Smoke Riser Extract AOV Shafts

Air Tightness Solutions have significant experience of testing Smoke Extract Shafts and can advise on the problematic areas of air leakage early on in the construction stage to ensure that the Shafts meet stringent targets.

Automatic Opening Vent Riser Shafts with Mechanical Smoke Ventilation Systems (MSVS) are installed in corridors, lobbies and stairwells of commercial and domestic builds. Their purpose is to ventilate the common areas that may become completely smoke logged following a fire. Leaky wall construction of a Smoke Extract Shaft can seriously affect the performance of a Smoke Ventilation System.

Lobby / Stair Case Pressurisation

A pressurisation system may be used in place of natural ventilators or shaft systems. An air supply system maintains a positive air pressure in the staircase, which prevents smoke from entering it from the fire location. Excess air pressure needs to be avoided, either by fan speed control or by pressure relief from the staircase.  Air leakage measurements are undertaken to ensure the positive pressure within the staircase is maintained when the escape route is in operation.

In the event of a fire, mechanical smoke vent systems offer the ultimate in smoke control as they remove smoke from the building, thus aiding the occupants’ means of escape and providing suitable access for firefighting services. This type of smoke extraction system comprises of a mechanical extract shaft that serves the common corridor and/ or lobby.

When smoke is detected within a protected lobby, only the fire damper to the smoke shaft on the fire floor will open (all other dampers will remain locked shut). In turn, the vent at the head of the staircase will open allowing the smoke to be removed and make up air for the smoke extraction system. The fan at the top of the mechanical smoke shaft extracts the smoke and prevents the migration of smoke into the adjacent compartments.

On detection of smoke within a lobby, only the fire damper to the shaft on the fire floor will open (all other dampers are locked shut) and the vent at the head of the staircase opens. The fan at the top of the shaft extracts the smoke and prevents the migration of smoke into the adjacent compartments.

Our knowledge and experience of smoke riser pressurise testing of Automatic Opening Vent Riser Shafts with Mechanical Smoke Ventilation Systems (MSVS) can be helpful at both the build and pre-completion stage.

Further guidance is available in the Colt Smoke Control in Apartments Leaflet, available as a free download from www.coltinfo.co.uk.  SCA “Guidance on smoke control to common escape routes in apartment buildings”, is also available as a free download from www.FETA.co.uk