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Home Glass, Glazing, Mirrors & Shelves Safety Security Glass

Safety/Security Glass

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The importance of Safety/Security glass

 

 

Demanding safety legislation has highlighted the critical areas where modern safety glazing must comply with the required safe practice.

 

 

Innovations in the development of Safety/Security glass has opened up new avenues of design, allowing people to be protected from personal injury or in the most extreme cases protecting buildings from various forms of attack.

 

 

With this in mind, there are a wide range of sophisticated products, in order to meet these ever increasing demands, without compromising on the design criteria of natural light and visibility.

 

 

 

 

The classification standards

 

 

EN 12600 Glass in building – Pendulum Test – Impact test method and classification for flat glass


The Pendulum Test is the standard for classifying flat glass products by performance under impact and by mode of breakage. It is similar to the previously used swing bag test whereby a weight cushioned with two rubber tyres is allowed to swing at the glass from 3 heights.

 

 

The second component is the mode of breakage defined as:

– TYPE A: numerous cracks appear forming separate fragments with sharp edges, some of which are large, typical of annealed glass.

– TYPE B: numerous cracks appear, but the fragments hold together and do not separate, typical of laminated glass.

– TYPE C: disintegration occurs, leading to a large number of small particles that are relatively harmless, typical of toughened glass.


The classifications are summarised in Table 1.

 

 

The classification has three components:

 

The classification is the drop height class (i.e. 1, 2 or 3) at which the product did not break or broke in accordance with the first two types of breakage that follows:

 

– Numerous cracks appear, but no shear or opening that allows 76 mm diameter sphere to pass through when a maximum force of 25 N is applied. Additionally, if particles are detached from the test piece up to three minutes after impact, they shall in total, weigh no more than a mass equivalent to 10,000 mm2 of the original test piece.
– Disintegration occurs and the 10 largest crack free particles are collected within three minutes all together and weigh no more than the mass equivalent to 6,500 mm2 of the original test piece.

 

The third component is the highest drop height at which the product did not break or when it broke, broke in accordance with TYPE B.

EN 356 Glass in building – Security glazing – Testing and classification of resistance against manual attack.

 

This specifies the requirements and test methods for glass designed to be resistant to manual attack. The glass is subjected to impact from a steel ball with a mass of 4.11 kg for classes P1A to P5A and an axe for classes P6B to P8B.

 

The classes of resistance are summarised below in Table 2.

 

 

The Complete Safety Solution Toughened Glass

 

What is toughened glass?

 

Toughened glass is manufactured by subjecting the finished glass size to a heating and cooling treatment which set up high compressive stresses at the surface, and balancing tensile stresses in the centre of the glass, which increases its strength. The result is a glass that is 5 times stronger than ordinary glass of the same thickness.

 

How it works

 

The high compressive surface stresses give the glass its increased resistance to mechanical and thermal stresses. It can, however, break under extreme loads or by severe impact. When broken, toughened glass shatters into small, blunt-edged fragments, reducing the risk of personal injury.

 

 

Heat strengthened glass is produced by a similar process to toughened glass, however, the strength developed is about half that of toughened glass.It does not meet the safe break criteria for safety glass because its breakage pattern resembles that of annealed glass. It is used to provide glass that is resistant to thermal stress and for laminating where greater glass strength is required.

 

 

 

 

Laminated Glass

 

What is laminated glass?

 

Laminated glass is produced by combining two or more sheets of float glass with one or more interlayers. The most popular interlayer used is a polyvinylbutyral (PVB) interlayer, which is processed with heat and pressure under factory conditions.

 

How it works

 

The interlayers ensure the integrity of the glass, by holding the broken pieces in place should any damage occur. In fact, glass fragments adhere strongly to the interlayer, while the resistant cushioning effect dissipates the energy.

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Its performance can be influenced simply by changing the number and thickness of each layer of glass and PVB interlayer.

 

Products

 

There are variations that are also available, for example; Protection against ultraviolet radiation, Solar control laminated glass and Thermal insulation laminated glass, please contact Bristol Glazing for more information.

 

 

 

 

 

 

 
Designed by DouglasDataSystems 2011