Fire doors are fire-resistant doors that help to reduce the spread of fire and smoke throughout a building. They are designed to be remained close at all times and should not be installed over flammable flooring materials such as carpet and certain types of tile. The ratings are based on how long the door can resist fire, ranging from 20 minutes up to 90 minutes. Fire doors must be inspected annually as proper maintenance and installation is vital to the operation of a fire door. There are four major components of fire doors; the composition material, hardware, seals, and sometimes windows.
Fire doors are usually made of a combination of wood, steel, glass, gypsum, and vermiculite boards. The actual composition is dependent on the fire rating of the door and the application.
The hardware on fire doors includes the hinges, latches, and sometimes the automatic closing device. The automatic closing device is important because if the door is kept open, it needs to close during a fire. This is commonly accomplished with a magnetic device that holds the door open until a fire alarm is engaged, at which time the electricity to the magnet is cut and the door closes.
The seals around the edges of fire doors are usually composed of a strip of material that expands when it is exposed to heat to prevent the spread of smoke and heat. The seals also include weather-stripping and other smoke gaskets.
When fire doors include windows, the windowpane must also be subjecting to fire-resistance rating. They tend to include wire mesh, fills between two or more panes, and specialty glasses. Not only does the glass need to be able to withstand the immense heat of fire without shattering or cracking, it also needs to be able to withstand the impact of the stream of water from a fire hose.