Early warning system for high bay warehouses

28 September, 2006

Early detection of fire is always an important issue, especially for large facilities such as high bay warehouses.

The suitability of the Stratos-HSSD aspirating smoke detection system from AirSense Technology for the protection of high bay warehouses was demonstrated in a project featuring the detectors installed in Project Annona, a food distribution centre for Unilever UK Foods. The presence of combustible materials in the fully automated warehouse would cause fire to develop quickly, and so early warning is crucial.

The protection of the warehouse from the threat of fire was high on the agenda. Electrical contractor for the project, WT Parker, appointed Daemon Fire and Security to carry out the installation. This company specified the installation of 12 Stratos-HSSD aspirating smoke detectors, incorporating the AirSense Technology manufactured

Apollo signalling protocol interface cards, enabled integration of the detectors with the existing site fire detection system.

A critical factor in the selection of detectors was the size of the building – a 31m high bay storage with a capacity of 90,000 pallets. Smoke stratification would have rendered conventional point detectors ineffective. Arthur Meddings, director of Daemon Fire takes up the story: “Beam detectors were initially proposed but we were against this. We recommended the aspirating smoke systems as we had experience of the system before and were satisfied with the performance and service. Hundreds of metres of air sampling pipes were installed in the warehouse to provide full coverage of the building. We tested the reaction time to the presence of very small quantities of smoke and it was very fast – the alarm sounded within two minutes.”

Beam detectors are frequently used for detecting smoke in such applications because of their simplicity and low-cost. However, they are much less sensitive than aspirating systems such as the Stratos-HSSD, providing a later response. Beam detectors are also prone to nuisance alarms if the beam is disturbed by pallet movements. Building movement caused by temperature change, sunlight and wind loading can also interfere with beam detection, causing nuisance alarms. Finally it is important to appreciate the effect of smoke stratification in such areas, where smoke frequently develops at a lower level than beams may be located.

The detector offers advances in terms of fully automated sensitivity setting. It features a perceptive artificial intelligence system know as ClassiFire, which is able to continually maintain optimum sensitivity through a process of self-conditioning. It is also able to distinguish between day and night or holiday shutdown periods, automatically applying appropriate sensitivity. The detectors require little maintenance and because they are installed at low-level, access for service is much easier than for ceiling level detectors.