A J Services manufacture a large number of different styles of fire and smoke dampers. Both fire and smoke dampers play a vital role in the safety of a building which has ductwork system which is connected to a HVAC system. Fire dampers have an attached fusible link which is set to be triggered when a pre-determined air temperature is reached - this forces the blades to shut and allows the fire/smoke to travel no further. The links monitor the air temperature and are traditionally set to 72 degrees, although this can be altered if asked. The dampers are rated at 2hrs, this means that they will contain the fire in place for 2hrs. The dampers are manufactured from galvanised steel and can be produced in sizes ranging from 80mm to 2000mm with options for both circular and square/rectangular ducting. The casing on all dampers is rectangular, so the dampers which are suitable for spiral tubing have an attached spigot - this is where the damper can be attached to tubing and as such the blades are described as out of stream. The rectangular dampers can have an attached spigot, no spigot or can be an induct damper. All dampers as standard are supplied with hanging cleats, and have options for drywall framing and HEVAC frames.