Fire & Safety : Keeping up with modern technology

Today’s fire systems have become much more sophisticated, especially over the last few years, and now save countless lives and millions of pounds worth of property every day.
This is due in the most part to advances in detection hardware and system software, both of which can clearly be incorporated into new systems and also retrofitted within existing installations.

So, bearing this in mind, are the fire detectors you specify always suitable for your customers’ risks, risks which are constantly changing as a building’s use alters?

More and more owner-occupiers and developers realise that to comply with the new Regulatory (Fire Safety) Reform Order (RRO) and meet the demands of their insurance companies, good Fire Detection & Alarm (FDA) system design is essential irrespective of whether it is for a new build or a refurbishment project. The key to this design, after the level of protection has been determined by the Fire Risk Assessment, is to use the latest technology available and in the process select the correct sensor for each application.

On the surface, the principles involved in the early detection and signalling of fires do not appear to have changed drastically. What has happened though is that the individual components used have evolved and are now put together to complement one another in ever more complex ways, and are then mathematically coordinated to provide the state-of-the-art systems now available. But of paramount importance is the ability for the discrimination of a new or updated system to be powerful enough to be able to distinguish between a real event and a false alarm consistently and precisely.

For the majority of people, one fire detector might seem much like any other and consequently the final decision regarding which to use, can often be left to the installer. However, Gent, one of the forerunners in fire detector design, has introduced a device that has moved the science of fire detection forward quite significantly. It is called an S-Quad multi-sensor and combines four separate sensing elements each able to recognise a different fire type or condition. It incorporates three different detection methods, each capable of sensing various conditions, some or all of which are present at an incipient fire.

Optical, Heat and Carbon Monoxide (CO), each react to a particular product of combustion; smoke particles, temperature rise, and the presence of CO respectively. Selecting which individual sensor to use has historically been a designer’s main concern, however with this technology, selecting the correct detection method for the various applications is simple and straightforward. Not just initially, but readily updatable, as and when the site conditions change, the sensor can have its State ‘changed’ as well.

The further advantage of updating to detectors that sense more than one of the products of combustion is to increase the chance of detecting a real fire more quickly. With recent advances in optical sensor technology using two optical measures from different angles, false alarms levels are vastly reduced. This ‘dual angle’ technology provides information about the nature and size of the particles, distinguishing between smoke, steam or dust, allowing more accurate discrimination between particles of combustion and the non-fire particles that could normally trigger false alarms.

If these sensors are connected to a powerful fire control panel, sophisticated algorithms can be used to match patterns of activity with hundreds of hours of test data. Pre-defined rules can be used that optimise the performance of the sensor for real world applications. For example, in a hotel bedroom full of steam, the readings from the dual optical elements and the lack of CO would pattern match as a false alarm, so increasing the fire trigger threshold and avoiding an unwanted alarm.

Panels can also now incorporate an enable/disable feature that can be programmed to automatically switch sensors from one state to another. For example in a restaurant below a bedroom, the detector can be programmed as a heat only detector during the day and a combined smoke and heat detector at night.

It is also possible to change the sensitivity levels of a detector – e.g. to increase sensitivity of the smoke sensors within a bedroom when the occupant is asleep.

A double knock or coincidence sensing feature can also reduce unwanted alarms by ensuring the control panel gathers information from more than one sensor within the same room. The information can be combined, enabling the system to react more quickly to real fires while ignoring potential false alarms from a single device. This technique has been common practice in computer rooms for some time but surprisingly is rarely used for more general applications. Another technique, using a combined sensor sounder, is to programme the sounder so it only operates when its own sensor is activated. This feature is extremely useful within a hotel bedroom or student’s bed-sit, where the occupant is alerted to a potential emergency situation, while other guests are left undisturbed until the situation is confirmed.

Gent continues the research by data-logging various fire phenomenon as well as known causes of false alarms. By including these analogue patterns within the memory of the fire control panel, the performance of both sensor and system can continue to be enhanced.

In summary, to keep FDA system performance at maximum, now there need only be one sensor for all applications that can be switched from state to state depending on the conditions present at the time, to ensure a real fire is detected quickly and without false alarms. These sensitivity states can be defined to match specific applications and risks. Selection of these states in the control panel allows each and every sensor in the system to be individually set to an optimum state that will balance early detection of real events and rejection of false alarms. In more advanced systems, these states can be automatically controlled by the time clock and calendar. This allows sensitivity to be increased during the night and at weekends for example when buildings are unoccupied.

Besides that, an audible alarm can be delivered that will guarantee minimum db levels throughout a building and, if a clearer message is required, can provide a synchronized speech and/or visual alarm to ensure the system complies to the requirements of the Disability Discrimination Act.

And remember, this technology is not just reserved for new systems. To update an existing system to conform to the new RRO, the features considered can be retrofitted to a fire detection system to bring customers the improved performance required, enabling them to meet the more stringent requirements of the new regulations. This could be a low cost route; system enhancement at minimal cost, upgrading existing software and perhaps replacing some other hardware, while still generally maintaining the existing wiring architecture.

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