05/06/2009 by David Slade.

How Sprinklers Work

All areas of the building to be protected are covered by a grid of pipes with sprinkler heads fitted into them at regular intervals. Water from a tank via pumps or from the service (town) main (if it can give enough flow) fill the pipes.

Each sprinkler head operates only when it reaches its predetermined operating temperature and will then spray water on to a fire. The hot gases from a fire are usually enough to make the thermal element in the head operate. Only the sprinklers in the immediate area of the fire open. The others remain closed. This ensures that no water is applied to areas where there is no fire and reduces the amount of water needed.

The sprinkler heads are spaced, generally on the ceiling, so that if one or more operate there is always sufficient flow of water. The flow is calculated so that there is always enough to control a fire taking into account the size and construction of the building and the goods stored in it or its use.

Sprinkler heads can be placed in enclosed roof spaces and into floor ducts to protect areas where fires can start unnoticed. In a large warehouse sprinklers may be placed within the storage racks as well as the roof.

At the point where the water enters the sprinkler system there is a valve. This can be used to shut off the system for maintenance. For safety reasons it is kept locked open and only authorised persons should be able to close it. If a sprinkler head opens and water flows through the valve it lets water into another pipe that caused a mechanical gong to sound. In this way, the sprinkler system generates and alarm at the same time as controlling or extinguishing the fire. It’s worth noting that only sprinklers can do this with equipment which operates independently of an electrical supply.

Wet pipe

These are the most common systems and are used in buildings where there is no risk of freezing. They are quick to react because water is always in the pipes above the sprinkler heads.

Wet systems are required for multi-storey or high-rise buildings and for life safety.

Alternate

As the name suggest Alternate systems can have the pipes full of water for the summer and be drained down and filled with air (under pressure) for the winter. This is important for buildings that are not heated.

Dry pipe

The pipes are filled with air under pressure at all times and the water is held back by the control valve. When a sprinkler head opens, the drop in air pressure opens the valve and water flows into the pipework and onto the fire. Dry pipe systems are used where wet or alternate systems cannot be used.

Pre-action

Like dry pipe systems the pipes are filled with air but water is only let into the pipes when the detector operates (e.g. smoke detectors). Pre-action systems are used where it is not acceptable to have the pipes full of water unless there is a fire.

Deluge and recycling

These are not strictly sprinkler systems and are only used in special cases for industrial risks.

Sprinklers in Dwellings

Introduction

While sprinklers have been used for the protection of property such as mills, factories, warehouses and department stores for well over 130 years there is now a growing recognition of their effectiveness in improving levels of life safety in other types of buildings. The 2006 versions of Approved Document B of the Building Regulations (in England and Wales) and the Technical Handbooks of Scottish Building Standards both incorporate clear recognition of the value of sprinklers in improving levels of safety for occupants as well as in preventing the spread of fire. Other developments have demonstrated the value of sprinklers in providing additional levels of safety for fire fighters in large, complex structures or in buildings where the fire load is excessive. With the incorporation of the latest fast-response sprinkler heads there is clear evidence that, even in the compartment of origin of a fire, occupants of sprinklered buildings enjoy a significant additional measure of life safety.

Sprinklers for Life Safety

There also appears to be a growing consensus that sprinklers offer a highly cost-effective way of reducing the UK’s appalling fire death toll. It seems generally acknowledged that, while fire detection systems and smoke alarms probably save around 80 - 100 lives each year, this figure is unlikely to improve. It is also clear that when its is the most vulnerable members of our society who die - the very young, the very old, the disabled, the infirm and those who use drugs and alcohol unwisely - only sprinklers can actually prevent fire deaths.

In the case of social housing, care premises, homes in multiple occupation, hostels and similar properties there now clear arguments that sprinklers offer the best chance of preventing deaths should a fire occur.

Just What is the Extent of the Problem ?

In the UK each year there are around 45,000 fires in dwellings and while many of these involve damage which is little more serious than the need to repaint the kitchen it must be remembered that more than 500 people have died in fires in their home in the UK almost every year since 1945.

The introduction of smoke alarms in the late 1970s has, it is true, helped to reduce some of this appalling death toll but even the best estimates suggest that only around 30 lives are saved by such early warning devices.

No Place Like Home ?

It is only when one examines the details of these tragic fires that one can begin to understand why it is that only active systems like sprinklers can prevent domestic tragedies. A disproportionate number of the very young, the very old, the disabled and - it has to be said, those affected by drugs and alcohol - are the people whose deaths feature in this grim annual tally.

One other group also features in the list of the most vulnerable and that is those who live in shared accommodation - sometimes known as ‘homes in multiple occupation’ or HMO’s. One calculation suggests that someone living in an HMO is eight times more likely to die in a fire than someone living in a single family dwelling. Some local authorities are now suggesting the landlords who let rooms in HMO’s which are three or more storeys in height should fit sprinklers. In Scotland, legislation introduced in 2005 now requires all new care and residential homes to be fitted with sprinkler protection and in some areas, sheltered housing is also being so protected.

So sprinklers, unlike smoke detectors which can only warn of the need for evacuation, can actually save those who cannot help themselves.

Benefits for Designers and Builders

One of the most often ignored benefits of sprinklers is the additional flexibility which this equipment provide to designers and builders. In unconventional or unusual buildings including sprinklers in a specification will often enable Building Regulations compliance to be achieved in a very cost- effective manner. Where changes of use are being anticipated, utilising sprinklers is often the only way in which means of escape requirements can be provided. In other situations, the freedom architects seek to implement a stylish or unorthodox design can only be accomplished using sprinklers.

Sprinklers have also been used as a compensating feature in developments where the Building Regulations cannot be complied with in respect of means of escape or access for the fire brigade. Some projects have even reported that providing sprinklers has resulted in a cost saving where the building authority has permitted trade-offs in respect of means of escape facilities.

Standards for Installation

Sprinklers can be installed using any one of a number of accepted standards. Systems in commercial and industrial premises (including offices, shops, hotels and placed of public assembly should be designed and installed in accordance with BS EN 12845 2004 Fixed fire fighting systems. Automatic sprinkler systems. Design, installation and maintenance While this standard can be used for any installation it will usually be simpler and more cost-effective to refer to BS 9251:2005 Sprinkler systems for residential and domestic occupancies. Code of practice. (For more information on the application of BS 9251, refer to BAFSA Technical Guidance Document No 1.

Types of Systems

While there are a range of different types of sprinkler systems used in a range of premises it is considered that only wet systems should be specified in domestic premises. These systems are the simplest, easiest to maintain and are also the most cost effective. Pipework can be in copper, steel or in CPVC (chlorinated polyvinyl chloride) which is approved for the purpose. Depending on adequacy of water pressure and flow it is sometimes possible for the sprinkler system to be connected (subject the approval of the water authority) directly to the cold water main where it enters the dwelling. Where tanks and pumps are necessary because the flow or pressure are inadequate these can be sourced from a range of companies who manufacture approved and certificated equipment.

System Design and Installation

While there is nothing mysterious about sprinkler systems the high reliability and effectiveness of these systems has come about over the years by strict adherence to the sprinkler rules and design standards. It would be wise to select a contractor who is not only capable and competent but who also has an established track record and who can offer proof of compliance with an established quality assurance system.

For example, all Installer members of the British Automatic Fire Sprinkler Association can provide documentary proof of compliance with international quality assurance standards and all also hold an approval (Registration or Certification) from a third party certification service which itself is accredited by a Government-approved body, the United Kingdom Accreditation Service (UKAS).

Most BAFSA Installer members have been in business for more than ten years and some for more than thirty - all can provide objective proof of their competence. BAFSA itself was founded in 1974.

Conclusions

Finally a few facts:

1. There have been no multiple fire deaths in the UK as a result of a fire in a dwelling with a working sprinkler system.
2. US experience shows than 98% of all fires in sprinklered dwellings are extinguished with only one sprinkler head operating. The same data suggests there is a 57% reduction in the likelihood of death for those in the room of origin.
3. Only the sprinkler heads in the immediate vicinity of the fire actually operate.
4. Sprinkler heads can be completely concealed.
5. Sprinkler systems do not need pumps or tanks if mains pressure is adequate.
6. Sprinklered buildings prevent fire fighter deaths.
7. Sprinklers do not ‘false alarm’ - they will only operate if there is an actual fire.
8. For a small additional cost, an alarm switch can be built-in to the system to call the fire and rescue service automatically should the sprinklers operate.
9. Maintenance costs for sprinklers are very low.
10. Sprinklers save lives - and property - and are the only devices which can detect a fire, sound the alarm, call the fire and rescue service and extinguish or control the fire.
11. Finally, despite many preconceptions and misinformation, sprinklers are not difficult, unsightly or expensive to install in homes or dwellings of any size.
12. Since the UK started to take the idea of sprinklered homes seriously in the late 1990’s, it has been estimated that 25 lives have already been saved by the systems.

Standards

To make sure a sprinkler installation will work it must be properly designed and installed. There are presently two independently accredited organisations which undertake the certification of sprinkler installers.

Firstly, LPCB/BRE Certification Ltd undertakes third party verification of industrial and commercial sprinkler systems installers to a standard known as LPS 1048. The same organisation certifies residential and domestic installers using a second standard, LPS 1301. Both these standards also call up the relevant British Standards and in the case of systems being installed to BS EN 12845, the LPC Sprinkler Rules and their Technical Bulletins. The LPC rules are obtainable from the FPA.

Secondly, Bodycote warrington also run two schemes for sprinkler installers under their Certifire brand. One of the these is for companies installing domestic and residential systems, the other for companies working on commercial and industrial sprinkler systems.

Both organisations permit their listed companies to issue certificates of conformity to the owners of sprinklered buildings.

These certificates are proof to building control departments, the fire and rescue service, local authorities and insurers that such systems meet the appropriate standards and have been installed correctly.

Generally in the United Kingdom, spinkler systems are designed to BS EN12845 and BS 9251, there are times where specific insurers or customers require systems to be designed and installed to comply with other international standards, sush as NFPA (National Fire Protection Association - US based rules) or Factory Mutual (FM Global - insurance company).

Legislation

Approved documents accompanying the Building Regulations in England and Wales make specific reference to the use of sprinklers (Regulations for Scotland and Northern Ireland differ slightly).

For life safety, new residential blocks over 30m high must be fitted with sprinklers to meet Approved Document B standards. Similarly an uncompartmented area in a shop or self storage building over 2000 square metres now requires sprinkler protection. There are corresponding regulations applying to large single storey buildings for industrial or storage use where the largest permitted unsprinklered compartment is 20,000 square metres.

When sprinklers are installed there may be significant benefits in respect of compliance with Approved Document B of the Building Regulations 2000 (as amended). For example: the installation of sprinklers can allow buildings to be built closer together (half the spacing is required) to adjoining premises. This is a major benefit where site space is limited. Other requirements in Approved Document B regarding travel distances for escape may also be able to be extended and certain requirements in respect of access for the fire service may be relaxed. There may also be the possibility for savings in construction and building cost by relaxation of certain passive fire protection measures and the freedom to allow ‘open plan’ design in three-storey dwellings and apartments.

In retail premises, sprinklers can be taken into account when calculating fire growth and smoke volume. This is turn allows the approval of longer distances of travel to exits.

The guidance issued to interpret the Building Regulations now recognises the use of sprinklers for life safety and it is clear that future legislation will call for the increased use of sprinklers. For existing buildings the Regulatory Reform (Fire Safety) Order 2005 which replaced most existing fire legislation in England and Wales requires employers and others (the Responsible Person in the Order) to consider whether the duties imposed by the Order could be better discharged by fitting fixed fire suppression systems. The guidance documents published in support of the legislation recognize this. For example, residential care homes fitted with sprinkler protection can adopt a policy of delayed evacuation in the event of a fire alarm and the usual requirements to fit self-closers to all bedroom doors may be relaxed.

Scotland

From 1 May 2005 all new care homes, sheltered housing and high rise residential accommodation above 18 metres high have had to be fitted with sprinklers. In addition, sprinklers are required in all covered shopping centres. Reference should be made to: http://www.sbsa.gov.uk/new/tbooks.htm for copies of the relevant guidance documents.

Wales

The Welsh Assembly is, at the time of writing, considering a Legislative Competence Order which if enacted would require the installation of sprinklers in a wide range of new dwellings. This is expected to be enacted by summer 2009.

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05/06/2009 by David Slade.

MPs were divided on the progress of sprinklers in schools

A number of MPs have called for a tougher approach to sprinkler systems being fitted in schools after hearing that in spite of the government’s presumption that all new and refurbished schools should be fitted with them, implementation of the policy is varied and inconsistent.

The comments were made last month during a Westminster Hall debate, a non-binding, consensual forum for MPs.

Ian McCartney MP, who secured the debate, said that in spite of the schools’ minister’s previous comments which virtually gave an instruction to local authorities to install sprinklers, this was not happening across the board. “We have already built hundreds of millions of pounds’ worth of new schools in the programme, and perhaps only one or two have been fitted with a sprinkler system.”

Mr McCartney urged the government to find a way to regulate so that no local authority is able to sign a contract, unless it precisely and clearly includes an instruction that sprinkler systems be fitted in all refurbished and new build schools.

While welcoming the increased emphasis on sprinklers in the schools’ fire safety document, Building Bulletin 100, the shadow minister for schools, Nick Gibb, said other measures were also needed. These included good security, better education programmes and a stronger sense of discipline in pupils.

Replying to the debate, schools’ minister Jim Knight pointed to a slight reduction since 2003 in the number of arson attacks and fires in schools. He said that the current version of the risk analysis tool in Building Bulletin 100 is more heavily weighted towards sprinklers, as the vast majority of schools will now be assessed as ‘average’ or ‘high’ risk. “The [government’s] position is now that sprinklers should always be installed in all new schools, except the very few schools if any that are assessed to be of ‘low’ risk and for which there is also no whole-life cost benefit.”

He said although it was difficult to judge impact of the new guidance as it was only introduced in 2007, the early indications were that whereas previously less than 10% of new schools had sprinklers installed, as many as 75% may now have them. “I would like to see the figure higher still, but it is clear that some progress is being made,” he added.

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