Fire fighting
Fighting fire is called the extinguishing of damaging fire .
Extinguishing procedure and extinguishing effects
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Deletion process
In order for a fire to burn, three factors, fuel , oxidizer (mostly oxygen ) and heat (ignition temperature ), shown in the combustion triangle , must be present in the correct mixing ratio. A catalytic converter can promote combustion, while an inhibitor can inhibit a fire. All fire-fighting methods are based on removing one or more of its basic requirements from combustion .
Remove the combustible material
The combustible material cannot normally be easily removed from a fire, but the fuel supply can sometimes be cut off. This can be the closing of a gas or oil line, for example. This method is also often used in forest fires by creating wide trenches and aisles.
Cooling
A fire goes out when the burning material is cooled below its ignition temperature . By far the best cooling effect for fire fighting is achieved through the use of extinguishing water or mains water . It is not just a matter of indirectly heating up the water (and cooling the burning substance), but of dissipating heat in the form of heat of vaporization .
Suffocation and repression
Suffocation occurs through the deprivation of oxygen by keeping the oxygen away from the combustible material or by displacing it. This can be done by simply covering it with a blanket or covering it with an air-impermeable layer ( e.g. extinguishing foam ).
Melting extinguishing powder creates a suffocating sintered layer on the hot material in the event of a fire. At higher temperatures, the decomposition of the powder forms small amounts of ammonia , which also has a suffocating effect on the fire. Gases such as argon , nitrogen or carbon dioxide as well as gas mixtures such as inergen or argonite displace the oxygen. With active fire prevention , the area to be protected is preventively deprived of the oxygen required for combustion by supplying nitrogen - a fire can no longer occur.
In the event of fires in electrical systems or materials that can be damaged by water, sprinklers or mobile extinguishers also use carbon dioxide or liquid nitrogen, whose effect is based on displacing the oxygen and cooling the fire.
Anti-catalytic effect
The anti-catalytic effect, also called inhibition , is based u. a. ensure that the radicals necessary for flame combustion are rendered ineffective through recombination .
Saponification in case of a fat fire
In the case of a fat fire , the burning liquid is extinguished by saponification in that the extinguishing agent forms a barrier layer over the oil or fat, thereby preventing the absorption of oxygen, at the same time the extinguishing agent cools the burning liquid below the auto-ignition temperature and thus prevents the fire from flaring up again.
Counterfire
In the case of a counterfire, a fire is set in such a way that it removes the fuel from the fire to be extinguished.
Main extinguishing effect and secondary extinguishing effects
The different extinguishing agents usually have not only one, but also several effects when extinguishing. The main extinguishing effect is that which has the greatest influence on the combustion. With water it is the cooling effect, with extinguishing foam it is suffocating.
In addition, secondary extinguishing effects come into play. Extinguishing water covers the flammable substance with a thin film, so it has a slightly suffocating effect. In addition, a strong jet of water breaks up the flammable material and thus increases the area of attack. The extinguishing foam contains water, which also has a cooling effect.
Procedure of the fire brigade
Fighting fires is the oldest and best-known task of the fire brigade . The most frequently used extinguishing agent is water , which used to be carried in buckets and later pumped with fire engines . Nowadays, motor-driven fire pumps are used.
In order to achieve quick and reliable success in extinguishing , the fire fighting should be as strong and simultaneous as possible. When using fire extinguishers , they should therefore be used simultaneously and not one after the other. The responsible fire brigade chief of operations makes the decision as to whether an internal or external attack is to be carried out.
Example: A straw warehouse burns to the full. No people are missing. There is therefore no need to carry out a human rescue in combination with an internal attack. The fire is fought by an outside attack. The primary aim must be to limit the fire to the warehouse and to prevent it from spreading to neighboring buildings. An internal attack could not limit the damage to the already destroyed warehouse and would be an unnecessary risk for the emergency services.
See also: The group in action
In order to give the unit leaders time to explore (access, spread of the fire, etc.), there is a deployment with provision . Only the water extraction point and the location of the distributor are known here. Once the situation has been explored, an external attack or an internal attack occurs.
External attack
In the event of an external attack, the fire is fought from outside through building openings such as windows, doors, skylights or parts of the building that have already burnt through. This is the safer method for firefighters if, for example, the stability of the building is a major threat to the emergency services. The risk of water damage is greater because when there is a lot of smoke it is often impossible to tell whether the water jet is actually hitting the fire area from the outside.
The external attack should remain the exception if possible. But especially smaller fire brigades with few personnel or equipment cannot carry out a personnel- and equipment-intensive internal attack. The reason for this lies, for example, in the requirement that a rescue team must be available for each attack team, provided that no human rescue measures are carried out.
Internal attack
In the case of an internal attack, also known as a regular attack, fire brigade members go into the building with breathing apparatus in order to find the source of the fire and extinguish it. The risk is greater here, but the extinguishing agent can be used much more efficiently. The use of pressure ventilators for tactical ventilation has proven its worth in internal attacks , which when used correctly generate a slight overpressure in the building. The smoke together with the unburned gases is removed from the interior, which minimizes the risk of a sudden flue gas ignition or a flue gas explosion and gives the attacking force a clear view. The assumption that the fire would spread faster through the addition of oxygen in the ambient air supplied has not proven correct in practice. The advantages of quick fire fighting and a clear view outweigh the above. The use of the pressure ventilator not only reduces the risk for the fire fighters, but also the risk of excessive water damage, as the source of the fire can be localized more quickly and fought more precisely.
For the safety of the firefighters, it is now recommended to carry additional equipment (e.g. lighting, rescue slings , dead man's alarm and rescue knife ) in addition to the prescribed personal protective equipment .
Thermal imaging cameras are also increasingly being used, with which sources of fire or people can be detected even in thick smoke. Here the cube view is used.
Special forms
In the case of inaccessible forest and bush fires , fire-fighting planes or helicopters (see Bambi Bucket ) are increasingly used to extinguish and transport water.
In and of itself, the extinguishing of burning oil wells - such as after the Second Gulf War - or oil production platforms at sea actually falls within the responsibility of the fire brigade, but this task is taken over by specialized companies (see Paul Neal Adair ).
Another fire brigade tactic is the bolt position , in which the prevention of reaching over to neighboring areas is in the foreground. If necessary, this is also used in combination with the tactic of giving up , in which the already completely lost object is left to the fire and the efforts are devoted to other tasks such as B. concentrate the locking just described.
Special features of fire fighting at sea are explained under Maritime fire fighting .
The pulse extinguishing process describes a type of fire fighting.
High-rise alarm
Another category of use is in high-rise buildings or skyscrapers . The superiors including the mobile command center must be alerted accordingly . The largest known incident of this kind was the 2001 fire and collapse of the WTC near the New York Fire Department ( professional fire department in New York City).
history
19th century
At the beginning of the 19th century, when a fire broke out, certain residents had to fetch the fire engine immediately . Not every village had one. A fire walker had to request another fire pump if necessary. In many localities of the Duchy of Nassau , when a fire was detected, the teachers of the village had to ring the bell and sound the alarm for the committee drum. The committee ensign had to have the committee (a slightly military-trained guard) manned all exits of the place so as not to let anyone out during the fire except fire walkers and those who were assigned to fetch the syringe. All residents able to work had to rush to the scene of the fire with a filled bucket and stand in double rows after the nearest water (e.g. stream, fire pond). “The bucket flew through the long chain of hands.” Following the express orders of the authorities, care had to be taken “that the women who were only confused by their lamentation were brought into the ranks”. Refusal to obey the commando, unauthorized removal from the scene of the fire or deliberate damage to the extinguishing equipment was punishable by severe physical punishment. The items rescued from the scene of the fire were closely guarded in a fire-proof location by the committee's teams. Anyone who tried to steal in the confusion was bound by the guard in the event of trespassing, put down by the things in order to receive punishment immediately after the fire was extinguished. But for those who distinguished themselves in the rescue work through zeal, courage and fearlessness, a reward of up to four talers was offered.
Changes in the deletion tactics
An old prejudice is: what the fire does not destroy, the extinguishing water does . In the meantime, the fire brigades have consistently professionalized their working methods. For every type of operation, care must be taken to ensure that not only the immediate danger is averted, but also that the consequential damage (e.g. caused by smoke and extinguishing water ), which often significantly exceeds the primary damage , is as low as possible. As a result, an operation often seems much less spectacular than before, because it is no longer just speed that counts, but also considered, sometimes seeming slower action. At that time, it was important to put out the fire as quickly as possible during fire operations. The amount of extinguishing water was insignificant ("oceanic extinguishing effect"). Today, an external attack (non-targeted spraying, so-called “facade washing”, “gable splash”) is avoided as far as possible in order to avoid water damage. With new and improved techniques, e.g. B. in the field of respiratory protection and jet pipe technology , the fire brigade has resources for more efficient fire fighting.
Since the extinguishing water is contaminated by fire smoke and other toxic combustion residues , it must be used as sparingly as possible with regard to the disposal of the extinguishing water that may be necessary.
See also
literature
- Roy Bergdoll, Sebastian Breitenbach: Die Roten Hefte, Issue 1 - Burning and Extinguishing . 18th edition. Kohlhammer, Stuttgart 2019, ISBN 978-3-17-026968-2 .
- Lothar Schott, Manfred Ritter: Fire Brigade Basic Course FwDV 2 . 20th edition. Wenzel-Verlag, Marburg 2018, ISBN 978-3-88293-220-1 .
- Diverse: Hamilton - Handbook for the fire brigade . Boorberg Verlag, 21st edition 2012. ISBN 978-3-415-04560-6
- Diverse: Andreas Pfeiffer - extinguishing agents in fire fighting . Springer Verlag, 1st edition 2016. ISBN 978-3-658-12971-2
Web links
- Photo galleries of fire fighting with helicopters from the air
- US equipment for high-rise operations (English with illustration; 40 to 50 kg)
- Water atomization in the jet pipe (Krüger, A., Radusch, R., Research Center for Fire Extinguishing Technology (Research Center for Fire Protection Technology, University of Karlsruhe), Westdeutscher Verlag, Cologne and Opladen 1956)
Individual evidence
- ↑ Drägerwerk AG & Co. KGaA: Dräger issue June 2010 - Fire against Fire , accessed on February 18, 2020 (pdf)
- ^ Franz-Josef Sehr : The fire extinguishing system in Obertiefenbach from earlier times . In: Yearbook for the Limburg-Weilburg district 1994 . The district committee of the Limburg-Weilburg district, Limburg-Weilburg 1993, p. 151-153 .