Fire Glazing - System Specification & Best Practice

Fire glass is rated according to three main classifications: integrity only (E), integrity with radiation control (EW) and integrity with insulation (EI). As one of the earliest fire safety glazing products on the market, wired glass is still commonly used today for E rated applications. However, continued advances in fire glazing technology have led to the development of clear and thinner products that are able to provide the full range of protection – from integrity only, up to fully insulated, which restricts heat transfer through the glass to the unexposed face.

From a design perspective, the challenge is often to achieve vast glazed areas. However, fire glass is only certified for use up to the maximum sheet size at which it was tested. It is important therefore to realise that fire protection performance is not achieved exclusively by the glazing – it must be proven to perform as part of a system along with the frames and seals.
 

The Importance of System Specification.

While specific testing procedures must be conducted in accordance with country legislation, best practice remains that the evidence/certificate should detail the glazing in application. For example, a test certificate should not only cover the fire glass, it should also confirm that the surrounding frame, seal and associated installation materials can withstand the same levels of fire integrity.

The testing of fire glass is always to maximum glazed size. However, in the context of system specifications, the importance lies in the detail of the complete construction. Any deviation from the specified materials, no matter how small they are deemed to be, will render testing certification invalid.

As such, at every point in the construction programme – from specification to installation – a critical factor to protect the integrity of fire protection performance is to ensure the system is being installed exactly as it is detailed. For example, where timber frames are being used, it is important to verify whether the beading tested as part of a system was hardwood or softwood, and if pins or screws were used. Although these might appear minor details, the difference between the fire performance of hardwood and softwood is significant.

It is important to realise that fire protection performance is not achieved exclusively by the glazing. It must be proven to perform as part of a system along with the frames and seals.

As modern aesthetics demand the frame profiles and bead sizes to be as small as possible, it is important to check the size of beading that has been tested. For example, a system may be approved with 25mm beading but the specifier may wish to detail 15mm. Under these circumstances the test evidence would not cover the system specification. This also relates to the frame orientation. If the system is tested with the bead to non-fire, then this is the only orientation that can be used under the test evidence.

Regarding fixing methods, pins are often preferred to screws as they offer a neater finish and are quicker to install. However, there is a danger that when exposed to fire, the pins could fall out more easily than screws and compromise the overall system integrity. It is therefore important to request full test evidence of pins performing in a fire rated glazing system. Where a fire rated system is being used with pins, it is recommended that they are pitched at 200mm centres.

Another particular detail of significance is the glazing media. Dependent on the application and performance requirements, sometimes inert media such as ceramic tape is specified and other times intumescent is required. While this might appear a small detail in the overall system construction, any change to the media could compromise integrity, which is why the fire glazing system must be designed and installed to the exact specification that was tested.

Understanding Testing Protocols.

Globally, system specifications and the associated testing of these remain of utmost importance. However, the idiosyncrasies of testing protocols across countries and regions means that validated testing in one country may not necessarily deliver compliance in another.

A good example of this is in the UK, where fire testing is currently undertaken to British Standards (BS). In 2013, the country will be required to comply with European (EN) testing standards. In this instance the assumption is that if a fire glass product or glazing system has been shown to meet 30-minutes fire integrity and or insulation with BS, that it will achieve that against the new EN testing.

Due to the differences in testing procedures in Britain and Europe, this is not the case. Current fire testing protocol in the UK leaves the thermo-couples in the testing furnace exposed. In contrast, EN testing techniques encase the thermo-couples in a ceramic and steel plate, which is intended to standardise heat detection across different types of furnace. Such standardisation should ultimately ensure more reliable test results and consistency of product performance throughout Europe. However, as it results in a more intense period of heat that was not present during BS testing, systems that currently achieve compliance may not reach the same integrity levels.

The assumption, if a fire glass product or glazing system has been shown to meet 30-minutes fire integrity and or insulation with BS, that it will achieve that against the new EN testing is not the case.

Due to the differences in testing procedures in Britain and Europe, this is not the case

This example illustrates the importance of understanding the testing procedures that are undertaken between countries, particularly when exploring the potential for specifying fire glazing products from overseas.

Putting Theory into Practice.

Pyroguard fire safety glazing has been installed at two new Royal Shakespeare Company (RSC) theatres in Stratford-upon-Avon. The much celebrated Royal Shakespeare and Swan Theatres have benefitted from high performance integrity and insulation glazing in fire doors throughout the development.

EI glazing was specified at 23mm and 15mm thicknesses to deliver 60/60 and 60/30 fire ratings respectively. Used as part of an internal fire door system, the product was required to deliver integrity and insulation performance for slim vision panels. The fire glazing challenge for this project was satisfying the UK building regulation requirements without compromising on the build schedule. Pyroguard met the necessary performance specification and could be delivered to site as bespoke cut sizes in a short space of time.

A new Extra Care development in Carlisle, UK, will benefit from superior levels of fire protection following the specification and installation of Pyroguard EI 30 INT – a high performance integrity and insulation glazing product.

The development at Heysham Gardens in Carlisle will provide 60 mixed tenure homes, principally for over 55’s who require some social care but wish to remain independent in their own homes. To ensure compliance with the UK’s Part B fire safety regulations, architects specified Pyroguard EI 30 INT, to ensure the required levels of fire protection could be achieved with screens in the communal area. Philip Brooks, of architects Day Cummins, explains: “Good day lighting and sightlines are key drivers on this Extra Care scheme. This can enhance visual recognition for those with failing eyesight or dementia, and can reduce reliance on artificial lighting. The fire glass helps to achieve these aims and ensures fire protection requirements are met.”

The fire glass was also installed at fixed sidelight panels next to fire doors, including flat entrance doors. The size and weight of the panels demanded that Pyroguard be installed on-site. By delivering the glass to site cut to size, the contractor was able to efficiently construct the glazing system.
Contact: For further information, go to www.pyroguard.eu

(Author)

Simon Ellison is Technical Manager for Pyroguard at CGI International