Ventilation pipes with small surface areas such as those used for aerating toilets, bathrooms and domestic kitchens (systems according to DIN 18017) can easily cause "cold smoke" to spread onto other floors during a fire. With the motorised shut-off dampers from the FKRS series from Trox, this danger can be avoided. Triggered by smoke detectors used to monitor the atmospheric environment, these devices automatically close when smoke is detected. The standard shut-off dampers which only react to temperature cannot prevent smoke from spreading through a building. The leakage volume flow measured when the damper has been closed is less than 0.5m3/h.