Cable penetrations: purpose, construction, types

In accordance with the requirements of fire safety, in the construction of any communications, cable penetrations - products, prefabricated structures, which are intended for passage of cables, pipelines, communication lines through walls and partitions, must be built. Their main purpose is to prevent the spread of fire to neighboring premises for flammable materials. They are arranged on the basis of SP 2.13130.2009 and GOST R 53310-2009. Their installation is mandatory and regulated by Federal Laws.

Fire compartments and cable penetrations

According to the requirements of fire safety, when building residential buildings, they are broken into fire compartments, which block fire and smoke on their territory, and prevent them from spreading beyond the compartment. However, through any room are engineering lines that violate the integrity, tightness of the fire compartment. In order to keep the fire resistance limits of the structure and mount cable penetrations.

A vivid example, which proves the need to install such structures, is a fire on the Ostankino TV tower in 2000. Here, the telecommunication lines were placed in a vertical shaft, without breaking it into fire compartments and laying protective passes. As a result, the fire quickly spread throughout the building.

Construction of cable penetrations

The simplest cable penetration is a metal sleeve, embedded in a wall or partition. Through the sleeve passes a cable, a pipeline whose outer diameter is slightly smaller than the diameter of the fire-fighting structure. The gap between the communication line and the inner wall of the sleeve is filled with a paste, thoroughly saturated with fat. That's why the simplest cable penetrations are also called oil seals. Also asbestos, rubberized rings, special padding can be used together or instead of tow.

Several other designs are being made at industrial facilities and power plants. They are two metal strips, the ends of which are connected by sleeves. To seal the gap between the communications and internal walls, use special diaphragms and washers. One such cable penetration serves to pass several engineering lines.

Materials for sealing

To create the possibility of laying an additional or replacement of the old engineering line, all the wires, cables and other communications pass through walls in boxes or scraps of metal pipes (sleeves). Therefore, the sealing of cable penetrations should be made of refractory, water-, gas-tight material, which is easy to remove.

At the same time, the ability to resist fire at the embankment should not be lower than the refractory capacity of the wall.

In SNiP 3.05.06-85 specific mixtures are indicated, which are allowed to fill the gap between the cable and the penetration:

• Cement-sand mixture in a ratio of 1:10;
• Composition of clay and sand with a ratio of materials 1: 3;
• Sealing compound of clay, sand and cement (1.5: 11: 1);
• Gypsum and expanded perlite, taken in the proportion of 2: 1;
• Other materials that meet the requirements of fire safety.

To seal cable penetrations is also allowed construction foam, if it is certified in accordance with the requirements of GOST R 53310-2009. Gaps in the walls can not be filled, if the partitions are not fire barriers.

Modular penetrations

In modern construction, modular penetrations are used to isolate fire compartments. They are steel or plastic frames, which are equipped with blind inserts or modules with holes. To protect against electromagnetic radiation, copper gaskets are installed. Tightness is created by tightening bolts.

In general, modular cable penetrations fireproof are a complex design, assembled in place from pre-fabricated sealing inserts from a hard-to-burn polymer. As fasteners, elements made of galvanized high-grade steel are used.

In this penetration, the cable is placed in a special sealing module and is compressed by the adapter for increased tightness. With the tightening of the tension bolts, the sealing inserts are squeezed, the cable is tightened and the gas and waterproof penetration is ensured.

Features of installation of cable penetrations

Mounting the penetrations has its own characteristics, which depend on the type of material of the supporting structure. So, laying cable systems in monolithic-concrete buildings, fireproof structures are laid directly in the formwork prior to pouring the concrete mixture. In the construction of prefabricated monolithic buildings, excavations are laid in blocks at the factory during their manufacture.

In houses made of brick for laying, cable systems are placed in special channels - strobes. In the finished monolithic structures, small holes are drilled with a diamond drill . The diameter of the penetration is calculated separately. During the construction or temporary operation of the building, the penetrations are made of special fireproof pillows.

Testing of cable penetrations

Depending on the place of operation, cable penetrations must meet the established requirements. So, when laying them on nuclear power plants, they should be tested for the ability to absorb, isolate or reflect radiation.

At ordinary construction sites, cable universal boring is tested by heating, by force (mainly on bending resistance), and also on fire resistance, water and gas insulating properties.