Understanding the risk of explosion and its consequences
Explosions, whether of industrial, criminal, or terrorist origin, generate devastating shockwaves, causing major material damage, loss of life, and the disruption of critical operations.
In this context, the installation of certified explosion-resistant doors, windows, and partitions becomes an absolute necessity to ensure the protection of sensitive infrastructure.
The main threats include:
- Accidental explosions on industrial or chemical sites
- Terrorist attacks or bombings using packages or vehicle-borne explosives
- Overpressure incidents in SEVESO-classified environments
- Military and urban detonations affecting civilian infrastructure
- Planned blasts aimed at breaching secure buildings (burglary, malicious intent, etc.)
European standards for explosion resistance of joinery
There are numerous reference standards for explosion resistance, as each scenario involves different types of explosions, attack contexts, distances, and intensities. An explosion in a confined space will have a very different impact than a blast in open air, just as a charge placed a few meters from a structure will differ greatly in effect compared to a shockwave travelling over a long distance.
This is why we approach every project on a case-by-case basis, working closely with our clients to precisely analyze their needs, the specific threats they face, and the constraints of their environment. Based on these factors, we recommend the most suitable solutions from our product range, and if necessary, we consult the market and our own R&D department to develop tailor-made solutions, tested and validated using rigorous protocols.
Nonetheless, explosion resistance of joinery is governed by several strict European standards that ensure reliability in the face of various types of explosive threats. These standards define the criteria for evaluating the resistance of doors, windows, partitions, and closures against explosions. Some of the most commonly used standards in this field include:
- EN 13123-1 & EN 13124-1: Laboratory tests using a shock tube to simulate a shockwave generated by a distant explosion.
- EN 13123-2 & EN 13124-2: Real-world tests, where explosive charges are detonated in open air to assess the impact on the joinery.
| Test type | Classification standard | Test method standard | Classes |
|---|---|---|---|
|
Shock tube |
EN 13123-1 |
EN 13124-1 |
EPR |
|
Open air |
EN 13123-2 |
EN 13124-2 |
EXR |
Let us also mention ISO 16933, which assesses the explosion resistance of security glazing under open-air conditions.
EN 13124-1: Test method for explosion resistance using a Shock Tube.
- Simulates the effects of an explosion ranging from 100 kg to 2,500 kg of TNT at a distance of 35 to 50 meters
- Measures the impact of a reflected blast wave on a door or window
- Classification based on the maximum pressure sustained and impulse duration
Laboratory procedure according to EN 13124-1:
- Installation of the door, window, or partition on a rigid test frame
- Exposure to a shock wave generated by a shock tube
- Measurement of peak pressures, durations, and specific impulses
- Evaluation of deformations and damage
EN 13123-1: Requirements and classification for explosion resistance in a Shock Tube
| Class | Maximum pressure (bar) | Positive impulse (bar·ms) | Duration (ms) |
|---|---|---|---|
|
EPR1 |
0,5 |
3,7 |
20 |
|
EPR2 |
1 |
9 |
20 |
|
EPR3 |
1,5 |
15 |
20 |
|
EPR4 |
2 |
22 |
20 |
EN 13124-2: Test method for explosion resistance in open-air conditions
- Tests the response of a product subjected to an outdoor explosion
- Simulates a bomb attack with charges placed 3 to 5.5 meters from the target
- Classification based on the ability of the tested element to remain in place and contain fragments
Real-condition test according to EN 13124-2:
- Installation of the product on an outdoor test site
- Detonation of a real explosive charge (TNT) at a defined distance
- Analysis of impact, projected fragments, and structural deformations
EN 13123-2: Requirements and classification for explosion resistance in open-air conditions
| Class | Explosive TNT charge mass (kg) | Distance (m) | Reflected pressure (bar) | Reflected impulse (bar·ms) |
|---|---|---|---|---|
|
EXR1 |
3 |
5 |
2,5 |
3 |
|
EXR2 |
3 |
3 |
8 |
5 |
|
EXR3 |
12 |
5,5 |
7 |
7 |
|
EXR4 |
12 |
4 |
16 |
10 |
|
EXR5 |
20 |
4 |
28 |
15 |
ISO 16933: Requirements and classification for open-air explosion resistance of security glazing
This standard specifies protection levels against charges placed in vehicles or explosive parcels.
Explosion resistance tests are carried out by certified laboratories, simulating real detonation scenarios and measuring the response of glazing systems to applied blast pressures.
Car bomb attack
In the classification code, the letters “EXV” refer to the type of explosion, specifically a car bomb.
The numbers indicate the nominal stand-off distance (expressed in meters), which corresponds to the distance between a 100 kg TNT equivalent explosive charge and the surface of the tested specimen, mounted in a reaction structure (test frame) of approximately 3 m x 3 m.
The letter (X) designates the hazard level observed during the test. For example, the classification code EXV25(C) means that a test was conducted with a standard explosion generating a peak blast pressure of 80 kPa and a positive phase impulse of 380 kPa·ms, resulting in glazing damage corresponding to hazard level “C”.
| Classification | Mean peak air-blast Pressure (kPa) | Mean positive phase Impulse (kPa-ms) |
|---|---|---|
|
EXV45(X) |
30 |
180 |
|
EXV33(X) |
50 |
250 |
|
EXV25(X) |
80 |
380 |
|
EXV19(X) |
140 |
600 |
|
EXV15(X) |
250 |
850 |
|
EXV12(X) |
450 |
1200 |
|
EXV10(X) |
800 |
1600 |
Parcel bomb or person-borne improvised explosive device (PBIED)
In the classification code, the letters “SB” refer to “Stachel-bomb”, indicating the type of explosion—such as a bomb contained in a bag or briefcase carried by hand.
The number indicates the standard explosion level used during the test, and the letter (X) designates the hazard level observed after the test.
For example, the classification code SB4(C) means that a test was conducted with a standard explosion generating a peak blast pressure of 800 kPa and a positive phase impulse of 500 kPa·ms, resulting in glazing damage corresponding to hazard level “C”.
| Classification | Mean peak air-blast Pressure (kPa) | Mean positive phase Impulse (kPa-ms) |
|---|---|---|
|
SB1(X) |
70 |
150 |
|
SB2(X) |
110 |
200 |
|
SB3(X) |
250 |
300 |
|
SB4(X) |
800 |
500 |
|
SB5(X) |
700 |
700 |
|
SB6(X) |
1600 |
1000 |
|
SB7(X) |
2800 |
1500 |
Interpretation of results
- Mean Peak Air-Blast Pressure: This refers to the average peak pressure of an explosion. It represents the maximum pressure exerted by the shock wave on a surface at the moment the explosion reaches its highest intensity. This pressure is measured in kilopascals (kPa) and determines the force of the shock wave on surrounding structures.
- Mean Positive Phase Impulse: This refers to the average impulse during the positive phase. It represents the amount of energy transferred by the shock wave over a defined period during the positive phase of the explosion (i.e., when the pressure is above normal atmospheric pressure). Expressed in kPa·ms (kilopascal-milliseconds), this value is essential for assessing the dynamic effects of the explosion on a structure, especially deformations and the duration of exposure to high-pressure loads.
Both parameters are crucial for evaluating the blast resistance of joinery and structural elements, as they influence the type and severity of the resulting damage.
Damage to security glazing is also assessed by the quantity, severity, and distance of projected “splitting”—that is, debris or fragments expelled during the explosion. These are indicated in the test results by a letter from A to F, with A representing no damage and F indicating numerous fragments projected over a large distance.
Applications and sectors concerned
Our blast-resistant solutions are essential for high-security risk sectors:
✔ Strategic infrastructure: Nuclear power plants, petrochemical sites
✔ Airports and train stations: Securing terminals and waiting areas
✔ Embassies and government buildings: Protection against terrorist threats
✔ Sensitive industrial sites: Protection against accidental explosions
✔ Banks and data centers: Securing critical assets
