About Mechanical Smoke Ventilation Systems

The integration of smoke-control systems have the ability to improve the safety of buildings significantly. Smoke ventilation systems are available in various forms and vary widely when it comes to complexity. For example: there are mechanical smoke ventilation systems, pressurization systems as well as natural-smoke venting. Regardless of the type of system, it is recommended by fire risk assessment Kent company, the Fire Risk Assessment Network, the objective basics are all the same and will include the following:

  • To make sure that escape routes are kept free from any smoke
  • To remove or contain smoke form an area experiencing a fire in order to prevent the smoke from moving into other areas
  • To accelerate fire-fighting operations
  • To minimize property loss and protect lives


Mechanical Smoke Ventilation System


How An Mechanical Smoke Ventilation System Works

The MSVS (Mechanical Smoke Ventilation System) acts effectively as a type of depressurization system. The system extracts heat and smoke out of an area which results in depressurization of the space. Due to the fact that surrounding areas like staircases have higher pressures, the air will be forced out of these areas and directed towards the smoke shafts preventing smoke from migrating into the staircases and the neighboring areas.

However, it is essential to stipulate that there is an extra inlet of air to a space that is depressurized in order to stop the space from becoming over depressurized. When a room becomes too depressurized, the smoke-venting equipment can become damaged and the pressure differentials that occur across the doors can cause the door handles to become difficult to pull open between the fire area and depressurized room.

The make-up of inlet air for these systems can be achieved in various ways and will be dependent on the layout of a building. Below are the 4 common methods used to achieve an air inlet:

  • Natural inlet of air through an AOV positioned at the top of a staircase
  • Natural inlet of air through external air
  • Mechanical inlet of air through a shaft
  • Natural inlet of air through a shaft

MSVS In Residential Buildings

The foundation of smoke-control systems in residential buildings is to stop smoke from moving into the area of a staircase in order for the occupants to escape from fires unhindered. In addition, this can ensure that fire services can have a protected and clear access to the source of the fire.

As an MSVS pulls smoke and heat from a common lobby or corridor that is not dependent on the buoyancy of natural smoke, the “shaft” area is significantly minimized when compared to natural systems. The area of a smoke shaft on a MSVS will depend on a number of factors like the size of an AOV opening in the shaft, the extraction rates of a fan, fire loading in the next room as well as the size of the lobby or the corridor. Once all these factors are taken into consideration the shaft area on the MSVS will typically range between 0.25m2 and 0.6m2. Fire engineers are able to provide the correct guidance in this matter.