Fire breaks out in a school, the flames are taking hold of a classroom and smoke is pouring into the corridors. The fire alarm has been sounded, leading to hundreds of frightened children following their teachers to assembly points on the playing fields, walking quickly but calmly as they have been taught.
It’s a scenario anyone involved in fire safety in schools, universities and associated buildings has imagined many times. It’s what they plan for and if it all goes to plan, everyone will get out safely. However, timelines are tight and the danger of students or teachers panicking in the face of a real blaze fills us with dread. Ask any risk manager what resource they would have if they could, and most will answer: “more time”.
More time to ensure an orderly and calm evacuation, one that will feel like just another drill; more time to deal with the fire itself while it is small and extinguishers and fire blankets remain effective; more time for the fire brigade, who need to travel, set up and assess the situation before they can start fighting the blaze.
Aspirating smoke detection buys you time
Gaining more time is a key reason for changing from the familiar point-type fire detectors to aspirating smoke detection (ASD). Also known as air sampling detectors, these systems suck air through a tubing system and test it for smoke using a powerful sensor. Each sampling hole along the tubing is therefore the equivalent of a conventional point-type detector and this equivalency is recognised in regulations around the world. A single ASD unit can have dozens of sampling points thanks to its powerful fan and yet still detect smoke at much lower concentrations than point detectors can.
That is why ASD is emerging as a favoured technology among fire safety and risk management decision makers who want to move from standard, deem-to-satisfy fire detection designs, to a performance-based design approach supporting early warning fire detection (EWFD) or even very early warning fire detection (VEWFD). The time advantage is not the only benefit of ASD when it comes to protecting schools, universities or halls of residence, but it is a very important and multi-faceted one.
More sensitivity, more information, more control
ASD units achieve their heightened sensitivity because of their ability to physically suck in air from a room for sampling and because it is then subjected to a more powerful sensor in a much bigger smoke chamber than would be practical in a point-type detector. High quality ASD detectors can detect smoke at 0,002% obscuration using a scattered light technique, compared to 2% in a point-type detector. That is extremely sensitive. However, contrary to what you might expect, with the right design considerations it can actually ensure fewer false alarms.
A high-quality ASD unit can offer several levels of pre-alarm before reaching a level where it will initiate public fire alarms and suppression systems. The unit can monitor whether a situation is getting worse or remaining stable, but also gives personnel the chance to investigate the situation on the ground. The initial, incipient stage of a fire is mostly smoke and can last anywhere from minutes to days. At this point, it is easy to suppress using basic fire-fighting equipment. This leads to two major benefits of EWFD with ASD: fewer false alarms and the ability to snuff out fires before they do any damage. Even more importantly, there will be more time for a safe and orderly evacuation of young people without causing concern or panic.
Sometimes ASD is the only choice
ASD’s advantage in terms of speed and reliability are considerable for any security, operations and risk management decision makers responsible for protecting schools, universities and similar large public buildings full of young people. In fact, there are also reasons why point-type detectors may not be appropriate in such spaces at all.
A further feature of ASD is that it can be used in a variety of spaces where conventional fire detectors simply cannot be deployed or maintained. Although this may not immediately seem like the case for educational establishments, large halls and atria fall into this category. This is because smoke from a fire in large indoor spaces with very high ceilings tends to stratify at a point of thermal equilibrium. Smoke cools as it rises and when it meets warm air higher up in a hall, it stops rising and spreads horizontally. The pipes of an ASD can be configured vertically around such an atrium to ensure that they will detect an incipient fire in such a space. Additionally, the unit housing the sensor, controls and fan will be in an easily accessible position, with at least one sampling hole at a similarly convenient point for testing. Contrast this with the need to carry out regular testing and maintenance on individual smoke detectors dotted around the ceiling of a large assembly or lecture hall!
ASD is also cost-competitive
In this regard, ease of maintenance can also ensure that the ASD is highly competitive when considering the total cost of maintenance. Additionally, maintenance and testing work on ASD devices is far less intrusive and it is not hard to envisage it being carried out while a lecture or class takes place. Other locations where point-type detectors are not suitable and ASD provides a workable alternative are the spaces inside false ceilings and raised floors, sometimes used in educational establishments to run cables and piping.
Take a performance-based approach
ASD is not new technology: Securiton has been developing and improving it for 50 years. However, in its latest forms it is an exciting fire technology which is gaining traction across a wide variety of industries and professionals. In particular, many fire safety professionals including system integration specialists, consultants, specifiers and IT personnel are now focusing on ASD as a way of achieving EWFD or VEWFD ambitions. In other words, they want to move from providing fire alarms as required by law, to taking a truly proactive approach to protecting their organisation’s people, property and profits.
Everybody agrees that fire safety is essential in schools, universities and halls of residence. That is why those responsible for designing, installing and operating fire detection in those institutions should be adopting a performance-driven approach that goes beyond what is required by law and embraces all available technologies. The benefits of performance-based design in fire safety are far-ranging, but most importantly of all, it maximises the ability to keep people safe.
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