EP1261396B1 - Inert rendering method with a nitrogen buffer - Google Patents

Abstract

The invention relates to an inert rendering method for preventing and/or extinguishing fires in enclosed spaces, wherein an oxygen-inhibiting gas is introduced into the target area in order to adjust a first basic level of inertion with a reduced oxygen content in comparison with natural conditions, and wherein an oxygen-inhibiting gas is further introduced in a gradual or sudden manner (in the case of a fire) into the target area in order to adjust one or more levels of inertion with a similarly reduced oxygen content. The invention also relates to a device for carrying out the method, comprising an oxygen-measuring device in the target area and a source of an oxygen-inhibiting gas. The aim of the invention is to provide an inert rendering method and device for carrying out said method enabling the storage of extinguishing gas needed to extinguish a fire in a simple, economical manner without having to resort to premises which are normally specially provided therefor.

Description

The invention relates to an inerting method for preventing and / or extinguishing fires in a closed space (hereinafter also referred to as "target space") in which a first Grundinertisierungsniveau is set by introducing an oxygen-displacing gas in the target space with reduced compared to natural proportions oxygen content and in which one or more different inerting levels with a further reduced oxygen content are or will be adjusted by further introducing, if necessary, stepwise or in case of fire sudden introduction of an oxygen displacing gas into the target space. The invention further relates to an apparatus for carrying out the method with an oxygen measuring device in the target space and with a source of an oxygen-displacing gas.

Methods and apparatus of the type in question are known in the art such as US-A-6 016 874, EP-A-0 700 693 or EP-A-0 301 464. The effect of the so-called "inert gas extinguishing technology" is essentially based on the fact that in closed rooms, which are only occasionally entered by humans or animals and their facilities would carry out conventional extinguishing procedures (water and foam) cause significant damage, the risk of fire is countered by the oxygen concentration in the affected area is lowered to a value of about 12% by volume on average, at which most flammable materials no longer burn. Fields of application are EDP areas, electrical switch and distribution rooms or storage areas with high-quality assets. The extinguishing effect is based on the principle of oxygen displacement. The normal ambient air consists of 21% oxygen, 78% nitrogen and 1% other gases. For deleting z. B. by introducing pure nitrogen, the nitrogen concentration in the target area further increased and thus reduces the oxygen content. It is known that a extinguishing effect starts when the oxygen content falls below a value of 15% by volume. Depending on the materials present in the room in question, a further lowering of the oxygen content to the mentioned 12 vol.% Or lower may be required.

As oxygen-displacing gases usually gases such as carbon dioxide, nitrogen, noble gases and mixtures thereof are used, which are usually stored in special ancillary rooms in steel bottles. To flood a target area with extinguishing gas, however, so far, especially in commercially used premises such as open-plan offices and warehouses, significant amounts of extinguishing gas to store. Since the pressure of the gas cylinders is limited due to the limit load capacity of the available fittings and also the capacity can not be increased arbitrarily, a considerable number of bottles is required to provide the extinguishing gases. This, together with the required pipes and fittings considerable requirements for the carrying capacity and size of the storage rooms. Even if the bottles were stored in basements, a considerable amount of construction work would be necessary to lay the supply lines in the target areas. By correspondingly large storage rooms also incur increased construction and operating costs.

Recent developments show that this problem can be counteracted by lowering the oxygen content to a basic inerting level, which is harmless to living beings, of on average about 17% by volume in the target areas. As a result, the amount of extinguishing gas to be held is reduced to achieve the Vollinertisierungsniveaus at an oxygen concentration of less than 15 vol .-% for fire prevention and / or extinction, which brings about an improvement of the bearing problem described. Nevertheless, however, structurally continue to provide special premises, which are suitable for storage of steel bottles due to their capacity and size. This leads, especially in the trend towards the creation of ever larger buildings, to considerable financial expenditure during the construction phase and during use.

It is an object of the present invention to provide an inerting method and an apparatus for carrying out this method, which allow the storage of extinguishable gas to be kept for the fire extinguishing without the usually specially provided premises in a simple and cost-effective manner.

This object is achieved by an inerting process in which in a first step a) in a closed buffer space, which is connected via leads to the target space, by introducing an oxygen-displacing gas, a buffer gas volume is generated whose oxygen content is so low that when mixed the buffer gas volume with the room air in the target space a Vollinertisierungsniveau for an extinguishing operation can be achieved, and passed in a second step b) the buffer gas volume if necessary via the leads in the target area and there with mixing of the room air of the target space and the buffer gas volume for setting one of the first Grundinertisierungsniveau different intertization levels is used.

The present invention is based on the consideration that the storage of the quenching gas, in particular because of the storage under pressure in special containers such as steel bottles, which require due to their weight and safety reasons again special premises, is problematic. On the other hand, given the prevailing conception of new buildings, especially in the commercial sector, a significant proportion of the premises are already separated for other use from the actually used by human and / or animal premises, the volume but only a small part Building installations such as Air conditioning systems, lighting and cable ducts are filled. At the same time, setting a Grundinertisierungsniveaus an oxygen concentration of on average about 17 vol .-% as close to the Vollinertisierungsniveau of less than 15 vol .-% in the target areas, the amount of necessary extinguishing gas vorhaltbar even without compression if appropriate buffer space would be available. This buffer space may be in parts of the premises, e.g. Zwischenendekken, raised floors, intermediate walls or adjacent equipment rooms arise, the walls of the buffer space can be fixed partitions or foils. The oxygen content of the buffer space located in the buffer space, which is set in the first step a) of the presented method, is so low that after mixing the buffer gas volume with the room air of the target area, which at a Grundinertisierungsniveau an oxygen concentration of about 17 vol. %, a full inertization level is set throughout the room which is below an oxygen concentration of 15% by volume for preventing and / or extinguishing fires.

However, certain volume and oxygen concentration ratios between the buffer space and the target space, which result from the following calculations, must be taken into account.

• V_N - das Volumen des Pufferraumes
• V_R - das Volumen des Zielraumes
• V_RN - das Volumen des Gesamtraumes

und

• K_N - die Sauerstoffkonzentration im Pufferraum
• K_R - die Sauerstoffkonzentration im Zielraum
• K_NR - die Sauerstoffkonzentration im Gesamtraum

There are

• V _N - the volume of the buffer space
• V _R - the volume of the target area
• V _RN - the volume of the total space

and

• K _N - the oxygen concentration in the buffer space
• K _R - the oxygen concentration in the target area
• K _NR - the oxygen concentration in the whole room

ergibt sich mit $${\mathrm{V}}_{\mathrm{N}\mathrm{R}}={\mathrm{V}}_{\mathrm{N}}+{\mathrm{V}}_{\mathrm{R}}$$

und $$\mathrm{V}=\mathrm{A}.\mathrm{H}$$

wobei

• V - das Volumen eines Raumes
• A - die Grundfläche eines Raumes
• H - die Höhe eines Raumes

ist
durch Einsetzen der Gleichung (2) in Gleichung (1) und Auflösung nach V_N/V_R $${\mathrm{V}}_{\mathrm{N}}/{\mathrm{V}}_{\mathrm{R}}=\left({\mathrm{K}}_{\mathrm{N}\mathrm{R}}-{\mathrm{K}}_{\mathrm{R}}\right)/\left({\mathrm{K}}_{\mathrm{N}}-{\mathrm{K}}_{\mathrm{N}\mathrm{R}}\right)$$

und schließlich durch Einsetzen der Gleichung (3) in (4) $${\mathrm{H}}_{\mathrm{N}}/{\mathrm{H}}_{\mathrm{R}}=\left({\mathrm{K}}_{\mathrm{N}\mathrm{R}}-{\mathrm{K}}_{\mathrm{R}}\right)/\left({\mathrm{K}}_{\mathrm{N}}-{\mathrm{K}}_{\mathrm{N}\mathrm{R}}\right)$$

From the basic equation of the volume and concentration ratios for the sum of the buffer and the target space before and after mixing $${\mathrm{V}}_{\mathrm{N}},{\mathrm{K}}_{\mathrm{N}}+{\mathrm{V}}_{\mathrm{R}},{\mathrm{K}}_{\mathrm{R}}={\mathrm{V}}_{\mathrm{N}\mathrm{R}}\cdot {\mathrm{K}}_{\mathrm{R}\mathrm{N}}$$

results with $${\mathrm{V}}_{\mathrm{N}\mathrm{R}}={\mathrm{V}}_{\mathrm{N}}+{\mathrm{V}}_{\mathrm{R}}$$

and $$\mathrm{V}=\mathrm{A},\mathrm{H}$$

in which

• V - the volume of a room
• A - the base of a room
• H - the height of a room

is
by substituting equation (2) into equation (1) and solving for V _N / V _R $${\mathrm{V}}_{\mathrm{N}}/{\mathrm{V}}_{\mathrm{R}}=\left({\mathrm{K}}_{\mathrm{N}\mathrm{R}}-{\mathrm{K}}_{\mathrm{R}}\right)/\left({\mathrm{K}}_{\mathrm{N}}-{\mathrm{K}}_{\mathrm{N}\mathrm{R}}\right)$$

and finally by substituting equation (3) in (4) $${\mathrm{H}}_{\mathrm{N}}/{\mathrm{H}}_{\mathrm{R}}=\left({\mathrm{K}}_{\mathrm{N}\mathrm{R}}-{\mathrm{K}}_{\mathrm{R}}\right)/\left({\mathrm{K}}_{\mathrm{N}}-{\mathrm{K}}_{\mathrm{N}\mathrm{R}}\right)$$

Equation (5) thus specifies the necessary height ratio H _{N /} H _R between the buffer space and the target space if a specific oxygen concentration K _NR as a full inertization level, a basic inertization level K _R in the target space and an oxygen concentration K _N in the buffer space is specified. Conversely, of course, from a predetermined ratio H _N / H _R can be concluded that the necessary oxygen concentrations.

Advantageous developments of the method are specified in the following subclaims.

A particular advantage of the method according to the invention is that a second Grundinertisierungsniveau different from the first Grundinarchieierungsniveau with reduced oxygen content or the Vollinertisierungsniveau can be set for the erase mode. As a result, the method is largely adaptable to the usage conditions of a building. For example, if a building complex is not used or entered by living beings during the night hours, lowering the base inerting level for daytime operation with an oxygen concentration of, for example, 17% by volume to a base inerting level for nighttime operation with an oxygen concentration of, for example, 15 vol. % the Vollinertisierungsniveau for the extinguishing operation with an oxygen concentration below 15 vol .-% by supplying a corresponding amount of oxygen displacing gas from the buffer space very quickly a extinguishing effect can be achieved. Of course, it is also possible to set the second basic inerting level for the night operation as a preventive measure for fire prevention and, if necessary, deletion on weekends or holidays, at or in which a building is not used.

A possible fire is prevented in a preferred manner, or - deleted - as a result of a fire detection signal - when the mixing of the room air of the target space and the buffer gas volume is done so that due to the predetermined amount and concentration ratios of oxygen in both rooms, a mean oxygen concentration between 8 vol.% and 17 vol.% in the target room. This can be done so that, initially in daytime operation, a basic inactivation level of e.g. 17 vol .-% is set, which is harmless to living beings present there. In night mode, in a second step, a further lowered basic inertization level of e.g. 15 vol.%, From which the full inerting level of e.g. 11 Vol .-% is easily achieved by rapid supply of an oxygen-displacing gas from the buffer gas volume in the target area. Preventing the formation of fires by setting the basic daytime inerting level, reducing the oxygen concentration to the night-time base inerting level and, in the event of fire, to the full inerting level below, most of the materials used in the monitored premises are no longer flammable.

Particularly advantageous is an oxygen content of the buffer volume of 10 vol .-% or less. This concentration offers sufficient security against possible leakage of the buffer space, can be achieved by a corresponding aggregate and offers the most effective lowering effect of the basic inerting level on the Vollinertisierungsniveau with mixing of buffer gas volume and room air.

Preferably, the buffer gas volume consists of a pure inert gas. Thus, especially in the monitoring of premises with highly flammable materials, a particularly large potential of an oxygen-displacing gas for maximum reduction of the oxygen content of the air in the target area is available.

In one possible embodiment, if necessary, the buffer gas volume or the buffer gas volumes of buffers of another room or other rooms can be conducted via a supply line into the destination space. It is advantageous in this embodiment that in cases where several rooms of a building are equipped with a buffer, the inert gas from all buffers can be used to extinguish the fire in one of the rooms (target area). Thus, the Vollinertisierungsniveau can be adjusted even in the rooms whose associated buffer gas volumes are dimensioned only for setting the respective Grundinertisierungsniveaus. This ensures that even in such areas a possible fire can be effectively combated.

The object of the present invention is also achieved by a device for carrying out the described method with a closed buffer space which is adjacent to the target space and which is connected to the target space via gas feed lines. In the buffer space, a buffer gas volume is generated by introducing an oxygen-displacing gas whose oxygen content is so low that when a mixture of the buffer gas volume with the room air in the target space Vollinertisierungsniveau for an extinguishing operation can be achieved.

Both the basic inerting of the target area from the buffer space can be controlled via the gas supply lines, as well as a rapid full inertisation of the target area.

Of course, it is also conceivable that a buffer space supplies several adjacent destination spaces.

Advantageous developments of the device are specified in the following subclaims.

A particular flexibility of the device according to the invention is achieved in that as a different from the first Grundinertisierungsniveau inerting a second Grundinertisierungsniveau with even reduced oxygen content or the Vollinertisierungsniveau for the erase mode is adjustable. Such a second basic inerting level, which is usually so close to the Vollinertisierungsniveau for the extinguishing operation that preventing fires in a closed room preventive possible, of course, can also be set on weekends or holidays, or in which a building is not used accordingly , Thus, reaching the Vollinertisierungsniveaus to extinguish fires in case of need by supplying an oxygen displacing gas from a buffer space is reached quickly.

Preferably, the buffer space is formed as a container, in particular as a tank. As a result, from the outset possible leaks, which may be present in the use of structurally given premises for storing the buffer gas excluded. The container can be structurally designed so that it can be optimally fitted using it in the available space in false ceilings or partitions.

In one possible embodiment, the respective buffer spaces of the rooms of a building are connected to the individual rooms via gas supply lines. In a case of need, therefore, the buffer gas volume or the buffer gas volumes of buffers of another room or the other rooms via these leads in be directed to the target area. The prerequisite for this is that several rooms of a building are each equipped with a buffer. It is advantageous in this embodiment that even in those cases in which the respective buffer gas volumes are dimensioned only for setting the Grundinertisierungsniveaus for the individual room, the Vollinertisierungsniveau can be achieved in the target area for extinguishing a fire.

Advantageously, rooms whose associated buffer gas volumes are dimensioned only for setting the respective Grundinertisierungsniveaus connected via flaps or valves with leads to buffer spaces of the other rooms. In case of fire, the supply of a target space can thus be controlled with buffer gas volumes of other buffer spaces and set again when reaching the Vollinertisierungsniveaus in the target area. This will u.a. achieved that the deletion of a fire in the target area as quickly and efficiently as possible.

For rapid mixing of the buffer gas volume and the room air, a mixing unit for mixing the room air of the target room with the buffer gas volume is preferably provided. Thus, in case of fire, a rapid mixing to achieve the Vollinertisierungsniveaus make in the target area. But also the control of the basic engineering level in the target area out of the buffer space is conceivable.

Advantageously, the equipment of the mixing unit with ventilation flaps and fans, which are arranged in or at the target area. This particularly simple construction allows the largely gas-tight closure of the buffer space with respect to the target area with closed ventilation flaps. With completely or partially opened ventilation flaps a controlled flooding of the target space is made possible.

Advantageously, a control device for controlling the oxygen content in the target area, provided with a signal generator for switching between a daytime operation and a post-operation. Such a control unit allows the adjustment of the inerting to the respective desired operating condition, the signal generator can perform the desired switching between daytime or nighttime operation independently of manual intervention and thus without necessary operating personnel.

One possible realization is that the control unit also monitors the air quality of the room air via measurement of the CO or CO ₂ content and controls the ventilation flaps or the fans for fresh air supply. An advantage of this embodiment is that thus no additional device for controlling the air quality of the room air is needed.

The signal generator can advantageously be designed so that it outputs a timing signal, a burglar alarm signal or an access control signal. If, for example, a time measuring device is used as the signal generator, an automatic changeover between daytime and postoperative operation can be preprogrammed. This type of default can also be made for days off, for example, for weekends at which usually no people in the monitored premises and the setting of a Grundinertisierungsniveaus below that for the daytime operation to prevent fires makes sense. The signal generator can, however, also be designed as an access control system which, when identifying persons who identify themselves, for example, via a code or a magnetic card, sends a signal to the controller, which then sets an inerting level harmless to living beings. When using a burglar alarm system as a signal generator, however, a switch to Vollinertisierung would be conceivable when an area is armed after leaving all persons present.

Preferably, by a fire alarm, z. As an automatic smoke or heat detector or a manual call point to trigger the mixing of the buffer gas volume with the indoor air of the target area in the extinguishing operation ensures that at any time a fire can be safely detected and deleted. In addition, this fire alarm can also trigger an audible and / or visual warning function for persons in the affected area. At the same time a coupling of the fire alarm with fire doors is possible, which are automatically closed when triggering the mixing of the buffer gas volume with the air of the affected area and separate this area from others.

Fig. 1

eine schematische Darstellung eines Raumes mit Pufferräumen 20, 20'und einem Zielraum 10 vor Vermischung des Puffergasvolumens 22, 22' und der Raumluft 12;

Fig. 2

die gleiche schematische Darstellung wie in Figur 1 nach Vermischung des Puffergasvolumens 22, 22' und der Raumluft 12;

Fig. 3

eine schematische Darstellung eines Gebäudes mit mehreren über eine Zuleitung 31 verbundenen Pufferräumen 20, 20';

Fig. 4

eine Tabelle mit den verschiedenen Volumenverhältnissen V und Raumhöhen H des Pufferraumes und des Zielraumes in Abhängigkeit von den jeweils darin vorliegenden Sauerstoff-konzentrationen K vor und nach der Vermischung; und

Fig. 5

ein Funktionsschaubild einer Vorrichtung zur Durchführung des erfindungsgemäßen Verfahrens.

Hereinafter, the present invention will be described with reference to exemplary embodiments, which are explained in more detail with the aid of the figures. Show it:

Fig. 1

a schematic representation of a room with buffer spaces 20, 20 'and a target space 10 before mixing the buffer gas volume 22, 22' and the room air 12;

Fig. 2

the same schematic representation as in Figure 1 after mixing the buffer gas volume 22, 22 'and the room air 12;

Fig. 3

a schematic representation of a building with a plurality of connected via a feed line 31 buffer spaces 20, 20 ';

Fig. 4

a table with the different volume ratios V and room heights H of the buffer space and the target space as a function of the respective oxygen concentrations K present therein before and after mixing; and

Fig. 5

a functional diagram of an apparatus for performing the method according to the invention.

For identical or equivalent parts, the same reference numerals are used below.

Fig. 1 shows a schematic representation of a room with buffer spaces 20, 20 'and a target space 10 before mixing the buffer volume 22, 22' and the room air 12. The buffer space contains a buffer gas volume with an oxygen content of 5 vol .-%, the target space a room air having an oxygen concentration at a basic inertization level of 17% by volume. The heights H of the buffer spaces 20, 20 'are indicated laterally.

2 shows the same schematic representation as in FIG. 1 after mixing the buffer gas volume 22, 22 'and the room air 12. Due to the altitude and concentration conditions, an oxygen concentration in the entire room is set to a full inertization level of 15% by volume according to equation ( 5). This can be done both at night to prevent fires and as a result of a fire detection signal.

FIG. 3 shows a schematic representation of a building with a plurality of buffer spaces 20, 20 'connected via a feed line 31. In the example, the individual rooms of the building are dimensioned only with buffer gas volumes for setting a basic inertization level. The individual buffer spaces 20, 20 'are connected via valves or valves 53 to the supply line 31. In case of fire, an additional supply of the target space 10 with buffer gas volumes 22, 22 'of other buffer spaces 20, 20' can thus take place and a Vollinertisierungsniveau set in the target area 10 become. This ensures that even here a fire in the target area 10 is combated as quickly and efficiently.

4 shows a table with the different volume ratios V and room heights H of the buffer space and the target space as a function of the respectively present therein oxygen concentrations K before and after mixing. Starting from the different oxygen concentrations in the buffer space and target space, different full inertization levels between 11% by volume and 15% by volume are achieved for the applied height and volume ratios. Thus, necessary concentration and volume ratios can be adjusted to the flammable materials mainly used in the rooms used.

Fig. 5 is a functional diagram of an apparatus for carrying out the method according to the invention. A buffer space 20, 20 'and a target space 10 can be seen. Buffer and target space are connected by supply lines 30, 30', which are equipped with mixing units 50, 50 ', consisting of fans 54, 54' and ventilation flaps 52, 52 ' , A generator 80 in this embodiment supplies both the buffer and the target space with nitrogen to set a predetermined oxygen concentration in the buffer gas volume 22, 22 'and the room air 12. This is detected by means of the oxygen measuring device 40, 40 'and passed as a signal to a control unit 60. This in turn controls the generator 80 via a signal line. The control unit 60 includes a timer 62 which can switch the generator via a further signal line into night or day mode. The generator 80 then produces the desired level in the buffer space 20, 20 'and the target space 10 by increasing or decreasing the supply of nitrogen. This prevents the formation of fires in advance. About fire detectors 70, 70 'but is also the triggering of the mixing units 60, 60 'possible on the direct path via the control unit 62, which sets this in case of fire in motion.

It should be noted at this point that all the above-described parts are taken for themselves and claimed in every combination, in particular the details shown in the drawings as essential to the invention. Variations thereof are familiar to the person skilled in the art.

LIST OF REFERENCE NUMBERS

10

Finish area

12

room air

20, 20 '

buffer

22, 22 '

Buffer gas volume

30, 30 '

leads

31

Gas supply line

40, 40 '

Oxygen measuring device

50, 50 '

mixing unit

52, 52 '

ventilation flaps

53

Flap / valve

54, 54 '

Fan

60

control unit

62

timer

70, 70 '

fire detector

80

generator

Claims (17)

1. lnertisation process to prevent and/or extinguish fires in an enclosed space (hereafter referred to as "the target room"), whereby an oxygen-displacing gas is introduced into the target room (10) in order to initiate a first basic inertisation with a reduced proportion of oxygen compared to natural conditions, and in which, through the further introduction of an oxygen-displacing gas into the target room (10) - which may be done either in stages or all at once, as required - one or multiple varying levels of inertisation are initiated,
   characterised by
   the following process stages:

   a) in at least one sealed buffer room (20, 20'), which is connected to the target room (10) via supply lines (30, 30), an oxygen-displacing gas is introduced to generate a volume of buffer gas (22, 22') whose oxygen content is so small that when the volume of buffer gas (22, 22') mixes with the room air (12) in the target room (10), an iner6sation level with a yet further reduced proportion of oxygen can be achieved; and

   b) the buffer gas (22, 22') is fed when needed via the supply lines (30, 30') into the target room (10), where the buffer gas (22, 22') is mixed with the room air (12) in the target room (10) to achieve an inertisation level different from the first basic inertisation level.
2. Procedure according to Claim 1,
   characterised in that
   the inertisation level which is different from the first basic inertisation level is a second basic inertisation level with a further reduced proportion of oxygen, or is the full inertisation level for the extinguishing procedure.
3. Procedure according to Claims 1 or 2,
   characterised by
   the mixing of the room air (12) in the target room (10) with the volume of buffer gas (22, 22'), in such a way that, as a result of the predetermined volume and concentration ratios of oxygen in both rooms, a medium oxygen concentration between 8 % and 17 % by volume is achieved in the target room (10), so that a potential fire can be prevented, or extinguished if a signal has been given that a fire has been detected.
4. Procedure according to any of Claims 1 to 3,
   characterised in that
   the proportion of oxygen in the buffer gas (22, 22') in the buffer room (20, 20') is 10 % by volume or less.
5. Procedure according to any of Claims 1 to 4,
   characterised in that
   the buffer gas (22, 22') consists of a pure inert gas or mixtures of inert gases.
6. Procedure according to any of the foregoing Claims,
   characterised in that
   when required the buffer gas (22, 22') is fed into the target room (10) from various buffers (20, 20') connected to valves (53) via a supply line (31).
7. Device for carrying out the procedure according to any of Claims 1 to 6, with

   - an oxygen measuring device (40, 40') in the target room (10); and

   - a source of oxygen-displacing gas,

   characterised by
   a sealed buffer room (20, 20'), connected to the target room (10) via gas supply lines (30, 30'), and in which an oxygen-displacing gas is introduced to generate a volume of buffer gas (22, 22') whose oxygen content is so small that, when the volume of buffer gas (22, 22') mixes with the room air (12) in the target room (10), a full inertisation level for an extinguishing procedure can be achieved.
8. Device according to Claim 7,
   characterised in that
   the inertisation level which is different from the first basic inertisation level is a second basic inertisation level with a further reduced proportion of oxygen, or is the full inertisation level for the extinguishing procedure.
9. Device according to Claim 7 or 8,
   characterised in that
   the buffer room (20, 20') is constructed as a container, in particular as a tank.
10. Device according to any of the foregoing Claims,
    characterised by
    a gas feed line (31) which connects the sealed buffer rooms (21, 21') of the individual rooms in a building, and via which if necessary the volumes of buffer gas (22, 22') of the individual rooms are fed into the target room (10).
11. Device according to any of the foregoing Claims,
    characterised by
    a valve unit (53) connecting the feed line (31) to the buffer rooms (21, 21') of the individual rooms in a building.
12. Device according to any of Claims 7 to 11,
    characterised by
    a mixing unit (50, 50') for mixing the room air (12) of the target room (10) and the buffer gas (22, 22').
13. Device according to Claim 12,
    characterised in that
    the mixing unit (50, 50') has ventilation flaps (52, 52') and ventilators (54, 54'), located in or near the target room (10).
14. Device according to any of Claims 7 to 13,
    characterised by
    a control unit (60) to regulate the proportion of oxygen in the target room (10), with a signal transmitter (62) to switch from a first basic inertisation level to one or multiple different basic inertisation levels.
15. Device according to Claim 14
    characterised in that
    the control unit (60) also monitors the air quality of the room air (12) by measuring the CO content and/or CO₂ content of the air, and triggers the ventilation flaps (52, 52') and/or the ventilators (54, 54') to supply fresh air.
16. Device according to Claim 14 or 15,
    characterised in that
    the signal transmitter (62) transmits a time measuring signal, an intruder warning signal or an access control signal.
17. Device according to any of Claims 7 to 16,
    characterised by
    a fire detector (70, 70') to initiate the mixing of the buffer gas (22, 22') with the room air (12) in the target room (10) during the extinguishing procedure.

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