,  13  and a piping system  15 ,  17  and is fluidly connected to the fire extinguishing medium container  3  by the valve assembly  9 . 
         [0035]    The fire detection system comprises a first and a second detection conduit  19 ,  21  each of which is filled with pressurized detection fluid, in the form of pressurized liquid, and connected to the valve assembly  9 . In this embodiment the fire detection system comprises a common detection fluid container  23  holding pressurized detection liquid and connected to the valve assembly  9  for pressurizing each of the first and second detection conduits  19 ,  21 . 
         [0036]    The detection liquid container  23  is of a design known per se and comprises pressurized detection fluid. In this embodiment detection fluid in the form of detection liquid is used. On delivery the liquid container  23  is filled with detection liquid, such as e.g. glycol-based anti-freeze, and pressurized with nitrogen gas to approximately 20-24 bar. 
         [0037]    The detection liquid container  23  is fluidly connected to the valve assembly  9  by a detection fluid tube  24 . 
         [0038]    Each of the first fire extinguishing sub-system  5  and the first detection conduit  19  is arranged in a first compartment  6 , and each of the second fire extinguishing sub-system  7  and the second detection conduit  21  is arranged in a second compartment  8 , as schematically illustrated in  FIG. 1 . The first and second compartments  6 ,  8  may be separated from each other by walls. By way of an example the first compartment  6  may be a first engine compartment and the second compartment  8  may be a second engine compartment. By way of a second example the first compartment may be an engine compartment and the second compartment may be a passenger compartment. Furthermore, one of the compartments may e.g. be a compartment for electrical components, battery, hydraulic components, cab heater or engine heater. Also, the fire extinguishing system may be installed in a building with separated rooms. 
         [0039]    The fire extinguishing medium container  3  is of a design known per se and forms two chambers, a first chamber for extinguishing liquid and a second chamber for a driving gas. The container chambers are separated from each other by means of a piston displaceably arranged in the container  3  and sealed with regard to the cylindrical wall by means of sealing rings. On delivery the fire extinguishing medium container  3  may be filled with extinguishing liquid and drive gas to approximately 105 bars. 
         [0040]    A release valve  25 , which is known per se, is arranged on the fire extinguishing medium container  3 . The release valve  25  is fluidly connected to the valve assembly  9  by a tube  27 . The release valve  25  is arranged to open supply of fire extinguishing medium from the fire extinguishing medium container  3  to the valve assembly  9  when a fire is detected in one of the first and second compartments  6 ,  8  by the detection system. To this end the release valve  25  is fluidly connected to the detection medium tube  24  by means of a tube  28 . The release valve  25  is thus arranged to open supply of extinguishing liquid from the fire extinguishing medium container  3  to the valve assembly  9  in response to a pressure drop in any of the first and second detection conduits  19 ,  21  caused by rupture of the first  19  or second detection conduit  21 . When the pressure in the detection fluid tube  24  has fallen to approximately 7 bar the release valve  25  on the fire extinguishing medium container  3  is activated and the fire extinguishing system  1  is released. Then, extinguishing liquid is sprayed into the engine compartment where fire has been detected. When the release valve  25  is opened extinguishing liquid is discharged from the pressure container  3  to the valve assembly  9  through the tube  27  fluidly connecting the valve assembly  9  to the fire extinguishing medium container  3 . The advantage of activating the release valve  25  this way. i.e. by means of pressurized detection conduits, is that it provides for an automatic system that works without the need of electricity or other external energy. 
         [0041]    Now referring to  FIG. 2 a   , the valve assembly  9  comprises a valve chamber  33  and a valve member, in the form of a cylindrical valve plunger  35 , displaceably arranged in the valve chamber  33  and sealed with regard to a cylindrical wall of the valve chamber  33  by means of sealing rings  37 . The valve chamber  33  comprises a first sub-chamber  33   a  to which the first detection conduit  19  is fluidly connected, and a second sub-chamber  33   b  to which the second detection conduit  21  is fluidly connected. The first and second valve sub-chambers  33   a,    33   b  are separated from each other by the movable valve plunger  35 . 
         [0042]    The cylindrical valve member  35  comprises a fluid passage portion  39  for distribution of fire extinguishing medium from the fire extinguishing medium container  3  to the first or to the second fire extinguishing sub-systems  5 ,  7 . In this embodiment the fluid passage portion  39  is formed by a circumferential recess in the cylindrical valve member  35 . In an alternative embodiment the fluid passage portion may instead, or as a complement to a recess, comprise channels through the valve member. 
         [0043]    The valve member  35  further comprises a first blocking portion  41  arranged at one side of the fluid passage portion  39  and a second blocking portion  43  arranged at the other side of the fluid passage portion  39 . 
         [0044]    Each of the first and second fire extinguishing sub-systems  5 ,  7  is fluidly connected the valve chamber  33  of the valve assembly  9 . To this end each of the first and second pipe systems  15 ,  17  is fluidly connected to the valve chamber  33  of the valve assembly  33 , as illustrated in  FIG. 2   a.    
         [0045]    The valve member  35  comprises a first force receiving surface, in the form of a first pressure surface  45 , arranged to be exposed to a first pressure force exerted by pressurized fluid in the first detection conduit  19 , which is fluidly connected to the first valve chamber  33   a,  and for moving the valve member  35  in a direction away from the first detection conduit  19 . 
         [0046]    The valve member  35  further comprises a second force receiving surface, in the form of a second pressure surface  47 , arranged to be exposed to a second pressure force exerted by pressurized fluid in the second detection conduit  21 , which is fluidly connected to the second valve chamber  33   b,  and for moving the valve member  35  in a direction away from the second detection conduit  21 . 
         [0047]    Now referring to  FIG. 2 b    the valve assembly  9  comprises a common detection fluid channel  49 . The common detection fluid channel  49  branches into a first sub-channel  51  fluidly connecting the detection fluid container  23  to the first valve chamber  33   a,  and into a second sub-channel  55  fluidly connecting the detection fluid container  23  to the second sub-chamber  33   b.    
         [0048]    The first sub-channel  51  comprises a first valve seat  55  against which a first ball  57  is seated. The first ball  57  is pressed against the first valve seat  55  by means of a first spring  59  supported by an inner wall of the first sub-channel  51 . The first valve seat  55 , the first ball  57  and the first spring  59  form part of a first check valve preventing fluid flow from the first detection conduit  19  to the common channel  49 . 
         [0049]    The second sub-channel  53  comprises a second valve seat  61  against which a second ball  63  is seated. The second ball  63  is pressed against the second valve seat  61  by means of a second spring  65 . The second valve seat  61 , the second ball  63  and the second spring  65  form part of a second check valve preventing detection fluid from flowing from the second detection conduit  21  to the common channel  49 . 
         [0050]    With reference to  FIGS. 3 a - c    the function of the fire extinguishing system  1  will be described hereinafter. 
         [0051]      FIG. 3 a    shows a state in which each of the first and second detection conduct  19 ,  21  is intact and filled with pressurized detection liquid. The pressure of the detection liquid in the first and second detection conduits  19 ,  21  is then P 1  and P 2 , respectively. A first pressure force F 1  is exerted on the first pressure surface  45  of the valve member  35  and a second pressure force F 2  is exerted on the second pressure surface  47  of the valve member  35 . Hence, the pressurized liquid in the first detection conduit  19  forms a first force applicator and the pressurized liquid in the second detection conduit  21  forms a second force applicator. 
         [0052]      FIG. 3 b    illustrates fire in the second compartment  8 , i.e. where the second detection conduit  21  and the second fire extinguishing sub-system  7  are arranged. In the event of fire in the second compartment  8  the second detection conduit  21  bursts due to heat generated by the fire. Consequently, detection liquid leaks from the detection conduit  21 , as illustrated by arrow A in  FIG. 3 b   . Then, the pressure in the second valve chamber  33   b  drops and the second pressure force F 2  is removed. The first check valve prevents fluid from being evacuated from the first detection conduit  19 . Hence, the first pressure force F 1  is maintained since the first valve chamber  33   a  is still pressurized. The valve member  35  is then moved to a first position, illustrated in  FIG. 3 b   , by the pressure force F 1  exerted on the first pressure surface  45  of the valve member  35  by pressurized detection liquid in the first valve chamber  33   a,  i.e. by the first force applicator, as illustrated by the arrow B in  FIG. 3 b   . The valve member  35  is moved to the first position upon a pressure difference between the first and second valve chambers  33   a,    33   b  of approximately 2-5 bar. In the first position the fluid passage portion  39  is positioned for distribution of fire extinguishing medium from the fire extinguishing medium container  3  to the tube  17  of the second extinguishing sub-system  7 . 
         [0053]    Also, the pressure in each of the detection tube  24  and connection tube  28 , which are fluidly connected to the second detection conduit  21 , drops upon leakage of detection fluid from the second detection conduit  21 . When the pressure in the detection fluid tube  24  has fallen to approximately 7 bar the release valve  25  on the fire extinguishing medium container  3  is activated. As soon as the release valve  25  is opened extinguishing fluid is supplied to the second fire extinguishing sub-system  7 , as illustrated by the arrow C in  FIG. 3 b   . In the first valve member position distribution of fire extinguishing medium to the first fire extinguishing sub-system  5  is prevented by the first blocking portion  41  of the valve member  35 . Fire extinguishing medium is thus supplied only to the second sub-system  7  when the valve member  35  assumes the first valve member position. 
         [0054]      FIG. 3 c    illustrates fire in the first compartment  6 , i.e. where the first detection conduit  19  and the first fire extinguishing sub-system  5  are arranged. In the event of fire in the first compartment  6  the first detection conduit  19  bursts due to heat generated by the fire. Consequently, detection liquid leaks from the first detection conduit  19 , as illustrated by arrow D in  FIG. 3 c   . Then, the pressure in the first valve chamber  33   a  drops and the first pressure force F 1  is removed. The second check valve prevents fluid from being evacuated from the second detection conduit  21 . Hence, the second pressure force F 2  is maintained since the second valve chamber  33   b  is still pressurized. The valve member  35  is then moved to a second position, illustrated in  FIG. 3 c   , by the pressure force F 2  exerted on the second pressure surface  47  of the valve member  35  by pressurized detection liquid in the second valve chamber  33   b,  i.e. by the second force applicator, as illustrated by the arrow E in  FIG. 3 c   . The valve member  35  is moved to the second position upon a pressure difference between the first and second valve chambers  33   a,    33   b  of approximately 2-5 bar. In the second valve member position the fluid passage portion  39  is positioned for distribution of fire extinguishing medium from the fire extinguishing container  3  to the tube  15  of the first extinguishing sub-system  5 . 
         [0055]    Also, the pressure in each of the detection tube  24  and the connection tube  28 , which are fluidly connected to the first detection conduit  19 , drops upon leakage of detection fluid from the first detection conduit  19 . When the pressure in the detection fluid tube  24  has fallen to approximately 7 bar the release valve  25  on the fire extinguishing medium container  3  is activated. As soon as the release valve  25  is opened extinguishing fluid is supplied to the first fire extinguishing sub-system  5 , as illustrated by the arrow F in  FIG. 3   c.    
         [0056]    In the second valve member position distribution of extinguishing fluid to the second fire extinguishing sub-system  7  is prevented by the second blocking portion  43  of the valve member  35 . Fire extinguishing medium is thus supplied only to the second fire extinguishing sub-system  5  when the valve member  35  assumes the second valve member position. 
         [0057]    Hereinafter a fire extinguishing system  101  according to a second embodiment will be described with reference to  FIGS. 4 and 5   a - b . Many features disclosed in the first embodiment are also present in the second embodiment with similar reference numerals identifying similar or same features. Having mentioned this, the description will focus on explaining the differing features of the second embodiment. 
         [0058]    The second embodiment differs from the first embodiment in that it comprises electrical detection conduits instead of pressurized detection conduits. 
         [0059]    The fire extinguishing system  101  thus comprises a first and a second electrical detection conduit arrangement  119 ,  121 . The fire extinguishing system  101  further comprises a container  3  for fire extinguishing medium, a first fire extinguishing sub-system (not shown), a second fire extinguishing sub-system (not shown), a valve assembly  9 , which is fluidly connected to the fire extinguishing medium container  3  by a tube (not shown), for distribution of fire extinguishing medium to the first or to the second fire extinguishing sub-system and a release valve  25  arranged to open supply of fire extinguishing medium from the fire extinguishing medium container  3  to the valve assembly  9 . 
         [0060]    In this embodiment the second fire extinguishing sub-system, which is arranged in the compartment where the second detection conduit arrangement  121  is arranged, is fluidly connected to the valve chamber  33  via a first valve port  10  of the valve assembly  9  and the first fire extinguishing sub-system, which is arranged in the compartment where the first detection conduit arrangement  121  is arranged, is fluidly connected to the valve chamber  33  via a second valve port  12  of the valve assembly  9  while in the first embodiment the first fire extinguishing sub-system is fluidly connected to the valve chamber  33  via the first valve port  10  and the second fire extinguishing sub-system is fluidly connected to the valve chamber  33  via the second valve port  12 . The reason for the crosswise connection of the fire extinguishing sub-systems in the second embodiment is that, upon detection of fire in e.g. the first compartment, the piston member  35  is moved in the opposite direction compared to the corresponding piston movement in the first embodiment. 
         [0061]    The first detection conduit arrangement  119  comprises a first force applicator, in the form of a pyrotechnical actuator  119   a,  and an energized electrical detection cable  119   b.    
         [0062]    The second detection conduit arrangement  121  comprises a second force applicator, in the form of a pyrotechnical actuator  121   a,  and an energized electrical detection cable  121   b.    
         [0063]    Each of the pyrotechnical actuators  119   a,    121   a  comprises a pyrotechnical charge capable of generating pressurized gas. 
         [0064]    Each of the first and second detection cables  119   b,    121   b  comprises two adjacent conductors and a meltable insulating layer therebetween. In the event of fire the insulating layer melts due to heat generated by the fire. Then, an electrical impulse is generated in the detection cable. 
         [0065]    The first detection cable  119   b  is connected to each of the pyrotechnical actuator  119   a  and the release valve  25  and arranged to activate each of the pyrotechnical actuator  119   a  and the release valve  25  in case of fire in the compartment where the first detection conduit arrangement  119  is installed. In the event of fire in the compartment where the first detection conduit arrangement is arranged each of the first pyrotechnical actuator  119   a  and the release valve  25  thus receives an electrical impulse from the detection cable  119   b.    
         [0066]    The second detection cable  121   b  is connected to each of the second pyrotechnical actuator  121   a  and the release valve  25  and arranged to activate each of the second pyrotechnical actuator  121   a  and the release valve  25  in case of fire in the compartment where the second detection conduit arrangement  121  is arranged. In the event of fire in the compartment where the second detection conduit arrangement  121  is arranged each of the second pyrotechnical actuator  121   a  and the release valve  25  thus receives an electrical impulse from the second detection cable  121   b.    
         [0067]    The release valve  25  may e.g. be activated in a known manner by means of a pyrotechnical charge arranged to be ignited by an electrical impulse from any of the first and second electrical detection cable  119   b ,  121   b.    
         [0068]    A first diode  151  is arranged to secure that only the second pyrotechnical actuator  121   a  is activated when an electrical impulse is generated by the second detection cable  121   b.    
         [0069]    A second diode  153  is arranged to secure that only the first pyrotechnical actuator  119   a  is activated when an electrical impulse is generated by the first detection cable  119   b.    
         [0070]    Now referring to  FIG. 5 a   , the pyrotechnical actuator  121   a  of the second detection conduit arrangement  121  comprises a pyrotechnical charge  121   c  which is arranged to be initiated by an electrical impulse from the second detection cable  121   b.  Upon initiation of the pyrotechnical charge  121   c  pressurized gas is generated and forwarded into the second valve chamber  33   b,  as illustrated by arrow G in  FIG. 5 b   . The pressurized gas exerts a pressure force on the force receiving surface  47  of the valve member  35 . Then, the valve member  35  is moved to a valve member position, in which the fluid passage portion  39  of the valve member  35  is aligned for distribution of fire extinguishing medium to the second fire extinguishing sub-system, by the force applied by pressurized gas in the second valve chamber  33   b,  as illustrated by the arrow H in  FIG. 5   b.    
         [0071]    Hereinafter a fire extinguishing system according to a third embodiment will be described with reference to  FIGS. 6 a - b   . Many features disclosed in the second embodiment are also present in the third embodiment with similar reference numerals identifying similar or same features. Having mentioned this, the description will focus on explaining the differing features of the third embodiment. 
         [0072]    The third embodiment differs from the second embodiment in that each of the first and second force applicator comprises a piston.  FIG. 6 a    shows a part of the second detection conduit arrangement  221 . The second detection conduit arrangement  221  comprises a force applicator, in the form of a pyrotechnical piston actuator  221   a,  and an energized electrical detection cable  221   b.  The pyrotechnical piston actuator  221   a  comprises a pyrotechnical charge (not shown) capable of generating pressurized gas. The pyrotechnical charge of the pyrotechnical actuator  221   a  is arranged to be initiated by an electrical impulse from the second detection cable  221   b,  and a piston  221   c,  illustrated in  FIG. 6 b   . Upon initiation of the pyrotechnical charge the piston is moved towards the valve member  35 , as illustrated by arrow I in  FIG. 6 b   . As soon as the piston  221   c  contacts the valve member  35  a force is exerted on the force receiving surface  47  of the valve member  35 . Then, the valve member  35  is moved to a valve member position, in which the fluid passage portion  39  of the valve member  35  is aligned for distribution of fire extinguishing medium to the second fire extinguishing sub-system, by the force exerted by the piston  221   c  of the pyrotechnical piston actuator  221   a,  as illustrated by the arrow J in  FIG. 6   b.    
         [0073]    It will be appreciated that numerous variants of the embodiments described above are possible within the scope of the appended claims. 
         [0074]    Hereinbefore it has been described that the fire extinguishing medium may be a fluid in the form of a liquid. It is appreciated that the fire extinguishing medium may be a fluid in the form of a gas, such as, e.g., Carbon dioxide, Nitrogen, Argon or compressed air. 
         [0075]    Hereinbefore is has been described that detection fluid in the form of detection liquid may be used. It is however realised that detection fluid in the form of detection gas, such as e.g. nitrogen, may be used instead of detection liquid. Then, the detection conduit is preferably gas-tight. For instance, a gas-tight detection hose formed from polyamide may be used.