There are two standards for security doors and windows which apply to blast resistance. This post addresses the difference between them - and why the distinction is important.
For a full introduction to the relevant resistance classes, tests and suitable application areas, download our PDF, A Guide to Standards for Security Doors and Windows.
Blast Resistance Standards
Standards for blast resistance measure the protection a security door or security window provides in the event of an explosion.
Standards provide a guarantee about resistance levels
In Europe, there are two distinct EN (European Norm) standards for blast resistance - one for confined explosions and the other for open air explosions.
1) Confined Explosions
A confined explosion, also known as a 'deflagration', is a lower pressure blast which occurs over a longer duration relative to other types of explosion.
This is typical of the sort of effect created by an industrial explosion at a site such as a chemicals plant.
Resistance against this type of blast is tested in a shock tube. This is to ensure that the whole explosion is channelled at the security door or window being tested, to accurately recreate the impact of a deflagration.
Name of Relevant Test Standard: EN 13123/124-1
2) Open Air Explosions
An open air explosion, also known as a 'detonation', is a higher pressure blast which occurs over a shorter period of time.
This is typical of the sort of effect created by a car bomb and is tested by exploding an amount of TNT at a specified distance from a security door or window.
The resistance class awarded is based on the quantity of TNT and explosion distance.
Name of Relevant Test Standard: 13123/124-2