The latest LED technology in visual alarm and indicating devices improves building occupant reaction time while highly accurate device self-testing ensures system readiness without disrupting building occupants. A reliable system and earlier awareness in an emergency allow occupants to leave the premises more quickly, saving lives.
When there’s a fire event, nothing is more important than saving lives. Early evacuation is critical for the ultimate safety of building occupants. For the greatest chance of successful and safe evacuation, building occupants need to be alerted as quickly as possible. However, in certain buildings and facilities, a fire event may not be evident to all occupants by audio alarm alone. New, addressable fire-alarm devices that incorporate innovative technologies have been designed to more quickly and effectively warn occupants of a potential fire hazard for faster evacuations.
Addressable fire-alarm devices provide an alert that occupants may see, hear or both in the event of a fire. These alarm devices include sounders, visual alarm devices (VADs) and visual indicating devices (VIDs).
Addressable fire-alarm devices: what they are and where they’re used
Addressable fire-alarm devices are integral parts of a fire-alarm system that connect to a central fire-alarm control panel and include sounders, VADs and VIDs. While they often work together to make up a system, each has a distinct function and purpose that provides specific benefits for different applications. A fire-risk assessment should be performed to determine the exact type and specification of the devices a space requires before applying any system design.
Sounders
As their name suggests, sounders are an audio alarm that use sound, such as a siren, to inform building occupants of a hazard in the event of a fire. Of all the fire-alarm devices, sounders are generally considered the most important and the most critical to include. In fact, sounders should be used as an integral part of any fire detection and alarm system in any building or facility.
Visual indicating devices (VIDs)
A VID is a beacon that, when activated, flashes a light to notify building occupants of a hazard. In order to raise awareness in the event of a fire, VIDs are generally used as a supplemental indication. But, when an event occurs, they cannot be used as the only means to alert building occupants.
Visual alarm devices (VADs)
A VAD, like a VID, is a beacon that, when activated, flashes a light to notify building occupants of a hazard. However, unlike a VID, a VAD has been approved to be used as a primary alarm. As part of a building’s fire-safety strategy, VADs are used to supplement sounders to provide an effective means of alerting and evacuating occupants. The effectiveness of VADs as a means of alert in the event of a fire is widely recognized. Regulations and codes of practice recommend VADs to be installed in places where audible devices alone would be ineffective or where they are impractical or undesirable. With the introduction of the EN54-23, the use of VADs has grown significantly.
Although VADs can be used as a means of visual alert in any building, there are specific sites where VADs are necessary. VADs are critical in buildings and facilities where a sounder may not alert occupants to a fire hazard on its own. They should be installed in buildings and facilities in which occupants may be wearing hearing protection due to excessive or high ambient noise, such as manufacturing facilities, or as an occupational tool, such as broadcasting studios, public assembly buildings and office buildings. VADs should also be installed anywhere occupants may be incapable of hearing sounders on their own, such as health-care facilities, hotels, assisted living facilities and care homes and any public building in which deaf and hard-of-hearing people may be present.
EN54-23 standard for visual alarm devices
Before the mandatory requirement of EN54-23 in January 2014, there was no EN standard for VADs. This absence of a standard left room in the industry for concern, misinterpretation and confusion over individual product performance. The European Committee for Standardization (CEN) released EN54-23 several years ago to regulate the use of visual alarm devices in fire detection and alarm systems in non-domestic premises. EN54-23 provides clarity in the way it standardizes requirements, test methods and performance criteria of VADs to ensure all device parameters are measured in a uniform manner throughout Europe.
There are four main requirements a VAD must meet for EN54-23 compliance:
- The coverage volume must be noted on the product or on supporting documentation.
- The VAD should meet the coverage volume requirement for at least one of the following categories: W (Wall), C (Ceiling) or O (Open Class).
- A minimum illumination of 0.4 lux is required on a surface covered by the VAD.
- The rate of flash should be set between 0.5Hz and 2Hz.
- The flash colour should be red or white for a single-stage evacuation process and amber for the first stage in a multistage evacuation process.
When in compliance, VADs may be used in buildings and facilities as a primary alarm.
Advanced technology for faster reaction to alarm activation
Fire alarm manufacturers have recently made innovations in device design that can help improve building occupant reaction time when the alarm is activated. The primary innovation is the strobe’s source of light. The light source in most visual indicating and visual alarm devices on the market have historically been xenon tube or light-emitting diode (LED) technology. In the last decade or so, LED has become more prevalent due to higher energy efficiency.
LED lights are more efficient than xenon lights because the way they produce light requires different amounts of electrical energy. In xenon light, the electrical current splits gas atoms in electrodes, which heats them up. Light is a by-product of this heat. The process requires energy to produce enough heat to also produce light. In LED technology, photons are released when electrical current interacts with electrons. The released photons appear as light. In comparison to xenon, very little heat accumulates, and less energy is required to produce light.
Beyond how it’s made, another difference between these two types of light may be the way the human eye reacts to each. Recent research concluded that the length of an LED light’s pulse influences the way LED light affects the human eye. Independent laboratory tests have looked specifically at the effect of LED light from a visual alarm device on the human eye and how that influences a person’s reaction time. These device-specific tests show that the duration of the pulse within visual alarm devices can, in fact, influence the way people react to it. The test results indicate that the shorter the pulse duration, the faster the person’s reaction.
From these test results, it can be assumed that shorter pulse durations of LED devices should result in quicker reactions during fire events. The light from shorter pulses gets the eye’s attention more quickly. This, in turn, helps a person recognize potential fire hazards sooner and allows them to act to evacuate earlier. Therefore, visual indicating and visual alarm devices designed with a shorter light pulse length can improve building occupant reaction times.
There are now devices on the market that take the results of this testing into consideration. These devices incorporate the latest innovations in light technology to operate LED devices with a pulse duration that does not exceed 20 milliseconds. This pulse duration is designed to alert occupants as early as possible.
An additional benefit of these advanced visual alarm and visual indicating devices is their low energy consumption. Their low levels of power consumption allow for more devices to be connected on a single loop. Because more devices can be used on a loop, system design is simplified and installation is easier and more cost-effective. Low power consumption also helps with standard compliance. When it comes to complying with EN54-23, power consumption is usually the biggest consideration.
Self-testing for less disruption and greater user confidence
To ensure fire detection systems are ready to protect buildings and their occupants, regular testing of the systems is critical. However, alarm activation can often be highly disruptive, especially to the operations of and occupants served in the health-care or hospitality industries. Regular alarm tests can interrupt procedures and cause occupant stress or panic.
A new range of fire alarms uses advanced features that enable the devices to automatically test themselves while minimizing occupant disruption. This self-test technology is called reflective light monitoring (RLM) in visual alarm devices and reflective sound monitoring (RSM) in sounding devices.
Triggered from the panel interface, RLM and RSM measure and test sound and light output. Automatic self-tests can be scheduled at any time, and the test duration is typically less than one second per device. The results of RLM and RSM are based on real output, not electronic measurements or simulations. Because RLM and RSM achieve a high level of accuracy with virtually no disturbance, end-users can be confident in their fire detection system performance without disrupting building occupants.
Early evacuation can save lives
When it comes to protecting life in a building, speed is critical. The more quickly a fire detection system can alert occupants, the earlier evacuation can begin. Advancements in addressable fire alarm device design can lead to earlier evacuations during an emergency. The latest LED technology can improve reaction time and encourage occupants to leave a building sooner. Highly accurate, incredibly short self-testing provides the reassurance that devices are always ready to warn occupants of potential hazards without disturbing them during testing.
In a fire event, seconds count. Quicker reaction times can make a difference when it comes to fast evacuation and, most importantly, saving lives. These new, addressable fire alarm devices are equipped with the technology necessary to enable effective, life-saving evacuation.
For more information, go to www.fireclass.co.uk
About the Author
Anja Schäfers, Product Marketing Manager, Fire Detection, Johnson Controls, Building Technologies and Solutions.
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