Natural smoke and heat exhaust ventilation (NSHEV) improves the door safety condition in case of fire inside of building.
Main risks during fire
In the event of fire inside of a building, smoke and heat, gases rise 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,90 per cent 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 resulting in a collapse called flashover.
Why use smoke ventilation?
For avoiding the above dangerous events, keeping escape routes clear for longer and also ensuringthat 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 or in the roof for let the building free from smoke and heat. Ventilation openings in the lower area increase thermal uplift generating a “chimney effect”.
The NSHEV consists of an electrical drive installed operating on vertical or horizontal window design and developed for resisting high heat (up to 300°C) with reliability (up to 10.000 cycles) tests according to EN12101 standard. NSHEV systems can be divided into two main categories -Façade Exhaust System & Roof Exhaust 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 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 fire.