Ventilation holes make passageways for fire
The popularity of forced ventilation systems is increasing dramatically, largely driven by air tightness regulations and increasing energy efficiency requirements. This means a dramatic increase of ventilation ducting and valves which inevitably penetrate the fire compartments, both in ceilings and walls. Mark Davies has the inside story
PVC VENTILATION ducting, if unprotected, offers open passageways for the spread of smoke and fire around a building. This can be both vertical and horizontal in the case of 'whole house ventilation systems'.
Ventilation ducting offers the perfect means for fire spread, the duct work, by its very nature, carries high volumes of air which would intensify a fire and the PVC ducting itself is combustible and so it creates its own fuel for the fire, therefore correct fire protection is critical.
Approved Document B of the Building Regulations is very clear that holes created in fire compartments need to be protected and with the increase in ventilation penetrations this has become a particular area of focus for improved and more onerous legislation.
There are a number of easy-to-install solutions for all ventilation fire protection requirements which meet the latest legislation such as those developed by Tenmat.
Ceiling air valves
Many ceilings, particularly in kitchens, are fire rated ceilings and therefore any penetration such as a downlight or air valve needs to be protected and the fire rating of hat ceiling reinstated to the same level as the ceiling without a penetration.
A good rule of thumb is, if fire rated downlights are fitted then a fire rated air valve is required. Every electrician is aware of the regularity with which fire-rated downlights are needed and the same should apply to air valves. In the past, fire rated air valves have generally been expensive mechanical devices. These mechanical devices have specific issues in that they rely upon regular maintenance to ensure proper function in the event of fire.
An additional problem with the mechanical fire rated air valves is that the fusible link which operates them is located behind the valve which means that the link is 'masked' from the fire in the room below leading to a delayed reaction of the valve in event of fire. The testing of many mechanical valves does not meet the latest European full-scale test standards and are often only tested for wall applications which can make them difficult to justify to Building Control.
The latest (Patent applied for) Tenmat Fire Rated Ceiling Air Valve developed by Tenmat utilises intumescent material to close the valve aperture and has no mechanical moving parts and so requires no maintenance. The intumescent material in the Tenmat Fire Rated Ceiling Air Valve is located directly upon the adjustable element of the valve and so is directly exposed to any fire in the room below which may occur, making valve closure rapid and reliable, giving complete peace of mind both to the installer and building occupants.
To ensure that the Fire Rated Ceiling Air Valves meet the latest European Standards, full scale fire tests have been undertaken utilising the EN test requirements. These test requirements are significantly more onerous than the previous British Standard test. The Fire Rated Ceiling Air Valves are now available in both Extract and Supply variants, in sizes from 80mm to 200mm in diameter from ventilation suppliers or electrical wholesalers.
The fire testing for PVC ventilation ducting fire protection has changed from the old British Standard testing to the latest and much more onerous European test standards. Most manufacturers of products which may currently be on the market are having great difficulty in meeting the new European standards. The major change for ventilation ducting is that the test requirements now need the ducts to be tested in an open / open format which means that the duct is fully open to the passage of fire from the first second of the fire test. This means that to pass the test the duct must be sealed and firestopped in seconds to avoid failure. Tenmat's range of ducting solutions are tested to the new standards. The Construction Products Regulation has now come into effect meaning that construction products with a harmonised European standard need to be CE marked in the UK.
Tenmat's Firefly 109 Vent Duct Fire Sleeve product range are CE marked. This combined with full testing to the most onerous standards makes the fitting of products a simple and reliable solution for both the installer and building occupants.
The Firefly 109 Vent Duct Fire Sleeves are available for both rectangular and circular ducts, through a range of wall constructions, and can even be used with minimal clearance between the duct and soffit.
In summary, ventilation causes many issues for fire protection and the regulation and test standards are now catching up to solve these problems. The products required to solve all ventilation fire issues are available and are now much more economically viable than in the past. Always remember that it is the responsibility of the installer to fire protect any holes which they may make, and so if ignored or incorrectly fire protected, they may well come back to haunt you.
// The author is the technical sales engineer of Tenmat //
3 March 2014