SMOKE VENTILATION: MAIN RISKS DURING FIRE
In the event of fire inside of a building, smoke and heat gases rise up in the building, creating a layer of dangerous gases under the ceiling, which fill up the room in a very short time.
The smoke precludes the visibility of the emergency exit or impedes the prompt intervention of the firemen. Due to the toxic substance of the smoke, the 90% of all fire victims die due to smoke inhalation.
Furthermore the high temperature inside of the building, could generate explosion or big damages to the building structures, with the consequent collapse, called flashover .
WHY USE NATURAL SMOKE VENTILATION?
To avoid the above dangerous events and keeping escape routes clear for longer and also ensure the fire service can quickly and safely locate and extinguish a fire, a natural smoke and heat exhaust systems (NSHEV) must be integrated in fire protection concept.
The NSHEV consist in a system of automatic opening windows installed in the upper sections of the façade and/or in the roof (smoke exhaust vents) for let the building free from smoke and heat. Ventilation openings (air inlets vents) in the lower area increase the thermal uplift, generating a “chimney effect”.
NATURAL SMOKE VENTILATION (NSHEV) DEFINITION:
The NSHEV consist in an electrical drive installed and operating on vertical or horizontal window design and developed:
– to open within 60sec from the event
– to resist to very high heat up to 300°C
– to be reliable up to 10.000 cycles in case of natural daily ventilation.
all according to EN12101 standard.
NSHEV systems can be divided in two main categories:
1) AIR INLET VENTS
2) SMOKE EXHAUST VENTS.
NATURAL SMOKE VENTILATION NSHEV SYSTEM:
NSHEV systems need electrical power supply 24Vdc and shall be connected to an electric system for smoke and heat extraction which are composed by a control unit and related smoke and heat detector and/or emergency push buttons. The control unit shall be include power supply backup solution aim to grant the 24Vdc even if the main power supply 230Vac is down due to the blackout caused by the fire.
