The UNI 7697 regulation defines “The safety criteria in glass applications” and identifies which types of glass are adapted to the performance, which they must be able to guarantee in order to be considered safe to the user.
In today’s article we will analyze the regulation with a focus on tempered glass and laminated glass; we will also look at identifying all the characteristics of a glass defined as safety glass.
When a glass can be defined UP TO STANDARD
According to UNI 7697, glass intended for use as fixtures is considered safe, and therefore compliant with the standard, if it belongs to one of the following types: tempered glass and laminated glass.
Laminated glass contains, between two or more panes, one or more layers of plastic material, usually PVB, which, in case of breaking does not allow glass fragments to break away from the whole.
Laminated glass should be used in case of:
- protection from risk of injury from loose, broken or sharp glass fragments;
- protection from risk of free-falling;
- protection of goods against the risk of burglary and vandalism;
- protection against firearms;
- protection against explosions.
Tempered glass is the result of the tempering process, which involves heat treatment of sheets with the aim of increasing their degree of resistance from breaking phenomena, including thermal shock.
In this case, the glass is considered anti-hardship for the simple reason that, if it breaks, it fragments into many small, not very sharp pieces, limiting the risk of injury.
In some cases it is allowed to use tempered glass for windows or interior dividers. In some cases it is necessary to add HST (heat soak test) treatment.
Glass standards for fixtures: what Europe says
Recently, in 2021, the Standards Authority updated UNI EN 7697 by adding some details, perhaps the most important step turns out to be the fact that the use of thermally tempered glass verified by Heat Soak Test (HST) treatment has been turned into an obligation (previously only “advice”), so as to avoid the breaking of the tempered glass projecting fragments outside that could generate danger due to their weight, drop height or location.
The regulation, therefore, provides criteria for the selection of the glass to be used, so that in the intended use, compliance between glass performance and the minimum requirements necessary for the safety of users is ensured.
The regulation refers to other normative references, among the most common:
- UNI EN 356: Building glass – Safety glass – Testing and classification of resistance against manual attack;
- UNI EN 1063: glass for building – Safety glass – Classification and tests of resistance against bullets;
- UNI EN 12150: Building glass – Thermally tempered soda calcium silicate safety glass;
- UNI EN 12600: Building glass – Pendulum test – Impact test method and classification for flat glass;
- UNI EN 14179: Building glass – Thermally tempered soda calcium silicate safety glass subjected to “heat soak test”;
- UNI EN 14449: Building glass – Laminated and laminated safety glass – Conformity assessment/Product standard.