EP2937116B1 - Reduction of noise and positive air pressure when discharging a gas extinguisher system - Google Patents

Description

Gas extinguishing systems and extinguishing methods are known from the prior art, in which an extinguishing fluid is led from a pressure container via a container valve and line system to one or more extinguishing nozzles during the discharge. The extinguishing fluid stored in the pressure container has an extinguishing liquid and a propellant gas. The extinguishing liquid is preferably a chemically acting extinguishing liquid. It is based in particular on halogen hydrocarbons (halons), such as HFC-227ea or HFC-23, or on fluorinated ketones, such as FK-5-1-12, which is sold under the brand name Novec ^® 1230. The propellant gas is preferably an inert gas such as nitrogen or argon, or carbon dioxide.

From the US patent US 7,434,628 B2 a fire extinguishing device is known, in particular for fighting fires in the cargo holds of aircraft. The fire extinguishing device has at least one extinguishing agent container that holds an extinguishing agent and a filter unit, wherein the extinguishing agent in the extinguishing agent container or containers can be directed to a fire source via a pipeline system with extinguishing agent outlet nozzles. The extinguishing agent is controlled from at least one of the extinguishing agent containers by means of a control unit and can be released into the pipeline system by means of a controlled valve unit. In the method there, extinguishing agent first emerges with the highest possible mass flow from a first extinguishing agent container, which does not have a valve unit controlled by a control unit, until the first extinguishing agent container is emptied, an initial extinguishing agent concentration A being reached in the room to be protected from fire, which is necessary for rapid suppression of the fire. Subsequently, extinguishing agent is controlled from a second extinguishing agent container by the control unit using the valve unit released periodically, so that a minimum extinguishing agent concentration M in the room to be protected from fire is never fallen below and the fire is prevented from flaring up again.

At the start of the discharge, the extinguishing fluid is mainly in the liquid phase in the pipe system. After the extinguishing liquid has been discharged, the extinguishing fluid then changes into a mainly gaseous phase in the line system. By “mainly” here is meant a volume fraction of the respective phase compared to the other phase of more than 90%. In terms of time for the phase transition, this is the period in which the propellant gas in the pressure vessel conveys or "presses out" the extinguishing liquid there from the pressure vessel until ultimately only the propellant gas is left in the pressure vessel. This remaining propellant gas is also emptied via the connected line system and further via the nozzles until it is typically depressurized.

It is also known that when such a gas extinguishing system is triggered and discharged, noise levels of up to 110 dB and more can occur. If there are magnetic hard drives in protected rooms, such as data centers that are connected to such a gas extinguishing system, it is known that these are impaired and can sometimes even fail at noise levels of more than 100 dB.

Based on the prior art mentioned at the beginning, it is an object of the invention to provide a method which reduces noise and excess room air pressure.

The task is solved with the subjects of the main claim. Advantageous embodiments of the present invention are set out in the dependent claims.

According to the invention, in a phase transition region with a significant decrease in the extinguishing fluid flow and a significant increase in noise and room air pressure accompanied, the mass flow or the mass flow is reduced or stopped.

This advantageously effectively reduces the further increase in noise, so that noise-sensitive components, such as magnetic hard drives, are not affected in the area of the erasing nozzles.

Another advantage is that pressure equalization flaps in protected rooms, which are opened in the event of a gas extinguishing system being triggered to reduce the excess pressure in the room in order to minimize damage to the building and people, can now be made smaller. The construction and cost effort is reduced.

According to a method variant, the mass flow is reduced in such a way that the sound level of the resulting noise is limited to a maximum of 100 dB.

According to one method variant, the mass flow is reduced in such a way that the room air overpressure is limited to an overpressure value in a range of 200 to 1000 Pa.

This advantageously minimizes the risk of harm to people who are in protected rooms. The excess room air pressure is based on the normal atmospheric pressure in the area surrounding the gas extinguishing system as a reference level. Normally, i.e. when the gas extinguishing system is not triggered, it corresponds to the ambient air pressure.

The (active) reduction in the quantity flow is preferably time-controlled. In this case, the reduction takes place via a timer with a predetermined delay time, such as a time relay. This can be used to at least indirectly trigger a throttle or a reducing valve in the line system of the gas extinguishing system, triggered by a trigger signal from the gas extinguishing system, in order to reduce the quantity flow of the extinguishing fluid. The timer can also be pneumatic or implemented hydraulically, as well as the control of the throttle. The adjustable delay time is preferably in the range from 5 to 15 seconds, in particular in a range from 7 to 10 seconds.

The volume flow reduction can also be controlled by line pressure, for example using a pressure sensor to record the line pressure.

The volume flow reduction can also be controlled by ambient air pressure, i.e. controlled by the room air pressure prevailing in the gas extinguishing system, such as using an air pressure sensor or differential pressure sensor. If the room air pressure exceeds a specified pressure value, such as a pressure value of 200 Pa, the throttle is activated to reduce the quantity flow.

The flow rate reduction can also be noise-controlled, such as using a microphone or a structure-borne noise sensor.

The volume flow reduction can still be carried out alternatively or additionally via the current fill level of the pressure vessel. In this case, a level gauge, such as a float, can be arranged in the pressure vessel. The level meter can also be an ultrasonic level meter.

Furthermore, the volume flow reduction can take place via the current weight of the pressure vessel, which decreases as the pressure vessel is unloaded. The current weight of the container can be measured using a weighing device, such as a scale or load cell.

Furthermore, alternatively or additionally, the volume flow reduction can take place via a measured value for the volume flow, such as by means of a flow meter, a volume flow meter or a mass flow meter. From a technological point of view, such measuring devices can measure the flow based on a rotating impeller or detect a fluid pressure falling along a measuring section. The measurement can also be carried out optically, such as based on the change in the refractive index in the liquid and gaseous phases, or using ultrasound.

According to one process variant, the reduction in the mass flow occurs in one stage. This makes it possible to implement the mass flow of the extinguishing fluid in a particularly simple manner. Alternatively, a two-stage or generally a multi-stage reduction of the mass flow is also conceivable.

The object of the invention is further achieved by a gas extinguishing system which has at least one pressure container for pressure storage of an extinguishing fluid. The extinguishing fluid has an extinguishing liquid and a propellant gas. The respective pressure container is connected to a line system on at least one extinguishing nozzle via a container valve or via a container valve trigger. The line system can include line pipes, header pipes and/or pressure hoses.

Furthermore, the gas extinguishing system has a trigger for opening the respective container valve in order to discharge the extinguishing fluid into the line system.

Typically all container valves have a trigger. The trigger on the first container valve is controlled by the fire alarm control panel. The remaining triggers are then preferably controlled together by the first opened pressure container.

The trigger can be an electrically, pneumatically or hydraulically controllable trigger that is mechanically connected to the respective container valve for opening. The gas extinguishing system also includes a throttle or reducing valve, which is arranged in the pipe system. The throttle can be controlled via a control device of the gas extinguishing system to (further actively) reduce or even stop the flow of extinguishing fluid.

According to the invention, the control device is set up to control the throttle during the phase transition from a mainly liquid phase to a mainly gaseous phase.

By activating the throttle, the extinguishing fluid flow is reduced. If the volume flow is already reduced due to the phase transition of the extinguishing fluid from the mainly liquid phase to the mainly gaseous phase, the volume flow is actively further reduced by activating the throttle.

Further according to the invention, the throttle for reducing the mass flow in the line system is dimensioned such that the sound level of the resulting noise can be limited to a maximum of 100 dB. This can be done, for example, as part of a type test of such a gas extinguishing system. As part of the design, for example, perforated diaphragms with different flow diameters can be tested.

Alternatively or additionally, the throttle according to the invention is dimensioned such that the room air overpressure can be limited to an overpressure value in a range of 200 to 1000 Pa. The design can also be carried out in such a way that both the aforementioned maximum sound level value and the overpressure value are adhered to.

The control device of the gas extinguishing system according to the invention can, for example, have a triggerable time delay element, ie a so-called timer. In the simplest case, the control device has an external electrical input for triggering the time delay element. The time delay element can then be triggered by the trigger, by an upstream fire alarm control panel or by a manually triggered extinguishing button to control the throttle. The trigger, the fire alarm panel as well as that Delete buttons can then be connected to the electrical trigger input as a switching input of the control device.

Alternatively or additionally, the control device can also have a first pressure sensor for detecting the line pressure in the line system of the gas extinguishing system and / or a second pressure sensor for detecting the excess air pressure in an area of the gas extinguishing system remote from the extinguishing nozzles. What is meant here by “removed” is that the second pressure sensor should not be arranged in the outlet sector or outflow area of the extinguishing nozzles.

Furthermore, alternatively or additionally, the control device has a microphone for detecting the noise in the area of the gas extinguishing system and/or a structure-borne noise sensor attached to components of the gas extinguishing system for detecting the structure-borne noise.

The control device can also alternatively or additionally have a mass flow meter for detecting the quantity flow of extinguishing fluid flowing in the line system. The flow meter can be arranged in front of the throttle or after the throttle, viewed in the flow direction of the extinguishing fluid.

The control unit can also alternatively or additionally have a fill level meter for detecting the fill level of a pressure vessel and/or a weighing device for detecting the weight of a pressure vessel.

According to one embodiment, the control device and the throttle are combined to form a structural unit. The control device has hydrodynamically and/or hydrostatically acting components for actuating the throttle. The structural unit consisting of control device and throttle can also be implemented "electronically-free", that is, without electrical components, for example by using mechanical, hydraulic and/or pneumatic components.

According to a further embodiment, the extinguishing fluid has a chemically active extinguishing liquid based on hydrogen halides and an inert gas, such as nitrogen or argon, or carbon dioxide as a propellant gas.

FIG 1

beispielhaft den zeitlichen Verlauf des während der Entladung einer Gaslöschanlage auftretenden Lärms und Raumluftüberdrucks nach dem Stand der Technik,

FIG 2

beispielhaft den zeitlichen Verlauf des während der Entladung einer Gaslöschanlage auftretenden reduzierten Lärms und Raumluftüberdrucks durch aktive Reduktion des Löschfluid-Mengenstroms gemäss dem erfindungsgemässen Verfahren,

FIG 3

ein Beispiel für eine erfindungsgemässe Gaslöschanlage mit einer im Leitungssystem angeordneten Drossel, welche über eine Steuervorrichtung zum Reduzieren oder Stoppen des Löschfluids-Mengenstroms ansteuerbar ist,

FIG 4

ein Beispiel für eine erfindungsgemässe Gaslöschanlage nach einer ersten Ausführungsform und

FIG 5

ein Beispiel für eine erfindungsgemässe Gaslöschanlage nach einer weiteren Ausführungsform.

The invention and advantageous embodiments of the present invention are explained using the following figures as examples. Show:

FIG 1

an example of the time course of the noise and excess room air pressure occurring during the discharge of a gas extinguishing system according to the state of the art,

FIG 2

For example, the time course of the reduced noise and excess room air pressure that occurs during the discharge of a gas extinguishing system through active reduction of the extinguishing fluid flow according to the method according to the invention,

FIG 3

an example of a gas extinguishing system according to the invention with a throttle arranged in the line system, which can be controlled via a control device for reducing or stopping the flow of extinguishing fluid,

FIG 4

an example of a gas extinguishing system according to the invention according to a first embodiment and

FIG 5

an example of a gas extinguishing system according to the invention according to a further embodiment.

FIG 1 shows an example of the time course of the noise and room air overpressure occurring during the discharge of a gas extinguishing system according to the state of the art.

In the upper part of the FIG 1 is the sound level LP in dB over time t as a measure of the noise, in the lower part of the FIG 1 the room air pressure p _R is plotted in bar.

As the FIG 1 shows, when the extinguishing fluid transitions from the liquid to the gaseous phase, on the one hand the noise and on the other hand the room air pressure or the ambient pressure increases significantly. The entered room air excess pressure p _R is based on the normal atmospheric pressure prevailing in the area of the gas extinguishing system as a reference level and typically has a pressure value of approximately 0 Pa if the gas extinguishing system is not triggered. In the present example, the phase transition is idealized as time t1. In practice, the phase transition occurs within a few seconds. In the present example, the maximum sound level value L _Max at time t2 is just over 110 dB. Such sound level values are highly critical for the proper operation of magnetic drives in data centers. At the same time, the room air pressure drops, finally recovers and then increases significantly. In relation to the entered room air overpressure p _R , this means that it initially becomes negative, then returns to zero, ie it approaches the normal pressure prevailing before the triggering, then increases significantly and reaches its maximum overpressure value P _Max at time t3. In order to avoid building and property damage in the area of the gas extinguishing system due to excessive room air pressure values, pressure compensation flaps are provided.

FIG 2 shows an example of the time course of the reduced noise and excess room air pressure that occurs during the discharge of a gas extinguishing system by actively reducing the extinguishing fluid flow ṁ according to the method according to the invention.

In the lower part of the FIG 2 The sound level LP is plotted over the time t and the room air pressure p _R is plotted underneath. To the right of time t1 is the course of the sound level LP and room excess pressure p _R for the not actively reduced Case of the mass flow ṁ is entered in dashed lines, whereas the corresponding curves for the case with reduction of the mass flow ṁ according to the invention are entered in dot-dashed lines and with a larger line width. In the upper part of the FIG 2 The course of the mass flow ṁ of the extinguishing fluid is also plotted.

According to the invention, the quantity flow ṁ is now reduced in a phase transition region T, which is accompanied by a significant decrease in the extinguishing fluid quantity flow ṁ and a significant increase in noise and the room air pressure.

In the course of the mass flow ṁ shown above, the significant decrease in the mass flow ṁ is detected at time t0. To the right of this, the course of the mass flow ṁ is shown, as it would proceed without the further reduction of the mass flow ṁ according to the invention. The detection of the significant decrease in the mass flow ṁ causes, for example, a change in the course of a logical binary switching state S shown below from the value 0 to the value 1. The logical value 1 can, for example, correspond to the activation of a throttle for actively further reducing the mass flow ṁ . A logical value of 0 therefore corresponds to no active reduction of the mass flow ṁ . The course of the now reduced mass flow ṁ is plotted below. This reduction ultimately limits the other increase in noise to a reduced sound level value L _Red of almost 100 dB at time t2 and limits the excess room air pressure p _R to a maximum pressure value P _Red at time t3.

FIG 3 shows an example of a gas extinguishing system A according to the invention with a throttle DR arranged in the line system LS, which can be controlled via a control device SV to reduce or stop the extinguishing fluid flow. At the outlet end of the line system LS, only one extinguishing nozzle D is shown as an example. The latter is the actual one Source of the noise and the increase in room or ambient pressure.

The gas extinguishing system A, for example, comprises only a single pressure vessel B for pressurizing an extinguishing fluid F. The latter has an extinguishing fluid L, such as ^Novec® 1230, and a propellant gas G, such as nitrogen. The pressure vessel B is connected to the line system LS and to the extinguishing nozzle D via a vessel valve BV. The gas extinguishing system A also has a trigger AL for opening the container valve BV in order to discharge the extinguishing fluid F into the line system LS. In the present example, the trigger AL is triggered by a fire alarm control panel BMZ.

According to the invention, a throttle DR is arranged in the line system LS, which can be controlled via a control device SV to reduce or stop the extinguishing fluid flow. The control device SV is set up to control the throttle DR during the phase transition of the extinguishing fluid F from a mainly liquid phase to a mainly gaseous phase. The phase transition can be determined, for example, sensorily, i.e. using sensors. The phase transition can also be considered as established after a predetermined delay time has elapsed after the gas extinguishing system A has been triggered.

FIG 4 shows an example of a gas extinguishing system A according to the invention according to a first embodiment. In this example, the gas extinguishing system A has several pressure vessels B. The left pressure container B is connected to the line system LS via a container valve BV and a pressure hose DS. If triggered, the container valve BV is controlled to open by a trigger AL. The other two are each connected to a common collecting pipe SR via a container valve trigger BVA and a pressure hose DS. The two right container valve triggers BVA are triggered together by the upstream container valve BV of the left pressure container B. Both the pressure hoses DS, common manifold SR and the pipe R for connecting the manifold SR to the extinguishing nozzle D are components of the line system LS.

As the FIG 4 further shows, the control device SV, which only has a pressure sensor S1 for detecting the line pressure, and the throttle DR are combined to form a structural unit BE. The control device SV can have (exclusively) mechanical, hydrodynamically and/or hydrostatically acting components for actuating the throttle DR, such as a pressure switch S1 as a pressure sensor, which mechanically changes its switching state when the pressure value falls below a predetermined value.

The control device SV and the throttle DR can, as a structural unit BE, have, for example, a common flow flap or a common flow valve, which preferably flips or snaps over irreversibly during the phase transition of the extinguishing fluid F, and consequently reduces the flow cross section for the extinguishing fluid F. This structural unit BE can also be designed in such a way that the flow flap or the flow valve can be reset again after the gas extinguishing system A has been unloaded.

FIG 5 shows an example of a gas extinguishing system A according to the invention according to a further embodiment. In this example, various configurations of the control device SV are shown together in one figure.

In the present case, the control device SV has a switching logic SL, which can be implemented, for example, by a processor-based control computer. The switching logic SL can alternatively have one or more switching relays or threshold switches with a preferably potential-free switching contact. On the output side, the switching logic SL controls the throttle DR to reduce the quantity flow ṁ . In the example shown, the latter is an electrically controllable throttle.

The control device SV can only have one of the detectors or sensors S1, S2, M, KS, MM shown for detecting the phase transition from the mainly liquid phase of the extinguishing fluid F into the mainly gaseous phase.

Alternatively or additionally, it can have a switching input for triggering a time delay element TIMER with a predetermined delay time by the trigger AL or by the upstream fire alarm control panel BMZ. In the case of at least two input signals, these can be OR-linked by the switching logic, so that in terms of time, the input signal that arrives first when the phase transition is detected or the time-delayed signal from the time delay element TIMER is decisive for the control of the throttle DR.

In the present example, the control device SV has a first pressure sensor S1 as one of several sensors for detecting the line pressure p _L in the line system LS of the gas extinguishing system A. Alternatively, the control device SV can be connected to this pressure sensor S1 for signals or data. If a detected line pressure value falls below a predeterminable comparison value, the throttle DR is activated.

Furthermore, the control device SV can have a second pressure sensor S2 for detecting the room air excess pressure p _R in the area of the gas extinguishing system A or can be connected to it in terms of signals or data. If a recorded room air overpressure value exceeds a predeterminable comparison value, the throttle DR is activated.

The control device SV can alternatively or additionally comprise a microphone M for detecting the noise in the area of the gas extinguishing system A or can be connected to it for signal or data technology. If a detected noise level value exceeds a predeterminable comparison value, the throttle DR is activated.

Furthermore, the control device can have a structure-borne noise sensor KS attached to components of the gas extinguishing system A for detecting the structure-borne noise or can be connected to it in terms of signals or data, such as on a pipe of the line system LS. If a recorded structure-borne noise level value exceeds a predeterminable comparison value, the throttle DR is activated.

Furthermore, the control device SV can have a mass flow meter MM for detecting the extinguishing fluid mass flow ṁ flowing in the line system LS. If a recorded value for the extinguishing fluid quantity flow ṁ falls below a predeterminable comparison value, the throttle DR is activated.

The control device SV can alternatively or additionally be connected to a level meter FM of a pressure vessel B in terms of signals or data. If a detected fill level value falls below a predeterminable comparison value, the throttle DR is activated.

Finally, the control device SV can also have a weighing device W, such as a scale or a load cell, or can be connected to it in terms of signals or data. If a recorded weight value falls below a predetermined comparison value, the throttle DR is also activated here.

Reference symbol list

A

Gas extinguishing system

AL

trigger

b

pressure vessel

BE

structural unit

BMZ

Fire alarm panel

BV

Container valve

BVA

Container valve actuator

D

Extinguishing nozzle

DR

Throttle, reducing valve, shut-off valve

D.S

pressure hose

F

Extinguishing fluid

FM

Level gauge, float

G

Propellant gas

KS

Structure-borne sound sensor

L

Extinguishing liquid

LMax

Maximum sound level value

LP

Sound level

LRed

reduced sound level value

L.S

Piping system

ṁ

Mass flow, mass flow

M

microphone

MM

Mass flow meter, mass flow meter

pl

Line pressure

PMax

Maximum overpressure value

pr

Room air pressure

PRed

Overpressure value

R

pipe, pipe system

S

switching state

S1, S2

Pressure sensor

SL

Switching logic, control computer

S.R

collecting pipe

SV

Control device

T

Phase transition region

t, t0-t3

Time, points in time

TIMER

Time delay element, timer, timing element

W

Weighing device, scales

Claims (8)

1. Method for reduction of noise and room air overpressure on discharge of a gas extinguisher system (A), wherein, during the discharge, an extinguishing fluid (F) is conveyed from a pressurised container (B) via a container valve (BV) and line system (LS) to an extinguishing nozzle (D), wherein the extinguishing fluid (F) stored in the pressurised container (B) has an extinguishing liquid (L) and a propellant gas (G), wherein the extinguishing fluid (F) is predominantly present in the line system (LS) at the beginning of the discharge in a liquid phase and, after discharge, the extinguishing liquid (L) changes into a predominantly gaseous phase, and characterised in that, in a phase transition area (T), which is associated with a significant reduction in the extinguishing fluid mass flow (ṁ) and a significant increase in the noise and the room air pressure, the mass flow (ṁ) is then reduced or stopped.
2. Method according to claim 1, wherein the mass flow (ṁ) is reduced such that the sound level (LP) of the noise arising is restricted to a maximum value of 100 dB.
3. Method according to claim 1 or 2, wherein the mass flow (ṁ) is reduced such that the room air pressure (p_R) is restricted to an overpressure value (P_Red) ranging from 200 to 1000 Pa.
4. Method according to one of the preceding claims, wherein the reduction of the mass flow (ṁ) is controlled by time, line pressure, ambient pressure, noise, via the fill level or the weight of the pressurised container (B) or via a value for the mass flow (ṁ) acquired by measuring technology.
5. Method according to one of the preceding claims, wherein the mass flow ( ṁ ) is reduced in a single stage.
6. Gas extinguisher system with at least one pressurised container (B) for pressurised storage of an extinguishing fluid (F), wherein the extinguishing fluid (F) has an extinguishing liquid (L) and a propellant gas (G) and wherein the respective pressurised container (B) is connected via a container valve (BV) or via a container valve actuator (BVA) on a line system (LS) to at least one extinguishing nozzle (D), wherein the gas extinguisher system has an actuator (AL) for opening the respective container valve (BV), in order to discharge the extinguishing fluid (F) into the line system, and a choke (DR) disposed in the line system (LS), wherein the choke (DR) is able to be activated via a control facility (SV) for reducing the extinguishing fluid mass flow ( ṁ ), characterised in that

   - the control facility (SV) is configured to activate the choke (DR) on phase transition of the extinguishing fluid (F) from a predominantly liquid phase into a predominantly gaseous phase,

   - the choke (DR) is dimensioned for reduction of the mass flow (ṁ) in the line system (LS) such that the sound level (LP) of the noise arising is able to be restricted to a value of maximum 100 dB and/or the room air overpressure (p_R) is able to be restricted to an overpressure value (P_Red) ranging from 200 to 1000 Pa, and

   - the control facility (SV) has at least one element selected from the list below:

   - a time delay element (TIMER) able to be triggered by the actuator (AL), by an upstream fire alarm control centre (BMZ) or by a manually activatable fire alarm button for activating the choke (DR),

   - a first pressure sensor (S1) for detecting the line pressure (p_L) in the line system (LS) of the gas extinguisher system and/or to a second pressure sensor (S2) for detecting the room air overpressure (p_R) in an area of the gas extinguisher system remote from the extinguishing nozzles (D),

   - a microphone (M) for picking up the noise in the area of the gas extinguisher system and/or a structure-borne sound sensor (KS) attached to components of the gas extinguisher system for detecting the structure-born sound,

   - a mass flow meter (MM) for detecting the extinguishing fluid-mass flow ( ṁ ) flowing in the line system (LS),

   - a fill level meter (FM) for detecting the fill level of a pressurised container (B) and/or a weighing facility (W) for detecting the weight of a pressurised container (B).
7. Gas extinguisher system according to claim 6, wherein the control facility (SV) and the choke (DR) are combined into one constructional unit (BE), wherein the control facility (SV) has mechanically, hydrodynamically and/or hydrostatically-acting components for actuating the choke (DR).
8. Gas extinguisher system according to claim 6 or 7, wherein the extinguishing fluid (F) has a chemically-acting extinguishing liquid (L) based on hydrogen halides and an inert gas, such as nitrogen or argon, or carbon dioxide as its propellant gas (G).

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