Blast protection

Blast protection keeps the people inside a building safe when an explosion happens close to it. ArxBridge supplies and installs blast rated doors, windows, glass and glazed facades across the UK. Architects and security consultants specify it for government buildings, transport hubs and other sites where a vehicle bomb is a recognised threat.

• EXV45 to EXV10ISO 16933 vehicle bomb classes
• 100 kg TNTReference charge behind every EXV test
• A to FHazard ratings for blast fragments
• SB classesRatings for hand-carried charges

How blast ratings work

ISO 16933 is the international standard for blast resistant glazing and glazed systems. It is published by ISO. Each EXV class describes a vehicle bomb of 100 kg TNT equivalent detonated at a set stand-off distance from the target. The number in the class name is that distance in metres.

EXV45 is tested at 45 metres. EXV10 is tested at 10 metres. A shorter distance means a far more severe test, so EXV10 is the most severe of the seven classes. The full set runs EXV45, EXV33, EXV25, EXV19, EXV15, EXV12 and EXV10. SB classes sit alongside the EXV set and cover hand-carried satchel charges rather than vehicle bombs.

Every test result also carries a hazard rating from A to F. This describes what the glazing does after the blast: whether it stays in the frame, whether fragments are thrown, and how far they travel. A means no break. F means a high hazard from flying fragments. A specifier should always ask for both the EXV class and the hazard rating, because a window can hold a high EXV class and still earn a poor hazard rating.

Doors, windows and shutters can also be rated under the European standards EN 13123 and EN 13124. These use EPR1 to EPR4 for shock tube tests and EXR1 to EXR5 for range tests. Where a project follows European test evidence, the blast ratings guide explains how the two systems line up.

Check the pair. An EXV class without a hazard rating tells only half the story. Ask for both before you specify.

Choosing the right blast product

Start from the threat assessment, not the product. The security consultant sets the charge size and the stand-off distance the site can achieve. That fixes the EXV class. The product then follows from the opening: doors for entrances, windows for occupied rooms, film where the frame must stay, curtain walling for glazed frontages.

Who specifies blast protection

Security consultants write the threat assessment and set the EXV class. Architects turn that into drawings and opening schedules. Main contractors procure the doorsets and facades and manage the installation sequence. Facilities teams inherit the upkeep: hinges, seals and locks on a blast door need the same planned attention as any safety system.

Blast protection appears most in government and defence estates, transport hubs, data centres and public spaces with crowded frontages. It is often specified alongside forced entry resistance from the Security range or ballistic protection from the Ballistic range, and the full product set sits under Products.