The current level of development of scientific and technological progress does not affect the existence of the fact that fire has been and remains one of the most dangerous enemies of human habitation for thousands of years.
Despite the widespread introduction of regulations requiring the use of exclusively non-combustible materials for interior decoration, the statistics remain relentless: people's homes today are by no means invulnerable.
Often the only thing left in the event of a fire for the residents is to flee, that is, to evacuate. The safest way to escape from multi-storey buildings is fire escape stairs.
Danger to people in case of fire is not only fire. The smoke is also dangerous. But the most terrible invisible enemy is carbon monoxide. A person may not notice its effects (unlike ordinary burning, carbon monoxide has neither smell nor color). Carbon monoxide poisoning is characterized by rapid development. After a few minutes, the victim may lose consciousness, after which hethere is practically no chance of salvation.
Therefore, in every house, as the most important condition for saving residents during a fire, smoke-free staircases are equipped. What are the types of smoke-free stairs and stairwells?
Stairs are an essential element of buildings
Staircase is an integral element of multi-storey buildings. There are ordinary structures that serve to communicate floors, as well as evacuation stairs, that is, smoke-free.
The presence of the latter is the most important condition under which people are evacuated in case of fire. For a number of buildings, it is dictated by SNIP, therefore, architects must necessarily provide for the design of structures.
Evacuation ladders: purpose
Evacuation ladders must be present in high-rise buildings. Such structures ensure the safety of residents during a fire or in case of other emergencies. The arrangement of evacuation stairs in various types of buildings is subject to certain standards regarding their size, configuration and placement. Regardless of the type of model, the general purpose of these structures is to ensure that people can safely exit the building if necessary.
Residents of the house, employees and visitors of the institution, using evacuation stairs, can leave the premises without danger to life and he alth. The evacuation exit is designed to protect them from fire and smoke. It is very important to ensurefree access to it for all those in the building.
Evacuation stairs can be used as an alternative exit from the premises. This is true for structures that are not equipped with a separate back door. Fire safety regulations prohibit the operation of buildings above three floors that are not equipped with an evacuation staircase.
Location
Special requirements apply to the location of evacuation stairs. Usually their placement is designed in the back of public buildings or from the end, if an open type exit is planned.
With the proposed arrangement of an emergency exit inside the building, a separate room or corridor is allocated for such a staircase. This is necessary in order to ensure the safety of people descending in the event of a fire and to prevent blocking the often only possible exit from the house.
Such a room must be equipped with a fire-resistant door that is capable of containing the flame for at least 1 hour. At the same time, it is important to ensure the sealing of the joints and the rapid removal of smoke.
Each floor must be equipped with an exit to the stairwell. Its width depends on the size of the passage and steps. Semi-closed models provide for the location within the premises of the site, the door from which leads to an external staircase. This is an excellent option for cases where it is not possible to completely seal the passage from smoke.
For open outdoor types, a special rule applies: distance fromthe edge of the stairs to the wall should be at least 100 cm. This reduces the risk of fire entering the emergency exit and prevents heating of the structure, as well as protective handrails.
Materials
Since this design is intended for use in extreme situations, including fires, certain requirements determine the choice of materials used for its construction. The main condition is to ensure the strength and fire resistance of the stairs. Therefore, the most popular materials are concrete and metal.
Materials that flammable, crumble or release toxic substances when heated are strictly prohibited.
Requirements of SNIP and GOST
GOST and SNiP standards regulate the norms by which all types of stairs are installed. They also apply to evacuation models.
- The standard slope of the evacuation stairs is such that the ratio of the length and height of the span is 2:1.
- For 1 march, 3-18 steps are allowed. For 2 marchers, their number should not exceed 16 pieces.
- The width of the tread should serve to ensure the comfort of movement, the optimal size is 24-29 cm.
- Step height is usually 20-22 cm.
- The width of the stairs is provided by the requirements such that 2 people can pass along it at the same time. The smallest allowable value is - 1 m. It is allowed to reduce the dimensions for outdoor structures to 70 cm.
- The area between the marches in size should correspond to the width of the stairs andexit to it.
- To ensure the safety of evacuation from the building in case of fire, it is necessary to provide an exit to the stairs, which leads to an open space or to a separate room, protected from fire and smoke.
Classification
Evacuation ladders are classified according to the type of material, location, and design features. There are three main types of modern evacuation stairs, which differ in such characteristics as purpose, width and configuration:
- located on special smoke-free stairwells inside the building;
- is located inside the building, and is not enclosed by walls;
- located outside and is an emergency exit design.
The latter is used exclusively for evacuation, while the first two types of stairs sometimes replace the main entrance.
About acceptable types of structures
For evacuation, direct marches are also used, equipped with intermediate platforms. In some cases, when there is not enough space for their location, vertical structures like firefighters are installed parallel or with a slight slope to the wall.
Strictly prohibited
It is forbidden to erect stairs according to fire safety rules:
- with winders;
- with curved and irregular spans;
- screw;
- with steps of different sizes.
What are smokelessstairwells?
The presence of such structures in the house is designed to ensure maximum safety of life and he alth of people in case of fire. They are marches of certain sizes, which must be located in the appropriate areas of the building.
One of the main requirements for an emergency exit is its isolation from smoke. Smoke-free stairwells are distinguished by the fact that during a fire they do not get OFP (fumes, smoke, etc.).
The presence of these structures ensures successful evacuation of people in multi-storey buildings in case of fire. Different requirements are placed on them depending on the specific type.
Types
Smoke-free staircases are divided into several types, which can be classified by their specific design features, location, access to them and principles of operation. Stairwell types:
- H1 is considered the base model. Characteristic features of the design is the availability of access using an open area. It is necessary to have a smoke-free approach to the emergency exit.
- H2 provides air pressure in the event of a fire.
- H3 is an analogue of H2, but provides for access to the march through the tambour-gateway. Additional air support is also provided, which is supplied both in case of fire and on a permanent basis.
Requirements
Fire safety in stairwellsensured by rules that provide for the safety of human life:
- Emergency lighting installed in all smoke-free stairs.
- The width of the doorway should be 1.2m or more and the height should be 1.9m or more.
- The width of the exits from flights of stairs should not be narrower than the width of the span.
- When installing a smoke-free cage adjacent to the elevator shaft, a ventilation hole is arranged in the wall to ensure free air access (at the level of the top floor).
- Personal belongings are prohibited in the passages to smoke-free stairwells. The landing should be uncluttered, as trash can interfere with the evacuation of people and the work of firefighters.
- Independent installation of partitions not provided for by the construction project, as well as cutting passages in existing fire bulkheads, is prohibited.
- It is obligatory to equip smoke-free flights of stairs with handrails made of non-combustible and low heating materials.
H1 smoke-free stairs
"Building codes and regulations" state: in buildings whose height is more than 30 m, smoke-free staircases of type H1 should be installed.
This view requires the installation of ladders that can be accessed from the landing of the floor, using open air space to move. The location of H1 can be a veranda, a balcony or a fenced landing, taken out of the room. This is due to the need to provide natural isolation from the smoky part of the building of the emergency exit. The best option for placing this type of staircase is the corner part of the building. The most advantageous position is the inner corner, equipped with additional piers. Their design feature is the absence of a direct connection with the floors of the building.
The usual placement of H1 cells is in the corners of buildings on the windward side. They are characterized by the presence of transitions of a balcony type, as well as fences with protective screens. The transition is carried out in the form of an open gallery or loggia, the width of the passage must be from 1.2 m. The width between the passages, as well as the gap from the wall to the window, must be at least 2 m.
H2 smoke-free stairs
Stairwell H2 is arranged in a building, the top floor of which is located at a height of 28-50 m. It can be permanent or open in the event of a fire alarm. It is also possible to install an autonomous backwater using electric air pumps that provide air pressure, which must be equipped with uninterruptible power supplies.
When designing ventilation, you should correctly calculate the thrust force (or backwater). The pressure should allow the fire doors to open freely to the stairs. The pressure on the lower floor should be at least 20 pascals, on the upper floor - no more than 150 pascals.
Tambours or sluices through which entrance to H2 stairwells is provided are equipped with fire doors. In smoke-free cages of this category, it is advisable to use a devicevertical partitions with a gap of 7-8 floors.
H3 smoke-free stairs
The H3 smoke-free stairwell is also being built using pressurized air. Their difference lies in the arrangement of special walk-through rooms with self-closing doors. Their dimensions must be at least 4 square meters. m. In cells of this type, air is pressurized into the space occupied by the stairs and into special locks. Air draft is carried out on a permanent basis or turns on automatically in case of fire or smoke.
Main Materials
When creating evacuation smoke-free passages, concrete is most often used. It is a fire-safe, durable and easy-to-use material. As an addition to the concrete base, steel structures are used, for example, in the manufacture of fences or doors. Metal spans are also justified in light construction structures.
Wooden elements are used in small volumes: wooden handrails or door handles, which must be treated with fire-fighting compounds.
