SNiP and GOST for a number of buildings provide for the installation of such equipment as a smoke-free staircase. It ensures the safety of people in the premises during a fire. Thanks to the presence of these structures, residents can be saved from fire and smoke.
Despite the introduction of regulations requiring the use of exclusively non-combustible materials for the construction and decoration of buildings, the situation with fire safety often remains critical. To avoid the death of people and animals from fire and combustion products, structures such as smoke-free stairwells were developed. Architects developing projects multi-storey buildings must take into account the requirements fire safety and provide for the existence of these evacuation routes and exits.
The smokeless stairwell is a structure made of non-combustible materials, the space of which is protected from the effects of fire and smoke. This is the main difference between evacuation stairs and those that serve to connect the floors of a building.
- H1 - located in the most protected from fire and smoke places in the building. Access to the H1 stairwell is possible through open corridors, which cannot be penetrated by fire and combustion products. In high-rise residential buildings such a transition is a balcony that acts as an air zone. Passing through this corridor, a person gets directly to the stairs of type H1, through which he can leave the building.
- H2 - is a room (complex of flights of stairs), fenced with walls made of non-combustible materials and equipped with ventilation ducts with air overpressure.
- H3 - a room located next to the flights of stairs, access to it is possible through special gateways. They provide for the presence of ventilation ducts that provide air overpressure either in continuous mode or with the onset of ignition. The entrance to the gateway is a fire door with an automatic porch.
All listed types of staircases are assembled from metal and concrete structures.
Doors leading to the exit from the building and the entrance to the area protected from fire and smoke have the status of evacuation doors and must comply with the requirements of SNiP 21.01.97. According to the rules and regulations of fire safety, the width of the emergency exits must be sufficient to enable the unhindered movement of the stretcher. Therefore, the boundaries for the width of evacuation corridors are set: at least 1.2 m.
Requirements for smoke-free staircases
Stairwells of type H1 are designed to ensure the evacuation of people in buildings whose top floor height exceeds 30 m. These include reinforced concrete structures of type A, B and C. Evacuation marches are located in the corners of the building. There should be a window on each floor of these fire and smoke protected rooms. Transitions leading to the emergency exit (balconies or galleries) must provide a constant flow of air.
Staircases of type H2 are designed to provide emergency exits in public and residential buildings from 28 to 50 m high. Tambour locks that serve as a passage to the safe area must be equipped with category E130 doors. The same requirements apply to H3 type stairwells.
Evacuation exits located on the outside of multi-storey buildings are often decorated with openwork gratings made of metal or other non-combustible materials. Therefore, the residents have a natural question: will these decorative panels and gratings for free air access, what is the main safety measure during a fire? But you can be calm about this: the experts took into account all the nuances, so the openwork lattices on the facades of the houses are sufficient for unhindered access fresh air openings.
There are a number of requirements for passages located with outside buildings (balconies and galleries) and leading to emergency exits:
- on the territory of such transitions it is forbidden to place bulky and other things of residents;
- laying of cables and wires is unacceptable;
- it is forbidden to lock or otherwise block the door that is the entrance to the safe area.
Video about testing the fire escape platform:
Compliance with these rules and requirements is required to be monitored not only by the fire safety service, but also by employees of communal departments. Administrative liability is provided for violation of the introduced rules. In order to ensure free access to the smoke-free zone, specialists regularly inspect these areas and urge residents of multi-storey buildings to report violations in a timely manner.
An analysis of the problem shows that the main danger to people's lives in a fire is the products of combustion that spread throughout the building in a time insufficient for evacuating people. The deterioration of visibility and the resulting panic, the irritating and toxic effects of combustion products on humans, are the main causes of death, as well as the main obstacle to successful work firefighters. To prevent the spread of combustion products from the premises of the fire source into the protected volumes of the building (staircases, elevator shafts, elevator lobbies, vestibule locks, etc.), special design and planning (1) and technical solutions(2). It is important to pay attention to the fact that in accordance with the requirements of regulatory legal acts and regulatory documents on fire safety, smoke protection of buildings should ensure not only the safe evacuation of people in the event of a fire, but also create the necessary conditions for fire departments to perform work to save people, detection and localization of a fire in a building, which is especially important for high-rise buildings and buildings elevated number of storeys. At the same time, one of the main ways for personnel of fire departments to access the floors in such buildings is smoke-free staircases, which will be described in more detail in this section.
1. To design and planning solutions aimed at providing necessary conditions evacuation, first of all, the installation of smoke-free staircases. The current regulatory documents give preference to type H1. The design and planning feature of this design of the staircase is the absence of a direct connection between its volume and the floors of the building, as well as in the arrangement of external passages (along balconies or loggias through the open air zone) on each floor, which makes it possible to provide the necessary conditions for its smoke-free. Schematically, the arrangement of such transitions to stairwells is shown in fig. 1÷3.
Rice. 1. Floor transitions through the outer air zone to smoke-free staircases of type H1 along balconies with solid end railings (in plan)
Rice. 2. Floor transitions through the outer air zone to non-smokeable staircases of type H1 along balconies without solid fences (in plan)
Rice. 3. Floor transitions through the outer air zone to non-smokeable stairwells of type H1 along the loggias (in plan)
Here it should be noted that it is not enough to simply provide for floor-by-floor transitions through the outer air zone, it is important not to violate the geometric dimensions established by regulatory documents, indicated in the above diagrams, in particular, size a, which regulates the distance from the window opening of the room with a possible source of fire to the doorway of the entrance to the volume stairwell, dimension b, which sets the minimum width of the pier, etc. Otherwise, there is a high probability of smoke in the indicated transitions, which is confirmed by calculations performed using the Fire Dynamics Simulator (FDS) 6.1.2 software-computer complex (see Fig. 4).
Rice. 4. Evaluation of smoke-free conditions for transitions through the outer air zone using the FDS software and computer complex
The program algorithm in which the calculation described above is performed corresponds to the field method for modeling a fire in a building, presented in Sec. IV adj. 6 "Methods for determining the calculated values of fire risk in buildings, structures and structures of various classes of functional fire hazard". The mathematical model of FDS is based on the use of partial differential equations describing the space-time distribution of temperature and velocities gas environment indoors, concentrations of the components of the gaseous medium (oxygen, combustion products, etc.), pressures and densities. RPP values are visually displayed using the FDS Smokeview 6.1.12 post-processing program. It allows you to view the results of FDS calculations in 3D, see the spread of smoke, changes in values in the measuring planes and other values.
The results of the program make it possible to evaluate the RPP indicators at each given point, which is clearly evidenced by the figures below (see Fig. 5 ÷ 10).
Rice. 5. O 2 concentration fields
Rice. 6. Temperature fields
Rice. 7. Concentration fields by HCL
Rice. 8. Concentration fields for CO 2
Rice. 9. Calculated fire scenario, the results of which are presented in fig. 4 ÷ 8
A large number of calculations for various types of outdoor crossings in combination with wind load and without it showed that the most optimal solution is with construction pylons that perform the function of side solid fences in accordance with the scheme shown in Figure 2.
Placement of outdoor transitions through an open air zone on the facades of buildings, in the decoration of which combustible substances and materials are (including ventilated facades) used (including ventilated facades) can lead to blocking of these transitions by combustion products in case of their ignition. When using such materials in the decoration of facades, it is advisable to provide smoke-free staircases of the H2 type in accordance with the requirements of SP 7.13130.2013, in particular, with entrances through tambour locks with air overpressure in case of fire in high-rise buildings, which will be discussed later.
2. To technical solutions systems are primarily smoke protection buildings. The use of these systems to ensure smoke-free escape routes of high-rise buildings and high-rise buildings is considered promising, because. this allows the most complete implementation of the ideas of architects and designers. The problems of using smoke ventilation systems in high-rise buildings and high-rise buildings are constantly discussed at scientific and technical conferences, seminars, as well as in the course of everyday communication between designers. The most rational is the method in which the systems inlet smoke ventilation create excess pressure in the protected volumes of the building, and exhaust provide forced removal of combustion products in accordance with the block diagram shown in fig. ten.
Rice. 10. Systems of supply (PD) and exhaust (VD) smoke ventilation in high-rise buildings
The main problems in the construction of supply smoke ventilation systems are associated with the protection of smoke-free H2-type staircases used instead of H1-type smoke-free staircases, which were mentioned above. To ensure the necessary safety conditions in the described staircases in high-rise buildings, a distributed supply of outdoor air is provided in accordance with the diagrams shown in Fig. eleven.
Rice. 11. Device for distributed supply of outdoor air by supply smoke ventilation (PD) systems to smoke-free stairwells of type H2
Protection by the supply smoke ventilation system in accordance with the diagram shown in fig. 10 in buildings with a number of floors of 12 or more with one outdoor air supply point, in most cases leads to the impossibility of complying with the pressure drop range regulated by regulatory documents - from 20 Pa to 150 Pa.
As alternative it is allowed to install continuous cuts or smoke-free staircases of type H3 - with entrances to the volume of the staircase through floor locks with air overpressure in case of fire, in accordance with the diagrams shown in fig. 12. In this case, the cut must be provided in such a way that the entrance and exit to various parts of the staircase are provided outside its volume.
Rice. 12. Arrangement of a smoke-free staircase type H2 with a dissection device and a smoke-free staircase type H3
An important feature in the construction of smoke-free staircases of the H2 type is the need to use a vestibule with air overpressure in case of fire on the lower floor, which has an exit to the outside of the building (see Fig. 13).
Rice. 13. The device of the tambour-lock with air overpressure in case of fire with a non-smokeable stairwell of type H2 on the lower floor of the building
For high-rise buildings, the need to protect floor exits to smoke-free H2-type stairwells through tambour locks with air overpressure in case of fire is additionally regulated in accordance with the diagram shown in Fig. fourteen.
Rice. 14. Arrangement of a smoke-free staircase type H2 in a high-rise building
The inclusion of supply smoke ventilation systems that provide outdoor air supply to the vestibule locks with smoke-free stairwells of the H3 or H2 type (in high-rise buildings) should be provided only on the floor with a fire source.
At the end of this review, it should be added that when designing smoke ventilation systems, in particular those providing protection for smoke-free staircases of the H2 or H3 type, it is important to take into account the following:
Control cabinets for supply and exhaust smoke ventilation systems must provide automatic control the integrity of the power supply lines of the system elements, the state of the final position of the dampers (shutters) fire dampers, with the issuance of an emergency signal to the control panel of the dispatching service;
For remote control of smoke ventilation systems, it is not allowed to use the IPR system of automatic fire alarm. For these purposes, it is necessary to provide separate buttons to be installed in the places regulated for IPR, with the signal output directly to the PPU of the smoke ventilation system;
Estimated definition the required parameters of smoke ventilation systems or general ventilation systems combined with them should be carried out in accordance with the provisions of SP 7.13130.2013, MD.137-13 "Calculated determination of the main parameters of smoke ventilation of buildings"
Grade technical condition smoke ventilation systems at high-rise construction sites should be carried out in accordance with GOST R 53300 at least once every 12 months, or more often if prescribed by the equipment manufacturer.
The implementation of this list will significantly improve the level of fire safety of high-rise construction projects in our country.
We hope that the presented material will be useful to you in practical activities.
Sincerely, the team of IB "One Atmosphere"
BIBLIOGRAPHY
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Federal Law No. 123-FZ dated July 22, 2008. Technical regulation on fire safety requirements. |
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SP 7.13130.2013. Heating, ventilation and air conditioning. fire safety requirements. |
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Estimated determination of the main parameters of smoke ventilation in buildings: Method. recommendations to SP 7.13130.2013. M.: VNIIPO, 2013. 58 p. |
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Methodology for determining the calculated values of fire risk in buildings, structures and structures of various classes of functional fire hazard. – M.: FGU VNIIPO, 2009. – 71 p. |
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Stetsovsky M.P. Study of heat and gas exchange on the floor of a fire and the determination of some parameters for the calculation of ventilation systems for smoke protection of residential buildings: Dissertation. M.: MISI im. V.V. Kuibysheva, 1978. 198 p. |
AT high-rise buildings- this is a guarantee of saving many human lives and ensuring the safety of property, people living there.
One of the conditions that must be met when putting multi-storey buildings into operation is the presence of a certain type of stairwells, which, in case of fire, do not smoke.
Smoke-free staircases include special designs that provide quick and safe evacuation from the facility.
This type of construction has its own classification, which distinguishes cells according to their technical parameters and structural design.
Functional purpose
A smoke-free staircase is a special design, which is implemented as a march of certain geometric dimensions, along which people can be quickly and efficiently evacuated in the event of a fire in one of the premises of the facility.
The main requirement that is put forward for this type of structures is the absence of smoke in their space during a fire.
The air zone of a non-smokeable staircase must be clean from smoke masses throughout the entire evacuation.
This will eliminate the death of people and their injuries, which often occur from suffocation with flue gases intensively released during a fire.
Among other things, a smoke-free staircase should provide an opportunity for rescuers to quickly get inside the premises in order to evacuate the people remaining there and start fighting the fire from the inside. The design of this kind of stairwells should provide for the transportation of evacuees using stretchers.
AT normative documents strictly stipulated when a smoke-free stairwell is required.
The objects where these structures must be mandatory include various multi-storey buildings (residential, industrial, general use).
Types of smoke-free stairs
According to the SNiP on fire safety of buildings, the stairs used in them are divided, taking into account fire resistance, the possibility of smoke and the degree of ignition, into the following types:
- internal stairs, which are part of the staircase structures of the building;
- open internal stairs;
- outdoor open stairs.
Simple escape stairs are classified into two categories.
- L1 - these are structures that are distinguished by the presence of fully open or glazed openings in the external partitions of each floor. Stairs of this type are used in buildings with a total height of no more than 28 m. On the platforms of these stairs it is forbidden to lay electric cables, pipes for gas and water mains, and also to store any things.
- L2 - structures with natural light, which is provided through open or glazed openings in the roofing of the building. This type of construction is used in houses whose maximum height is not more than 9 m, in rare cases - 12 m. Such stairs are used in buildings that belong to I, II and III degrees of fire resistance.
Types of smoke-free stairwells
Depending on the device of the smoke-free staircase, its location, the organization of access to it, the principle of use, they are divided into three categories:
- H1 - these are types of stair structures, for which they are distinguished by the presence of free access through open areas. Approaches to such evacuation structures must be smoke-free.
- H2 - this type of smoke-free stairwells is distinguished by the presence of air backwaters.
- H3 - these openings are in many ways similar to the previous ones, but they differ in that the exits to the marches must be carried out through special vestibules in the form of locks. There is also air support, which can be carried out both in case of fire and constantly.
Stairwells H1
Smoke-free staircase H1 refers to mandatory elements, which must have public and residential buildings, the height of which is 30 meters or more. Features of this type of cells are access to them.
In order to get to the non-smokeable staircases of type H1, one should get through the corridor to an open outdoor area, made in the form of a balcony or a separate fenced area.
These access requirements are established to ensure that the escape route is naturally isolated from smoke-filled areas. The best place for the location of this type of structures is the corner part of strongium.
It is especially advantageous to place them on inner corner with additional piers. In order for the landing to meet all fire safety requirements, all the nuances of its location should be taken into account even at the design stage of knowledge.
Otherwise, it will be necessary to re-equip the structure in order to fulfill all the established requirements.
Stairwells H2 and H3
Smoke-free staircases H2 and H3 are a slightly different type of evacuation structures that are designed for use in buildings whose height is more than 50 meters. In the construction of most modern facilities, it is H2-type landings that are used.
Smoke-free stairwells of the H2 type are characterized by the presence of an air overpressure provided by means of a ventilation duct. The exits to such staircases are through inner part buildings.
H2 and H3 types of smoke-free staircases are structures with air support, but in the second case, the obligatory presence of a vestibule in the form of a gateway is provided, which should be placed on sections of the path leading to emergency exits. The use of outbuildings in the form of vestibules will significantly improve the protection of people from smoke and fire.
When creating a vestibule, only those materials that do not support combustion are used, and the presence of a fire door should also be provided, in which there should be an automatic porch.
As for the design of this staircase, it is similar to that of the H2 type cage.
The presence of a ventilation duct will allow you to supply air flows and create the required backwater passage. This will prevent the ingress of smoke and combustion products to the places of evacuation of people.
Technical requirements for stairs
In addition to the requirements listed above for smoke-free cages, other conditions are also established that relate to the geometric dimensions of their structural elements.
March width
The width of the passage should be 1.2 m when measured in the air zone. The width of the approach to this passage should be at least 1.1 m.
The passage must be such that two people can easily pass there or it is possible to transport the injured person using a stretcher. In one march, up to 18 ordinary steps are allowed.
Step Height
The overall dimensions of the steps on the march should be optimal for each type of smoke-free stairwells.
The width of the step should be sufficient so that the human foot can comfortably and stably sit on its surface.
As for the value of the step height, it can be 1.5 times smaller than the width.
Each of the structural elements of the evacuation marches must correspond to each other in terms of their overall dimensions.
Height of escape route passage
In order for a person to move freely by evacuation, the height of his ceilings should not be less than 1.9 m.
Other nuances
For the manufacture of smoke-free stairs, such building materials should be used that can withstand heating and ignition in direct contact with an open flame and heated structural elements of the building.
Basically, concrete is used to build staircases, which differs high level fire safety. In addition, concrete marches are highly durable and easy to use.
To strengthen the structure of marches, as well as to create fences, metal structural elements are used.
Conclusion
If we summarize the information presented above, we can conclude that smoke-free staircases are important structural elements that provide the building with the required level of fire safety.
In addition to smoke-free stairs, other kinds of special structures can be used at the facilities, which may differ in design, but functional purpose have the same.
It is important that smoke-free stairs and other similar structures fully comply with the norms of SNiP, which determines the fire safety of an object.
If they contradict the normative documentation, then their use will be possible only as emergency moves.
When erecting stairs in multi-level premises, builders must take into account the fact that in the event of a fire, it is the stepped structure that can become the only way to get out into the air and save people. Depending on how adapted the system is to the evacuation of people in the building, staircases are usually divided into types H1, H2, L1 and L2. The main design features of these spans, as well as the requirements for them, will be discussed in this article, illustrated with a large number of photos and videos.
Before proceeding with the design of a multi-level building, the architect must Special attention development of sketches of staircases
What is a staircase
Before the construction of the stairs begins, a special vertical opening is designed for it in the building - the stairwell.
A staircase is a combination of all elements of a stepped structure, as well as walls, ceiling, floor, window and doorways - stepped marches;
- sites;
- fences;
- walls with door and window openings;
- ceilings and floors.
Types of stepped platforms are classified depending on their fire safety and the degree of smoke in the event of a fire The main criterion by which stairwells are divided into types is fire safety and unhindered evacuation of people in the event of a fire and smoke.
In case of fire, it is the stairs that may be the only way to evacuate people from the building Classification of stairwells
Depending on the level of smoke in the event of a fire, staircases can be:
- ordinary - this species subdivided into types L1 and L2;
- smoke-free - types H1, H2 and H3.
Cages of stepped constructions can be normal and non-smokeable Ordinary staircases
Structures that may be subject to smoke in case of fire belong to ordinary landings, which in turn are divided into two main types - L1 and L2. Next, consider them in more detail in the photo.
This drawing schematically shows two types of conventional ladder systems - L1 and L2 Type L1
Stepped platform L1 is characterized by the presence on each floor of glazed windows located in bearing wall buildings through which natural light enters the room. In some cases, these gaps in the wall may not be glazed.
Glazed window openings must be located at each level of the staircase belonging to type L1 Type L2
The L2 type landing has natural lighting, which enters the span through glazed open gaps made in the coating. The photo below clearly demonstrates this type of conventional staircase.
Type L2 is characterized by the presence of natural light entering the cage through glazed or open wall gaps. Smoke-free staircases
The main requirements for this type of system are:
- the presence of special locks for entering the stepped cage of air flows from a smoke-free zone;
- the presence of evacuation passages that allow people to leave the dangerous premises at the time of ignition.
Smoke-free structures also have their own division - these are types H1, H2 and H3. Let's analyze them in more detail.
In many multi-storey buildings, smoke-free stairwells are used, which are safer for operation in extreme conditions. Type H1
This type of staircase has an entrance from the floors of the building through the street part of the building through an open passage, free from smoke. This type of construction is often used in administrative, public and educational institutions whose height exceeds 30 meters. It is considered the most suitable for carrying out the evacuation of people from a building engulfed in smoke.
Distinctive feature step cage type H1 is the presence of an exit from the stairs directly to the street Type H2
Site H2 is distinguished by the presence of a special ventilation support through which, in the event of a fire, clean air will be supplied to the stairs, which will enable people to get oxygen. This option is used in rooms whose height is 28 meters. A photo of the design is shown below.
Type H2 is equipped with a special overpressure for supplying clean air in case of fire. Type H3
Smoke-free stepped cage type H3 is equipped with an entrance from the floor through the vestibule, as well as oxygen overpressure with the possibility of multiple air supply to people in case of fire in the room.
If we are talking about low buildings, then ordinary stairs of the L1 and L2 types are more often used here, while in high-rise buildings it is necessary to build systems related to the types H1, H2 and H3 We examined the main types of staircases, according to the standards of SNiP. However, the above classification does not apply to household stepped structures installed in country dwellings for the transition between two or three levels.
This photo shows a staircase system illuminated natural way through windows in the wall located throughout the structure Requirements for stairs and stairwells
Since ladder systems serve evacuation purposes in the event of a fire, they must be built in accordance with the standards prescribed by SNiP 21-01-97.
All standards and regulations of SNiP 21-01-97 to the cages of the stairs must be taken into account at the very beginning of construction According to this regulatory act, the following requirements are imposed on staircases located inside multi-level buildings:
- 1 m 35 cm - for buildings of class F 1.1;
- 1 m 20 cm - for houses with more than 200 people on each floor;
- 0.7 meters - for stairs designed for a single workplace;
- about 90 cm - in all other cases.
This photo schematically shows three types of smoke-free landings, according to the requirements for them 2. The permitted slope of the structure for carrying out evacuation measures is 1:1.
3. Depth of tread - not less than 25 cm.
4. Step height - no more than 22 cm.
5.Slope for open systems - 2:1.
According to the norms, the slope for open staircases is acceptable in a ratio of 2: 1 6. Designs open view must be made of non-combustible materials and mounted near blank walls, class at least K1 with the highest fire resistance limit. The platforms of such stairs must have a fence with a height of at least 1 m 20 cm.
7. The width of the platform must correspond to the width of the march.
The width of the march should be sufficient to carry out the evacuation of people from the building in case of fire or in case of smoke, this is especially true for children's and school institutions 8. The doors to the cage, when opened, should not block the march and the platform.
9. Blocking of staircases with cabinets and other equipment is not allowed.
SNiP norms allow equipping the staircase with special luminous railings 10. The use of luminous railings is allowed.
11. Landings of type H1 must have an exit to the outside.
12. Cells of types L1, H1 and H2 should be illuminated natural light through specialized openings facade walls on every floor.
13. Type H2 sites are equipped with blind (non-opening) windows.
When building a staircase, it is necessary to take into account all fire safety standards for it. Related videos
In the video below you will find additional information on the topic discussed.
The most terrible element at all times was considered fire. A lot of water has flowed under the bridge since Prometheus taught people to use his benefits. But until now, the question of fire safety. A fire is especially dangerous in multi-storey buildings that simultaneously accommodate a large number of people.
Types of smoke-free staircases
Most people who are victims of a fire die from smoke poisoning and carbon monoxide, which is why smoke-free evacuation routes are so important in this regard if a possible fire is suspected. The main routes of evacuation from multi-storey buildings were and remain flights of stairs. Building codes and regulations (SNiP) provide for the construction of smoke-free staircases of three types: H1, H2 and H3.
Smoke-free stairs are divided into the following categories by building codes and regulations:
- H1 - stairs, the entrance to which is through an open space outside the building;
- H2 - stairwells with an additional air pressure device;
- H3 - stairwells, the entrance to which is through specially created zones with air overpressure.
General requirements for smoke-free stairs
According to fire safety rules, all smoke-free stairs must be equipped with emergency lighting. The width of the doorway must be at least 1.2 meters, and its height must exceed 1.9 meters. The exits from flights of stairs should not be arranged along the width of the already span. If a smoke-free cage is arranged through a wall with an elevator shaft, then a air vent at the level of the upper floor for free air access.
In the passages to smoke-free stairs and on landings no personal items are allowed. It is forbidden to independently mount unforeseen construction project partitions. It is also not possible to cut passages in existing fire bulkheads.
Smoke-free flights of stairs must be equipped with handrails made of non-combustible and slightly heated materials.
Arrangement of smoke-free stairs of the first type (H1)
In buildings above thirty meters, according to " building codes and the rules” staircases should be arranged according to the smoke-free class H1. This type requires stairs that can be accessed from the landings of the floor through an open air space. Design feature such structures in that they are not directly connected to the floors of the building.
Usually, H1 cells are located in the corners of buildings and structures on the windward side and have balcony-like transitions, enclosed by protective screens.
The transition can be made in the form of a loggia or open galleries, the width of the passage must be at least 1.2 meters. The width of the wall between the aisles, as well as the gap to the nearest window, cannot be less than two meters.
The width of the aisle must ensure the transport of fire victims on stretchers!
Installation of smoke-free stairs of the second type (H2)
Stairs arranged according to the H2 type are recommended in buildings whose top floor is located at a height of twenty-eight to fifty meters. The air pressure in the H2 cells is arranged according to the principle of stove draft and can be permanent or open during a fire alarm. It is also possible to have an autonomous backwater device from electric air pumps.
The principle of operation of a smoke-free ladder (PD - pull ventilation system)
Electric pumps providing air pressure must be equipped with uninterruptible power supplies.
The thrust force (or backwater) must be carefully calculated when designing ventilation. The pressure must be such that any person can open the fire doors to the stairs. On the lower floor, the pressure on the door should be at least twenty pascals, on the upper floor - no more than one hundred and fifty pascals.
The entrance to the flights of stairs H2 is arranged through vestibules or locks equipped with fire doors of the corresponding category.
It is advisable to arrange vertical partitions in smoke-free cells of the second category every seven or eight floors. Air support is mounted in the upper zones of the resulting compartments.
Installation of smoke-free stairs of the third type (H3)
The third type of smoke-free stairwells also uses air pressure. The difference from cells arranged according to the H2 type lies in the arrangement of special rooms for the passage of people with self-closing doors on closers. Rooms must be at least four square meters. The air supply in cells of this class is carried out both in the space occupied by the stairs, and in the locks arranged in this way. Air draft can be carried out on a permanent basis or turn on automatically during a fire or smoke.
Materials for manufacturing
The main material used in the construction of evacuation smoke-free passages is concrete. Concrete is fire-safe, durable and easy to use. The use of steel structures, such as fences or doors, is an addition to the concrete base. Also, the use of metal spans can be justified in light building structures.
Application wooden elements possible in a small volume, for example, wooden door handles or handrails, provided they are treated with fire-fighting compounds.
Other types building materials when constructing smoke-free stairs, they are practically not used.
Other types of evacuation structures
Other designs can be used as an alternative to smoke-free stairs. For example, staircases of category L1 and L2 with natural light through window openings.
Various outside residential and public buildings. In the event of a fire, evacuation is carried out through such stairs and fire-fighting equipment is delivered.
In this article, the device of smoke-free staircases was described in detail. Why are they needed, what are the varieties. In addition, considered general principles fire safety in relation to staircases. Our site is dedicated to stairs and everything connected with them, so ask questions, suggest interesting topics for articles - our authors will fulfill any wishes of site visitors.