Assessing Glass in Fire


By Mike Wood, for Pilkington UK Ltd

Fire safety risk assessments cannot sensibly be carried out without considering the use of glass in compartmentation and escape ways.  Mike Wood on behalf of Pilkington UK, stimulated by new research on students as a particular risk group, offers some essential guidance for fire-resistant glazing to provide a reminder of core principles.

As the spring term enters full swing and the angst of exams – at least for now – is over, Britain’s student population will take the opportunity to throw itself into the joys partying. This is simply part of student life. But few will give much thought to the risks of fire, and they are likely to be unaware that they are seen in fire safety circles as a group with a distinctive lifestyle that leads to a particular fire safety risk profile.

Zurich Municipal has recently produced research on the fire risks posed by students.  The headline finding is that 81% of students typically – and inadvertently – show distinctive behaviours that, for a variety of causes, raise the risks of fire and its consequences. That isn’t to curmudgeonly knock youthful high spirits.  The research is matter of fact. It concludes that there are some aspects of student living that lead to raised fire safety risks. 33% of the sample said that they were not aware of the fire safety procedures in their halls or rented accommodation. Two thirds carried out cooking after midnight, 50% under the influence of alcohol; 43% regularly dried clothes in their rooms over heaters, 24% often burning candles.

Information from the Department of Communities and Local Government (DCLG) show 514 fires in student accommodation last year.  58% of all incidents come from cooking (for example, fat build up on grill pans, frying pans left unattended on the hob) plus 9% of fires from chip pans or deep fat fryers. Other significant causes of fire are faulty electrical appliances, power leads, irons or hair straiteners left on (7%).  Universities are aware of the risks and take steps through their facilities management and support services to raise awareness.  Some have video clips on their support web pages, demonstrating the various hazards and illustrating how easy it is in a packed student study bedroom – including accelerants such as nail polish remover and strong alcohol – for a fierce fire to develop rapidly, consuming the room contents within only a few minutes.

The fire safety risks do not only come from the student way of life.  Student accommodation in university halls and in privately managed rented properties such as houses in multiple occupation (HMO’s) are also important factors.  Many HMO’s are likely to be older buildings not originally intended for multiple occupancy, where the original fire safety precautions fall short of modern levels of safety and where various refurbishments and renewals over the years may not have been carried out to best practice current trade standards.

As recent fires in high rise blocks of apartments and separate flats illustrate (e.g. Lakanal House and Shirley Towers), multi-story blocks concentrating large numbers in one building provide a proportionately higher risk than the same occupancy spread over separate individual dwellings.  Risk increases with building height and number of stories, being critically dependant on the number of people in the building and the provisions for escape.  Hazard assessment should consider the chances and possible speed of fire spread.  The complexity and accessibility of the means of escape should be evaluated, including the condition and suitability of all fire doors, lobbies, escape stairs and firefighter access stairs or lifts.  Fire separation between individual dwellings is potentially crucial as is the completeness of compartmentation throughout the buildings. Isolation and protection of the kitchen area to prevent rapid fire spread should be a particular focus, particularly in HMO’s and student halls where several share the same facilities.

In any risk assessment an evaluation of the glazing in common areas will surely be necessary at some stage given the extensive use of glass in today’s buildings.  That, for example, will likely include glazing in doors, screens, partitions, and even external glazing where the panels look out on external escape ways or adjoining windows and neighbouring buildings, perhaps where there are concerns about external fire spread to other floors through the facade glazing.  In many cases it is advisable for the fire risk assessor or fire safety manager to call for advice and guidance from an experienced specialist in fire-resistant glazing.

Pilkington NSG can offer some core principles as a basic guide that can at least help in putting questions to the specialist:

  • Standard glass products such multiple glazed units, single glazing, toughened glass and laminated safety glass (“safety” referring to impact) do not have significant resistance against fire. Assumptions in that respect should not be relied upon.
  • There are several varieties of fire-resistant glazing, based on different fire-resistant technologies. They all require care if installations are to function optimally as intended.  In each case the manufacturer’s guidance must be followed; and there must not be any “We know better” attitudes.
  • Fire-resistant glass, of whatever type, must be installed as part of a fire-resistant glazed system of matched, specified components. There must be no mixing and matching between different fire-resistant glazed systems.
  • Details of the approved fire-resistant glazed system must be followed, in particular the extent of edge cover on the glass, expansion allowances if specified, specific bead dimensions and shape, the glazing arrangement, fixings and glazing materials.
  • Fire-resistant performance is classified as either integrity – a physical barrier against fire – or insulation – acting as both a physical and effective heat barrier.  Clear glass can still let through relatively high levels of heat, causing smouldering on the non-fire side (maybe even secondary ignition); and insulation as the lower risk specification may therefore be the preferred option.
  • The fire-resistant glazed system must have applicable test evidence which is appropriate for the application.  That evidence is a test report for the particular configuration being considered, produced by an independent UKAS-accredited testing organisation. No other source evidence is acceptable.
  • Claims for fire resistance should be determined according to applicable British test standards, that is, BS 476-22:1987 (as allowed under regulatory guidance) or BS EN series (e.g. BS EN 1364 -1:1999 Fire resistance tests for non-load bearing elements – Part 1: Walls; BS EN 1634-1:2008 Fire resistance and smoke control tests – part 1: For doors, shutters and openable windows).
  • The most unhelpful term in considering fire resistance – too often and too widely used – is the generic, and meaningless, “fire rated.” All fire-resistant glass should be tested and classified as integrity or insulation together with an appropriate time as achieved in a standard furnace test (e.g. 30, 60, 90, maybe 120 minutes).
  • Fire-resistant glass should be clearly marked.  The stamp on the glass should, at least, identify the glass by name and manufacturer (e.g. Pilkington Pyroclear®) with its fire resistance performance.
  • The stamp should be permanent, legible and readable after glazing. It is normally put in the bottom right hand corner of the pane. Impact rating, if required for the situation, should also be included (e.g. classification to BS EN 12600:2002 Glass in building – Pendulum test – Impact test method and classification for flat glass).
  • Assessment reports – based on the opinion of a UKAS-accredited organisation with access to applicable test reports – may also be used to support application.  But these have to be properly approved and authenticated, and based on applicable source test evidence.
  • Similarly, certificates under a UKAS-accredited third party certification scheme, referenced to source test reports, may also be used – but their use must be confirmed by the main company responsible for the fire-resistant glazed system named in such certificates, and not just downloaded from the web.
  • The fire-resistant glazing system must be installed as approved, according to the applicable source test evidence.  Changes must not be made, and can only be considered with reference to the owner of the source test reports for their approval.
  • Repair or refurbishment of existing fire-resistant glazed systems should be carried out according to the original system specification.  If that is not known, or cannot be done, then call in the specialist (rather than trying to second-guess what might have been the original components).

Pilkington provides through its product range a comprehensive set of solutions for the applications where fire-resistant glass is required.

Most basic applications are for straightforward integrity fire resistance, used in particular to provide sufficient fire separation for protected escape before conditions become untenable.  Pilkington Pyroshield 2, wired glass, provides a well tried and trusted traditional option, and Pilkington Pyroclear® now provides an alternative in clear glass.  Pilkington Pyroclear® is a new type of advanced modified fire-resistant toughened glass based on innovative proprietary developments and high quality manufacturing control, produced on equipment specifically developed for the job. It gives an enhanced level of reliability compared with others in this category.

Pyroshield
Pilkington Pyroshield™

Where a relatively higher level of integrity performance with some additional insulation benefits may be required – for example, where the risks of safe escape are at a higher level, where the building may be more complex or where there may be relatively more at stake should fire break out – then Pilkington Pyrodur® Plus provides an excellent added value option.  Pilkington Pyrodur® Plus provides all the requirements expected of integrity fire resistance with the added benefit of a measure of full insulation (achieving 20 minutes insulation in standard tests, a considerable advantage compared with other integrity types).

Full insulation performance at classification times from 30 minutes up to 180 minutes is provided by Pilkington Pyrostop®. Insulation fire resistance is usually recommended for those situations where there risks of prolonged exposure are much higher, the occupancy particularly vulnerable, or where there are concerns about protecting the building, assets and adjacent properties.  It would also be a recommendation to protect firefighters in emergency response and rescue operations.

Pyrostop pyrodur
Pilkington Pyrostop®

The Pilkington tried, tested and trusted range of fire-resistant options – Pilkington Pyrostop®,Pilkington Pyrodur® Plus, Pilkington Pyrodur®,Pilkington Pyroclear® and Pilkington Pyroshield 2 – provide a wide scope of application in a variety of glazed systems. All are based on specific fit-for-purpose technologies under the distinctive Pilkington name for product quality and reliability.  Advice is available from the Pilkington Help Line 01744 69 2000 and www.pilkington.com/products/bp/bybenefit/fireprotection/default.htm,

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