WO2012062484A1

WO2012062484A1 - Test for leaktightness of a pipeline system for firefighting systems

Info

Publication number: WO2012062484A1
Application number: PCT/EP2011/053975
Authority: WO
Inventors: Dirk Sprakel; Ulrich Hiltemann; Max Lakkonen
Original assignee: Fogtec Brandschutz Gmbh & Co. Kg
Priority date: 2010-11-08
Filing date: 2011-03-16
Publication date: 2012-05-18
Also published as: DE102010050505A1; EP2638377A1

Abstract

Method and system for testing for leaktightness of dry pipeline systems (2) in firefighting systems, in particular in rail vehicles, comprising generating gas overpressure in the pipeline system (2), capturing an actual gas pressure and/or an actual gas volume flow in the pipeline system (2), comparing the captured actual gas pressure with a prespecified gas pressure and/or comparing the captured actual gas volume flow with a prespecified gas volume flow. In order to detect a leakage, it is proposed that a warning signal be emitted if the actual gas pressure should deviate from the prespecified gas pressure.

Description

Leak test of piping system for

Fire-fighting equipment

The subject matter relates to a method and a system for leak testing of dry pipeline systems in

Firefighting systems.

Firefighting systems are usually divided into wet and dry systems. Wet plants are characterized by the fact that extinguishing fluid is permanently stored in their pipelines. In case of fire, the pressure of the

Loschfluids increased in the pipelines and possibly opened valves to discharge liquid can be discharged from extinguishing nozzles in the field of fire. In itself dry

Fire fighting systems, the pipes are filled with air or gas. In case of fire, the extinguishing fluid is first pumped into the pipes and from there to the extinguishing nozzles

transported to be discharged from the extinguishing nozzles.

Especially in rail transport mainly dry fire fighting systems are used. This has the advantage that the pipes are filled with extinguishing fluid only in case of fire and thus are easier to wet systems. In addition, in case of leakage in the

Piping system does not immediately extinguishing fluid from the

Piping out. As in particular rail vehicles

are permanently in motion, exert these dynamic loads on the piping systems, so that in contrast to installed in real estate fire fighting systems rather to leaks in the pipelines. There exiting Extinguishing fluid, especially in rail vehicles

is undesirable, one therefore uses dry systems.

However, even with dry systems, it must be ensured that they are free of leaks, since in case of fire, the

Extinguishing fluid safely through the piping to the

Fire source facing extinguishing nozzles must be transported. Especially in high-pressure systems with

Extinguishing medium pressures between 5 and over lOObar work, but also with low pressure systems, those with lower

Working to ensure that there is no leakage in the piping system. If this can not be ensured, it is not assured that in case of fire

in fact, the extinguishing fluid is applied at the location of the source of the fire. Rather, a part or everything

Extinguishing fluid escape through the leakage and safe firefighting is then impossible.

For this reason, the object was the object of a method and a system for leak testing of per se dry piping systems, especially in

Rail vehicles to make available, which makes a leak detectable in a particularly simple manner. This object is achieved according to a first aspect by generating a gas pressure in the piping system, detecting an actual gas pressure and / or an actual gas volume flow in the piping system, comparing the detected actual gas pressure with a desired gas pressure and / or comparing the detected Actual gas volume flow with a desired gas volume flow, and outputting a warning signal upon detection of a deviation of the actual gas pressure from the target gas flow rate. Gas pressure and / or the actual gas volume flow of the desired gas volume flow.

It has been recognized that in open piping systems a desired pressure or a desired gas volume flow can be determined, which is achieved when a test pressure is applied to the pipeline system, without leaks

are present, e.g. immediately after installation. In this case, gas only exits or enters from the open nozzles, so that a setpoint can be determined.

The test pressure can be a negative pressure or an overpressure. As soon as there is a difference between the actual pressure and the setpoint pressure or the actual volume flow and the setpoint volume flow, a leak can be determined. For this purpose, it can be determined whether a gas volume flow is produced by escaping or entering gas. It can also be determined whether there is a temporal pressure gradient, ie the pressure in the interior of the pipeline changes. A comparison of a desired pressure gradient with an actual pressure gradient allows leakage detection.

Especially with the use of open nozzles connected to the open piping system, gas also leaks out of the nozzles in the case of the gas overpressure in the pipe paring system. In the case of the gas negative pressure in the

Piping system enters through these nozzles gas. However, it can be measured or calculated how large the amount of gas that can leak from the open nozzles in a leak-free piping system. With the help of this

Information, the target gas pressure can be determined. Also is it is possible to measure or calculate the nominal gas volume flow.

Thus, for testing purposes in a leak-free

Piping system a gas pressure can be used with a certain pressure and it can be measured which one

Volume flow flows at a measuring point. The volume flow is determined from the gas, which is the sum of all

Openings in the piping system, in particular the openings provided by the nozzles, flows. In the event of a leak, the piping system has, in addition to the openings through the nozzles, at least one opening in the region of the leakage, through which gas likewise enters and exits, whereby the gas volume flow at the measuring point can be increased. In this case, an actual gas volume flow deviates from the desired gas volume flow.

If the actual gas pressure deviates from the desired gas pressure or the actual gas volume flow deviates from the desired gas volume flow, it is possible to infer a leakage and a

corresponding warning signal are output.

By the subject method, it is possible to dry in itself piping systems during operation

Check leakages without flooding the piping systems with extinguishing fluid or costly investigations

to have to perform. Checking an open

Piping system can be done regularly at certain intervals. So it is possible, for example, that once a day or once a week, the gas pressure is generated and the actual gas pressure or the actual gas volume flow is measured. If there are deviations from the setpoint values, a

Warning signal will be issued.

If there is a warning signal, a technician can check the piping system and correct the leak. This ensures that in the event of a fire, the piping system is highly likely to be free of leaks and good firefighting can take place. According to an advantageous embodiment is

proposed that the pipe system connected nozzle body are open so that in the case of overpressure gas exits the nozzle or in the case of a negative pressure gas enters through the nozzle, wherein the target gas pressure and / or the target gas volume flow takes into account the gas thus exiting has been. As already explained at the beginning, open nozzle systems often use open nozzle bodies in open pipeline systems. Open nozzle bodies are characterized by the fact that the nozzles or nozzle inserts not

sealed against the piping system. Gas can escape from the piping systems or into the

Pipe system, depending on how the

Relative pressure within the piping system to the ambient pressure is. In the case of overpressure can thus escape gas from the piping system through the nozzle body. The pressure drop or the volume flow of the gas which emerges from the nozzle body can be measured and / or calculated. Thus, it is possible to take into account when determining the desired gas pressure or the desired gas volume flow, that are connected to the piping open nozzle body. To calibrate the system can, for example, immediately after assembly, for example, the gas pressure on the

Piping system are given and measured at a measuring point of the gas pressure or the gas flow rate. This usually corresponds to the nominal gas pressure or the nominal gas volume flow, since immediately after assembly no

Leaks in the piping system should be present.

Subsequently, the pipeline system can be put into operation and in the case of a test, the previously measured target gas pressure or desired gas flow rate can be compared with an actual gas pressure or actual gas volume flow measured during the test period. If the values deviate from each other, something has changed in the area of the pipeline system,

For example, a leak has occurred. This leads to an altered actual gas pressure or an altered actual gas volume flow, which can be detected.

When comparing the actual gas pressure with the desired gas pressure or the actual gas volume flow with the desired gas volume flow, for example, the ambient temperature can be taken into account. Different ambient temperatures result in different gas pressures or gas volume flows, so that a deviation of the actual values from the desired values without leakage in the piping system can occur, for example under changed temperature conditions in the

Comparison to the conditions during calibration. The ambient pressure and the relative humidity can also lead to variations in the actual values. These variations due to the changed environmental conditions can be taken into account when determining the target values. One

Comparison of the actual values with the desired values can then take place taking into account the mentioned variations, so that a deviation of the actual value from a target value, which is dependent on changed environmental conditions,

can be disregarded. According to an advantageous embodiment, it is also proposed that the target gas pressure and / or the nominal gas volume flow is measured with A) open range valves and / or B) at least partially closed range valves, wherein the range valves a main line of the

Piping system with attached

Area and nozzle bodies fluid-tight closes connects. Regularly piping systems through

Main lines and area lines formed. A

Main can be, for example, through a whole

Vehicle and a wagon extend and thereof, branched off by valves, divide area lines. To the

Area lines, the nozzle body can be connected. Area management makes it possible to move a larger surveillance area into smaller units

subdivide so that firefighting can be targeted. In case of fire, it is possible only the

To open range valves that relate to areas that are facing the fire. Thus, the extinguishing fluid is only in

Range of a fire deployed and used effectively.

Leaks usually occur more often on the main lines, as these extend over a larger area and on the other hand larger pipe cross-sections

exhibit. Therefore, to improve the inspection of the piping system, a measurement of the actual values can be made

For example, only the main line done. In this case if all of the range valves were closed and a leak could be clearly assigned to the main line.

It is also possible to open in each case a range valve in regions and to perform a measurement and a comparison of the actual values with the desired values. Thus, it is possible leaks

individual areas or the main line, which simplifies a repair, since the fault does not have to be searched consuming.

So it is for example possible, computer-aided

Test routine to be controlled in the first all area valves are closed, and then partially the

Range valves are opened, in each case the actual value is compared with the target value. It is also possible to open all range valves and the actual values at a

completely open system to be measured and compared with the target values. According to an advantageous embodiment is

proposed that the actual gas pressure and / or the actual gas volume flow is measured, each with an open range valve and / or with fully closed range valves. The measured actual values can be compared with the corresponding setpoint values, the setpoint values being calibrated with a corresponding open or

closed area valves have been determined. Thus, in some areas a review of the piping system can take place. With completely closed range valves, a check of the main line is thus possible and with each open range valve, the check of the respectively open range. Checking for leaks is improved by measuring the actual values over a longer period of a measurement interval. For example, it is possible to measure the time variation of the actual gas pressure within a measuring interval.

For example, during calibration, it can be determined that a gas overpressure, which is initially 5 bars, decreases by 1 bar within a 5 minute period. This pressure decrease is due to openings in the

Pipe system, which are given for example by nozzle body. This temporal change can be based on the target values, for example in the form of a desired value profile which determines the gas pressure over time

maps. The measured actual values (the actual value profile) can then be compared with the desired values and, in the event of a deviation within the measuring interval, it is possible to conclude that an undesired leakage has occurred.

The gas volume flow can, for example via a

Measuring interval measured and a setpoint curve (setpoint profile) are detected. For example, the gas flow rate may decrease over time as the gas pressure through the orifices of the nozzle bodies also decreases. In particular, if the gas overpressure is provided via a pressurized gas container, the change in the gas volume flow or the gas pressure may result. By measuring the nominal profile

Within a measuring interval, whereby the measuring interval should be selected as long as possible, the

Measurement accuracy can be increased and thus a leak is detected safer. According to an advantageous embodiment, it is proposed that the gas pressure is generated by means of a compressed gas container and / or a pump and / or a pressure generating device of the rail vehicle. It is also possible for the gas pressure to be generated by a pressure generating device, eg a compressor, which is self-sufficient by the rail vehicle. The printed product device can also serve as the sole pressure source without pressure accumulator.

When using a gas cylinder, it is

For example, at the beginning of a test it may be filled with a defined volume at a defined pressure. Subsequently, the compressed gas container can be connected via a valve with the piping system and that in the compressed gas container gas can be in the

Flow piping system. The change in the gas pressure or the gas volume flow over time can be measured and compared with desired values (nominal profiles).

When using a pump, it is possible, for example, that it is first connected to the compressed gas container. It is also possible that the pump is connected directly to the piping system. In this case, the pump would keep the pressure constant and the gas flow rate could be measured. The measured value can be compared with a desired value and if the measured gas volume flow exceeds the nominal gas volume flow, it can be concluded that there is a leakage. Rail vehicles usually have their own

Pressure generation directions, for example, to operate the brakes or clutches. These

Pressure generating devices can be used to fill the compressed gas containers for test purposes, so that no further means for filling the gas cylinder is necessary.

According to an advantageous embodiment is

proposed that nozzle bodies connected to the pipeline system are closed in such a fluid-tight manner by means of caps and / or rupture disks that in the case of

Under normal conditions, substantially no gas escaping from the nozzle or that in the case of a negative pressure under normal conditions substantially no gas through the

Nozzle enters the piping system. The gas pressure that can be applied to the piping system for testing purposes may be selected to be less than the bursting pressure of the bursting disks. In this case, the bursting discs do not burst and the pressure within the

Piping system should remain constant. A

Pressure change can be detected and possibly evaluated as an indication of a leak. Are the

Nozzle body completely closed by the rupture discs or caps, in the test case, the gas flow rate is zero or close to zero, since no, or only little gas from the

Nozzle bodies should leak. However, if the volume flow is greater than a certain limit, it can be concluded that there is a leak. The caps can, for example

Teflon caps that have a sufficient seal of the

Ensure nozzle body against the piping system. - -

It is also proposed that nozzle bodies connected to the piping system are closed by a check valve in such a way that in the case of a negative pressure in the

Piping system essentially no gas through the

Nozzle body enters the piping system, however, in the case of a fluid pressure in the piping system fluid exits through the nozzle body from the piping system. The check valve may be designed to close at a negative pressure in the piping system. Then, a gas from the environment may enter the piping system through the valve. Thus, a leakage test can be performed.

In case of fire, on the other hand, extinguishing fluid, e.g. Water, put into the pipeline with pressure. This pressurized fluid causes the check valve to open causing the fluid to exit through the nozzle orifices.

A check valve can between main and

Division line as well as immediately before or arranged as part of a nozzle head.

In order to prevent condensate or dirt from forming within the piping system, it is necessary

proposed that the gas with which the overpressure is generated, is substantially free of impurities. The gas with which the overpressure is generated can

be dry, oil-free and / or free of dirt particles.

Otherwise, there is a risk that the dirt particles or oil is in the nozzle body and in the case of fire, the nozzle body are added. Also valves must be free from

Dirt particles, as they must be opened safely in case of fire. If the gas is not dry, so in the - -

Piping system introduced by the tests on leaks air moisture, which is reflected on the pipes and possibly leads to rust or encrustations. This must also be prevented.

It is also proposed that for test purposes test guest is used, which is olfactorily detectable. This can be either a gas with a natural odor or even a gas which is mixed with odors. Then a leakage detection can also be additionally detected by "sniffing".

Another object is a leak testing system according to claim 10.

The piping system advantageously has two ports that can be used separately. A first connection is connected to a fluid supply device, via which the extinguishing fluid can be brought into the pipeline. A second connection, separate therefrom, is intended, for example, for pressure generating means with which the gas pressure is brought into the pipeline system for test purposes.

Subsequently, the object is based on a

Embodiment showing drawing explained in more detail. In the drawing show:

Fig. 1 shows schematically a piping system with a

connected extinguishing fluid supply and pressure generating means;

2 shows a nozzle body with a rupture disk; - -

Fig. 3 shows a sequence of a method according to a

advantageous embodiment. Fig. 1 shows a piping system 2 with a thereto

connected extinguishing fluid supply 4 and

Pressure generating means 6.

The piping system 2 is formed of a main pipe 2a and region pipes 2b connected thereto. The

Main line 2a is connected to the area lines 2b via

Section valves 8a, 8b connected. The

Pressure generating means 6 have a

Pressure generator 6a and a pressure tank 6b. The pressure generating device 6a may be, for example, a pump. Also, it is possible that the

Pressure generator 6a a connection with

Pressure generating means of the rail vehicle and thus has the high-pressure pump of the rail vehicle, which is needed for example for the hydraulic system uses. The

Pressure generating means 6 are connected via a valve 10 and a port 12 to the main line 2a of the piping system 2. The main line 2a is further connected to the extinguishing fluid supply 4, which is connected via a valve 14 to a high-pressure cylinder 16. In case of fire will not with one

shown fire detector detects a fire and transmits an activation signal to the valve 14. The valve 14 opens and the extinguishing fluid stored in the extinguishing fluid supply 4 is driven by means of high pressure from the high-pressure cylinder 16 from the container 4 into the pipe 2a. At the same time, one of the area valves 8a, b is opened and the extinguishing fluid can escape through the extinguishing nozzles 22 connected to the area lines 2b and thus fight the fire.

For a safe fire fighting, however, it is necessary that no leaks occur in the pipeline 2, in particular in the main line 2a and the area line 2b. For this purpose, a test method described below can be used.

Immediately after the installation of the piping system 2, a calibration routine may be performed. Here, a defined pressure on the pressure tank 6b and the valve 10 is first given to the piping system 2. One

Sensor 18 is arranged in the pipeline system 2, which can measure the pressure in the pipeline system 2 and / or the volume flow in the pipeline system 2. One after the other, the area valves 8a, b are completely closed or opened and in each case the pressure or the volume flow in the

Pipe system 2 by means of the sensor 18 measured.

By way of example, the measurement of the pressure in the pipeline system 2 with closed range valves 8 will be described. First, the pressure tank 6b is filled with gas at a defined pressure via the pressure generating means 6a. Subsequently, the connection between pressure generating device 6a and pressure tank 6b is closed and via a control computer 20, the valve 10 is opened. At the same time the

Control computer 20, the area valves 8 closed. Of the

Gas pressure in the pressure tank 6b is distributed to the main line 2a. By means of the sensor 18, the gas pressure in the Main line 2a measured. It is possible to measure a pressure profile over a period of time. In a completely dense system, the pressure remains constant. For tolerated leaks, the pressure gradually decreases, the

Pressure decrease, however, is low.

The pressure profile is stored as desired gas pressure in the control computer 20. Subsequently, the valve 10 is closed via the control computer 20 and the piping system 2 and the

Main line 2a vented, so that there is a normal pressure in the main line 2a. Subsequently, for example, the area control valve 8a can be opened via the control computer 20 and at the same time the pressure tank 6b can be filled again via the pressure generating device 6a. Subsequently, the connection between the pressure generating device 6a and the pressure tank 6b is closed and the control computer opens the valve 10. The gas pressure from the pressure tank 6b then escapes into the main line 2a and via the area valve 8a in the

Area management 2b. The gas escapes via the nozzles 22.

By means of the sensor 18, a volume flow in the

Pipeline 2a are measured. This volume flow results from the gas escaping from the nozzles 22.

In addition, a pressure profile, which plots the pressure over time, detected and in the control computer 20

get saved. Both the pressure profile and the

Volume flow can be used as a target value in the control computer

get saved. After the system has been calibrated immediately after assembly, the control computer 20 may periodically,

For example, once a day, once a week, once a month, once a year, the procedure just described be performed again. The pressure and volume flow values (actual values) measured via the sensor 18 are compared with the desired values stored in the control computer 20. If the actual values deviate from the desired values, it can be concluded that there is a leakage in the respective pipe region.

The nozzles 22 are shown by way of example in FIG. 2. On the one hand it is possible that the nozzles are completely open, allowing gas from the pipeline directly through the

Nozzle openings 22a can escape. However, it is also possible that the nozzles are connected to the pipe via a rupture disk 22b, wherein the rupture disk 22b seals the nozzles 22a with respect to the pipe. In this case, the nozzle 22 in the test case also no gas

leak, so that the pressure should remain substantially constant. In this case, it would be possible to capture the pressure profile during calibration and to compare it with pressure profiles from the test routines. Flow rates should not normally occur because the piping over the

Rupture discs 22 is sealed.

Instead of or in addition to the area valves 8 or the Bestscheiben 22 b, it is possible to use non-illustrated check valves. These seal the pipeline from the environment at a negative pressure in the

Pipeline off. When fluid is under pressure from the pipeline should exit, the check valves open automatically by the fluid pressure.

3 shows by way of example a method as already described above. In a first step 30, the

Pressure tank 6b filled via the pressure generator 6a with gas at a certain pressure. Subsequently, the control computer 20 controls the valves 8 a, 8 b in such a way that they close and the valve 10 is opened by the control computer 20.

Then it can be decided whether a volumetric flow measurement or a pressure measurement should take place in the sensor 18 (34). First, the measurement of the pressure will be described. The sensor 18 measures (36) the pressure in the pipe 2a

closed valves 8a, 8b. Here, a pressure profile is recorded over time. Subsequently, the detected pressure profile in the

Control computer 20 compared with a desired profile (38). If the measured actual profile differs from the nominal profile, a

Warning message 40 issued. If the actual profile lies within a tolerance range in the nominal profile, the control computer 20 is activated

Bleed signal output and the pipe 2a is vented (42).

Subsequently, the not shown vent opening is closed again and, for example, a range valve 8a opened (44). Subsequently, the pressure tank is refilled in steps 30 and 32 and the valve 10 is opened. In step 34, it is decided to perform a volumetric flow measurement.

In the volume flow measurement is via the sensor 18 of the

Volume flow within the pipe 2a measured (46). Since the nozzles 22 are open and the area valve 8 has been opened, gas escapes via the pressure tank 6b and the

Main line 2a and the area line 2b from the nozzle 22. The thus escaping gas represents a desired opening and causes a volume flow in the pipe 2a, which is allowed. Only in the event of leakage either in the main line 2a or the area line 2b would more gas escape than would be the case via the nozzles 22. This led to an increased volume flow, which would be detected in a subsequent comparison (48) with a nominal volume flow. If the measured volume flow deviates from the setpoint volume flow, a warning signal is output again (40), otherwise the lines 2a, 2b are again emptied (42).

The described steps can be done individually for each area individually as well as for the main line 2a alone

be performed. Leaks either in the main line 2a or in the area line 2b lead to changed

Volume flows or to changed pressure profiles over time, so that they can be reliably detected.

With the aid of the method and the system shown, it is possible to dry on itself piping systems

Check leakages without having to fill the pipeline with extinguishing fluid. The method described can be with High pressure and run with low pressure, with a

High pressure, for example, over 5 bar, more preferably above 10 bar, in particular more than 60 bar and a low pressure is below the above ranges. The nozzles 22 may be closed with rupture disks 22b as well as Teflon caps (not shown). In these cases, primarily pressure profiles are recorded and no volume flows, since these are likely to occur only in the event of a leak. The system described can be used particularly advantageously in rail vehicles, as they regularly with

dry piping systems are equipped. In addition, in rail vehicles, the risk of leakage is very large, since the pipes installed there are constantly exposed to dynamic loads.

Claims

Patient requests

Method for leak testing of dry

Piping systems in firefighting systems,

especially in rail vehicles, with

Generating a gas pressure in the piping system, detecting an actual gas pressure and / or an actual gas volume flow in the piping system,

Comparing the detected actual gas pressure with a desired gas pressure and / or comparing the detected actual gas volume flow with a desired gas volume flow,

Issuing a warning signal upon detection of a deviation of the actual gas pressure from the desired gas pressure and / or the actual gas volume flow from the desired gas volume flow.

A method according to claim 1, characterized in that connected to the pipe system nozzle body are open so that in the event of overpressure gas exiting the nozzle or in the case of a negative pressure gas enters through the nozzle, wherein the target gas pressure and / or the target Gas volume flow, the gas thus exiting has been taken into account.

A method according to claim 1, characterized in that the target gas pressure and / or the desired gas volume flow with

A) open area valves and / or

B) is measured at least partially closed range valves, wherein the range valves a connect connected nozzle bodies fluid-tight sealable.

A method according to claim 3, characterized in that the actual gas pressure and / or the actual gas volume flow, each with an open range valve and / or with fully closed range valves is measured.

A method according to claim 1, characterized in that a temporal change of the actual gas pressure and / or the actual gas volume flow is measured within a measuring interval.

A method according to claim 1, characterized in that the gas overpressure by means of a

A) Gas cylinder, and / or

B) a pump, and / or

C) a pressure generating device

of the rail vehicle or a self-sufficient of the rail vehicle pressure generating device is generated.

A method according to claim 1, characterized in that connected to the piping nozzle bodies are closed in such a fluid-tight manner by means of caps and / or rupture discs that in case of overpressure under normal conditions substantially no gas exiting the nozzle or that in the case of a negative pressure under normal conditions essentially no gas enters the piping system through the nozzles.

A method according to claim 1, characterized in that connected to the piping system nozzle body via a check valve are sealed so that in the case of a negative pressure in the piping system in

Essentially no gas through the nozzle body in the

However, in the case of a fluid pressure in the piping system fluid exits through the nozzle body from the piping system.

A method according to claim 1, characterized in that the gas with which an overpressure is generated in the

Is substantially free of impurities or that the gas with which the pressure is generated is an olfactorily detectable gas.

0. leak testing system in firefighting systems,

especially in rail vehicles, with

a dry piping system and it

connected, preferably open nozzle bodies, a fluid supply device for pressurizing the pipeline system with fluid in case of fire,

Pressure generating means for generating a gas pressure in the piping system,

Detecting means for detecting an actual gas pressure and / or an actual gas volume flow in the

Piping system

Comparative means for comparing the detected actual gas pressure with a desired gas pressure and / or comparing the detected actual gas volume flow with a desired gas volume flow,

Evaluation means for outputting a warning signal upon detection of a deviation of the actual gas pressure from the desired gas pressure and / of the actual gas volume flow from the desired gas volume flow. Leakage inspection system according to claim 10, characterized in that the piping system has a first connection for the fluid supply device and a second connection for the pressure generating means, which is separate from the first connection.