Chris Atkinson, marketing manager of Domus Ventilation, explains how his company’s new fire stop will save installers time and money
UNTIL recently the only recognised method of providing a fire stop for a plastic duct passing through a fire compartment wall has been achieved by the use of two intumescent fire collars mounted either side of the compartment wall with the duct passing loosely through the middle.
Typically, intumescent fire collars are steel-fabricated flanged sleeves filled with exfoliated graphite or sodium silicate compound that are bolted, using steel (non-flammable) anchors, to the compartment wall.
Intumescent compound expands in fire at a ratio of about 10:1. Therefore, the larger the hole to close off, the thicker the band of intumescent.
The actual rating of the collar (hours of closed protection) is dependent on the type and amount of intumescent and the integrity of the actual housing. A rating of two hours covers all of the current requirements of Document B of the UK Building Regulations.
Because of the sometimes complex nature of the fabricated housings, the need for steel anchors and the extended labour times taken on installation, the costs can be quite considerable. In some installations contractors have been known to take a gamble on which side of the compartment wall a fire is likely to occur and only fit one collar. If a fire starts on the non-protected side of the wall, the insulating properties of the wall could seriously impair the reaction of the collar.
When collars cannot be installed because of space restrictions or the duct is passing through a wall at any angle other than 900 or the duct immediately changes direction on passing through the wall, some installers have been using poorer quality flexible intumescent wraps.
Wraps rely on the structural integrity of the wall itself to provide the expansion containment, (this renders them wholly unsuitable for stud walls). However, most installers either forget or simply don't know about the expansion ratio and expect a narrow wrap to close any size of aperture in any thickness of masonry.
With the current trends in legislation and more onerous insurance requirements, Certified and Approved systems are becoming the norm.
Aimed at the specification and new build markets the Domus FireBrake connector is a fire protection innovation, being the first product in the UK to provide protection as an integral part of a uPVC duct system.
The FireBrake connector concept is based on the principle 'keep it simple' to remove any ambiguity regarding most installation scenarios. With its 125mm length and rugged steel sheath it can provide protection in a much wider field of application than any other plastic duct fire stopping system currently on the market.
Domus intumescent FireBrake connectors offer a more reliable and practical method to firestop uPVC duct systems. This revolutionary, injection moulded duct connector has been extensively tested by BRE to both BS476 Part 20 and the more onerous prEN1366-3. It provides up to a two hour rating in most installations. Domus intumescent FireBrake connectors form an integral and seamless part of the duct system.
Like all intumescent products, FireBrake is activated when exposed to the heat of a fire, the exfoliated graphite, (which with FireBrake is part of the formulation used to mould the product), expands to crush the melting duct and fill the wall or floor penetration.
Although a technically advanced fire protection product, FireBrake is as easy to install as a duct connector. It can be fitted into precast, core cut or other accurately-produced openings using standard ductwork installation techniques, familiar to all site engineers.
No additional fixing is necessary, apart from the use of a standard acrylic-intumescent-mastic for making good. This will save both time and money on site and, most importantly, provide unrivalled reliability for the life of the duct system.