"What makes a place feel like home? Above all, whoever you are or how much you have, it is somewhere where you feel safe" writes the Rt Hon James Brokenshire MP, Secretary of State for Housing, Communities and Local Government, in the Foreword to his new plan, December 2018.
The first words in the new implementation plan "Building a Safer Future" following the extreme shock of the Grenfell catastrophe sets the theme. Fire safety is now a fundamental Government objective. The first pages of the plan leave no room for doubt: that the Government intends to pursue "clearer standards and guidance to support better understanding by those carrying out building work of what is required to make buildings safe," also to ensure that "people working on buildings use safe products."
Nobody should really need to be reminded of the fundamental requirements for safety in fire. Regulations for protection of people in buildings against fire depend fundamentally on using safe products that are implicitly fit for their intended purpose.
But how to ensure product safety in practice is not spelt out by regulatory guidance, apart from specifying classes of performance and referencing test methods to demonstrate compliance.
Nor does the Government’s new plan say specifically how product safety is actually to be achieved, apart from referring in passing and in general terms to the rigour of product testing, marketing and labelling. How those aspects play out in practice is left to the industry, designers, specifiers, suppliers and the various control authorities.
Key to the Government’s list should have been added “product responsibility” and “ownership” by suppliers and installers.
Where the requirement is to provide fire resistance there is already a system of good practice in place to demonstrate performance. Fire resistance is a tested property of products and elements of construction, to evaluate the ability of a barrier (such as a glazed screen) to maintain its fire separation function, and to minimise the risks of fire spread, when exposed to fire from one side.
The furnace test method for fire resistance of building materials has deep roots. The temperature-time test curve is based worldwide on the ISO 834 standard, said to originate in deliberations as early as 1918. The British BS 476 standard test procedure comes from Part 1 in 1953. The current standard BS 476 Part 22 was introduced in 1987, following the similar Part 8 in 1972. The new pan-European fire resistance test standards were introduced in 1999, after a process of discussion, for a common procedure across the CEN member countries, intended to encourage better reproducibility from one test centre to another. Details differ from the traditional and still current BS 476. But the principles of product performance are essentially the same under both BS and BS EN test methods for the important respects of limiting fire penetration, using the same prescribed pass/fail criteria.
In view of such a history of fire resistance testing, it should accordingly be no surprise to find that established products are likely to have an extensive record of fire resistance testing behind them. Pyrostop and Pyrodur, for example, are extensively tried and tested. They have been on the market for several decades, as well in many countries worldwide (from Europe to Japan, the Far East and USA). They have an extensive depth of testing behind them in all sorts of framed systems and applications, for a range of test times for 30, 60, 90, 120 and even in some cases 180 minutes.
The standard fire test curve is intended to represent a flashover condition, i.e. when the fire has consumed the combustibles in its place of origin and has reached a maximum state of development in that area. It’s a representative fire condition. But real fires in practice will most likely be significantly different. And in some case the fire condition arising in reality may well be far more intense than the test conditions provide.
A key consideration should therefore be the stability and robustness characteristic of the product’s fire resistance technology. That fundamentally determines how the products based on that technology can respond when the conditions in practice are more intense than envisaged in the test classification process, and how safe the product can be in conditions that have not been anticipated.
Pyrostop and Pyrodur, for example, are both based on a chemically-designed silicate interlayer that bonds to glass when heated, expands (intumesces) to insulate when exposed to fire, remains stable and cannot add substantially to the fire. The interlayer is inorganic and specifically designed to provide robust protection when replicated in several interlayers, one after the other, against the unpredictability of fires that may arise in practice. Behaviour of the technology in response to fire is inherently dependable. The interlayer stable structure allows robustness and longevity to be built into the product by replicating one layer after another. Consistency and repeatability are as much a key consideration as a level of performance demonstrated in just a single test.
The following prime considerations should therefore apply in evaluating product safety for a fire-resistant glass:
Firstly, considerations of product pedigree. That is, the depth of test evidence, including scope of application and number of successful tests over many years, the maximum glazing sizes that are approved and the extent of glazing arrangements and configurations. The robustness and effectiveness of the underlying product technology is a key indicator. In those respects, Pyrostop and Pyrodur both have extensive test records for use in a range of varied applications.
Secondly, the strength of product ownership and branding. That’s indicated by the communication materials that are used and the access to further advice and guidance on the use of the products, for example handling and glazing guidelines, and test information summaries. A sign of a valued product is the strength of attachment to the product brand and the length of time that brand has been around in the market. For Pyrostop, that is since the 1970’s, leading the way.
Thirdly, factory, product and technology control, all together as a package. That includes commitment to product performance with in-house testing. Both CE marking for glass products and third-party product certification are indicators, but those should also be taken together with factory production control. Pyrostop and Pyrodur, for example, are produced essentially in a chemical plant designed for tight control and consistency of production. On the factory site, close to the plant, are two major furnace test facilities, modelled on the typical German state pattern 3m by 3m furnace for large-scale testing, which at least match any in UK test houses. Those are used for routine testing and systems development within an extensive R&D test and monitoring programme linked to product and plant operation.
Confidence in product safety, as the Government seeks, is far more than simply reliance on a limited number of tests. Understanding and appreciating the safety of products in likely fire scenarios, and those that perhaps cannot be anticipated, needs an in-depth consideration. There are several elements that have to be considered, taken together as a whole.
That should include the product’s pedigree, the full track test record, its history of use, the developed scope of application backed by appropriate certification, and especially the reliability of the underlying product technology.
T A Anders Limited is a longstanding Licensed Supplier of the well tried and tested Pilkington Pyrostop and Pilkington Pyrodur fire-resistant glass and glazed framed systems. We stock the entire range at our modern factory in Trafford Park, Manchester, and can process, distribute, install in proprietary frames and provide fire safety and product guidance if required. For further information, please contact T A Anders Limited on 0161 736 2487 or email@example.com or visit www.andersglass.co.uk for product specification advice, information and test evidence.
These opinions are offered in good faith but it is the responsibility of the reader to satisfy themselves as to their veracity and form their conclusions