Basements are considered one of the most vulnerable places in the field of fire safety. That is why fire protection and fire extinguishing rules in these areas are given so much attention.
Fire protection for basements
In modern buildings, all structural elements of basements are either made of or treated with fire-resistant materials. For this, it is used in the form of slabs, as well as high-temperature paints, etc.
According to the rules, large and complex basements must be divided into sections by fire-resistant partitions. Since these rooms can communicate with residential floors and even the attic via elevator shafts and communication channels, all these passages are also necessarily treated with fire-resistant compounds.
Features of fires in basements
Since basements usually have no windows and few doors, fires in them have certain characteristics. At first, the fire spreads very quickly, but then due to the minimal air flow, the speed decreases. But the amount of combustion products increases, the smoke there is thicker and heavier.
The main danger is that smoke and combustion products can penetrate through the ceilings into residential floors, cutting off the possibility of evacuation for people.
Fire service actions
When called, fire services must:
- Act in two directions at once - in basements and on the first and higher floors.
- A fire reconnaissance is carried out, during which the degree of smoke and the possibility of removing smoke, the danger to people and their evacuation routes, the likelihood of the fire spreading to other rooms, the presence of ventilation, and the points of entry of fire extinguishing agents into the basement are assessed.
- Take measures to prevent panic and organize rescue operations. If at the time of arrival the smoke has already spread beyond the basement, it is necessary to begin evacuating people immediately.
- Smoke control measures are in place.
- If the fire has not spread beyond the basement, measures must be taken to protect the first floor.
- To extinguish, use jets of water or air-mechanical foam (in case of heavy smoke).
It is also very important to turn off the electricity and gas supply; for this, the relevant services will go to the site.
Example. Determine the required amount of forces and means to extinguish a fire in the basement of a five-story residential building of fire resistance class II.
Fire situation. In a section of the basement measuring 5.4 x 11.8 x 2.4 m, utility sheds are burning, the temperature in the burning section is high, in two apartments on the first floor above the fire site the floor is heated, the basement and the stairwell of the second entrance are filled with smoke.
Month - November, time -17.00. The first to arrive at the fire was the SVPCH-5 guard, consisting of two squads at AC-30 (130) 63A and AN-30 (130) 64A. On call No. 2, four additional departments at the AC and AN arrive at the scene of the fire. For fire extinguishing, the nearest fire hydrants are used, located 60 and 140 m away on a water supply network with a diameter of 150 mm and a constant pressure of 30 m.
1. Based on the situation, to extinguish the fire we will use volumetric extinguishing with medium expansion foam using GPS-600 generators. To protect the premises in the adjacent sections of the basement and on the first floor, water trunks B should be supplied.
2. Determine the required number of generators for volumetric fire extinguishing [see. formula (3.20) and table. 3.32]:
N GPS - 600 =V p / V t GPS =5.4 ´11.8´2.4 / 120 = 2 GPS-600 generators.
3. Determine the required amount of foaming agent for extinguishing aie fire using formula (2.18) and table. 3.30:
N by = N GPS-600 Q by GPS 60t р =5.4 ´11.8´2.4 / 120= 432 l
In fact, the guard truck pump contains 500 liters of foam concentrate, and the tank truck contains 150 liters. Therefore, for volumetric fire extinguishing, a foam concentrate is sufficient and a fire truck pump must be used to supply foam.
4. Determine the required number of barrels B for protection. Taking into account the characteristics of the building, the situation during the fire and the requirements of the Battle Regulations for protection, it is necessary to supply two V. barrels to the first floor apartments above the burning site and one barrel each to adjacent sections of the basement (see Fig. 6.2) - a total of 4 B. barrels.
5. Determine the actual water consumption for fire extinguishing and for protection (see formulas (2.14)-(2.16), tables 3.25 and 3.30:
Q f =N GPS-600 Q in GPS + N w st.B Q st.B =2´5.64+4´3.2"24.2 l/s
where Q st.B is the water flow from trunk B at a pressure of 30 m.
6. We check the facility’s supply of water for fire extinguishing purposes.
According to the table 4.1 we find that the water yield of a ring water supply network (Q water) with a diameter of 150 mm at a pressure in the network of 30 m is 80 l/s. Consequently, the object is provided with water, since
Q water = 80 l/s > Q f = 24.2 l/s and N pg = N m
7. We determine the required number of fire engines, taking into account the use of pumps at full tactical capability
N m = N GPS-600 /2+ N st.B /4 = 2/2 +4/4=2 machines (one for supplying foam, the second for supplying water barrels).
8. Determine the maximum distances for supplying water and foam At provided that the combat crews have fire hoses with a diameter of 51 and 77 mm:
a) when supplying foam from a car pump
l pr = 20/(SQ 2) = =20/(0.015´6 2) = 740 m;
b) when supplying water from a tanker truck, taking into account the maximum possible introduction of trunks B
l pr = 20/(SQ 2)=23/(0.015´9.6 2) = 540 m.
Rice. 6.2. Scheme of extinguishing a fire in the basement of a residential building
for supplying water and foam, since the maximum distances significantly exceed the distances from hydrants.
9. Determine the required number of personnel using formula (5.12)
N personal comp = N GPS-600 ´2 + N fl st.B ´Z +N p st.B ´3 +N m ´1 +N pB ´1 +N st = =2´2 +2´3 +2´3 +2´1+1+1= 20 people.
10. Determine the required number of main fire departments [see. formula (5.14)]
N department = N personal status /5 = 20/5 = 4 departments.
Thus, in order to ensure combat operations in full and taking into account the necessary reserve of foam concentrate, additionally call two operational departments (guard), units for ASO and AT, a police detachment, a gas emergency service and the city energy service to the fire.
Combat operations to extinguish fires in an unbreathable environment are carried out by departments and units of the gas and smoke protection service (GDZS). Each gas and smoke protection worker must be able to calculate the duration of work in an oxygen-insulating gas mask (OCG). He must clearly know that in order to return from the place of hostilities to clean air, it is necessary to leave in the gas mask cylinder as much oxygen as was consumed when moving to the place of work (according to the pressure gauge), plus half of this amount for unforeseen accidents, summing this with amount of oxygen, which corresponds to the residual pressure in the cylinder equal to 0.2-0.3 MPa for normal operation of the reducer. The fire extinguishing diagram is shown in Fig. 6.2. In a combat situation, the duration of work in oxygen-insulating gas masks is determined according to table. 6.1.
TABLE 6.1. DURATION OF OPERATION IN OXYGEN-OIL GAS MASKS (KIPs) DEPENDING ON THE CAPACITY OF THE CYLINDER AND THE PRESSURE IN IT
| Cylinder pressure | Cylinder capacity, l | ||||||
| 0.7 | 1.0 | 2.0 | |||||
| MPa | at | VO 2, l | t "slave, min | VO 2, l | t "slave, min | VO 2, l | t "slave, min |
| - | - | ||||||
| - | - | ||||||
| - | - | ||||||
| - | - | ||||||
| - | - | ||||||
| I | |||||||
| 21. | |||||||
Note. The table was compiled with an average oxygen consumption of the gas and smoke protector of 2 l/min.
Description of the presentation by individual slides:
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Extinguishing a fire in the basement The basements of buildings and structures have different purposes. As a rule, heating and other pipelines, boiler rooms, boiler rooms, and storage rooms are located in basements. In industrial buildings - communications related to ensuring the technological process. When a fire occurs in the basement, high temperatures and dense smoke are created, the smoke spreads to the rooms above, posing a threat to people's lives. Fire may spread through ventilation ducts, hatches, shafts, installation and other openings. Conducting combat operations is hampered by a complex layout, lack of a sufficient number of openings and entrances, and in unlit and smoke-filled basements.
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When extinguishing a fire in the basement, it is necessary to organize reconnaissance of the basement and the premises above, during which it is necessary to establish the presence of a threat to people’s lives and immediately organize work to rescue them, as well as identify the possibility of fire spreading horizontally and vertically, take measures to reduce smoke in the premises by closing or opening door and window openings, smoke hatches, installing lintels. The commander of a fire department must constantly remember about the possible collapse of building structures and the need to ensure safe working conditions for personnel, therefore, simultaneously with actions to stop the fire, it is necessary to carry out intensive cooling of structures, turn off the power supply, and organize the smooth operation of a security post or checkpoint of the fire control station.
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There are different methods for extinguishing fires in basements. This includes extinguishing using water, foam and powder guns with their direct introduction into the fire, filling the basement with foam, carbon dioxide and other inert gas, and in some cases, filling the basement with water. If it is impossible to penetrate through the existing openings to the source of combustion, fire extinguishing agents are introduced through specially made openings in the ceiling. A fire quickly develops along combustible structures of corridors and galleries, especially if combustible materials, synthetic pile coverings, and films were used for finishing interior spaces and interiors. The speed of fire spread in such rooms towards open openings can reach 7-8 m/min.
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Extinguishing fires on floors When extinguishing a fire on floors, especially in rooms with one exit, including in apartments of residential buildings, there is often a need to rescue people. On the second and third floors, along with the use of internal staircases, in some cases manual fire escapes are used to lift firefighters, fire-fighting equipment, extinguishing equipment and evacuate people. Starting from the fourth floor, the actions of firefighters to extinguish fires become significantly more difficult. Often, during fires in buildings where there are no smoke-free main escape routes, the stairwells become filled with smoke, and people on the third and higher floors cannot leave the danger zone on their own. To carry out rescue operations on the fourth and higher floors, aerial ladders are used. However, due to the limited extension length, ladder trucks cannot fully satisfy the needs of the fire department when extinguishing fires in buildings above 15 floors. Articulated car lifts, which can raise the working platform to the level of the fire floor, have proven themselves well when extinguishing fires on the floors of buildings. Sometimes the use of aerial ladders and articulated lifts is also limited due to the lack of platforms and entrances, uneven terrain and a number of other reasons. Upon arrival at the scene of the fire, the fire extinguishing director must conduct reconnaissance on the burning floor, on the floors above and below, and in the attic. Find out the presence of people who are in danger, determine the ways and means of rescuing them. Fire reconnaissance is carried out wearing respiratory and eye protection. Groups of firefighters assigned to conduct reconnaissance are provided with a hose line with a barrel. During reconnaissance, the power and lighting networks are turned off.
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The greatest danger when extinguishing a fire on floors is the spread of fire in the vertical direction: through ventilation ducts or hollow partitions, therefore the fire extinguishing manager, having identified by reconnaissance the presence of a ventilation unit and hollow partitions, must take measures to quickly dismantle the ventilation ducts or partitions in the necessary places in order to to create a gap and prevent the fire from spreading to the upper floors. A guide to hidden fires in ceilings, partition walls and ventilation ducts can be the release of heated dense smoke from under baseboards and various openings in structures. To find open sources of combustion, feel the floor in places where combustion is most likely. Combustion areas located under a layer of plaster are detected by yellowing or collapse of the plaster. If hidden combustion is detected in the hollow structures of partitions and ventilation ducts, reconnaissance is carried out on all upper floors and the attic. In modern residential buildings with a sectional layout, the development of a fire usually ends in one apartment and less often in a section. But there are known cases of fire spreading to adjacent sections and to higher floors, even with fireproof intersection walls and interfloor ceilings, through openings in central heating pipes, as well as water supply and sewer pipes, elevator shafts into the outer fence.
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Fighting Fires in Attics The attic space is the part of the space between the roof and the attic floor. The roof and attic floor are the main enclosing structures of attic spaces. The supporting structures of the roof can be made of wood, reinforced concrete or metal, and sheet steel, tiles, roofing felt, roofing felt, etc. are used as roofing materials. Ventilation ducts and chambers, heating networks and other engineering equipment are usually placed in the attic. The use of combustible insulation, as well as the storage of various property, increases the fire load of attics and creates favorable conditions for the rapid development of a fire. In addition, the development of fires in attics is facilitated by the constant movement of air through the windows. Exits to the attic are eliminated from public staircases, as well as from fire escapes. A fire in the attic can become large even before the arrival of fire departments due to late detection and the high speed of fire spread through combustible structures. A fire in the attic floor is usually accompanied by dense smoke not only in the attic, but also in the stairwells. At the same time, there is a threat of fire spreading to the floors below.
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Attic spaces are a hard-to-reach part of the building, so when conducting reconnaissance, special attention is paid to the study of staircases with access to the attic and external fire escapes. The place of the most intense burning is determined by external signs: escaping flames, intense smoke escaping from under the eaves and dormer windows. During the reconnaissance, the design features of the attic and the location of the ventilation chambers, as well as the possibility of fire spreading through them, are clarified. For reconnaissance, marching and stationary fire escapes are used. When a fire develops with simultaneous burning of the attic floor and roof structures, the combat actions of firefighters are aimed at protecting the floors. To do this, the roof is opened closer to the eaves on the windward side, not far from the burning site. The attic floor is usually opened from below, from the upper floor. The first barrels for extinguishing fires in attics are supplied, as a rule, along internal stairs. To extinguish the fire, water jets from the overlapping trunks and medium expansion foam are used. The subsequent supply of trunks to the fire is carried out through attic windows and holes prepared at the eaves, along automobile, external, retractable stairs and articulated lifts.
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To protect the upper floors, provision is made for supplying overlapping shafts to them. The roof is also opened to release smoke, reduce the temperature, and allow the roofers to enter the attic. Fires are extinguished at heights and on steep roof slopes, which requires special precautions and compliance with occupational health and safety regulations. High temperatures and dense smoke complicate the working conditions for extinguishing fires in attics. The accumulation of workers in the attic and on the roof is unacceptable; opening work is carried out by small groups of two or three people. It is recommended to move along the roof along the ridge. When extinguishing fires in attic spaces, it is not recommended to use an elevator to lift firefighters and equipment to a height, since it may stop at any time due to a power outage in the building.
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Firefighting is not the same everywhere. There are simpler and more complex objects (in terms of the ability to quickly eliminate a fire).
This is due to the geometric parameters of the room, the presence of convenient approaches and many other nuances.
Therefore, there are clear rules for conducting operations to eliminate fires occurring under certain conditions.
The peculiarities of extinguishing fires in the basement are associated with many inconveniences in carrying out such actions.
Effectively extinguishing fires in the basements of shopping malls and residential buildings requires maximum professionalism from fire departments.
The key to success here is strict execution of instructions and well-coordinated team work.
The biggest problem facing liquidators is limited space and visibility. Here you have to work almost by touch.
Features of the basement
The standard basement of a residential multi-storey building or enterprise differs from other premises in that it is replete with a system of branched communications.
Inside there are various life support organs, and power supply lines are connected to them.
The location of basements at the lowest point of buildings also imposes its own difficulties associated with the spread of combustion products over the entire area of the house.
The main conditions and features that liquidators will have to encounter when extinguishing fires in basements:
- Low ceiling height in the room. Basements rarely exceed 2 meters in height, and the level of most of them is usually around 1.5 meters;
- Insufficient lighting level. In basements there are usually a minimum of windows or no windows at all, limited to artificial lighting;
- Poor ventilation. It is known that in the absence of intense air flow and a humid environment, smoke can linger in one place for a long time;
- The passages in the basements are not designed to move a large number of people and equipment, so they are made as narrow as possible.
In most cases, all partitions that divide the basement into rooms are made of durable, non-combustible materials, such as reinforced concrete blocks, with monolithic slabs as ceilings. It is not possible to make auxiliary passages or openings in these structures for the evacuation of people or equipment, or to organize additional access points for fire equipment.
Another undesirable point can be considered a common ventilation system and garbage chute channel with the rest of the multi-story building. Through these ducts, smoke and carbon monoxide freely penetrate into the upper floors, which often requires a full-scale evacuation of residents.
Fires in the basement - distinctive features
As mentioned above, the characteristics of the architectural structure of the premises and the location of the areas play a big role in the specifics of fires, which is very important for subfloor spaces.
The very nature of a fire in the basement of an apartment building has the following features:
- There is a rapid dynamics from the moment of fire to a full-scale disaster, associated with a high concentration of fire and a rapid increase in temperature;
- Combustion is accompanied by the formation of a large concentration of harmful substances, which is due to insufficient ventilation of the basement;
- Smoke can cover both the lower and upper floors, and there is no way to prevent this;
- Since the flames move up electrical and other communications, the fire can quickly spread to other areas of the building;
- A large concentration of high temperatures can lead to the destruction of concrete structures, floor slabs and, as a result, the collapse of the structure;
- A fire may be accompanied by an increased risk of electric shock when electrical equipment burns.
If there is a fire in the basement and the fire is gaining strength, there must be the fastest possible response to such a development of events. Delay may result in the entire building being engulfed in flames in a short period of time.
Almost always, after operations to eliminate basement fires, a total replacement of water, electrical and other communications damaged by fire is required. In some cases, major repairs of load-bearing structures are necessary - the use of construction work.
Features of extinguishing fires in basements of buildings
When a fire occurs in the basement, the fire department follows certain instructions in its actions, including the following:
- Reconnaissance of the situation;
- Choosing tactics for conducting operations;
- Organization of measures to evacuate residents;
- Creating safe working conditions for others;
- Organization of measures to prevent the spread of fire to the upper floors.
Reconnaissance is a primary and very important point in the overall operation to combat a disaster. At this stage, experts determine: the size of the premises, their connection with each other, the layout, the presence and location of passages, the presence of channels for the spread of flame to other objects, the presence of flammable and combustible liquids in the premises, and the electrical situation.
Firefighting tactics directly depend on intelligence. If increased smoke is observed, smoke exhausters are used.
If there is a danger of electric shock, the building is disconnected from the power grid. Depending on the specifics of combustion and flame propagation, the use of certain means is chosen to extinguish fires in the basements of buildings.
If there is a danger of smoke or fire spreading to residential premises, residents are evacuated with the possible creation of first aid stations. At this stage, additional exit routes for people and smoke exhaust channels are organized.
A full-scale fire in the basement requires not only the evacuation of residents, but also the creation of conditions for the safe coexistence of others.
To do this, it is mandatory to cordon off the area in case of collapses, explosions and the danger of fire. In this case, checkpoints may be created.
To prevent the fire from spreading to other floors if such a turn of events is likely, fire brigades are divided into two divisions.
The former are engaged in eliminating the source of the fire, the latter are organizing measures to block the fire bridges.
Conclusion
The most important things to understand in case of fires in the basement are:
- The need for rapid warning of the situation to fire services;
- If events develop actively, quickly evacuate residents from a burning house;
- All possible assistance to firefighters, including information about the internal structure of the basement, the presence of entrances and exits.
A basement fire is a serious disaster and can result in extensive damage, loss of property and injury, so basement fire suppression tactics should be implemented as quickly as possible.
For greater reliability and security, basements should be equipped with fire alarm systems.
This is extremely necessary, since the basement is not a very visited place.
Multi-storey high-rise buildings have long been a characteristic feature of modern and developing cities; this is all caused by the shortage of urban territory for residential development and the cost per square meter of housing. Under administrative buildings and industrial buildings there are garages and multi-level basements, auxiliary equipment, cable and other communications. As a rule, many modern basements are equipped with automatic fire detection and extinguishing systems.
Typical designs of many residential buildings provide for the placement of utility rooms in the basements; currently, such utility rooms can be littered by the residents themselves, forming a large fire load; all this can cause a fire if unauthorized persons handle the fire carelessly. Basements in older residential buildings are not equipped with a fire detection system.
Extinguishing a fire in such zero-level premises is always associated with a number of difficulties. There is always a risk of explosion due to the presence of various kinds of utility and other structures there. Their failure can leave residents without electricity, heat and water for a long time.
The difficulty of extinguishing also lies in the small area of the room and its location. Narrow passages and low ceilings should be taken into account, which can significantly impede passage, and as a result.
The following can complicate extinguishing fires in the basements of buildings:
- poor ventilation,
- insufficient lighting,
- complex layout,
- obstructions on the paths of progress,
- the presence of flammable liquids and gases, as well as gas cylinders.
As a rule, there are practically no windows in basements, and artificial sources provide dim light. Insufficient ventilation contributes to the accumulation of high concentrations of carbon dioxide in the air during a fire, which leads to suffocation.
Another problem in case of fire is fireproof partitions and too low ceilings. Because of them, it is extremely problematic to create additional exits if necessary.
Fires in basements contribute to the rapid development of smoke on the upper floors due to the general ventilation system and the presence of a garbage chute.
Features and tactics
Actions when extinguishing a fire should always be aimed at quickly identifying the source of the fire and eliminating it. It is extremely important here to prevent the formation of thick smoke and monitor the condition of structures, as they may collapse.
The rate of burnout in the basement reaches up to 1 kg per 1 sq. m. meter per minute and can increase depending on the fire load. Already in the first hour, the temperature in the rooms rises to 600 degrees or more, and a large emission of thick and toxic smoke is formed, which rushes down the flights of stairs and flights. Fills the upper floors, thereby preventing residents from using.
Upon arrival of the unit, first of all, the RTP clarifies the situation, establishes possible evacuation routes, if necessary, increases the rank of the fire call and duplicates the request to call life support services. If necessary, issues orders. Upon arrival, police officers decide to cordon off the firefighting area to avoid accidents. All actions and decisions taken by the RTP must be in compliance with labor protection.
GDZS units are created, security posts are set up, one unit takes all measures and at the same time another is sent to search for the source. Fire nozzles are used to extinguish the fire and protect the floors of the first floor.
All forces arriving at the increased number must immediately be involved in the work of extinguishing the fire, commands are given by the RTP, until the arrival of management and.
For a developed fire, several extinguishing areas are created, depending on the layout of the basement and the speed of fire spread. A reserve of GDZS units is created to alternate the work of gas and smoke protectors.
Smoke release is organized by opening window openings on the floors, technological hatches or doors to the attic. With help, they organize a supply of fresh air to the flights of stairs and remove smoke from the basement. Residents of the upper floors are rescued using retractable ladders or articulated lifts.
It is possible to use special or. Victims from the lower floors are evacuated along flights of stairs using hood-type rescue devices connected to.
When extinguishing a fire, it is most advisable to supply generators with high expansion air-mechanical foam. The number of barrels for extinguishing will depend on the volume of the basement room, the flow rate and the coefficient of destruction of the foam. Due to its properties, the foam formed with the help displaces hot gases and lowers the temperature in the room, preventing the destruction of reinforced concrete floors and the spread of fire to the overlying floors through technological openings.
After the fire is localized, the gas and smoke protection service is sent back to the basement to completely eliminate the remaining fires and dismantle structures if necessary. On the first floors, it is necessary to constantly monitor the condition of the ceiling; in areas where there is strong smoke, carry out a control opening and make sure there is no fire. Additionally, organize watering.