Method for reducing noise and room air overpressure on discharge of a gas extinguisher system

Abstract

Noise and room air overpressure on discharge of a gas extinguisher system is reduced. During the discharge, an extinguishing fluid is conveyed from a pressurized container via a container valve and line system to an extinguishing nozzle. At the beginning of the discharge the extinguishing fluid is predominantly present in the line system in liquid phase and after discharge it assumes a predominantly gaseous phase. In a phase transition period, which is accompanied by a significant reduction in the extinguishing fluid mass flow and a significant increase in the noise and the room air pressure, the mass flow is then reduced or stopped. Due to the reduction of the mass flow, the sound level of the noise arising is advantageously reduced to a value of a maximum of 100 dB and the room air pressure to an overpressure value ranging from 200 to 1000 Pa.

Claims

1. A method of reducing noise and room air overpressure on discharge of a gas extinguisher system, the method comprising: during the discharge, conveying an extinguishing fluid from a pressurized container via a container valve and line system to an extinguishing nozzle, the extinguishing fluid stored in the pressurized container having an extinguishing liquid and a propellant gas, wherein the extinguishing fluid is present in the line system at the beginning of the discharge predominantly in a liquid phase and, upon discharge, the extinguishing liquid changes into a predominantly gaseous phase; and detecting a phase transition period that is associated with a significant reduction in an extinguishing fluid mass flow and a significant increase in the noise and a room air pressure, and in response to detecting the phase transition period, activating a choke or a throttle to reduce or stop the mass flow.

2. The method according to claim 1, which comprises reducing the mass flow to thereby restrict a sound level of the noise arising during the discharge to a maximum value of 100 dB.

3. The method according to claim 1, which comprises reducing the mass flow to thereby restrict the room air pressure to an overpressure value ranging from 200 to 1000 Pa.

4. The method according to claim 1, wherein the phase transition period is detected dependent on a parameter selected from the group consisting of time, line pressure, ambient pressure, noise, a fill level of the pressurized container, a weight of the pressurized container, and a value for the mass flow acquired by measurement.

5. The method according to claim 1, which comprises reducing the mass flow in a single stage.

6. The method according to claim 1, wherein the phase transition period is detected dependent on a signal from a sensor.

7. The method according to claim 6, wherein the sensor is selected from the group consisting of a pressure sensor, a microphone, a sound-born sensor, and a mass flow meter.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 shows an example of the timing curve of the noise occurring during the discharge of a gas extinguisher system and of the room air overpressure according to the prior art;

(2) FIG. 2 shows an example of the timing curve of the reduced noise occurring during the discharge of a gas extinguisher system and of the room air overpressure by active reduction of the extinguishing fluid mass flow in accordance with the method according to the invention;

(3) FIG. 3 is a diagram of an exemplary gas extinguisher system according to the invention with a choke disposed in the line system, which is able to be activated via a control facility for reducing or stopping the extinguishing fluid mass flow;

(4) FIG. 4 shows an example of an inventive gas extinguisher system according to a first form of embodiment; and

(5) FIG. 5 shows an example of an inventive gas extinguisher system according to a second form of embodiment.

DETAILED DESCRIPTION OF THE INVENTION

(6) Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is shown an example of the timing curve of the noise occurring during the discharge of a gas extinguisher system and of the room air overpressure according to the prior art.

(7) In the upper part of FIG. 1 the sound level LP in dB is plotted over the time t as a measure for the noise, in the lower part of FIG. 1 the room air overpressure p.sub.R in bar is plotted along the same time axis.

(8) As shown in FIG. 1, on transition of the extinguishing fluid from the fluid into the gaseous phase, the noise on the one hand and the room air overpressure or the ambient pressure on the other hand increase significantly. The plotted room air overpressure p.sub.R in this case is related as reference level to the normal atmospheric pressure obtaining in the environment of the gas extinguisher system and typically, in the non-actuated case of the gas extinguisher system, has a pressure value of around 0 Pa. The phase transition is represented idealized in the present example as point in time t1. In practice the phase transition occurs within a few seconds. In the present example the maximum sound level value L.sub.Max at point in time t2 lies at 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 falls, finally recovers and then increases significantly. Related to the plotted room air overpressure p.sub.R, this means that this first becomes negative then becomes zero again, i.e. approaches the normal pressure obtaining before actuation again, then rises significantly and reaches its maximum overpressure value P.sub.Max at point in time t3. Therefore pressure equalization flaps are provided in order to avoid damage to buildings and materials in the area of the gas extinguisher system caused by room air overpressure values that are too high.

(9) FIG. 2 shows, by way of example, the graph over time of the reduced noise and room air overpressures occurring during the discharge of a gas extinguisher system by active reduction of the extinguishing fluid mass flow m in accordance with the inventive method.

(10) In the lower part of FIG. 2 the sound level LP is again plotted over the time t and below this curve the room air overpressure p.sub.R is plotted. To the right of point in time t1 the curve of the sound level LP and room overpressure p.sub.R for the not actively reduced case of the mass flow m is plotted as a dashed line, against this the corresponding curves for the case with inventive reduction of the mass flow m are plotted as a dotted and dashed line with a thicker line width. Additionally the curve of the mass flow m of the extinguishing fluid is plotted in the upper part of FIG. 2.

(11) In accordance with the invention, now, in a phase transition period T, which is associated with a significant reduction in the extinguishing fluid mass flow m and a significant increase in the room air overpressure, the mass flow m is reduced.

(12) In the upper curve of the mass flow m shown, at point in time t0, the significant reduction of the mass flow m is detected. Shown to the right thereof is the curve of the mass flow m as said curve would proceed without the inventive further reduction of the mass flow m. The detection of the significant reduction of the mass flow m has the effect for example of changing a course of a logical binary switching state S shown below said curve from the value 0 to the value 1. The logical value 1 can correspond to the activation of a choke or throttle for active further reduction of the mass flow m for example. A logical value of 0 consequently corresponds to no active reduction of the mass flow m. The curve of the now reduced mass flow m is plotted below this curve. This reduction ultimately has the effect of restricting any further increase in noise to a reduced sound level value L.sub.Red of around 100 dB at point in time t2 and of restricting the room air overpressure p.sub.R to a maximum pressure value P.sub.Red at point in time t3.

(13) FIG. 3 shows an example for an inventive gas extinguisher system A with a throttle or choke DR, disposed in a line system LS, which is able to be activated via a control facility SV for reducing or stopping the extinguishing fluid mass flow. Only one extinguishing nozzle D is shown at the output-side end of the line system LS for example. The latter is the actual source for the noise and the increase in room or ambient pressure for example.

(14) The gas extinguisher system A only comprises a single pressurized container B for example for pressurizing an extinguishing fluid F. The latter has an extinguishing liquid L, such as Novec 1230 for example, and a propellant gas G, such as nitrogen for example. The pressurized container B is connected via a container valve BV to the line system LS and to the extinguishing nozzle D. The gas extinguisher system A also has an actuator 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 actuator AL is actuated by a fire alarm control center BMZ.

(15) In accordance with the invention a choke DR is disposed in the line system LS which is able to be activated via a control facility SV for reducing or stopping the extinguishing fluid mass flow. The control facility SV is configured to activate the choke DR during phase transition of the extinguishing fluid F from a predominantly liquid phase into a predominantly gaseous phase. The phase transition can for example be established by sensors. The phase transition can also be deemed to be established after a predetermined delay time has elapsed after the actuation of the gas extinguisher system A.

(16) FIG. 4 shows an example for an inventive gas extinguisher system A according to a first form of embodiment. In this example the gas extinguisher system A has a number of pressurized containers B. The left-hand pressurized container B is connected via a container valve BV and by a pressure hose DS to the line system LS. The container valve BV is activated in this case in the event of being actuated by an actuator AL to open the valve. The two other containers are each connected via a container valve actuator BVA and via a pressure hose DS in each case to a common conduit SR. The two right-hand container valve actuators BVA are actuated together by the upstream container valve BV of the left-hand pressurized container B. Both the pressure hoses DS, collective pipe SR and also the pipe R for connecting the collective pipe SR with the extinguishing nozzle D are components of the line system LS.

(17) As FIG. 4 also shows, the control facility SV, which has only one pressure sensor S1 for detecting the line pressure, and the choke DR are combined into one constructional unit BE. The control facility SV in this case can have (exclusively) mechanically, hydrodynamically and/or hydrostatically-acting components for actuating the choke DR, such as a pressure switch S1 for example as pressure sensor, which mechanically changes its switching state when the pressure drops below a predetermined pressure value.

(18) The control facility SV and the choke DR can for example have a common flow flap or a common flow valve as a constructional unit BE which, on phase transition of the extinguishing fluid F preferably flaps or springs or snaps irreversibly, and consequently reduces the flow cross-section for the extinguishing fluid F. This constructional unit BE can also be embodied so that the flow flap or the flow valve can be reset again after the discharge of the gas extinguisher system A.

(19) FIG. 5 shows an example for an inventive gas extinguisher system A in accordance with a further form of embodiment. In this example different embodiments of the control facility SV are shown together in one figure.

(20) In the present case the control facility SV has a switching logic SL, which can be realized for example by a processor-assisted control computer. As an alternative the switching logic SL can have one or more switching relays or threshold switches with a preferably floating switching contact. On the output side the switching logic SL activates the choke DR for reducing the mass flow m. In the example shown the latter is an electrically-activatable choke.

(21) The control facility SV can only have one of the detectors or sensors S1, S2, M, KS, MM shown for detection of the phase transition from the predominantly liquid phase of the extinguishing fluid F into the predominantly gaseous phase.

(22) As an alternative or in addition it can have a switching input for triggering a time delay element TIMER with a predetermined delay time by the actuator AL or by the upstream fire alarm control center BMZ. In the case of at least two input signals these can be logically combined by the OR switching logic, so that in respect of time the first input signal arriving on detection of the phase transition or the time-delayed signal from the time delay element TIMER is definitive for the activation of the choke DR.

(23) In the present example the control facility SV has, as one of a number of sensors, a first pressure sensor S1 for detecting the line pressure p.sub.L in the line system LS of the gas extinguisher system A. As an alternative the control facility SV can be connected to this pressure sensor S1 for exchange of signals or data. If a detected line pressure value is below a predeterminable comparison value, the choke DR is activated.

(24) Furthermore the control facility SV can have a second pressure sensor S2 for detecting the room air overpressure p.sub.R in the area of the gas extinguisher system A or be connected to the latter for exchange of signals or data. If a detected room air overpressure value exceeds a predeterminable comparison value, the choke DR is activated.

(25) The control facility SV can furthermore, as an alternative or in addition, have a microphone M for picking up the noise in the area of the gas extinguisher system A or be connected to the latter for exchange of signals or data. If a noise level value exceeds a predeterminable comparison value the choke DR is activated.

(26) Furthermore the control facility can be connected to a sound-borne sensor KS attached to a component of the gas extinguisher system A for detecting the structure-borne sound or can be connected to the latter for exchange of signals or data, such as e.g. to a pipe of the line system LS. If a detected sound-born noise level value exceeds a predeterminable comparison value, the choke DR is activated.

(27) Furthermore the control facility SV can have a mass flow meter MM for detecting the extinguishing fluid mass flow m flowing in the line system LS. If a detected value for the extinguishing fluid-mass flow m falls below a predeterminable comparison value, the choke DR is activated.

(28) As an alternative or in addition the control facility SV can be connected for exchange of signals or data to a fill level meter FM of a pressurized container B. If a detected fill level value falls below a predeterminable comparison value, the choke DR is activated.

(29) Finally the control facility SV can also have a weighing facility W, such as scales or a force measuring cell, for example or be connected to the latter for exchange of signals or data. If a detected weight value falls below a predeterminable comparison value, the choke DR is also activated here.

(30) The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: A Gas extinguisher system AL Actuator B Pressurized container BE Constructional unit BMZ Fire alarm control center BV Container valve BVA Container valve actuator D Extinguishing nozzle DR Choke, throttle valve, reduction valve, restriction valve DS Pressure hose F Extinguishing fluid FM Fill level meter, float G Propellant gas KS Sound-borne sensor L Extinguishing liquid L.sub.Max Maximum sound level value LP Sound level L.sub.Red Produced sound level value LS Line system m Mass flow M Microphone MM Mass flow meter p.sub.L Line pressure P.sub.Max Maximum overpressure value p.sub.R Room air overpressure P.sub.Red Overpressure value R Pipe, pipe system S Switching state S1, S2 Pressure sensor SL Switching logic, control computer SR Conduit pipe SV Control facility T Phase transition period t, t0-t3 Time, points in time TIMER Time delay element, timer, timing element W Weighing facility, scales