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Testing beyond fire resistance

When it comes to fire safety glass, testing is an integral part of the industry. However, with complex specifications and changing customer demand, testing can go far beyond a glazing system’s fire performance. From impact resistance and anti-attack to real-world weathering and light transmission, here, Dr Vince Crook, Technical Development Director from Pyroguard, explores some of the key tests that fire safety glass can undergo…

Going behind the scenes of a fire safety glass test

Fire safety glass isn’t just about withstanding fire – it’s about meeting a broad range of rigorous standards to ensure all-round performance and safety. With changing trends and market requirements, customers are increasingly demanding more from their system specifications, with a multitude of tests required to verify these multi-functional capabilities.

Fire tests

Used to gauge the level of fire protection to be expected from a glazing system, the result of this test is critical to meeting Building Regulations and other legislation. Representing a significant investment by a manufacturer, new fire test evidence can be undertaken on the back of external market influences, changing legislation, commercial factors or customer requirements.

Performed in an approved laboratory, the installation and testing process will be overseen and inspected by the testing body. Closely monitored for multiple factors, including smoke, heat and deflections, a ‘pass’ will only be granted to glazing systems that achieve or exceed specific thresholds, as laid out by the relevant Test Standard.

Weathering tests

With glass known for its aesthetic value, specifiers will want a product that will stand the test of time. In locations with continued exposure to wind, rain, UV light or heat, this can be difficult to achieve, with each of these factors known to adversely affect the appearance of fire safety glass.

According to ISO 12543-4:2011, all fire glass products should be put through a series of accelerated ageing tests in a controlled laboratory environment. Here they will be subjected to varying conditions for a set period of time, measuring the ability of the glass to cope with differing circumstances.

However, this isn’t always wholly reflective of real-world conditions, with some manufacturers, such as Pyroguard, also performing real-world weathering tests. This involves samples being installed on test sites around the world, such as Arizona and Florida, exposing the glass to the radiant energy present in sunlight and other varying conditions, including humidity, dew and rain.

Impact tests

With the rise of glass façades, atriums and balustrades, testing the impact resistance of products is essential, making a measurable difference to the safety of building residents. Impact tests are carried out in accordance with Test Standard EN 12600:2002. Any glass designated as a safety glass must have evidence of its classification against this standard, displaying its ability to resist a soft body impact, whether purposeful or accidental.

The testing uses a large-scale pendulum-style test rig, where an impactor with two pneumatic tyres is fitted to a weight, totalling 50 kg. This pendulum is then lifted and swung at the specimen, striking a glazing sample from one of three drop heights, with the classification awarded based on the performance of 12 samples. These classifications range from Class 1, the highest performance possible under this standard, to Class 3.

Some projects also require testing the glazing within a complete system to prove its real-world durability against impacts. This presents an additional challenge, as the glazing beads, glazing tape and the entire system must work together to hold the glass securely in place during the assault.

Anti-attack testing

Following recent changes to Approved Document Q, enhanced security requirements are set for new dwellings. According to Standard EN 356, ground floor, basement and other easily accessible windows must be able to resist physical attack from potential intruders by being sufficiently robust, rated Class P1A or higher.

Having this anti-attack performance can also be a special project requirement, where additional criteria is required from the glass. For example, on project Depot Boijmans Van Beuningen in The Netherlands, resistance against axe attack (up to a P6B rating) was required for additional security to the museum’s valuable exhibits.

Tested according to EN 356, anti-attack classifications involve a hard body drop test, whereby a 4.11 kg steel sphere represents a blunt instrument, such as a hammer attack.

Line load tests

Key for façade applications, line loads are essential to ensure the robustness of the glass under stress. According to Approved Document K, line loads are tested by applying a horizontal force to the glass system at the height where a person could reasonably come into contact with it and measuring the deflection according to KN/m.

Line load calculations are commonly done to augment testing and will be bespoke for all projects, making it essential to work with a glass manufacturer and framing system house with the relevant technical experience and expertise.

Light transmission values

Light transmission testing, the measurement of how well light passes through glass, can be an important consideration on the more demanding architectural projects, where aesthetics and visual impact are key. Tested according to EN 410, it involves illuminating a sample with a light source and measuring the intensity of the light before and after it passes through the pane.  Given the complexity of multi-functional glasses, light transmission calculations are often performed on glass combinations to find project specific solutions.

Acoustic testing

With acoustics becoming an increasing priority for building design, acoustic test evidence is something that can often be requested on projects within the office, healthcare, residential and hotel sectors. While some architects may look to achieve sound reduction properties by sectioning off different areas or using solid walls to minimise the spread of noise, glass partitioning presents a far more aesthetically pleasing option.

Many fire safety glass solutions can double-up in an acoustic control capacity, dependant on the pane thicknesses, glass density and number of interlayers. In fact, given that fire rated glasses are commonly multi-laminates and often have thick gel interlayers, they can act as very good acoustic panes.

Glasses can be assigned a Weighted Sound Reduction Index (Rw Value), which measures how much a material can reduce sound by, with a higher Rw Value meaning better acoustic control. Tested in controlled laboratory conditions, the glass sample is subjected to sounds at a range of frequencies, with the sounds transmitted through the glass then recorded and measured.

 

As a leading global manufacturer of fire safety glass, Pyroguard operates a comprehensive test programme for its vast product range, covering each of these areas in detail. As well as ensuring its wide portfolio of products meet all relevant legislation for the region they are to be installed in. Pyroguard’s robust bank of test evidence can provide specifiers with peace of mind that they have chosen the optimum solution for the application.

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