Duct ventilation appts operating should mechanical extraction fail - has slatted shutter held open by spring pressure and closed by electromagnet plunger operated relative to duct air pressure

摘要

The ventilator has a casing (1) with a shutter grille of slats (2) which are pivoted about a horizontal axis (3). The slats are held in the open position by a return spring (4), or closed against spring pressure by an electromagnet, when its coil (5) is energised from an electric supply. The shutter may be part of the casing assembly. The solenoid plunger may be fixed to the slats and its supply operated relative to duct air pressure. The grille duct position may ensure ventilation should the mechanical ventilator fail. ADVANTAGE - Ventilator slats open if fan stops, to continue ventilation by natural free air draught.