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INTRODUCTION

The purpose of this guide is to give some background and commentary on the purpose and uses of sprinkler systems and to explain their important features clearly. It will explain some of the engineering behind the standards and regulations which apply and clear up some of the common misunderstandings about sprinkler systems. It is not intended to be a design guide; the correct implementation of the standards called for in the LPC Rules for automatic sprinkler installations incorporating BS EN 12845^† (the LPC Rules) should be entrusted to individuals with appropriate levels of qualification, training and experience.

There is much mystique associated with sprinkler systems; sometimes the LPC Rules are seen by those outside the sprinkler industry as difficult to understand and too rigid in application. It is true that the parameters of sprinkler design are often applied as set in the stone – and it can be frustrating for other building services disciplines when those rules cannot be manipulated to suit a particularly difficult problem or similar issue. The reality is that with almost all other building services, their function can be fully proven during the commissioning stage and any shortfall in capability addressed at that time.

Sprinkler systems cannot be fully tested in their working situation because, of course, the ultimate test of the design will only occur in a very extreme set of circumstances of a fire in a building and these cannot normally be replicated at commissioning stage. It is inevitable, therefore, that extreme caution is used when considering if adjustments (known as non-compliances) to the requirements stated in the LPC Rules can be accommodated. It is usual for the persons ultimately responsible for accepting such changes (possibly the local authority or fire insurers) to be consulted prior to the event – time constraints can often lead to a ‘stick to the LPC Rules' policy. That is not to say that adjustments cannot be made but these should be based on sound engineering principles, erring on the side of caution where there is doubt, and be discussed with all relevant parties prior to implementation.

Although other international standards are discussed in this guide, the principal guidance here relates to the LPC Rules.

BS EN 12845:2004 is able to stand alone but the LPC Rules include BS EN 12845 (2003 edition), as well as a series of technical bulletins which supplement the core document. Where there is conflict, the LPC technical bulletins would take precedence. The technical bulletins are owned, published and maintained by the Fire Protection Association (FPA). Before 2003, when BS EN 12845 was introduced, the core document used in the LPC Rules was the 1990 edition of BS 5306-2 Fire extinguishing installations and equipment on buildings – Specification for sprinkler systems.

Sprinkler protection should not be considered in isolation but should be part of a package of measures used throughout premises on how to deal with firerelated issues. Indeed, there may be significant interaction between elements of the measures, such as the sprinkler system and the fire alarm and detection system, which are vital to the management of any fire incident. Good fire awareness and management of fire risks and practices will serve to reduce the likelihood of the operation of the sprinkler system.

The possible effects of sprinkler activity on the site, and such factors as firewater run-off, must be carefully considered. The environmental effect of contaminated firewater running to water courses is one of the issues which should be included in the process. That is not to say that the presence of a sprinkler system will increase the likelihood of problems with run-off. Indeed, the fact that sprinklers are likely to act promptly to control an outbreak of fire may reduce the likelihood of very large firewater discharges taking place when the fire and rescue service (FRS) deploys its firefighting jets onto an established fire.

^† The LPC Rules for automatic sprinkler installations incorporating BS EN 12845 refers to the 2003 edition of BS EN 12845: Fixed firefighting systems – Automatic sprinkler systems – Design, installation and maintenance. This edition has now been superseded by the 2003 edition of BS EN 12845, but the LPC Rules have not been updated accordingly because there are no material differences between the two versions.