Drop Testing

BS EN 356 provides test methods and classification for resistance of glazing against manual attack. No standard exists for the testing and classification of structures containing glass resistant to manual attack. It is recommended that the complete glazed structures should be tested in accordance with BS EN 356 energy levels with pass rates one level lower (i.e. the structure for glass certified Class P5A should be tested to Class P4A energy levels) to verify that the impact does not dislodge the glass.

Testing Methods:

EN 356: 1999 Classifications

1. Hard body drop test
4.11 kg steel sphere (100mm diameter)

Axe test

Impact from hammer followed by axe
Minimum no. of strikes to create opening

Ballistic glass to EN1063 is constructed similarly to EN356 glass. However, due to the nature of its expectations it is usually much thicker. There are still ‘all glass’ and ‘glass-polycarbonate’ options but it is important to remember that ballistic glass is NOT designed to resist physical attack (despite its thickness) and physical attack glass is not designed to resist ballistic attack (despite its construction).

When ballistic or bullet glass is tested, it has to undergo a varying number of shots under controlled conditions. The number of shots and the spacing of the shots is dependent upon the test classification. For instance, in general terms, BS EN1063 testing requires 3 shots at 120mm spacing but an NIJ IV test would require only 1 shot. Further, EN 1063 European testing requires angle shots when the glazing unit is installed in a frame system (still attempting to find areas of weakness) whereas NIJ or UL 752 ballistic testing requires only ‘straight on’ shots.

It is also very important to remember that approved and certified glazing is only as good as the frame system that supports it. Therefore it is always important to ensure that a tested ballistic or bullet system is considered rather than simply installing an approved glass into someone else’s framing. See our Data Sheets TDSBB1005 and TDSBB1006 and TDSBB1007 for further information and details of compatible glass and framing systems.

This is a combination of glass and polycarbonate. The polycarbonate layer is bonded to the inside face of the bullet glass and that prevents the inner glass layers from breaking away and creating ‘spall’. This combination of glass and polycarbonate creates a lighter weight product and at the same time reduces the overall thickness of the bullet glazing.

A comparative example would be between an all glass BR6 Non Spall glass (approximately 71mm thick) and a glass polycarbonate construction which again to BR6 would be around 38mm thick.

The consideration when using glass polycarbonate ballistic glazing is that the polycarbonate on the inside face can become scratched and fogged generally through overzealous cleaning, particularly with abrasive cleaning products. The suggested method of cleaning polycarbonate surfaces is usually water with special attention to any additives that may be suggested by specialist cleaning product manufacturers.

Spall allowed glass is a good alternative and using the above as an example then the BR6 Spall Allowed glass is 50mm thick and falls in between the BR6 NS and BR6 glass polycarbonate bullet glass. As with the BR6 NS ballistic glass it has a glass surface on both the attack side and also the protected side and therefore presents no problems when cleaning. The only time that real consideration may need to be given to Spall Allowed bullet glass is perhaps if it is used as a counter screen where the persons face is normally within around 450mm of the glass.

Glass Polycarbonate BS EN 1063 Product Details:

All Glass Construction – weights and thicknesses for ballistic and blast protection glass

BS EN1063 Glass Chart

References: S = Spall – small particles of the inner glass surface are allowed to fall from the back of the glass when tested and touch the witness card

NS = Non Spall – no particles of glass fall from the back of the test piece and touch the witness card

• BS EN1522/23 and EN 1063 - FB7/BR7 – 7.62 Armour Piercing Ammunition - Rifles
• BS EN1522/23 and EN 1063 - FB6/BR6 – 7.62 NATO ammunition - Rifles
• BS EN1522/23 and EN 1063 - FB5/BR5 – 5.56 NATO ammunition - Rifles
• BS EN1522/23 and EN 1063 - FB4/BR4 - .44 Magnum Handguns
• BS EN1522/23/1063 - FB3/BR3 – Handguns .44 Handguns
• NIJ 0108.01 IV - 7.62 Armour Piercing Ammunition - Rifles
• NIJ 0108.01 IIIA - .44 and 9mm Ammunition - Handguns
• UL752 Level 9 - 7.62 Armour Piercing Ammunition - Rifles
• UL752 Level 5 - 7.62 Ammunition - Rifles
• UL752 Level 3 - .44 Magnum handguns
• AK47 Kalashnikov Assault Rifles

Catastrophic failure of moving components happens regularly when products are tested at high speeds. Striving to save weight and increase efficiency when manufacturing components can sometimes lead to fatigue or failure particularly when some components revolve at many thousands of revolutions per minute.

It is also important in many instances to observe the test component and sometimes film the test itself, meaning that the test rig or equipment under test needs to be protected with clear glass. A fragmenting component is very similar to a bomb blast which often produces fragmentation or shrapnel as once referred to. Although it can be difficult to predict the size of individual pieces of fragmentation, we have been successfully supplying ballistic glass for test rig enclosures, machine guards and also for laboratories for many years.

Standard all glass ballistic construction can range from 13mm thick up to 81mm thick. This can sometimes be difficult to fit into an existing test cabinet or enclosure and in those instances we also offer a special glass/polycarbonate product which is thinner and lighter compared to all glass products. Also see Security Glass page above http://www.blastandballistics.com/products/security-glass.php for glass thicknesses.

• Applications for Ballistic Glass panels:
• Machine guarding
• Test Rig and Test Machinery Enclosures
• High speed test screens – free standing
• Mechanical testing
• High Speed Engine and Gearbox test rigs
• Laboratory/chemical testing
• Risk of fragmentation
• Risk of blast injury
• Special surface coatings for light transmission
• Test rig enclosures for Aerospace, Turbines, Mechanical Seals, High Speed Motors

Email: sales@blastandballistics.com