Glass and Human Impact
Glass in its annealed form, framed and intact is not an immediate threat but when it is broken the long shards turn into effective cutting devices with sharp edges and momentum. Fortunately glass can be modified to change these properties and reduce the risk of injury dramatically. There are standards and codes of practice that state where impact resistant glass must be used but the list of locations is not exhaustive. Anywhere where there is a risk of human contact should be evaluated for the potential risk of breaking glass.
Generally glass is considered a risk in areas of low level glazing and in and around doors. The risk locations are the areas where accidental damage may cause the glass to break. Another risk area is where glass may be loaded to a high level due to the pressure applied by bodies as in the case of glass floors and barriers. In floor and barrier locations the contact with the glass will be predicted rather than by accident. A further area of interest is overhead glazing where the integrity failure of glass may have dire consequences unless the glass is modified.
The most frequently used glass used to improve personal safety is tempered and laminated glass products. Rarely do we suggest a combination of tempered and laminated glass because it can show undesirable characteristics of both glasses.
Tempered glass achieves its impact resistance by having the strength increased by a factor of 4 and when it breaks it collapses into small relatively harmless particles.
Laminated glass is no stronger than the annealed glass it is formed from but the interlayer bonds the panes together. The bonded panes resist penetration and holds the broken panes together reducing the risk of harm.
Glass is categorized for its impact resistance in ASTM C1048.