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INTRODUCTION

This report describes an experimental study that provides research information and data to assist with understanding the mechanisms for successful water mist fire protection systems. The work was commissioned by BRE Trust and carried out by BRE Global from April 2007 to March 2010.

The project was undertaken with three project partners: two water mist system suppliers and one insurer. The two industry water mist system suppliers provided the systems, and gave operational and maintenance support during the experimental programme. The insurer provided information and advice, and arranged for a site inspection.

In UK buildings, systems are increasingly being considered and used for the fire protection of buildings, including commercial premises such as hotels, offices and retail units.

Water mist systems are becoming an attractive option for reasons of loss prevention and business continuity. They can provide property and asset protection in buildings by limiting the extent of damage associated with a fire and thereby limiting unnecessary wastage of resources, time, salvage and re-instatement operations.

Other reasons that water mist systems are being considered for new applications are that, compared with automatic sprinkler systems, they can be cost efficient, involving relatively small quantities of water, smaller tanks/ containers and less pipework. Therefore, water mist systems are seen as more sustainable and a 'greener' fire protection solution than automatic sprinkler systems. In addition to property and asset protection, water mist can be considered for life safety purposes and could be used as a compensatory feature to other prescriptive fire safety measures.

However, the acceptability of water mist systems is often unproven, the limits of their effectiveness are largely unknown and appropriate acceptance criteria are not well established. Successful water mist performance can only be achieved by carefully engineered designs to meet particular applications. Fire protection success or failure is highly sensitive to design details. Variables such as nozzle spacing, water flow/pressure, obstructions, nozzle blockages, high ceilings, large compartment volumes, openings and shielded fires can influence the firesuppression effectiveness of a system.