What distinguishes a fire door from a standard door?

Print 03 Jul 2020

Fire doors are one of the most important fire safety products in a building. They prevent flames and smoke from spreading in a building and are essential to permit inhabitants, visitors and employees to evacuate the building safely. Fire doors are basically the way in which a building delays a fire.

But what actually distinguishes a fire door from a standard door? Well, it is no use, for example, inserting fire-resistant glass in a standard door and thinking you have a fire door. The doors have to meet a number of requirements. These requirements come in different classifications.

Doors in different classifications

Several classifications are linked to the performance of fire doors. Each classification describes smoke resistance, insulation and fire resistance performance, usually 30, 60, 90 and 120. The numbers are times, indicating the number of minutes for which the door can delay the fire before the fire breaks through.

Glass with no fire resistance is:

  • Float glass
  • Laminated glass
  • Toughened glass

A door that is flame-retardant
The biggest difference between a fire door and a standard door is that a fire door can withstand extreme heat. Our fire doors are made of aluminium, a metallic chemical with a melting point of approximately 660 degrees. In an actual fire, the temperature will reach 900-1000 degrees Celsius. Consequently, a fire door needs additional reinforcement other than glass with fire resistance.  

A fire door has additional reinforcement
In the event of fire and high temperatures, the profiles will expand, and the aluminium will melt in just 10 minutes. In order that a fire door remains in place and has a fire-retardant effect in, for example, fire class EI 60, it is secured with additional reinforcement so that it holds out for the remaining 50 minutes:

  • The fire glass panes are secured with steel clips.
  • The door is secured at the rear so that it does not fall out of the profile.
  • The door is secured at the top by pins that go from the door leaf into the frame, so that it is held in place.

Avoid heat release
Fire cloth is placed on the rear of the lock case here. Different types of material are used to seal the cavities in the profiles:

  • In a fire door in fire class EI 30, rockwool is used as insulation inside the profiles.
  • In a fire door in fire class EI 60, Palstop is used. This is a compressed material that has a cooling effect inside the profiles.

The lock case is the weak point on a door because, in addition to there being no room for fire insulation in this part of the profile, there is also a lot of metal, which is the material used to make the lock case and which is very thermally conductive. For this reason, details such as placing fire-retardant cloth on the rear of the lock case are essential in Sapa’s fire doors.

Testing fire doors
There is a huge range of fire door designs today. Please note that fire doors are often sold as complete doors and door components, including the door frame and necessary furniture to hold the door in place. This is to ensure that the door provides the specified fire resistance, because the door set is tested as a complete component.

It is a legal requirement for manufacturers of fire doors to prove that the fire doors function as claimed and in accordance with requirements. This is usually done in tests performed by an independent third party. Such a test is performed by a door set being built into a suitable structure and a realistic fire test being performed to decide how long the product resists fire. This test provides proof for the structure of precisely this door set. 

The design and purpose of a fire door are the same as for other doors for everyday use. However, if a fire occurs, a fire door will perform its primary purpose, which is to protect life and the building in which the fire occurs, and other buildings nearby.

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