The Changing Face of Fire Detection.

The options available to buyers of fire detection equipment are now more diverse than ever. This article looks at the range of technologies on the market and offers some advice on finding the most suitable solution for a particular situation, as well as assessing the likely impact of innovation and regulatory developments on the future of fire detection.

The rapid evolution of fire detection technology means more lives are being saved than ever before. Moving on from the one-size-fits-all systems of the past, a wide array of solutions now exist to provide the best possible protection in a range of environments, each with their own characteristics.

It is now possible to detect any or all of the main indicators of fire, which are smoke, heat, carbon dioxide or carbon monoxide and even flame. However, while this increased level of sophistication represents a huge leap forward, it also presents buyers with a more difficult decision-making process because cost, scale, location, technology, regulation and risk assessment are all vital considerations in choosing the system that best serves the particular purpose.

What are the Options?

Alarms that used ionisation were once the preferred option, but problems with their disposal in light of their radioactive components mean they have largely been rendered redundant and are even banned in some countries. Instead optical smoke detectors were adopted as the most common solution. Inefficiencies caused by high air movements incorrectly activating the ionisation detectors have now been overcome by using optical systems as a standard choice. When smoke particles enter the chamber within the device, they disturb a beam of light and trigger the alarm. In many cases, these devices have been augmented over the past decade with the addition of heat detection elements to create a combined opto-thermal solution expanding the scope of fire detection across two important indicators; smoke and heat.

However, the ubiquitous use of such devices gave rise to a new challenge – a growing number of false alarms. In a kitchen, for example, the use of opto-thermal devices is problematic because of the heat that is ordinarily generated. These issues prompted many industry bodies to introduce training courses to help managers choose the right fire detection devices for a specific environment, although lack of expert knowledge remains a problem.

For example, regulations have changed in the UK over the past decade, relieving the fire services of responsibility for issuing fire safety certificates and giving local facilities managers the responsibility for conducting their own risk assessments. In many cases, with a poor understanding of their specific needs and how to match those needs with the systems available, they opted either for too many detectors, leading to issues with false alarms, or too few, leading to increased risk.

Reducing False Alarms.

Finding ways to overcome the costly and disruptive consequences of false alarms has been a continued focus for the fire detection industry, particularly where smoke alarms react to air particles other than smoke, such as steam. It is an issue that has proven particularly troublesome in food factories and hotel bathrooms for example, where continual false alarms place the emergency fire services under unnecessary pressure.

One answer lies in coupling smoke detectors with carbon monoxide (CO) detectors, so that an alarm is only triggered when both smoke and CO are detected. This more multi-layered approach, which could additionally incorporate heat detection as a third indicator of danger and even electronic algorithms to make the system more intelligent, is key to reducing false alarms. By incorporating multiple technologies into single systems the move towards comprehensive fire detection need not be highly expensive, which is vital at a time when there is pressure to keep costs down while simultaneously improving the all-round effectiveness of fire detection.

Focusing on heat detection, there are now three accepted standards. One which measures the rate of the temperature rise to identify a fast-burning fire, another with a mid-range temperature limit of 70 degrees C and a third with a higher temperature limit of 90 degrees C. The first (A1R) is not suited to a kitchen where rapid temperature rises might be caused simply by opening an oven door. The second (BS) is better in a mid-sized kitchen and the third (CS) is more suited to an industrial kitchen. An additional option has emerged in the shape of analogue heat detectors. These are programmable and allow the user to select any of those three standard activation temperatures to suit their own needs.

More recently Eaton’s Fire Systems, for example, has introduced a more flexible and cost-effective solution with its five-in-one detector incorporating optical and thermal elements including three levels of heat detection within the conventional panel product. Even more advanced has been the development of addressable fire detection, an intelligent loop system that allows larger buildings such as hospitals and hotels to narrow down the source of the fire alert to a particular room or area. This has the advantage of cutting down the time spent and distance covered by fire crews when searching a building for the origin of the fire alert. Another advantage of addressable systems is that the optical chamber can be deactivated during the day, for example, if work is underway that could generate smoke and lead to false alarms. This could then be reactivated overnight to provide protection.

Developing Technologies.

Innovation is responsible for solving a range of specific problems in fire detection. In kitchens, for instance, heat detection has long been a challenge, while refrigerated areas present their own set of problems with smoke detectors potentially mistaking condensation for smoke and activating a false alarm. The answer is an aspirating system that draws air into a set of pipes and samples it in a laser chamber to identify smoke particles. With adjustable sensitivity and filters, this ensures accuracy in specific environments. A similar solution can be used in lift shafts and other enclosed voids that are hard to reach, enabling a sample pipe to be fed down to floor level for the purpose of performing annual inspections.

The speed at which fires are detected is another area where technology development has enabled progress. For buildings such as large warehouses, the historic risk was that a smoke detector situated on a wall over ten meters from the floor might take too long to pick up on the rise of smoke, by which time a fire may have rapidly spread at ground level. The solution is the beam detector, which sends a beam of infrared (IR) light to a reflective surface, perhaps 100 meters away and an alarm is triggered if smoke interrupts the path of the beam. This technology is now undergoing further advances with the addition of motorised beam detectors that intelligently ensure the beam is accurately aligned and can cope with the barely perceptible structural shifts that can affect a building over time.

Another trend in larger buildings is the creation of networks, where separate fire detection panels are linked to provide a complete solution that will not be put fully out of action by a single fault within one part of it. An interesting development around this trend is that the data communicated between the panels can be fed into a building management system or a graphical package to give the relevant team of people a broad view of activity.

Working with Regulations.

Of course, regulatory changes have had a huge influence on the shape of fire detection today, and some of the most recent developments are concerned with the way alerts are communicated to people with hearing impairments or people in crowded and noisy environments.

In the EU, for instance, the EN54 standard for fire detection was recently updated with Part 23, which underlines the requirement for visual alarms at any site where, according to the findings of a risk assessment, there may be staff or visitors with hearing impairments or people wearing ear defenders. This regulation defines the necessary light output levels needed to provide a suitable visual alarm. However, general awareness remains relatively poor among many buyers and manufacturers.

A technical challenge to be overcome by many manufacturers is that they have typically focused on minimising the electrical current used by fire detection devices in order to achieve optimal efficiency in operation. However, the power that is needed to drive visual alerts at the levels now required will force many producers to undertake a major review of the way their systems are built and run.

Forecasting the Future.

Expanding on the issue of alarms, one of the most significant areas of development we can expect to see over the coming months is the advancement of emergency voice alarm communications (EVAC).

If you take a shopping centre as an example, people’s recognition of a fire alarm can be obscured by the array of individual security alarms within stores, along with other sounds and visual interferences. A voice system will not only clarify the nature of the alarm but can also help direct people out of a building with a customised set of automated instructions.

It is advisable to broadcast these instructions via a dedicated set of speakers, which have specific features that make them resistant to the effects of fire as opposed to a standard public address system where circuitry could be quickly damaged in a fire.

Further developments in this regard are likely to centre on refuge intercom systems. Unlike standard radio signals that can be impeded by ionised particles in the air, these emergency telephones will continue to operate and can be positioned on staircases, for example from which people with physical disabilities can call for help. For a similar circumstance, Eaton’s Fire Systems business has recently introduced a complete alarm product for disabled toilets, whereby a pull cord provides a direct link into an emergency phone system.

It is with this kind of integrated thinking that fire detection is likely to develop, becoming ever more accurate across a wide range of circumstances and environments, more user-friendly and more comprehensive as a form of protection.