Beyond the Brush: The Advantages of Fin-Type Intumescent Seals

Brush seals were the first on the market (in fact, Lorient were the first to introduce them, back in 1979!), and hence they have popular appeal as the traditional smoke seal solution. Although they are still effective as smoke seals, the Building Regulations have moved on since they were introduced, most notably with the requirement for doors to provide acoustic containment, and also be easy to operate to allow access for all. With so many doors now needing to conform to these requirements, the brush-style smoke seal is simply not up to the challenge any more. Brushes are particularly poor at providing acoustic containment, as the brush fibres allow air to pass straight through, and therefore sound too. They also tend to become more compact overtime, which reduces their capability in maintaining a smoke barrier or in providing sound insulation.

Fin-style seals provide a much more modern, comprehensive and indeed hygienic solution. They have better acoustic containment properties (particularly ones with dual fins) and are much more effective as smoke barriers.

It's important though that the fin seal remains continuous around ironmongery for both acoustic and smoke containment - but this can be a challenge if the seal has centrally positioned fins. Offset fins make this much easier. This is why Lorient have introduced the Finesse™ and DS seals, with offset dual fins, for a complete acoustic, smoke, fire and low-friction solution.

Lorient has extensively tested the DS seal, which is Certifire approved and cycled 100,000 times on a full-size door assembly, without failure. As part of Lorient’s QC procedures, these seals undergo regular durability testing to ensure all seals are capable of achieving 100,000 cycles as a minimum. As long as the seal is correctly installed, and the doors are suitably maintained, it will provide years of reliable service. The Finesse™ seal has been similarly tested too. It's unique in the industry, as its fins start at the product's base and wrap around the seal's sides, helping to hold it securely in place in the groove, and providing extra durability.

Tests were undertaken on a typical FD30S door assembly with a laminated softwood core and in conjunction with the LAS8001 si drop seal. These tests proved that smoke seals with elastomeric fins provide far superior acoustic performance: