IT202000026257A1 - HEAT ACTIVATED RELEASE VALVE FOR FIRE-FIGHTING SYSTEMS, FIRE-FIGHTING SYSTEM AND ITS OPERATING METHOD - Google Patents

Description

HEAT ACTIVATED RELEASE VALVE FOR FIRE-FIGHTING SYSTEMS, FIRE-FIGHTING SYSTEM AND RELATED METHOD OF

DRIVE

The present invention relates to a release valve for fire-fighting systems, a related fire-fighting system and a related operating method.

Pi? Specifically, the present invention relates to a heat activated extinguishing gas release valve for the release of extinguishing gas of a gas fire extinguishing system.

The present invention also relates to a fire-fighting system comprising this valve.

How ? Known, among the systems for the active protection of fires are included gas systems, also called "clean agent" systems. These systems use inert gases or gaseous extinguishing chemicals to saturate the environment in which they are released and put out the fire. Inert gases extinguish fire by reducing the oxygen concentration in the environment, gaseous extinguishing chemicals by more effective mechanisms. complexes, including the development of endothermic reactions. In the following of the present description said inert gases and said gaseous extinguishing chemical substances will also be identified as a whole as extinguishing gases.

Gas fire extinguishers were first used over a century ago when the first carbon tetrachloride fire extinguishers were invented. The major developments occurred, however, only in the years immediately following the Second World War, when ?Halon? (for example Bromochlorodifluoromethane) and, at the beginning of the 90s, with the introduction of its substitutes having a lower environmental impact, in part, still present on the market.

The inert gases most commonly used in gas fire-fighting systems today are Argon Ar, Nitrogen N2, individually or in mixtures, both normally present in the atmosphere and with low environmental impact. The chemicals most used in gas fire-fighting systems, on the other hand, are HFC-227ea or 1,1,1,2,3,3,3-Heptafluoropropane, HFC-125 or Pentafluoroethane and FK 5-1-12 or Perfluoro( 2-Methyl-3-Pentanone.

Gas systems can be advantageously used on objects and/or machinery of different types, including electronic and live ones, without damaging them irreparably and in areas normally manned by personnel, unlike what is foreseen for ?traditional? systems? (e.g. those that use water, foam or powder).

Furthermore, gas systems guarantee total saturation of the environments in which these gases are released, also known as "total flooding", allowing for the formation of a homogeneous concentration of extinguishing agent within the room in question in a very short time, usually within 10 seconds of release.

This feature makes possible the rapid extinction even of fires present in the most? hidden and less accessible than the environments in question.

The characteristics and advantages of gas fire-fighting systems have favored their wide diffusion, especially in areas where the value of the protected capital is? relevant and where it is necessary to be able to guarantee the safety of personnel, and in particular in the case of personnel commanded to supervise the protected environment even during a fire.

Gas fire extinguishing systems must also follow specific safety regulations, such as the technical standard ?Standard for Clean Agent Fire Extinguishing Systems - NFPA 2001? drawn up by the National Fire Protection Association (NFPA) for the United States, the UNI EN 15004 standard ?Fixed fire-fighting installations - Gas extinguishing systems? valid for Italy and based, together with other national standards, on the ISO 14520 ?Gaseous Fire-Extinguishing Systems? standards, which define the reference standard.

Although the valve described by the present patent is particularly suitable for use in gas systems which adopt chemical substances as extinguishing agents, this can? be used as a release valve for other classes of extinguishing agents, including but not limited to inert gases, water spray, fire-fighting powder, fire-fighting foam.

In prior art fire-fighting systems, manually operated valves are often used for the release of the extinguishing agent, which are in turn connected to the neck of the cylinder containing the extinguishing gas. These valves can also be indicated with the expression ?shut-off valves? or ?discharge? valves.

The activation of these valves involves the displacement of one of their pistons and therefore the flow of the extinguishing agent (in the form of a compressed liquid) through the discharge port of the valve itself.

An example of such systems? described in EP 1 302 710 B1.

In the ?traditional? ? often also present a small rupture disc which performs the function of a safety device, to prevent the fire-fighting system from exploding or being damaged due to an increase in the pressure difference between the cylinder and the external environment, especially if caused in a relatively short period of time. Said safety device releases the extinguishing agent into the external environment.

However, these traditional valves usually have high head losses, as better illustrated below.

? therefore, the object of the present invention is to provide a discharge valve in which the load losses are considerably reduced with respect to valves of the ?traditional? type.

?, in fact, it is well known that the efficiency of a valve ? directly related to the ?load loss? which the fluid undergoes, whether it is in the gaseous, liquid or mixed phase (fluid in two-phase conditions), while crossing the valve itself. The head loss, often also improperly referred to as ?pressure loss?, is equivalent to the loss of the overall energy possessed by the fluid as it passes through the device.

The pressure drop for a given fluid in a given phase depends exclusively on the characteristics of the valve in terms of tortuosity? of the free passages (paths made by the fluid) and by the shape of the ?wet? of the valve itself (i.e. the parts in contact with the fluid). In other words, the valves pi? efficient, that is? those which induce a lower loss of energy on the fluid during their crossing are those which allow the fluid itself to follow a sufficiently regular path, with limited abrupt changes of direction and narrowing and with rounded internal shapes.

In a fire-fighting system, a lower pressure drop in the discharge valve translates into a series of advantages which directly and indirectly affect the efficiency and cost-effectiveness of the system. of the entire plant. At parity? diameter of the discharge valve, capacity? of the cylinder, operating pressure and, obviously, the type of extinguisher, a system equipped with a discharge valve with reduced or contained pressure drop in fact allows, in virtue? of the greater energy possessed by the fluid downstream of the valve, to improve the transfer of the same fluid from the cylinder to the nozzles and therefore to the environment to be protected, with the possibility? to cover greater distances and therefore to place the cylinders in points pi? distant from the place to be protected, or transfer a greater quantity? of fluid per unit? of time. The possibility? to place the cylinders in places remote from the risk to be protected in particular, it could be useful, when not essential, in disadvantaged and/or inaccessible places and/or with limited space available to position the cylinders near the environment to be protected and in any case to the advantage of greater flexibility? of installation of the system.

Furthermore, a discharge valve with reduced pressure drop allows, for the same considerations of an energy nature, to reduce the quantity? and the pressure of the pressurization gas (propellant, usually nitrogen) necessary for the correct functioning of the system (the pressurization gas, in fact, constitutes an accumulation of potential energy which moves the extinguisher during discharge).

A small amount? of propellant has the double advantage of freeing up space in the cylinder for the extinguishing agent, which translates into the possibility? to use a cylinder of lesser capacity? and therefore of lower cost (greater ratio extinguishing mass/propellant mass) or, in virtue? of the lower operating pressure, to reduce the thickness of the cylinder itself, with a further reduction in cost.

Another feature of the discharge valve object of the present invention ? the possibility? practice of making a device having a diameter greater than that typical of the ?traditional? valve. The simplicity? constructive and functional of the invention, is reflected directly, as well as on its cost, also on the possibility? of manufacturing valves of significant diameter.

The ?traditional? valve commonly used presents, in fact, considerable complexity? constructive, with extensive use of mechanical parts and with significant weights; such complexity? construction normally does not allow the creation of devices with a nominal diameter sufficient to be installed on cylinders larger than 350 liters of capacity. Merely by way of example, are currently marketed at most cylinders of capacity? 343 liters coupled to valves of nominal diameter of 3? (88.9mm). Said 3 valve? it has a weight of 18.82 kg (without considering the actuation devices), a length of 241 mm and a diameter of 129 mm. This sometimes imposes system configurations made up of numerous cylinders in parallel. The production of a valve according to the prior art with a diameter equal to or greater than 5? would it involve insurmountable difficulties? techniques and, in any case, prohibitive weights and dimensions.

In the state of the art, shut-off valves actuated automatically, both mechanically and by heat, are also known.

Examples of such valves for fire extinguishing systems are disclosed in EP 3 460 300 A1, US 6 394 188 B1 and US 2016 102 773 A1.

In particular, in EP 3 460 300 A1 ? described a valve for the release of pressurized fluids, said valve? activated by the opening of a reverse acting rupture disc, in turn operated by a mechanical device which regulates its opening without perforating the disc.

In US 6 394 188 B1 ? on the other hand described a valve for the release of extinguishing gases comprising an inflatable membrane which separates said extinguishing gas from the outlet of the valve and which opens following the explosion of an explosive charge disposed inside the plant, in which said explosive charge ? operated by a heat sensor.

In US 2016 102 773 A1 ? on the other hand, a valve for the release of extinguishing gases is described comprising a frangible diaphragm actuated through the expansion of a fluid following the administration of heat, an actuator regulated by a heat sensor.

However, each of the solutions proposed in the prior art has significant operating limitations.

The valve described in EP 3 460 300 A1 consists of a rupture disc, of the reverse acting type, whose opening ? caused by an external device for the instabilization of the dome. In particular, said instabilization ? induced through a strut (operated, alternatively, electric, pneumatic or squib) which, if necessary, hitting the top? of the dome, it unstabilises it causing the disc to break. Although this solution is undoubtedly effective, it is rather complicated, expensive and subject to malfunctions.

The device described in US 6 394 188 B1 foresees the actuation by means of an explosive charge, with all the contraindications of the case, among which the prohibition in force in many countries to use this type of system for the actuation of the fire-fighting system as well as the necessary permissions for their manipulation.

The device described in US 2016 102 773 A1 provides for the aid of a fluid which has the characteristic of expanding when? a certain amount is transferred to him? of thermal energy; however, the fracture of the diaphragm must occur on both sides (cylinder side and outlet side of the valve) simultaneously to properly achieve the purpose of actuating the system. Other drawbacks of the system described are that the auxiliary fluid is dispersed in the environment to be protected as well as? the risk of fragmentation of the diaphragm and consequent clogging of the pipes downstream of the valve.

In particular, the rupture discs of the valves of the prior art have the sole function of preventing any accidental overpressures which may be created within the extinguishing agent cylinder from leading to the collapse of the cylinder itself.

In fact, these rupture discs only ensure their opening at a predetermined pressure, at room temperature.

Purpose of the present invention? therefore that of overcoming the drawbacks of the prior art.

Furthermore, the purpose of the present invention ? to provide a gas release valve for fire systems that is more? efficient compared to a traditional valve and which minimizes the load losses of the extinguishing fluid passing through it.

Another purpose of the present invention ? that this valve is simple and cheap, if compared to the valves of the prior art.

Furthermore, the purpose of the present invention ? that of providing a gas release valve which is simple and reliable, both in terms of production and operation.

Again, the object of the present invention ? that these valves are more? safe, if compared to valves of the prior art.

Finally, the purpose of the present invention ? that this valve guarantees the release of a greater quantity? of extinguishing gases, within the discharge time of 10 seconds prescribed by the technical standards, compared to a ?traditional? valve? having the same diameter.

? therefore object of the present invention is a release valve for fire-fighting systems, consisting of a tubular body with a first end? and a second end? and comprising: coupling means with a source of an extinguishing gas at a working pressure, arranged at said first end; an outlet, located at said second end; a rupture disk, disposed in a position included between said coupling means and said outlet, wherein said rupture disk is made of material subject to mechanical degradation when heated, being configured to ensure sealing of said release valve at said working pressure when subjected to temperatures lower than a predetermined temperature and to open at said working pressure upon reaching said predetermined temperature ; heating means, adapted to heat said rupture disk to said predetermined temperature and; actuator means, connected to said heating means, for actuating the heating of said rupture disk to said predetermined temperature by means of said heating means and the consequent opening of said rupture disk with release of extinguishing gas towards said outlet.

According to the invention, the rupture disk can be engraved with a? perimeter incision near? of its outer edge in such a way as to be able to open at said working pressure along said perimeter incision, when heated to said predetermined temperature.

Furthermore, according to the invention, the rupture disc can be made of metallic material, preferably aluminium.

Always according to the invention, the rupture disc can be non-fragmentable.

Furthermore, according to the invention, said predetermined temperature can be between 150?C and 400?C.

Again, according to the invention, said heating means can be an electric resistance disposed in correspondence with said rupture disk.

Furthermore, according to the invention, the release valve can comprising a fill port disposed at a position comprised between said coupling means and said rupture disk.

Furthermore, according to the invention, said tubular body can include a housing, arranged in a position between said first end? and said rupture disc, for housing a safety disc.

Always according to the invention, said tubular body can include a pressure gauge, arranged between said first end? and said rupture disk.

Finally, according to the invention, said rupture disc can be of the type of plan type, forward acting or reverse acting.

A further object of the present invention is a fire-fighting system comprising a source of extinguishing gas coupled to a release valve according to the invention via said coupling means of said release valve.

According to the invention, said plant can comprising a circuit of a fire-fighting system connected to a release valve according to the invention, via said outlet of said release valve.

In the end, ? object of the present invention is a method of operating a fire-fighting system according to the invention, wherein said actuation means are activated to actuate said heating means so as to heat said rupture disc to said predetermined temperature, causing said rupture disc to rupture rupture and allowing the flow of extinguishing gas through said release valve, from said source of extinguishing gas to said release valve outlet.

The invention will come now described for illustrative but non-limiting purposes, with particular reference to the drawings of the attached figures, in which: figure 1 shows a release valve for fire-fighting systems according to the present invention.

With particular reference to figure 1, a release valve 100 according to the present invention, for the release of an extinguishing fluid, in particular gas, comprises:

a tubular body 1 having a first end? 1? and a second end? 1?, comprising

- coupling means 10 disposed on said first end? 12, for coupling the tubular body 1 with an extinguishing gas filling source and the fluid connection with this extinguishing gas source, for example a cylinder or a system containing this extinguishing gas at a working pressure;

- an outlet 11, for the exit of the extinguishing gas from said release valve 100, disposed on said second end? 1?, in which this output can? be connectable to a downstream hydraulic system, such as the pipes of a fire-fighting system, for example by means of a threaded surface 11?;

- a rupture disk 2, arranged downstream of said coupling means 10 and upstream of said outlet 11, in which said rupture disk 2 is? configured to maintain the seal at said working pressure, and to open once a predetermined temperature induced on the rupture disk 2 itself has been exceeded, said rupture disk 2 being made of material subject to mechanical degradation when heated, as better illustrated below;

- heating means 3, in particular a resistance 3, able to heat said rupture disc 2 to said predetermined temperature, being for example in direct contact therewith; And

- actuator means (not shown in the figure), connected to said heating means 3, so as to actuate them to allow the rupture disk 2 to open.

In the embodiment shown in Figure 1, the coupling means 10 are a threaded surface 10 arranged at said first end? 1? of said tubular body 1 and which can be screwed onto said extinguishing gas cylinder, for the connection of fluid therewith.

In alternative embodiments (not shown), the coupling means 10 may be different from those shown. By way of example, these coupling means can alternatively be constituted by a bolted coupling flange or by an externally threaded portion, male type, coupled to the extinguishing gas filling source, instead of the threaded portion 10, female type, shown in the Figure 1.

The rupture disk 2 ? engraved with a? perimeter incision near? of its outer edge (or outer circumference), in such a way as to ensure sealing at said working pressure when subjected to temperatures lower than said predetermined temperature, and to be able to open at said working pressure along said perimeter incision when heated to said predetermined temperature temperature, for the release of said extinguishing gas towards said outlet 11.

In particular, once the rupture disk 2 ? brought to said predetermined temperature by means of said heating means 3, the mechanical resistance of the rupture disc 2 in correspondence with the perimetric incision decreases causing it to open along said external circumference.

This predetermined temperature? preferably between 150?C and 400?C, being chosen according to the material in which it is? made said rupture disk 2.

In particular, the rupture disk 2 ? preferably in aluminum or other metallic material whose mechanical resistance characteristics decrease as the temperature increases.

? in fact it is known that metals can undergo different forms of mechanical degradation, if subjected to sources of high heat.

Thus, the rupture discs 2 constructed of metallic materials within the valve 100 may also experience such mechanical degradation.

The rupture disk 2 ? moreover of the non-fragmentable type, to prevent the breaking fragments from obstructing the piping of the system to which this valve 100 ? associated.

The rupture disk 2 ? preferably a flat type rupture disc, forward acting or reverse acting, configured to open at a predetermined rupture pressure, greater than said working pressure.

Finally, preferably, this rupture disc has a diameter between 2.5cm and 20cm, depending on the dimensions of the tubular body 1 of the valve 100. Rupture discs with a smaller diameter are used for smaller sized valves.

The heating means 3 are preferably a resistance 3, in particular a resistance 3 of the circular type, with a square or rectangular section (also called microtubular heater), preferably comprising an external steel shell, so as to heat said rupture disk 2 in a uniform.

The actuating means can be any element capable of activating the heating of the heating means 3, such as for example a switch to be operated manually/semi-automatically, capable of connecting/disconnecting the heating means 3 to electrical power supply means, or a unit? control connected to a smoke detector or the like, capable of actuating the release valve 100 automatically.

The release valve 100 further comprises:

- a filling port 12 or pressurization port 12, for the unidirectional entry into the release valve 100 of extinguishing gas at said working pressure, in which this filling port 12 is? disposed between said first extremity? 1? and said second end? 1? and ? connectable to a respective outlet of said extinguishing gas filling source; And

- a housing 13, arranged approximately at the height of said filling port 12, for housing a calibrated safety disc (not shown in the figure).

The calibrated security disc (not shown) ? calibrated at a burst pressure higher than said working pressure and lower than the bursting pressure of the rupture disc 2, to preserve the rupture disc 2 in the event of any accidental overpressures.

The calibrated security disc, ? therefore arranged in the housing 13, having the purpose of preserving the release valve 100 from any accidental overpressures. In this way, any accidental overpressure that should occur in the extinguishing gas cylinder (for example due to accidental overheating of the cylinder itself) would cause the safety disk to burst instead of of the rupture disc 2, thus preventing the accidental activation of the fire-fighting system.

In one embodiment (not shown), it can? be present only the filling door 12 or the housing 13 with safety disk, or neither of the two elements.

The release valve 100 shown in figure 1 also comprises a pressure gauge 4 arranged inside the tubular body 1, in correspondence with said filling port 12, to measure said working pressure. However, other positions of this pressure gauge are possible, as long as? upstream of the rupture disk 2.

Furthermore, preferably, said manometer 4 ? an analogue manometer, equipped with a pressure transducer (also called ?manometer-pressure switch?). In one embodiment (not shown), this pressure gauge 4 can? even not be present.

Finally, the valve 100 comprises sealing means 5, 6, 7, 8 to ensure the sealing of the elements arranged inside it.

In particular, the valve 100 shown in figure 1 comprises

- a counterstrike ring 5, in particular made of steel, brass or other similar material, immediately upstream of which to install said rupture disk 2,

- an o-ring 6, for the hermetic coupling of the sealing disc 5, and therefore of the rupture disc 2, with the tubular body 1, and

- two further lower o-rings 7, 8, to ensure the seal of the gas cylinder when screwed onto said threaded surface 10.

In alternative embodiments (not shown), these sealing means could be different from the sealing means 5, 6, 7, 8 described with reference to Figure 1, but in any case shaped in such a way as to perform the sealing functions illustrated above.

In particular, if said coupling means 10 between the extinguishing gas filling source and the release valve according to the present invention is made through bolted flanges, the o-rings 7 and 8 can be replaced by a gasket placed between the flanges themselves.

During operation of the valve 100, the actuator means cause current to flow in the resistance 3, which heats the rupture disc 2 up to said predetermined temperature, thus causing it to rupture.

By way of example, said resistance 3 pu? be connected to a battery, in particular a lithium ion battery or other similar technology, having an adequate supply power to ensure efficient and rapid heating of said resistance 3.

Some illustrative but non-limiting examples of valves 100 according to the present invention are now described.

Example 1

? a prototype of the valve 100 has been created, in which the tubular body 1 has a diameter equal to 6.35cm in correspondence with said threaded surface 10 and with said outlet 11.

The rupture disk 2 inserted inside the tubular body 1? a flat type rupture disc 2, made of aluminium, pre-scored along the outer circumference, which cannot be fragmented, having a nominal rupture pressure equal to 40 bar (4?10<6>Pa) at room temperature.

The heating means 3 are a microtubular heater 3 with a square section, of approximate dimensions 5x5 mm.

Said heating means 3 are connected to an electric power wire, coming out of the tubular body 1, which is in turn connected to a lithium ion battery.

The thread surface 10 ? been screwed to a cylinder for extinguishing gas with a suction tube, having a capacity? equal to 50 liters and equipped with a suction tube.

The dip tube? in turn connected to said filling port 12.

Through said filling port 12, the assembly, consisting of the cylinder with dip tube and the valve 100, is been loaded with 20 kg of extinguishing agent FK 5-1-12, pressurized with nitrogen N2 until reaching said working pressure, which in the case in example ? equal to 25bar (2.5?10<6>Pa) at 21?C.

The exit 11 ? been connected to a pipe with a diameter of 6.35cm and a length of 10m, which simulates the route of the pipes of a fire-fighting system.

Finally, inside the tubular body 1, in particular through further inlets, the analog pressure gauge and the safety disc calibrated at a pressure of 32 bar (3.2?10<6>Pa) were respectively applied.

Once electrical energy has been supplied to the heating means 3, these have reached a temperature of 500°C in about 80 milliseconds, causing the mechanical degradation of the rupture disc and therefore its opening, causing the extinguishing agent FK 5-1-12 to flow out inside the pipe.

Example 2

? a valve prototype 100 has been created having a tubular body 1 with a diameter of 12.7 cm in correspondence with said threaded surface 10 and with said outlet 11.

The rupture disk 2 inserted inside the tubular body 1? a reverse acting type rupture disc 2 having a rupture pressure of 55 bar (5.5?10<6>Pa) at room temperature in aluminium.

The heating means 3 are a resistor 3 with characteristics similar to those of the previous example 1.

Said heating means 3 are connected to an electric power wire, coming out of the tubular body 1, which is in turn connected to a lithium ion battery.

The threaded surface 10 of the tubular body 1 ? been screwed to a cylinder for the containment of extinguishing gas, having a capacity? equal to 200 litres, equipped with dip tube.

The dip tube? in turn connected to said filling port 12.

Through said filling port 12, the assembly consisting of the cylinder with dip tube and the valve 100? was loaded with 100 kg of extinguishing agent FK 5-1-12, pressurized with nitrogen up to a pressure of 30 bar at 21 ?C.

The threaded portion 11? of the exit 11 ? in turn connected to a pipe with a diameter of 6.35cm and a length of 10m, which simulates the route of the pipes of a fire-fighting system.

Finally, inside the tubular body 1, in particular through further inlets, an analog pressure gauge and the safety disc calibrated at a pressure of 40 bar (4?10<6>Pa) were respectively applied.

Once electrical energy has been supplied to the heating means 3, these have reached a temperature of 500°C in about 75 milliseconds, causing the mechanical degradation of the rupture disc 2 and therefore its opening, causing the extinguishing agent FK 5-1- to flow out 12 inside the pipe.

In the foregoing the preferred embodiments have been described and variations of the present invention have been suggested, but ? to be understood that the experts of the branch will be able to make modifications and changes without with what? leave its scope of protection, as defined by the attached claims.

Claims (10)

1. Release valve (100) for fire-fighting systems, consisting of a tubular body (1) with a first end? (1?) and a second extremity? (1?) and comprising: coupling means (12) with a source of an extinguishing gas at a working pressure, arranged at said first end? (1?); an outlet (11), arranged in correspondence with said second end? (1?); a rupture disk (2), arranged in a position comprised between said coupling means (12) and said outlet (11), wherein said rupture disk (2) is? made of material subject to mechanical degradation when heated, being configured to ensure sealing of said release valve (100) at said working pressure when subjected to temperatures lower than a predetermined temperature and to open at said working pressure upon reaching said predetermined temperature; heating means (3), adapted to heat said rupture disk (2) to said predetermined temperature e; actuator means, connected to said heating means (3), for activating the heating of said rupture disk (2) to said predetermined temperature by means of said heating means (3) and the consequent opening of said rupture disk (2) with release of extinguishing gas towards said outlet (11). 2. Release valve (100) according to claim 1, characterized in that said rupture disk (2) ? engraved with a? perimeter incision near? of its outer edge in such a way that it can open at said working pressure along said perimeter incision when heated to said predetermined temperature. 3. Release valve (100) according to any one of the preceding claims, characterized in that said rupture disc (2) is? made of metal material, preferably aluminum. 4. Release valve (100) according to any one of the preceding claims, characterized in that said rupture disc (2) is? non-fragmentable type. 5. Release valve (100) according to any one of the preceding claims, characterized in that said predetermined temperature ? between 150?C and 400?C. 6. Release valve (100) according to any one of the preceding claims, characterized in that said heating means (3) are an electric resistance arranged in correspondence with said rupture disk (2). 7. Release valve (100) according to any one of the preceding claims, characterized in that it comprises a filling port (12) disposed in a position comprised between said coupling means (12) and said rupture disk (2). 8. Release valve (100) according to any one of the preceding claims, characterized in that said tubular body (1) comprises a housing (13), arranged in a position between said first end? (1?) and said rupture disc (2), for housing a safety disc. 9. Fire-fighting system comprising an extinguishing gas source coupled to a release valve (100) as defined in claims 1-8 via said coupling means (12) of said release valve (100). A method of operating a fire extinguishing system as defined in claim 9, wherein said actuating means are activated to operate said heating means (3) so as to heat said rupture disk (2) to said predetermined temperature, causing rupture of said rupture disk (2) and allowing the flow of extinguishing gas through said release valve (100), from said source of extinguishing gas to said outlet (11) of the release valve (100).