Dampers combine safety and control functions

Lindab’s Tri-safe 3-IN-1 damper can prevent the spread of fire and smoke through ventilation ductwork and also control airflow volume. These dampers are fitted with the LindabSafe double-seal system, so they are quick and easy to install and achieve an airtight seal that is three times better than the highest performance level specified in the DW/144 ductwork standard. The system has been fire tested to BS 476 20-22 for a 4-hour duration. These dampers comprise a spring-loaded circular blade of 1.5 mm galvanised steel that acts as a butterfly valve. It can be adjusted between fully open and fully closed to control air volume and is secured by a thermal link that melts at 72°C; other links are available. An external handle enables the blade to be adjusted and indicates its position. The damper blades can be reset and the thermal link replaced from outside the units, which are available for ducts from 100 to 315 mm in diameter. Motorised versions are available to control smoke or smoke and fire.