Smoke extraction from an object

Smoke extraction systems are vital in case of fire, they keep rooms smoke-free and thus give people orientation.

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Hidden Fields
28 February 2022 Fire Safety

Smoke extraction systems such as SHEV systems ensure smoke-free rooms in the event of a fire and provide orientation for people - if they function and are regularly maintained! We will introduce you to various SHEV systems: Where is which SHEV system useful? What are the advantages and disadvantages? And what about maintenance?

What a SHEV system is used for

SHEV systems conduct smoke and heat out of the building, thus reducing the smoke load in the room and keeping escape and rescue routes clear for longer. Smoke extraction is extremely important because toxic smoke is more dangerous to people than fire (smoke poisoning)!

SHEVS systems exchange the air in the building, in the upper part of the building the toxic smoke and heat is discharged, at the same time fresh air or oxygen is supplied in the lower part of the building. Supply air from below is important so that the smoke in the lower part of the room is pushed upwards (chimney effect).

Smoke extraction or a smoke-free room has many advantages:

  • People in the building can orient themselves more easily and get to safety.
  • Rescue forces can save people, animals and property more easily.
  • Firefighters can see better, orientate themselves more quickly and fight the fire.
  • The danger of an explosive flashover is reduced.
  • Consequential fire damage is reduced and thus also business interruptions.

Smoke extraction from buildings by means of smoke and heat extraction systems

RWA-Anlage Bestandteile

The term smoke and heat extraction system (SHEV) is a generic term and describes the complete SHEV system, regardless of the area of application, functions or release types. Such a SHEV system consists of several parts, including:

  • Smoke and heat exhaust ventilators (SHEV)
  • Release and operating elements
  • Power supply
  • Ducts
  • Air supply systems
  • Smoke barriers

First of all: What is a smoke and heat exhaust ventilator?

A smoke and heat exhaust ventilator (SHEV) is the opening element that is installed in the building roof or wall to remove smoke and heat. This can be, for example, the following:

  • Skylight dome
  • Window
  • Louvres
  • Flap ventilator

This smoke and heat extraction device is used in natural (NSHEV) as well as in mechanical smoke extraction systems (MRWG). 

Smoke Extration From Objects

Smoke extraction through a natural smoke extraction system

Natural smoke exhaust systems (NRA) are installed in rooms that have an exterior wall or ceiling and where hot smoke can be generated. An NRA system relies on the thermal buoyancy principle - hot smoke, heat and fire gases rise upwards. Through an automatic or manual release, the natural smoke and heat exhaust ventilator (NSHEV) opens, for example, the skylight dome on the roof and discharges hot smoke and fire gases above it. Natural smoke and heat exhaust ventilators can have an electrical, pneumatic or pyrotechnical release. They are installed in particular in:

  • Stairwells
  • Places of assembly
  • Production halls or warehouses
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The electric NRA system can also be used as a ventilation system, i.e. it can be controlled manually, e.g. to ventilate a room well on very warm days. On the orange manual button of the natural smoke and heat exhaust system are two additional buttons for opening and closing the system for this purpose. The release button behind the safety glass of the manual button is only intended for use in case of fire.

Tip: NRA systems are more effective and cheaper than MRA systems, but they only work with hot smoke.

Maintenance of a natural smoke extraction system

As a rule, annual maintenance by a competent person. The operator must carry out and document a visual inspection at least once a year between the maintenance intervals. We would be pleased to carry out the maintenance of your NRA system.

Smoke extraction through a mechanical smoke extraction system

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Mechanical smoke extraction systems are usually installed in interior rooms or where no sufficient opening to the outside can be installed. These can be, for example, the following rooms:

  • Basement rooms
  • Underground garages
  • Sales areas or
  • Interior rooms in a multi-storey building.

Mechanical smoke extraction systems are coupled with mechanical ventilation and fans in order to direct heat as well as cold or warm smoke from the room through ventilation pipes to the outside via an opening element. At the same time, fresh air is also fed into the building via other air openings or supply air fans (air exchange). With Mechanical smoke extraction systems, it is imperative that the motor drive or fans receive power all the time, i.e. corresponding electrical lines must be separately protected from fire and heat.

Maintenance of mechanical smoke extraction systems

Annual maintenance by a competent person. The operator must carry out and document a visual inspection at least once a year. We will gladly carry out the maintenance of your MRA system.

Smoke extraction through a smoke protection pressure system

A smoke protection pressure system (also called a pressure ventilation system, overpressure system or safety overpressure ventilation system/SÜLA® system), ensures that no smoke enters from surrounding rooms by means of a controlled overpressure in a certain area. For this purpose, it is mandatory that a fire alarm system has been installed in all rooms and that the pressurised ventilation system is automatically switched on with the first smoke alarm. In addition, there must be self-closing fire doors to the surrounding rooms that close in the event of an alarm. However, the overpressure may only be set high enough so that people can still open the fire doors to get to safety. At the moment the door is opened, the pressure is increased to prevent smoke from entering the protected area. Smoke protection pressure systems are often installed in the following areas:

  • Stairwells
  • Fire brigade lifts
  • Escape tunnels

Maintenance of smoke protection pressure systems

Annual maintenance by a competent person. The operator must carry out and document a visual inspection at least once a year. We will be happy to carry out maintenance on your RDA system.

Smoke extraction from a (underground) garage

The smoke extraction of a (underground) garage aims at forcing the smoke into a certain area of the garage so that it can either escape to the outside through a natural opening or be mechanically directed to the outside through a smoke extraction system (mechanical smoke extraction system). The following conditions determine whether a garage smoke extraction system is suitable:

  • Area and height of the garage
  • Location of the garage room, i.e. whether it is above or below ground level
  • Specified protection goal

The Model Garage Ordinance M-GarVO specifies the requirements.

Garagenentrauchung

Maintenance of garage smoke extraction

If a mechanical smoke extraction system is installed, it must be maintained once a year by a qualified person. In addition, an inspection in accordance with the TPrüfVO is required every 2-6 years (depending on the federal state). We are happy to carry out the maintenance of the garage smoke extraction system.

Smoke extraction through heat extraction

A heat vent is an opening on the roof or on the upper façade that opens at a certain temperature. This allows heat to be dissipated. In principle, a heat exhaust vent is similar to an natural smoke and heat extraction system, but the heat exhaust vent opens much later because it is only opened by, for example, a melting of thermoplastic surfaces.

A heat exhaust can therefore extend an existing SHEVS, but not replace it.

Lift shaft smoke extraction

A lift shaft smoke extraction system basically has one fixed task: to remove smoke from the lift shaft in the event of a fire. In addition, it often has a second task: ventilating the lift shaft if necessary.

Lift shaft smoke extraction systems are primarily intended to prevent a fire or smoke from spreading over several floors. Smoke detectors are installed in the lift shaft for this purpose, and smoke extraction is started when they are triggered. Ventilation is used when heat accumulates in the lift shaft or when extra fresh air is needed because the lift is stuck with people inside.

Maintenance of lift shaft smoke extraction systems

At least once a year by a competent person. We will be happy to carry out maintenance on your lift shaft smoke extraction system.

Smoke extraction from a staircase

A smoke extraction system in a stairwell/room ensures that rising smoke is extracted and that the stairwell can continue to be used as an escape and rescue route. Doors leading to the stairwell must be equipped with self-closing fire doors. Smoke extraction systems for stairwells are required in buildings

  • 13 metres or more in height,
  • five storeys or more, or
  • where the stairwell is inside (depending on the MBO for each federal state).

Natural or mechanical smoke and heat extraction systems form the basis, as do the specific requirements from the fire protection concept.

Treppenhaus Entrauchung

Maintenance of staircase smoke extraction systems

At least once a year by a competent person. We will be happy to carry out maintenance on your staircase smoke extraction system.

We hope we have been able to give you a good overview of smoke extraction and smoke extraction systems. If you are missing any information or would like to receive a quotation for the maintenance of a smoke and heat extraction system, please do not hesitate to contact us. Thank you for reading this blog article.

Do you still have questions about smoke extraction systems?

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