Pressurized staircase: what is its real importance in case of fire?
Based on Technical Instruction (IT) No. 13/2011 of the Fire Department of the State of São Paulo, which talks about the basic requirements for emergency exits in case of fire, pressurization of the stairs is the system responsible for enabling the exit of the people of the burning places, in a safe way.
The fire prevention system is broad and includes a series of factors and measures. In this article, we will primarily talk about the pressurized ladder. Understanding how this system works and why it is so fundamental.
First Paragraph in IT 13/2011:
"Objective:
1.1 Establish the minimum requirements necessary for the design of pressurization systems for safety stairwells in buildings.
1.2 Keep emergency stairwells free of smoke to allow occupants to escape from a building in case of fire. This system can also be activated in any case where it is necessary to evacuate the building.
TECHNICAL INSTRUCTION No. 13/2011 STATE SECRETARIAT OF SP. Available at: https://www.bombeiros.com.br/pdf/instrucoes-tecnicas-13.pdf.
Access on 31 May. 2019
Dimensioned issues
IT nº 13 specifies all parameters that must be strictly followed in buildings. Mainly as a way to maintain safety in the event of a fire.
Parameters such as: width of the exits, distance traveled, handrail, floor, wall, lining, ceiling and material of the objects present in the structure of the building were regulated. All this, so that the production of more fire and smoke in the place is not facilitated or encouraged.
Other normative references (NBR's) were used as a basis for the creation of IT 13. These cite important factors such as: fire door, emergency lighting system, electric elevators, electrical installations and reaction to fire of the materials that are formed in the construction.
because this system
é So important?
There are data that estimate that in fatal fire cases, the number of deaths from asphyxia exceeds the number of deaths from burns.
This is very serious!
Treatment of smoke poisoning according to Medicina Net. Available at: https://www.mdsaude.com/2013/01/fumaca-incendio.html Accessed on May 31, 2019.
Without a system that protects this escape route (the fire escapes), this place is certainly compromised due to smoke, putting people's safety at risk.
In addition to being toxic, due to the high degree of smoke, high temperature smoke causes internal swelling and burns throughout the respiratory tract. Promoting the closing of the airways, leading to death by poisoning or asphyxiation.
But what is pressurization?
Pressurization is the system that prevents fire smoke from entering emergency exits, so that people can be safely evacuated.
Through this system, which consists of a fan (with an independent power source), panels, louvers, and air filters , air is drawn from an external environment and blown into the stairwell through ducts and grilles on all floors, maintaining the area under positive pressure.
In addition, this system must be well balanced. All floors must receive airflow calculated to maintain equal positive pressure.
In the event of a fire, the smoke detector will activate the pressurization system which will start working immediately.
Having the guarantee that the ladder will remain pressurized, the fire department is able to act effectively in removing people from the site. Since the smoke will not invade the emergency exits.
Installation
There are 2 ways to implement this system. Where the fan can be installed in an engine room or in an antechamber.
This fan is located in a separate environment, captures the outside air that is routed and inserted into the floors until they reach a positive pressure that varies between 40 and 60 pa. In this way the smoke that is outside is prevented from entering the place.
System stages
There are 2 ways to have your ladder pressurized:
- In the 1-stage system, the ladder is only pressurized when the smoke detector is activated.
- In the 2-stage system, the environment is kept under constant pressurization. However, the air flow volume is kept low, and when the alarm is triggered, the pressurization level increases.
The use of air filters in the pressurization system of fire escape stairwells promotes the capture of dust particles that remain suspended in the air.
G1 (ABNT) filters – coarse metal filters – are primarily indicated for this system and are installed at the external air intake.
What differs where the system will be installed is the size of the building. And this can range from small and medium-sized buildings as well as large commercial buildings (where they are usually installed in a machine room).
other needs
For efficiency, it is necessary that in addition to pressurization, the fire doors are effective so that there is no loss of air that pressurizes the environment.
Likewise, it is of utmost importance that there is an independent source power system in the building. Because it's no use having the ladder pressurized, without the guarantee that everything will work correctly. Especially in the event of a power outage during a fire.
The pressurization system has:
- Smoke detector
- Alarm system
- Inflation System
- Exhaust System
- Fans
- shutters
- Grills
- Air Filters
- ducts
- Fire Door
- Independent electrical power system
It is through pressurizing the air that stairs become a safe escape route for people.
It is through the stairs that the Fire Department works and ultimately saves many lives!
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