Inert gas fire fighting system having a pressure control valve

An inert gas fire fighting system is designed to extinguish fire by discharging inert gas fire extinguisher stored in a gaseous state in a fire extinguisher storage vessel into an object fire fighting section while maintaining the concentration of the inert gas fire extinguisher in the object fire fighting section at no less than the fire extinguishing concentration. A vessel valve of the fire extinguisher storage vessel is a pressure control valve which controls the gas pressure P of the inert gas fire extinguisher on the discharge side to no more than the reference gas pressure P0 determined by a gas pressure P1 of a constant-pressure gas source. This makes it possible to increase the charging pressure of the inert gas fire extinguisher without increasing the pressure resistance grade of the secondary side equipment units of the fire fighting system.

BACKGROUND OF THE INVENTION 
The present invention relates to a gas fire fighting system for 
extinguishing fire by discharging an inert gas fire extinguisher stored in 
a gaseous state in fire extinguisher storage vessels into the object fire 
fighting section, and maintaining the concentration of the fire 
extinguisher in the object fire fighting section at no less than a fire 
extinguishing concentration. 
Conventionally, equipment using inert gas such as carbon dioxide, 
halogenated gas, etc. as a fire extinguisher has been put into practical 
use as a gas fire fighting system for extinguishing fire by discharging 
the gas fire extinguisher into an object fire fighting section and 
maintaining the concentration of the fire extinguisher in the object fire 
fighting section at no less than a fire extinguishing concentration. 
When inert gas such as carbon dioxide, halogenated gas, etc. is used as 
fire extinguishers, the fire fighting system is designed in such a way as 
to liquefy the fire extinguishers under pressure and store them in the 
fire extinguishing equipment in a charged state in a fire extinguisher 
storage vessel composed of a high-pressure gas vessel. In case of a fire, 
the carbon dioxide or halogenated gas is sent from the fire extinguisher 
storage vessel to an injection head through piping by opening a vessel 
valve of the fire extinguisher storage vessel by using an appropriate 
electrical means or pneumatic means and discharging it from the injection 
head into the object fire fighting section. At that time, the inert gas, 
such as carbon dioxide, halogenated gas, etc., is sent in a liquid state 
up to the injection head and, the moment when it is discharged from the 
injection head into the object fire fighting section, it is vaporized and 
gets into a gaseous state so as to fill the object fire fighting section 
and extinguish the fire. 
The gas fire fighting system using inert gas such as carbon dioxide, 
halogenated gas, etc. is widely used not only in oil facilities and with 
electric equipment, but also in other general facilities, because of 
advantages such that it can rapidly extinguish fire, hardly stains the 
inside of the object fire fighting section with the fire extinguisher, 
does not spoil electric insulation, demonstrates powerful fire 
extinguishing effects even against an object of fire fighting of 
complicated structure, as the fire extinguisher penetrates through gaps, 
maintains a certain level of fire extinguishing capacity over a long 
period of time with no change of fire extinguisher, etc. 
However, in recent years, problems regarding ozone layer depletion have 
arisen on a worldwide scale, and the production of fire extinguishers 
containing halogenated hydrocarbon components such as halogenated gas, 
etc. was discontinued in January, 1994, making such fire extinguishers 
practically unusable. As a result, carbon dioxide has become the only fire 
extinguisher currently in use for gas fire fighting systems, except for 
special fire fighting systems using expensive rare gases such as argon, 
etc. 
On the other hand, this fire fighting system using carbon dioxide is also 
known to have the following problems: 
(1) The design concentration of carbon dioxide in the object fire fighting 
section at the time of fire fighting is approximately 35%. At this 
concentration, there is a possibility of producing a serious state 
claiming human life due to the toxicity (anesthetization) of carbon 
dioxide in case there is someone in the object fire fighting section. 
(2) In case of a fire, the carbon dioxide is sent to the injection head in 
a liquid state and turns into a gas by evaporation the moment when it is 
discharged into the object fire fighting section. At that time, carbon 
dioxide absorbs heat of evaporation from the surrounding air, making the 
saturated vapor pressure of the room air drop, causing dew condensation of 
water content in the air and producing static electricity. As a result, 
the room air becomes hazy and presents a risk of serious secondary 
disasters by not only creating obstacles to evacuation and relief of 
people and fire fighting, but also causing defective insulation or trouble 
with electric equipment due to dew condensation or static electricity. 
(3) Because carbon dioxide has a density much higher than that of air, the 
carbon dioxide discharged into the object fire fighting section is liable 
to not only stagnate in the lower part in the object fire fighting section 
and deteriorate in its fire extinguishing effects, but also disperse to 
the outside through openings at the bottom of the object fire fighting 
section. 
(4) In view of the fact that problems of the greenhouse effect on the earth 
are being discussed on a worldwide scale, there is a possibility that the 
use of carbon dioxide may also be restricted in the future, in the same 
way as halogenated gas. 
By the way, the assignee of the present invention previously proposed a 
fire fighting system using as fire extinguisher nitrogen gas or a mixed 
gas (hereinafter simply referred to as "mixed gas") prepared by mixing at 
least one kind of perfluoroalkane (perfluorobutane (C.sub.4 F.sub.10)), 
hydrogenofluoroaklane (trifluoromethane (CHF.sub.3), heptafluoropropane 
(C.sub.3 HF.sub.7), pentafluoroethane (C.sub.2 HF.sub.5), or 
hyrogenefluorohalogenoalkane (iodotrifluoromethane (CF.sub.3 I)) 
(hereinafter generically referred to as "fluoric compounds") in nitrogen 
gas at a proportion no higher than 10 vol. %, to solve a lot of problems 
inherent in the gas fire fighting systems (Japanese Patent Application 
Publication Nos. 08-141102 and 08-243186). 
However, it has been found that the following problems exist even in the 
case where nitrogen gas or mixed gas are used as fire extinguisher of gas 
fire fighting systems: 
(1) Nitrogen gas or mixed gas used as the fire extinguisher of gas fire 
fighting systems are stored in a state of pressurized gas, and therefore 
require a number of fire extinguisher vessels necessary for fire 
extinction of an object fire fighting section of a volume several times 
larger as carbon dioxide or halogenated gas, which are in a liquefied 
state due to pressurization, and thus require a large installation space 
for the fire extinguisher vessels. 
(2) To reduce the number of fire extinguisher vessels to be installed, it 
is necessary to increase the charging pressure of the inert gas fire 
extinguisher to be charged in the fire extinguisher vessels. However, if 
the charging pressure of the inert gas fire extinguisher is increased, the 
high gas pressure of the inert gas fire extinguisher comes to be applied 
also to the secondary side equipment of the fire fighting system, such as 
a selecting valve, main piping, a branch pipe, an injection head, etc. 
This makes it necessary to increase the pressure resistance grade of those 
secondary side equipment units, thus leading to a sharp increase in 
equipment costs, and also making the application to existing facilities 
impossible. 
SUMMARY OF THE INVENTION 
The object of the present invention is to provide an inert gas fire 
fighting system and a pressure control valve for an inert gas fire 
fighting system capable of increasing the charging pressure of inert gas 
fire extinguishers without increasing the pressure resistance grade of the 
secondary side equipment units of the fire fighting system, by solving 
problems inherent in gas fire fighting systems using an inert gas fire 
extinguisher stored in a gaseous state, such as nitrogen gas, a mixed gas, 
etc., in fire extinguisher storage vessels. 
To achieve the object, the inert gas fire fighting system of this invention 
is first realized as an inert gas fire fighting system for extinguishing 
fire by discharging an inert gas fire extinguisher stored in a gaseous 
state in fire extinguisher storage vessels in an object fire fighting 
section, and maintaining the concentration of the inert gas fire 
extinguisher in the object fire fighting section at no less than the fire 
extinguishing concentration needed. A vessel valve of the fire 
extinguisher storage vessels is a pressure control valve for controlling 
the gas pressure of the inert gas fire extinguisher to the discharge side 
at no more than the reference gas pressure determined by the gas pressure 
of a constant-pressure gas source. 
The inert gas fire fighting system of the invention is secondly realized as 
an inert gas fire fighting system designed to extinguish fire by 
discharging an inert gas fire extinguisher stored in a gaseous state in a 
fire extinguisher storage vessel in the object fire fighting section, and 
maintaining the concentration of the inert gas fire extinguisher in the 
object fire fighting section at no less than the fire extinguishing 
concentration needed. A collecting pipe connects the fire extinguisher 
storage vessels with the selecting valve and has a pressure control valve 
for controlling the gas pressure of the inert gas fire extinguisher at the 
discharge side to no more than the reference gas pressure determined by 
the gas pressure of a constant-pressure gas source. 
In this case, it is possible to change the reference gas pressure by 
adjusting the gas pressure of the constant-pressure gas source, with the 
use of a pressure regulator, etc., for example. 
Moreover, at 35.degree. C., it is possible to use fire extinguisher storage 
vessels filled with an inert gas fire extinguisher at 180 kgf/cm.sup.2 or 
more. 
Furthermore, nitrogen gas can be used as an inert gas fire extinguisher. 
The pressure control valve for the inert gas fire fighting system of the 
invention is composed of a flow channel valve provided in a flow channel 
of an inert gas fire extinguisher. A spring urges the flow channel valve 
in the direction closing the flow channel of the inert gas fire 
extinguisher. A gas feed port of a constant-pressure gas source is 
provided and a piston is provided in a cylinder which is connected at one 
end to the gas feed port and at the other end to the discharge side of the 
flow channel of the inert gas fire extinguisher. An operating bar is 
formed at the end of the piston for operating the flow channel valve in 
the direction opening the flow channel of the inert gas fire extinguisher. 
According to the present invention, it is possible to control the gas 
pressure of the inert gas fire extinguisher to the discharge side of the 
pressure control valve at no more than the reference gas pressure 
determined by the gas pressure of a constant-pressure gas source at no 
less than the fire extinguishing concentration needed, by either using a 
pressure control valve as the vessel valve of the fire extinguisher 
storage vessels, or by using a pressure control valve as the collecting 
pipe connecting the fire extinguisher storage vessels with the selecting 
valve. Thus the application of high gas pressure of the inert gas fire 
extinguisher to the secondary side equipment of the fire fighting system 
is avoided. 
This makes it possible to increase the charging pressure of the inert gas 
fire extinguisher without increasing the pressure resistance grade of the 
secondary side equipment units of the fire fighting system, to reduce the 
required installation space of the fire extinguisher storage vessels, and 
to reduce the equipment costs, thanks to the absence of any need of 
raising the pressure resistance grade of the secondary side equipment 
units of the fire fighting system. It also makes it possible to apply 
inert gas fire extinguishers stored in a gaseous state in the fire 
extinguisher storage vessels to existing facilities, because there is no 
need to raise the pressure resistance grade of the secondary side 
equipment units of the fire fighting system. 
Moreover, this pressure control valve, which has the function of 
maintaining the gas pressure of the inert gas fire extinguisher at the 
discharge side of the pressure control valve at the reference gas pressure 
until the pressure of the fire extinguisher in the fire extinguisher 
storage vessels drops to no higher than the reference gas pressure, can 
maintain a constant discharge volume of the inert gas fire extinguisher, 
even in cases where the pressure of the inert gas fire extinguisher in the 
fire extinguisher storage vessels has dropped because of the discharge of 
the inert gas fire extinguisher. Therefore, it is possible to effectively 
utilize the capacity of the fire fighting system and thus reduce equipment 
costs.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention will be explained hereafter based on illustrated 
embodiments. 
FIG. 1 shows a first embodiment of the inert gas fire fighting system of 
the present invention. 
This embodiment represents an inert gas fire fighting system having three 
object fire fighting sections 6-1, 6-2, 6-3. 
The inert gas fire fighting system uses fire extinguisher storage vessels 
1, storing an inert gas fire extinguisher, nitrogen gas for example, in 
the fire fighting system in a pressurized state and charged in high 
pressure gas vessels (180 kgf/cm.sup.2 at 35.degree. C.). 
The inert gas fire fighting system of this embodiment is provided with five 
extinguisher storage vessels 1-1, 1-2, 1-3, 1-4, 1-5. To each vessel 1 is 
connected a connecting pipe 3 through a vessel valve 2. Connecting pipes 3 
are further connected to a collecting pipe 4, which is then connected to 
main pipings 5-1, 5-2, 5-3 that extend up to the respective object fire 
fighting sections 6-1, 6-2, 6-3. 
The main pipings 5-1, 5-2, 5-3 are provided with selecting valves 9-1, 9-2, 
9-3 so as to selectively feed inert gas fire extinguisher to the object 
fire fighting sections 6-1, 6-2, 6-3. 
The main pipings 5-1, 5-2, 5-3 are connected to branch pipes 8-1, 8-2, 8-3 
provided respectively in the object fire fighting sections 6-1, 6-2, 6-3. 
Branch pipes 8-1, 8-2, 8-3 are connected to a plural number of injection 
heads 7-1, 7-2, 7-3 disposed at appropriate places in the object fire 
fighting sections 6-1, 6-2, 6-3. 
By the way, since the respective object fire fighting sections 6-1, 6-2, 
6-3 are usually different in volume from one another, the volume of the 
inert gas fire extinguisher required for fire fighting naturally varies 
from section to section. For that reason, in addition to changing the bore 
size of the main pipings 5-1, 5-2, 5-3 depending on the volume of the 
respective object fire fighting sections 6-1, 6-2, 6-3, the inert gas fire 
fighting system is constructed in such a way that, in case of a fire, a 
number of fire extinguisher storage vessels 1 corresponding to the object 
fire fighting sections 6-1, 6-2, 6-3 forming the subject of fire fighting 
are opened. Here, the number of fire extinguisher storage vessels 1 to be 
opened is set as five for object fire fighting section 6-1, three for 
object fire fighting section 6-2, and one for object fire fighting section 
6-3. 
In the drawing, 9-1, 9-2, 9-3 are selecting valves, 10-1, 10-2, 10-3 are 
selecting valve opening devices, 11-1, 11-2, 11-3 are starting gas 
vessels, and 12-1, 12-2, 12-3 represent solenoids for releasing the 
starting gas vessels. 
Moreover, in the drawing, 13-1, 13-2, 13-3 are starting gas pipelines for 
controlling the releasing of selecting valves 9-1, 9-2, 9-3. Starting gas 
vessels 11-1, 11-2, 11-3 are connected to the selecting valve opening 
devices 10-1, 10-2, 10-3 by disposing nonreturn valves 14-1, 14-2, 14-3, 
14-A, 14-B at proper points on their way. The passable direction of the 
nonreturn valves 14-1, 14-2, 14-3, 14-A, 14-B is indicated with the 
direction of arrow marks in the drawing. 
The numbers 1, 2, 3 at the end of these members correspond to the suffixes 
1, 2, 3 of the object fire fighting sections, respectively. 
The vessel valve 2 is a pressure control valve which controls the gas 
pressure P of the inert gas fire extinguisher on the discharge side of the 
vessel valve 2 to no more than a reference gas pressure P0 determined by 
the gas pressure P1 of a constant-pressure gas source, as indicated in 
FIG. 2-4. 
This pressure control valve is composed of a flow channel valve 22 having 
three guide members 22a provided in a flow channel 21, a spring 23 for 
urging the flow channel valve 22 in the direction closing the flow channel 
21, and a gas feed port 24 from a constant-pressure gas source (in this 
embodiment, starting gas vessels 11-1, 11-2, 11-3 filled (110 kgf/cm.sup.2 
at 35.degree. C.) with nitrogen are used as the constant-pressure gas 
source). A piston 26 is provided in a cylinder 25 which is connected at 
one end to the gas feed port 24 and at the other end to the discharge side 
of the flow channel 21 for the inert gas fire extinguisher. An operating 
bar 27 is formed at the end of the piston 26 for operating the flow 
channel valve 22 in the direction of opening the flow channel 21, and a 
spring 28 urges the piston 26 in the direction opposite to that of the 
flow channel valve 22. 
Next, the motions of this pressure control valve will be explained. 
When gas of a gas pressure P1 (110 kgf/cm.sup.2) is fed from the starting 
gas vessels 11-1, 11-2, 11-3 as the constant-pressure gas source to the 
gas feed port 24, it makes the piston 26 move against the urging force of 
the spring 28 to operate the flow channel valve 22 against the urging 
force of the spring 23 by means of the operating bar 27 formed at the end 
of the piston 26, and open the flow channel 21 for the inert gas fire 
extinguisher. 
If the flow channel 21 is opened, inert gas fire extinguisher flows into 
the flow channel 21 from the fire extinguisher storage vessel 1, and the 
gas pressure P2 (180 kgf/cm.sup.2 at 35.degree. C.) of the inert gas fire 
extinguisher in the fire extinguisher storage vessel 1 acts on the other 
end side of the piston 26. The piston 26 then moves in the direction 
releasing the operation of the flow channel valve 22 by operating bar 27, 
making the flow channel valve 22 also move in the direction closing the 
flow channel 21 of inert gas fire extinguisher under the urging force of 
the spring 23. 
However, because the gas pressure P1 (110 kgf/cm.sup.2) of the starting gas 
vessels 11-1, 11-2, 11-3 is acting on one end side of the piston 26, the 
flow channel valve 22 does not completely close the flow channel 21. The 
flow channel valve 22, the piston 26, and the operating bar 27 are 
balanced in an instant and, in the case of this embodiment, the gas 
pressure P of the inert gas fire extinguisher on the discharge side of the 
flow channel 21 is maintained at the same value as the gas pressure P1 
(110 kgf/cm.sup.2) of the starting gas vessels 11-1, 11-2, 11-3. 
In this case, the gas pressure P of the inert gas fire extinguisher on the 
discharge side maintained by the pressure control valve, i.e., the 
reference gas pressure P0, can be changed by either adjusting the gas 
pressure itself of the constant-pressure gas source i.e., the starting gas 
vessels 11-1, 11-2, 11-3, by providing a pressure regulator on the 
starting gas vessels 11-1, 11-2, 11-3 and adjusting the gas pressure P1 by 
means of this pressure regulator, by using springs of different spring 
constants for the springs 23, 28, or by having a different top diameter to 
bottom diameter ratio of the piston 26, etc. It is desirable to construct 
the system in a way to make the reference gas pressure P0 agree with the 
gas pressure P1 of the constant-pressure gas source, from the viewpoint of 
the design of the inert gas fire fighting system. 
This pressure control valve has a function of not only stopping the gas 
feed from the constant-pressure gas source to feed port 24, but also 
closing the flow channel 21 of the inert gas fire extinguisher by 
evacuating the gas inside the cylinder 25 over the piston 26. It is also 
possible, by utilizing this function, to construct the system in a way to 
close the once-opened fire extinguisher storage vessel. 
Because this pressure control valve has, as shown in FIG. 5, a function of 
maintaining the gas pressure P of the inert gas fire extinguisher on the 
discharge side of the pressure control valve at the reference gas pressure 
P0 until the pressure of the fire extinguisher in the fire extinguisher 
storage vessels 1 drops to no higher than the reference gas pressure P0, 
it can maintain the discharge volume of the inert gas fire extinguisher 
constant by maintaining the gas pressure P of the inert gas fire 
extinguisher on the discharge side of the pressure control valve at the 
reference gas pressure P0 even in the case where the pressure P2 of the 
inert gas fire extinguisher in the fire extinguisher storage vessels 1 has 
dropped. 
FIG. 5 shows, as an example for reference, the relation between the gas 
pressure P' of the inert gas fire extinguisher on the discharge side of 
the vessel valve and the gas pressure P2' of the inert gas fire 
extinguisher in the fire extinguisher storage vessel in a case where a 
vessel valve having a pressure reducing function is used. In the case of a 
vessel valve having a pressure reducing function, as the gas pressure P2' 
of the inert gas fire extinguisher in the fire extinguisher storage vessel 
drops as a result of discharge of the inert gas fire extinguisher, the gas 
pressure P' of the inert gas fire extinguisher on the discharge side of 
the vessel valve also drops in proportion to it, and the discharge volume 
of the inert gas fire extinguisher decreases (a difference from the case 
of the pressure control valve is indicated with shaded part). To discharge 
the prescribed volume of inert gas fire extinguisher in a prescribed time 
t, it becomes necessary to take measures such as increasing the inside 
diameter of the piping or mitigating the degree of depressurization 
(increase the initial gas pressure P' of inert gas fire extinguisher on 
the discharge side of the vessel valve), etc., but this presents a problem 
of high equipment cost. 
Next, an explanation will be given of the operation in case of fire for the 
inert gas fire fighting system of the first embodiment. 
Now, supposing that a fire broke out in the object fire fighting section 
6-1, if the person who discovered the fire operates a push button (a case 
of manual operation) corresponding to this object fire fighting section 
6-1, an electric signal is sent to the solenoid 12-1 for opening the 
starting gas vessel, and the solenoid 12-1 works to open the starting gas 
vessel 11-1. 
The starting gas discharged with the opening of the starting gas vessel 
11-1 is first introduced into the selecting valve opening device 10-1 to 
open the selecting valve 9-1. The gas then passes through the starting gas 
pipeline 13-1 via the nonreturn valve 14-1, and passes through the 
nonreturn valve 14-A and the nonreturn valve 14-B to reach all vessel 
valves 2 and open all of the five fire extinguisher storage vessels 1. 
At that time, the selecting valve 9-2 and the selecting valve 9-3 are not 
opened because the gas cannot pass through the nonreturn valve 14-2 and 
the nonreturn valve 14-3. 
Because the vessel valve 2 is a pressure control valve which controls the 
gas pressure P of the inert gas fire extinguisher on the discharge side at 
no more than the reference gas pressure P0 determined by the gas pressure 
P1 of the constant-pressure gas source, the inert gas controlled at no 
more than the reference gas pressure P0 (110 kgf/cm.sup.2) is sent from 
the opened five fire extinguisher storage vessels 1 to the injection head 
7-1 through vessel valve 2, connecting pipe 3, collecting pipe 4, 
selecting valve 9-1, main piping 5-1, and branch pipe 8-1, and then 
discharged from the injection head 7-1 into the object fire fighting 
section 6-1. 
Moreover, supposing that a fire broke out in the object fire fighting 
section 6-2, if the person who discovered the fire operates the push 
button (a case of manual operation) corresponding to this object fire 
fighting section 6-2, an electric signal is sent to the solenoid 12-2 for 
opening the starting gas vessel. The solenoid 12-2 works to open the 
starting gas vessel 11-2. 
The starting gas discharged with the opening of the starting gas vessel 
11-2 is first introduced into the selecting valve opening device 10-2 to 
open the selecting valve 9-2. It then passes through the starting gas 
pipeline 13-2 via the nonreturn valve 14-2 and passes through the 
nonreturn valve 14-B to reach the vessel valves 2 and open three of the 
fire extinguisher storage vessels 1 i.e., fire extinguisher storage 
vessels 1-3, 1-4, 1-5. 
At that time, two of the fire extinguisher storage vessels 1, i.e., fire 
extinguisher storage vessels 1-1, 1-2, are not opened because the gas 
cannot pass through the nonreturn valve 14-A. 
Moreover, the selecting valve 9-1 and the selecting valve 9-3 are not 
opened because the gas cannot pass through the nonreturn valve 14-1 and 
the nonreturn valve 14-3. 
Because the vessel valve 2 is a pressure control valve which controls the 
gas pressure P of the inert gas fire extinguisher on the discharge side at 
no more than the reference gas pressure P0 determined by the gas pressure 
P1 of the constant-pressure gas source, the inert gas controlled at no 
more than the reference gas pressure P0 (110 kgf/cm.sup.2) is sent from 
the opened three fire extinguisher storage vessels 1-3, 1-4, 1-5 to the 
injection head 7-2 through vessel valve 2, connecting pipe 3, collecting 
pipe 4, selecting valve 9-2, main piping 5-2, and branch pipe 8-2, and 
then discharged from the injection head 7-2 into the object fire fighting 
section 6-2. 
Moreover, supposing that a fire broke out in the object fire fighting 
section 6-3, if the person who discovered the fire operates the push 
button (a case of manual operation) corresponding to this object fire 
fighting section 6-3, an electric signal is sent to the solenoid 12-3 for 
opening the starting gas vessel, and the solenoid 12-3 works to open the 
starting gas vessel 11-3. 
The starting gas discharged with the opening of the starting gas vessel 
11-3 is first introduced into the selecting valve opening device 10-3 to 
open the selecting valve 9-3. It then passes through the starting gas 
pipeline 13-3 via the nonreturn valve 14-3 to reach the vessel valve 2 and 
open one of the fire extinguisher storage vessels 1, i.e., fire 
extinguisher storage vessel 1-5. 
At that time, four of the fire extinguisher storage vessels 1, i.e., fire 
extinguisher storage vessels 1-1, 1-2, 1-3, 1-4, are not opened because 
the gas cannot pass through the nonreturn valve 14-B (naturally, it cannot 
pass through the nonreturn valve 14-A either). 
Moreover, the selecting valve 9-1 and the selecting valve 9-2 are not 
opened because the gas cannot pass through the nonreturn valve 14-1 and 
the nonreturn valve 14-2. 
By the way, because the vessel valve 2 is a pressure control valve which 
controls the gas pressure P of the inert gas fire extinguisher on the 
discharge side at no more than the reference gas pressure P0 determined by 
the gas pressure P1 of the constant-pressure gas source, the inert gas 
controlled at no more than the reference gas pressure P0 (110 
kgf/cm.sup.2) is sent from the opened fire extinguisher storage vessel 1-5 
to the injection head 7-3 through vessel valve 2, connecting pipe 3, 
collecting pipe 4, selecting valve 9-3, main piping 5-3, and branch pipe 
8-3, and then discharged from the injection head 7-3 into the object fire 
fighting section 6-3. 
The above explanation has been given on a case where there are three object 
fire fighting sections and the number of fire extinguisher storage vessels 
1 is five. However, the number of object fire fighting sections and the 
number of fire extinguisher storage vessels 1, as well as the number of 
fire extinguisher storage vessels 1 to be opened, are not restricted to 
those of the present embodiment (the same is true with the second 
embodiment and the third embodiment to be indicated hereafter), but may be 
set optionally as required. 
FIG. 6 shows a second embodiment of the inert gas fire fighting system of 
the present invention. Reference numbers for components of the second 
embodiment similar to the first embodiment are provided with similar 
reference numerals, but have their numbers increased by 100. A repeated 
discussion of similar components may be omitted here for the sake of 
brevity, and reference may be had to the above discussion concerning the 
first embodiment for the corresponding components. 
This embodiment is a variation of the first embodiment and is realized by 
providing, as a constant-pressure gas source, a constant-pressure gas 
vessel 117 filled with nitrogen gas (110 kgf/cm.sup.2 at 35.degree. C.) 
apart from the starting gas vessels 11-1, 11-2, 11-3. 
Moreover, it is also possible to use, as a constant-pressure gas source, a 
gas vessel filled with high-pressure gas and provided with a pressure 
regulator, and to adjust the gas pressure P1 by means of this pressure 
regulator, or to constitute the constant-pressure gas source by a high 
pressure generator and an accumulator maintaining the pressure generated 
by the high pressure generator. 
In this way, by providing a constant-pressure gas vessel 117, even if the 
number of the fire extinguisher storage vessels 101 to be installed, i.e., 
the number of vessel valves (a pressure control valves), increases, it 
becomes possible to easily change the capacity of the constant-pressure 
gas vessel 117 accordingly and thus maintain the prescribed reference gas 
pressure P0. 
Furthermore, in the drawing, 115-1, 115-2, 115-3 represent piston valves 
disposed in the starting gas pipelines 113-1, 113-2, 113-3 in place of the 
nonreturn valves 14-1, 14-2, 14-3 of the first embodiment. 116-1, 116-2, 
116-3 are nonreturn valves provided at proper places between the starting 
gas vessels 111-1, 111-2, 111-3 and the constant-pressure gas vessel 117. 
The passable direction of the nonreturn valves 116-1, 116-2, 116-3 is 
indicated with the direction of the arrow marks in the drawing. 
The numbers 1, 2, 3 at the end of the above-described members correspond to 
the suffixes 1, 2, 3 of the object fire fighting sections, respectively. 
Next, explanation will be given on the operation in case of fire of the 
inert gas fire fighting system of the second embodiment. 
Now, supposing that a fire broke out in the object fire fighting section 
106-1, if the person who discovered the fire operates the push button (a 
case of manual operation) corresponding to this object fire fighting 
section 106-1, an electric signal is sent to the solenoid 112-1 for 
opening the starting gas vessel and the solenoid 112-1 works to open the 
starting gas vessel 111-1. 
The starting gas discharged with the opening of the starting gas vessel 
111-1 is first introduced into the selecting valve opening device 110-1 to 
open the selecting valve 109-1, and then passes through the nonreturn 
valve 116-1 to open the constant-pressure gas vessel 117 and the piston 
valve 115-1. 
As a result, the constant-pressure gas of the constant-pressure gas vessel 
117 passes through the starting gas (constant-pressure gas) pipeline 113-1 
via the piston valve 115-1, passes through the nonreturn valve 114-A and 
the nonreturn valve 114-B and reaches all of the vessel valves 102 and 
opens all of the five fire extinguisher storage vessels 101. 
At that time, the selecting valves 109-2, 109-3 and the piston valves 
115-2, 115-3 are not opened, because the gas cannot pass through the 
nonreturn valve 116-2 and the nonreturn valve 116-3. 
By the way, because the vessel valve 102 is a pressure control valve which 
controls the gas pressure P of the inert gas fire extinguisher on the 
discharge side to no more than the reference gas pressure P0 determined by 
the gas pressure P1 of the constant-pressure gas source, the inert gas 
controlled at no more than the reference gas pressure P0 (110 
kgf/cm.sup.2) is sent from the opened five fire extinguisher storage 
vessels 101 to the injection head 107-1 through vessel valve 102, 
connecting pipe 103, collecting pipe 104, selecting valve 109-1, main 
piping 105-1 and branch pipe 108-1, and is then discharged from the 
injection head 107-1 into the object fire fighting section 106-1. 
Moreover, supposing that a fire broke out in the object fire fighting 
section 106-2, if the person who discovered the fire operates the push 
button (a case of manual operation) corresponding to this object fire 
fighting section 106-2, an electric signal is sent to the solenoid 112-2 
for opening the starting gas vessel and the solenoid 112-2 works to open 
the starting gas vessel 11-2. 
The starting gas discharged with the opening of the starting gas vessel 
111-2 is first introduced into the selecting valve opening device 110-2 to 
open the selecting valve 109-2, and then passes through the nonreturn 
valve 116-2 to open the constant-pressure gas vessel 117 and the piston 
valve 115-2. 
As a result, the constant-pressure gas of the constant-pressure gas vessel 
117 passes through the starting gas (constant-pressure gas) pipeline 113-2 
via the piston valve 115-2, passes through the nonreturn valve 114-B, and 
reaches the vessel valves 102 and open three of the fire extinguisher 
storage vessels 101, i.e, fire extinguisher storage vessels 101-3, 101-4, 
101-5. 
At that time, two of the fire extinguisher storage vessels 101 i.e., fire 
extinguisher storage vessels 101-1, 101-2 are not opened because the gas 
cannot pass through the nonreturn valve 114-A. 
Moreover, the selecting valve 109-1, the selecting valve 109-3, the piston 
valve 115-1, and the piston valve 15-3 are not opened because the gas 
cannot pass through the nonreturn valve 116-1 and the nonreturn valve 
116-3. 
By the way, because the vessel valve 102 is a pressure control valve which 
controls the gas pressure P of the inert gas fire extinguisher on the 
discharge side to no more than the reference gas pressure P0 determined by 
the gas pressure P1 of the constant-pressure gas source, the inert gas 
controlled at no more than the reference gas pressure P0 (110 
kgf/cm.sup.2) is sent from the opened three fire extinguisher storage 
vessels 101-3, 101-4, 101-5 to the injection head 107-2 through vessel 
valve 102, connecting pipe 103, collecting pipe 104, selecting valve 
109-2, main piping 105-2, and branch pipe 108-2, and is then discharged 
from the injection head 107-2 into the object fire fighting section 106-2. 
Furthermore, supposing that a fire broke out in the object fire fighting 
section 106-3, if the person who discovered the fire operates the push 
button (a case of manual operation) corresponding to this object fire 
fighting section 106-3, an electric signal is sent to the solenoid 112-3 
for opening the starting gas vessel and the solenoid 112-3 works to open 
the starting gas vessel 111-3. 
The starting gas discharged with the opening of the starting gas vessel 
111-3 is first introduced into the selecting valve opening device 110-3 to 
open the selecting valve 109-3, and then passes through the nonreturn 
valve 116-3 to open the constant-pressure gas vessel 117 and the piston 
valve 115-3. 
As a result, the constant-pressure gas of the constant-pressure gas vessel 
117 passes through the starting gas (constant-pressure gas) pipeline 113-3 
via the piston valve 115-3, reaches the vessel valves 102, and opens one 
of the fire extinguisher storage vessels 101 i.e, fire extinguisher 
storage vessel 101-5. 
At that time, four of the fire extinguisher storage vessels 101, i.e., fire 
extinguisher storage vessels 101-1, 101-2, 101-3, 101-4, are not opened 
because the gas cannot pass through the nonreturn valves 114-B. 
Moreover, the selecting valves 109-1, 109-2 and the piston valves 115-1, 
115-2 are not opened because the gas cannot pass through the nonreturn 
valve 116-1 and the nonreturn valve 116-2. 
By the way, because the vessel valve 102 is a pressure control valve which 
controls the gas pressure P of the inert gas fire extinguisher on the 
discharge side to no more than the reference gas pressure P0 determined by 
the gas pressure P1 of the constant-pressure gas source, the inert gas 
controlled to no more than the reference gas pressure P0 (110 
kgf/cm.sup.2) is sent from the opened fire extinguisher storage vessel 
101-5 to the injection head 107-3 through vessel valve 102, connecting 
pipe 103, collecting pipe 104, selecting valve 109-3, main piping 105-3 
and branch pipe 108-3, and then is discharged from the injection head 
107-3 into the object fire fighting section 106-3. 
FIG. 7 shows a third embodiment of the inert gas fire fighting system of 
the present invention. Reference numbers for components of the third 
embodiment similar to the first embodiment are provided with similar 
reference numerals, but have their numbers increased by 200. A repeated 
discussion of similar components may be omitted here for the sake of 
brevity, and reference may be had to the above discussion concerning the 
first embodiment for the corresponding components. 
This embodiment is a variation of the first embodiment and is realized by 
providing, at a proper point on the collecting pipe 204 connecting between 
the fire extinguisher storage vessels 201 and the selecting valves 109-1, 
109-2, 109-3, a pressure control valve 18 for controlling the gas pressure 
P of the inert gas fire extinguisher on the discharge side to no more than 
the reference gas pressure P0 determined by the gas pressure P1 of the 
constant-pressure gas source. As a constant-pressure gas source, is 
provided a constant-pressure gas vessel 219 filled with nitrogen gas (110 
kgf/cm.sup.2 at 35.degree. C.) apart from the starting gas vessels 211-1, 
211-2, 211-3. 
Moreover, it is also possible to make up the system in a way to utilize the 
starting gas vessels 211-1, 211-2, 211-3 as in the first embodiment, or to 
use as a constant-pressure gas source a gas vessel filled with 
high-pressure gas and provided with a pressure regulator to adjust the gas 
pressure P1 by means of this pressure regulator, or to constitute the 
constant-pressure gas source by a high pressure generator and an 
accumulator maintaining the pressure generated by the high pressure 
generator. 
In this way, by providing a pressure control valve 18 on the collecting 
pipe 204, it becomes possible to use ordinary vessel valve for the vessel 
valve 202 and thus reduce the equipment costs. The primary side equipment 
units of the fire fighting system such as vessel valve 202, connecting 
pipe 203, collecting pipe 204, etc. between the fire extinguisher storage 
vessels to the pressure control valve 18 are subject to the high gas 
pressure of the inert gas fire extinguisher. For that reason, those 
primary side equipment units must be constructed in a way to resist this 
high pressure. However, the collecting pipe 204, etc. have a high pressure 
resistance because of a smaller inside diameter as compared with the main 
pipings 205-1, 205-2, 205-3, and there is thus no need of increasing the 
pressure resistance grade of the primary side equipment units of the fire 
fighting system. This makes it possible to not only reduce the equipment 
costs but also to even apply the system to existing facilities as it is. 
The numbers 1, 2, 3 at the end of those members correspond to the numbers 
1, 2, 3 suffixed to the object fire fighting sections respectively. 
This pressure control valve 18, which basically has the same construction 
and same actions as the pressure control valve used for the vessel valve 2 
of the first embodiment, is composed, as shown in FIG. 8, of a flow 
channel valve 182 provided in a flow channel 181 for inert gas fire 
extinguisher. A spring 183 urges the flow channel valve 182 in the 
direction closing the flow channel 181. A gas feed port 184 connects with 
the from constant-pressure gas vessel 219 and a piston 186 provided in 
cylinder 185 is connected at one end to the gas feed port 184 and the 
other end to the discharge side of the flow channel 181. An operating bar 
187 is formed at the end of the piston 186 for operating the flow channel 
valve 182 in the direction opening the flow channel 181. A spring 188 
urges the piston 186 in the direction opposite to that of the flow channel 
valve 182. 
Next, explanation will be given in the operation in case of fire for the 
inert gas fire fighting system of the third embodiment. 
Now, supposing that a fire broke out in the object fire fighting section 
206-1, if the person who discovered the fire operates the push button (a 
case of manual operation) corresponding to this object fire fighting 
section 206-1, an electric signal is sent to the solenoid 212-1 for 
opening the starting gas vessel and the solenoid 212-1 works to open the 
starting gas vessel 211-1. 
The starting gas discharged with the opening of the starting gas vessel 
211-1 is first introduced into the selecting valve opening device 210-1 to 
open the selecting valve 209-1, passes through the nonreturn valve 214-1 
to open the constant-pressure gas vessel 219, and passes through the 
nonreturn valves 214-A, 214-B to reach all vessel valves 202 and open all 
of the five fire extinguisher storage vessels 201. 
At that time, the selecting valve 209-2 and the selecting valve 209-3 are 
not opened because the gas cannot pass through the nonreturn valve 214-2 
and the nonreturn valve 214-3. 
By the way, because the pressure control valve 18 which controls the gas 
pressure P of the inert gas fire extinguisher on the discharge side to no 
more than the reference gas pressure P0 determined by the gas pressure P1 
of the constant-pressure gas source is provided on the collecting pipe 
204, the inert gas discharged from the opened five fire extinguisher 
storage vessels 201 and sent to the collecting pipe 204 through vessel 
valve 202 and connecting pipe 203, is controlled to no more than the 
reference gas pressure P0 (110 kgf/cm.sup.2) by the pressure control valve 
18, sent to the injection head 207-1 through selecting valve 209-1, main 
piping 205-1 and branch pipe 208-1, and then discharged from the injection 
head 207-1 into the object fire fighting section 206-1. 
Moreover, supposing that a fire broke out in the object fire fighting 
section 206-2, if the person who discovered the fire operates the push 
button (a case of manual operation) corresponding to this object fire 
fighting section 206-2, an electric signal is sent to the solenoid 212-2 
for opening the starting gas vessel and the solenoid 212-2 works to open 
the starting gas vessel 211-2. 
The starting gas discharged with the opening of the starting gas vessel 
211-2 is first introduced into the selecting valve opening device 210-2 to 
open the selecting valve 209-2, passes through the nonreturn valve 214-2 
to open the constant-pressure gas vessel 219, and passes through the 
nonreturn valves 214-B to reach the vessel valves 202 and open three of 
the fire extinguisher storage vessels 201 i.e., fire extinguisher storage 
vessels 201-3, 201-4, 201-5. 
At that time, two of the fire extinguisher storage vessels 201, i.e., fire 
extinguisher storage vessels 201-1, 201-2, are not opened because the gas 
cannot pass through the nonreturn valve 214-A. 
Moreover, the selecting valve 209-1 and the selecting valve 209-3 are not 
opened because the gas cannot pass through the nonreturn valve 214-1 and 
the nonreturn valve 214-3. 
Because the pressure control valve 18 valve which controls the gas pressure 
P of the inert gas fire extinguisher on the discharge side to no more than 
the reference gas pressure P0 determined by the gas pressure P1 of the 
constant-pressure gas source is provided on the collecting pipe 204, the 
inert gas discharged from the opened three fire extinguisher storage 
vessels 201-3, 201-4, 201-5 and sent to the collecting pipe 204 through 
vessel valve 202 and connecting pipe 203, is controlled to no more than 
the reference gas pressure P0 (110 kgf/cm.sup.2) by the pressure control 
valve 18, sent to the injection head 207-2 through selecting valve 209-2, 
main piping 205-2, and branch pipe 208-2, and then discharged from the 
injection head 207-2 into the object fire fighting section 206-2. 
Moreover, supposing that a fire broke out in the object fire fighting 
section 206-3, if the person who discovered the fire operates the push 
button (a case of manual operation) corresponding to this object fire 
fighting section 206-3, an electric signal is sent to the solenoid 212-3 
for opening the starting gas vessel and the solenoid 212-3 works to open 
the starting gas vessel 211-3. 
The starting gas discharged with the opening of the starting gas vessel 
211-3 is first introduced into the selecting valve opening device 210-3 to 
open the selecting valve 209-3, passes through the nonreturn valve 214-3 
to open the constant-pressure gas vessel 219, and passes through the 
nonreturn valves 214-3 to reach the vessel valves 202 and open one of the 
fire extinguisher storage vessels 201, i.e., fire extinguisher storage 
vessel 200-5. 
At that time, four of the fire extinguisher storage vessels 201, i.e., fire 
extinguisher storage vessels 201-1, 201-2, 201-3, 201-4, are not opened, 
because the gas cannot pass through the nonreturn valve 214-B (naturally, 
it cannot pass through the non-return valve 214-A either). 
Moreover, the selecting valve 209-1 and the selecting valve 209-2 are not 
opened because the gas cannot pass through the nonreturn valve 214-1 and 
the nonreturn valve 214-2. 
Because a pressure control valve 18 valve which controls the gas pressure P 
of the inert gas fire extinguisher on the discharge side to no more than 
the reference gas pressure P0 determined by the gas pressure P1 of the 
constant-pressure gas source is provided on the collecting pipe 204, the 
inert gas discharged from the opened one fire extinguisher storage vessel 
201-5 and sent to the collecting pipe 204 through vessel valve 202 and 
connecting pipe 203, is controlled to no more than the reference gas 
pressure P0 (110 kgf/cm.sup.2) by the pressure control valve 18, sent to 
the injection head 207-3 through selecting valve 209-3, main piping 205-3, 
and branch pipe 208-3, and then discharged from the injection head 207-3 
into the object fire fighting section 206-3.