Places of a mass congestion of people shall be equipped with the fire-prevention alarm system. But since carbon monoxide is invisible and spreads with great speed, besides signaling it is obligatory smoke removal system (CDS) - a set of air ducts and equipment for the forced removal of smoke from premises.
Let us see what elements are included in the CDS, what are the features of system design for private houses and public spaces. In addition, let us designate the norms of calculation, installation and maintenance rules for the smoke removal complex.
The content of the article:
- Types of smoke removal systems
- The main and additional components of the CDS
- The use of the CDS in private homes
- Fire Safety Standards for Installation
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Designing a CDS in a building
- The main locations of the CDS
- Where not to mount smoke removal system
- How to calculate the required amount of ventilation
- SDU mounting technology
- Ventilation system maintenance
- Conclusions and useful video on the topic
Types of smoke removal systems
The smoke evacuation system from the premises is arranged in the event that the threat of ignition of filling the confined space with poisonous volatile emissions is great.
Installing it is rational if it is impossible to remove the products of combustion with banal airing, or even when the window is open, the movement of polluted air mass to the windows will be too slow.
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Systems that remove smoke, burning and airborne toxins are arranged in public, industrial, and commercial buildings.
Smoke removal systems are constructed wherever the organization and operation of natural ventilation is impossible: these are staircases, metro stations, elevators, mines and similar objects that do not have direct communication with the street
This type of system is designed to provide conditions for the evacuation of people in the building in case of an emergency or a fire.
Smoke extraction system is an integral part of smoke ventilation, working in tandem with air suppression system
The system that removes smoke and ashes is equipped with powerful fans that capture and exhaust air from the premises with a fumes of concentration that is dangerous to people.
Fans of the system are supplied with check valves, which exclude reverse movement of smoke and thermal decomposition products.
Competently designed smoke removal system must fully cope with the removal of products suspended in the air of combustion products, ensuring safe evacuation until the moment of arrival of the Ministry of Emergency Situations
The design of smoke removal systems is influenced by the requirements for clean air, the purpose of the building, vibration rates, local meteorological data, operational safety.
Smoke removal systems
Scope of use of chimneys
Smoke removal
Smoke ventilation part
Smoke Exhaust Fan
Device to remove smoke from the room
Device requirements
Design factors
According to the method of removing the smoke from the premises of the system can be divided into two types:
- Static.
- Dynamic.
Their functionality is based on fundamentally different processes.
Static cds at the time of fire detection, it turns off ventilation and oxygen supply from the outside and blocks smoke in the same room, preventing it from spreading.
If there is a possibility of filling the premises with toxic gases in case of fire, you should not save on the smoke exhaust system (+) device
At the same time the temperature in the room is heated to a critical level of 1000 ° C. If people are evacuated from a building through this room, then it is dangerous and can lead to poisoning, burns and impede evacuation.
Dynamic sds work differently. There is an increase in air circulation due to the work of powerful fans and the removal of carbon monoxide, which prevents the accumulation of smoke.
Smoke levels are decreasing, but carbon monoxide concentrations still occur. Also, the air temperature rises. The main purpose of the dynamic CDS is to gain time for evacuation. She perfectly copes with this goal.
If we talk about the pricing criteria, the static CDSs are cheaper than the dynamic ones. This is one of those cases where it is better not to save on security. When using dynamic systems, chances of avoiding volatile toxins poisoning are higher. It should be noted that fire safety regulations allow both types of systems to be installed.
Even the simplest ventilation significantly increases the chances of rescue in case of fire. It is precisely because of the absence of the CDS in the old high-rise buildings that the need for their modernization arises. The same applies to old buildings adapted for storage and production needs.
The main and additional components of the CDS
The main elements of a dynamic system are powerful fans that pump air. They remove from the premises not only carbon monoxide, but also a fine suspension, such as ash, soot, and fumes.
This equipment is able to work with air, the temperature of which does not exceed 600 ° C. This margin of safety is sufficient to ensure the safe removal of people from the building.
Fans pump air masses through smoke shafts. This is an extensive network of channels, which is mounted according to the project. Different parts of the CDS have different bandwidth - it depends on the complexity of the system.
Pipes designed for air discharge in small rooms have a smaller perimeter and are not connected with the general course of the smoke shaft
These elements are made of non-combustible materials. The most popular smoke mines are made from cold rolled black steel.
Another component of the CDS is fire retardant valves. Their task is not to let the flame into the ventilation and prevent its spread throughout the building. Mostly used models with electric or electromagnetic drive.
Fresh air enters air ducts. They represent the pipes to which the fans are connected, supporting the air mass. Channels are brought to the places where people are evacuated, including to the elevator shafts.
The main component of any CDS is the control unit. The panel connects to a fire alarm, less often - directly to the sensors.
As soon as a fire signal is given, the control unit turns on the CDS, which begins to remove smoke from the building. At the same time, the automation opens all hatches and adjusts the operation of the fans.
Another element of the system is automatic, which opens windows and doors in case of fire. These elements are not included in the mandatory composition of the systems. They are used in places where there is a large glazing area, and this makes it impossible to install smoke chambers.
The use of the CDS in private homes
According to the standards in residential buildings do not require the installation of the CDS. It is believed that for the release of products of combustion open enough windows. The only exception may be buildings owned by private individuals and used for commercial purposes. For example: a hotel, boarding house, private clinic or school.
Since the number of residents in a country house is usually small, the work of a standard system for removing smoke from a room during a fire allows people to leave the house in a safe environment.
To notify about the fire enough to install a fire alarm. This is quite enough for a private house.
If you want to protect your stay in a private house, you can use a different type of ventilation device that removes smoke. This is a complex of electronics that controls the opening of doors and windows when receiving signals from sensors (+)
It is necessary to pay attention to the sensitivity of the installed sensors. If they have a low threshold, the overall system performance will drop dramatically.
Fire Safety Standards for Installation
For places of mass gathering of people the requirements are different. In high-rise buildings, people's lives depend on this system. When leaving their apartments in large numbers, tenants will have to move slowly, as the capacity of the elevators is limited, and descending the stairs takes time.
Mandatory CDS is installed in the following rooms:
- residential high-rise buildings;
- shopping, business, sports and cultural centers;
- production premises;
- infrastructure facilities and schools.
These requirements also apply to gambling and entertainment businesses. In addition, there are other objects to which these requirements apply.
Designing a CDS in a building
Before calculating and designing a CDS, it is necessary to study the factors that need to be considered:
- Building characteristics - number of storeys, area and a clear evacuation plan in case of fire.
- Glazing features - the number, location and area of windows.
- Characteristic of smoke permeability of materials from which the building is made, insulation and facade.
The development of the CDS project for a building can only be carried out by companies that have received a license from the Emergencies Ministry. Drafted project also before installation should be agreed with the Ministry of Emergency Situations.
The main locations of the CDS
In buildings with a height of more than 28 m for different purposes from administrative to household use, a system for exhausting smoke and combustion products is obligatory. The height of the building is determined without taking into account the basement and attic technical premises.
The CDS should pass along corridors longer than 15 m, where there are no natural sources of fresh air, no window openings, balconies or loggias.
In the rooms of the basement and corridors, if they are used not only for the maintenance of building communications, but also as underground parking lots, warehouses and industrial premises. Ground floor evacuation paths also require CDS.
In addition to the general corridors, a method must be provided for the removal of combustion products from each workshop, production or administrative premises in which people stay for a long time.
If the premises or corridors have a system for automatically opening windows when a fire alarm is triggered, then it is not necessary to lay the SDS in them.
Where not to mount smoke removal system
In rooms that are equipped with autonomous fire extinguishing systems of powder, foam or water type. This applies to systems that determine the source of fire and extinguish it automatically. It is worth noting that parking lots are an exception.
If a CDS is installed in each room, then it is allowed not to equip a common corridor with a system for removing combustion products. This rule is valid only if each room has an area of less than 50 square meters. m. Otherwise, the installation of smoke ventilation in the corridor will be mandatory.
How to calculate the required amount of ventilation
There are clear recommendations for the design, the data of the Ministry of Emergency Situations of the Russian Federation. The document provides formulas for calculating the required ventilation parameters. Also in the text of the recommendations are given tables on the properties of materials used in the construction of the building.
Here are examples of formulas and tabular data for design and calculations.
In determining the air permeability of the facade of a building, one formula is used. However, it is worth making corrections for wind direction and fluctuations in ambient temperature (+)
An important characteristic of the system is its resistance to the temperature of hot smoke. In addition, throughput and pressure resistance (+) are taken into account.
The power of the CDS should be sufficient to maintain the room. Indicator air circulation rates must not exceed 1 m / s. This restriction is dictated by safety considerations - the flow of air increases the source of fire.
The parameter can be adjusted by reducing or increasing the valve cross section. The valves are installed from the accounting of one to 600-800 square meters. m
At each point that requires the installation of the CDS, there must be at least one inlet, through which fresh air enters. The parameters of the holes for air flow are determined by the area of the premises
Air movement is carried out by external fans. Since these systems use forced air circulation, during the design it is allowed to take more than two turns of air pipes.
SDU mounting technology
In addition to the threat of poisoning, smoke causes loss of orientation and panic during evacuation. There are designated areas where the smoke removal system should run.
First of all they include:
- stairways and platforms;
- foyer;
- corridors, passages and galleries;
- porches.
In addition to the evacuation destination, the CDS allows firefighters to quickly enter the building. This allows them to find the source of ignition, localize it and eliminate it. This is primarily beneficial for the owner of the building, as it allows to minimize the possible damage from fire.
Installation work begins with laying chimney pipes and ventilation. This stage consists of mounting individual modules. First, special clamps are installed in the ceiling to which each module is attached.
Modules are connected in series. When they are attached, sealing is performed. These pipes must be installed in strict accordance with the design.
Branches are installed as needed. As a rule, these are elements that have one or two channels. Such a fork must be installed in each zone where, according to the regulations, the air masses must be circulated.
The openings of the channels are closed with a special grille. Chimneys transport combustion products to larger smoke mines.
Each smoke shaft leads to an exhaust fan, which is installed directly on the roof of a building. Fans are mounted directly at the exit of the smoke chambers. They are mounted in strict compliance with the recommendations of the manufacturer.
Above the fan there is a small section of the shaft that leads to the sunroof. Hatches should be installed in accordance with the manufacturer's recommendations.
There are models of fans that are located vertically on the roof of the building. These models do not need security hatches. They use less automation, but they do not look aesthetically pleasing
In parallel with the chimney pipes are mounted for air overpressure. They can be mounted near chimneys. It is necessary to pay attention to the fact that the holes for the removal of air should not be located near. If you do not comply with this rule, the efficiency of the system will decrease dramatically.
Over the chimney extends wiring. It should be three phase power cable with a voltage of 380 V and a nonflammable braid. It is connected to the electronics necessary for the automatic opening of the hatches and system valves.
The cable should not come into contact with and in close proximity to the heated parts of the chimney. Most often, the cable is fixed above the parallel branch of the air overpressure.
This protects against short-circuits that occur when the wire melts. Incorrect wiring leads to failure of the entire smoke removal system.
The final stage of installation work is the connection of an alarm or sensor system. In buildings with large areas do zoning. Separate control units are responsible for each section. There are systems where ventilation and smoke removal must be started manually.
Ventilation system maintenance
After installation of ventilation system and smoke removal shafts check for good condition. This is done before and during the work of supervisory authorities. The test consists in the sequential testing of each element of the system for operability.
After the building is commissioned, the supervisory authorities will check its working condition during scheduled inspections. If the system fails, the owner will be given an order to eliminate this problem. It is recommended to carry out maintenance work that will be performed by the organization - the installer of the equipment.
If a faulty CDS leads to mass death during evacuation, the building owner will be criminally responsible for violating fire safety regulations.
Conclusions and useful video on the topic
Installation standards and ventilation test rules:
It is important to monitor the performance of the ADD, since if operated improperly, debris and foreign objects can get into the ventilation pipes. This may be due to poor installation, when part of the construction waste remains in the ventilation.
When accumulating debris, the air supply can be partially or completely blocked. Preventive inspection should be carried out regularly - it will save people from death if a fire occurs.
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