What will the NRA replace

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For natural smoke extraction via roof openings, natural smoke extraction devices (NRWG) with geometrically free smoke extraction surfaces (Ag) or with aerodynamically effective smoke extraction surfaces (Aw) can be used in accordance with the respective specifications.

Geometrically free smoke extraction areas (Ag) can easily be checked on site with a folding rule. These are the areas on the side after the opening, which are free for the outflow of smoke gases, which, for example, in the case of a dome light, are made up of two triangular and one rectangular areas. If, depending on the opening width, this area is larger than the light area, the light area corresponds to the geometrically free smoke extraction area.

Aerodynamically effective smoke extraction areas (Aw) are determined in the wind tunnel, and a test certificate is issued for the determined value. NRWG with after DIN 18232 smoke and heat free Aw values ​​determined can be used for the smoke extraction function without taking into account the main weather direction in the roof. However, if the NSHEV is combined with a ventilation function, it is advisable to align the hinge side to the main weather side.

A natural smoke and heat extraction system (NRA) includes at least smoke and heat extraction devices (NRWG)

  • an automatic triggering that reacts to smoke and / or heat (mostly integrated in the NSHEV)
  • a manual trigger option
  • Corresponding energy supply (also effective in the event of a power failure) and cables
  • sufficient ventilation openings
Rooms with a floor area of ​​more than 1,600 m² are usually divided into smoke sections of a maximum of 1,600 m² with smoke curtains. In order for a smoke extraction system to work safely in an emergency, it is prescribed, among other things, that the suitability of the NSHEV is specifically proven. NSHEVs for installation in roofs and walls are classified as building products requiring verification according to the building regulations list. According to the Federal Law Gazette from 01.09.2006, the building product natural smoke ventilation (NRWG) may only be placed on the market if it is in accordance with DIN EN 12101-2 Keeping smoke and heat free - Part 2: Regulations for natural smoke and heat ventilation devices checked and the corresponding CE marking is attached. This applies to both horizontal and vertical installation.

The requirements for the construction product of natural smoke extraction are directed towards the entire product and not just individual components. This also applies if the final assembly of individually delivered components only takes place on the construction site. For so-called openings for smoke evacuation or for fume cupboards made individually on the construction site from components from different manufacturers that have not been tested and certified according to DIN EN 12101-2, the usability can also be determined in individual cases by the respective top building supervision of the federal state, in that the construction project is taking place. In these cases, too, the respective entire construction (covering of the building envelope, hinges and fittings, opening units, control elements, etc.) has to be considered in terms of its usability and functionality (snow load, wind pressure or suction, behavior at high and low temperatures, wear behavior or functionality). Service life, determination of the smoke extraction area, etc.) as well as possible further requirements resulting from the local conditions or the construction.

RWA release stations are to be identified by the sign "Rauchabzug". In accordance with DIN 18232-2, air intake openings are to be marked with the sign "RWA air intake opening - please keep clear". For natural smoke extraction through external walls, windows can be used in addition to blinds (louvre fans). Since both dynamic pressure and suction can prevail on every external wall depending on the wind direction, special rules (e.g. DIN 18232-2) and a wind direction-dependent control are required for the installation.
Source: Daylight and Smoke Protection Association (FVLR), Detmold

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