Unsecured staircases (H1, H2, H3) and fire escape ladders

The current level of development of scientific and technological progress does not in any way affect the existence of the fact that the fire for millennia has been and remains one of the most dangerous enemies of the human dwelling.

Despite the widespread introduction of rules prescribing the use of exclusively non-combustible materials for interior decoration , statistics remain inexorable: people's homes today are by no means invulnerable.

Often the only thing that remains in case of a fire to tenants is to flee, that is, to evacuate. The safest way of evacuation from high-rise buildings is the fire escape ladders.

The danger to people in a fire is not only fire. Smoke is also dangerous. But the most terrible invisible enemy is carbon monoxide. A person may not notice its effects (unlike conventional burning, carbon monoxide does not have a smell or color). Carbon monoxide poisoning is characterized by rapid development. In a few minutes, the victim may lose consciousness, after that, he has almost no chance of salvation.

Therefore, in each house, as a most important condition for the rescue of residents during a fire equipped with smoke-free staircases. What are the types of smoke-free stairs and staircases?

Staircase - an integral element of buildings

The staircase is an integral part of multi-storey buildings. There are different types of structures used to post floors, as well as evacuation ladders, that is, smoke-free ones.

The presence of the latter is the most important condition under which people are evacuated during a fire. For a number of buildings, it is dictated by the SNIP, so it is mandatory for architects to create the design of the facilities.

Evacuation ladders: purpose

Evacuation ladders must certainly be present in high-rise buildings. Such designs ensure the safety of tenants in the course of a fire or in the event of other emergencies. Arrangement of evacuation ladders in different types of buildings is subject to certain standards regarding their size, configuration and location. Regardless of the type of model, the general purpose of these structures is to ensure the safe exit of people from the building if necessary.

Residents at home, employees and visitors of the institution, using evacuation ladders, can leave the premises without danger to life and health. Evacuation output is designed to protect them from fire and smoke. It is very important to ensure the free passage to it of all those in the building.

Evacuation ladders 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 rules prohibit the use of buildings above three floors, not equipped with an evacuation ladder.

Location:

Separate requirements are made to the location of evacuation ladders. Usually, they are projected in the back of public buildings or at the end, if an open type outlet is planned.

With the proposed arrangement of an evacuation exit inside the building, a separate room or corridor is allocated for such a ladder. This is necessary in order to ensure the safety of the descending people in the event of a fire and to prevent the blocking of the often only possible exit from the house.

Such a room should be equipped with a fire-resistant door that is capable of holding the flame for at least 1 hour. It is important to ensure the sealing of joints and quick removal of smoke.

Each floor must be equipped with an exit to the stairwell. Its width depends on the size of the passage and the steps. Semi-closed models provide for location within the premises of the site, the door from which leads to the outer staircase. This is an excellent option for cases where it is impossible to completely isolate the passage from the smoke.

For outdoor exterior types, a special rule applies: the distance from the edge of the ladder to the wall should be from 100 cm. This reduces the risk of fire entering the emergency exit and prevents the heating of the structure, as well as the protective handrails.

Materials

Since this design is intended for use in extreme situations, including fires, certain requirements are determined by the choice of materials used for its construction. The main condition is to ensure the strength and fire resistance of the stairs. Therefore, materials such as concrete and metal are the most popular.

The use of materials that readily ignite, crumble or release toxic substances when heated, is strictly prohibited.

Requirements SNIP and GOST

Standards GOST and SNiP are regulated by the rules by which all types of stairs are installed. They also touch on evacuation models.

• The standard deviation of the evacuation ladder is such that the ratio of the length and height of the span is 2: 1.
• For 1 march, the presence of 3-18 steps is acceptable. For 2-march their number should not exceed 16 pieces.
• The width of the tread should serve to provide comfort of movement, the optimal size is 24-29 cm.
• The step height is usually 20-22 cm.
• The width of the ladder is stipulated by the requirements such that two people can pass through it simultaneously. The smallest permissible value is 1 m. It is allowed to reduce the dimensions for external structures to 70 cm.
• The area between the marches in size should correspond to the width of the stairs and exit to it.
• To ensure the safety of evacuation from the building during a fire, it is necessary to provide access to the staircase, which leads to an open space or to a separate room, protected from fire and smoke.

Classification

Evacuation ladders are classified by type of material, location, and also by design features. There are three main types of modern evacuation ladders, which differ in such characteristics as purpose, width and configuration:

• Is located on special non-smokeable staircases inside the building;
• It is located inside the building, and is not enclosed by walls;
• Is located outside and is a design of the emergency exit.

The latter is used exclusively for evacuation, whereas the first two types of stairs sometimes replace the main entrance.

On admissible types of constructions

For the evacuation, direct marches equipped with intermediate platforms are also used. In some cases, when there is not enough room for their location, in parallel or with a slight inclination to the wall are installed vertical structures like firefighters.

Strictly forbidden

Fire safety rules are forbidden to build stairs:

• With running steps;
• With a curved and irregular shape of spans;
• Screw;
• With steps of unequal sizes.

What are unprofitable staircases?

The presence of such structures in the house is designed to ensure maximum safety of life and health of people in case of fire. They are marches of certain sizes, which should be located in suitable areas of the building.

One of the main requirements for evacuation is its isolation from smoke. Non-smoky staircases are distinguished by the fact that during a fire they do not fall into the RPT (fumes, smoke, etc.).

The presence of these structures ensures a successful evacuation in the event of a fire in people in multi-storey buildings. Different requirements are imposed on them depending on the specific type.

Types

Non-smoky staircases are divided into several types, which can be classified according to certain design features, location, access to them and the principles of operation. Types of staircases:

• H1 is considered the base model. The characteristic features of the design is the availability of access by means of an open platform. It is necessary that the approach to the evacuation exit is not smoke-free.
• H2 provides the presence of air pressure in the event of an outbreak.
• H3 is analogous to H2, but provides for the provision of access to the march through a gateway-gateway. There is also an additional supply of air, which is supplied both during a fire and on an ongoing basis.

Requirements

Fire safety in staircases is ensured by rules that provide for the preservation of human life:

• In all smoke-free ladders, emergency lighting is installed.
• The width of the doorway should be from 1.2 m, and the height - from 1.9 m.
• The width of the exits with stair flights should not be already the width of the span.
• When installing a smoke-free cell adjacent to the elevator shaft, a ventilation opening (at the level of the upper floor) is arranged in the wall to ensure free air access.
• In the aisles to non-smoke-free staircases, the placement of personal belongings is prohibited. The staircase must be uncluttered, since trash can become a hindrance to the evacuation of people and the work of firefighters.
• It is forbidden to install self-contained partitions that are not foreseen by the construction project, as well as to cut through the passages in the existing fire-fighting bulkheads.
• Mandatory equipment of smoke-free ladder marches with handrails from materials that are non-combustible and not very warm.

Non-smoke ladders H1

"Building rules and regulations" read: in buildings with a height of more than 30 m, smoke-free staircases such as H1 should be constructed.

This type requires the installation of stairs, which can be penetrated from the floor area, using for promotion a space with open air. The location of H1 can be a veranda, balcony or enclosed staircase, taken out of the premises. This is due to the need to provide natural insulation from the smoky part of the evacuation exit building. The optimal variant of 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 constructive feature is the lack of 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 balcony transitions, 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 from 1.2 m should be provided. The width between the aisles, like the interval from the partition to the window, should be at least 2 m.

Non-smoke ladders H2

Staircase H2 is arranged in a building, the upper floor of which is at an altitude of 28-50 m. In H2 cells, air pressure is created (the principle of furnace traction). It can be permanent or it can be opened in case of a fire alarm. It is also possible to install a stand-alone support using air electric pumps that provide air pressure, which must be equipped with uninterruptible power supplies.

When designing the ventilation, the thrust (or thrust) must be correctly calculated. The pressure should ensure that the fire doors can be freely opened to the ladder. Pressure on the lower floor must be at least 20 pascals, on the upper - no more than 150 pascals.

Tambours or floodgates, through which the entrance to the stairwells H2 is provided, are equipped with fire doors. In non-smoke cells in this category, it is advisable to arrange vertical partitions with an interval of 7-8 floors.

Non-smoke ladders H3

The unblocked staircase H3 is also constructed using air backing. Their difference lies in the arrangement of special passage rooms with self-closing doors. Their size should be at least 4 square meters. M. In cells of this type, air is poured into the space occupied by the ladder and into special locks. Airlift is carried out on a permanent basis or is activated automatically in case of fire or smoke.

Basic Materials

When creating evacuation smoke-free passageways, concrete is most often used. It is safe in fire prevention, durable and easy to use material. As a supplement to the concrete base, steel structures are used, for example, in the manufacture of fences or doors. Metal spans are also justified in light structures.

Wooden elements are used in a small volume: wooden handrails or door handles, which must necessarily be treated with fire fighting compounds.