FS North: Fire detection and alarm system integrity

According to Paul, it has never been more important to ensure the survivability of a fire system. He explained: “We need to ensure that the operation of a building’s fire protection measures is maintained. Key to this is the use of distributed technology for system integrity and survivability. Deployment of fault-tolerant and failsafe technology is also important, as is protecting distributed system communications with fire network cabling. Overall, the integration between the building management system and the fire detection and alarm system should be kept simple and failsafe.”

Distributed EN54 fire networks are more common now, Paul went on, whereby control panels are networked together to form a single system. Fire network cabling is very important in such systems, he reiterated. “The use of enhanced fire-resistant cabling for networks is recommended, particularly where detection and notification are required for periods longer than would be the case in single-phase evacuation.”

Paul then moved on to multi-sensors, describing them as “the future of fire detection”. He explained how they use a combination of, usually, heat and optical detection – pointing out that carbon-monoxide sensors are not general-purpose detectors, as CO is not always present in a fire situation.

Multi-sensors can measure multiple fire phenomena and/or different aspects of fire phenomena. Said Paul: “They can be combined to discriminate towards a genuine fire and nuisance signal to make appropriate failsafe decisions.”

Paul also reminded delegates that the terms ‘multi-sensor detection’ and ‘multi-criteria detection’ are not interchangeable. The latter term is used mainly in Germany and the US and is not applicable in the UK. He explained: “Multi-sensor detection measures multiple fire phenomena, e.g. smoke, heat, CO, while multi-criteria detection means the measurement of different parameters of one fire phenomenon.”

He then went through the new standards to cover multi-sensor technology, i.e. pr EN54-30 (CO and temperature detectors), pr EN54-31 (CO, temperature and smoke), and pr EN54-29 (temperature and smoke).

Paul discussed the use of algorithms within multi-sensor technology, describing them as “a logic function within a sensor to improve its performance, including optimising its performance in a particular environment”. Algorithms have great potential to help meet one of the biggest challenges faced by the industry – how to reduce false alarms without compromising detection capability – but the need for compliance and related approval of all modes and settings on a detector is hampering progress in this regard.

Summing up, Paul said: “The use of software in multi-sensor fire detectors opens up a vast range of possible fire-response profiles. Specifiers need to understand these profiles and their intended use within a building’s fire/evacuation strategy. Engineers must understand the fire risk and settings used in each detector, to ensure system design compliance. Finally, I urge you to make sure you are using failsafe algorithms that are designed to optimise sensor response without compromising safety.”