Heeding the loud song of the sirens
Published: 01 January, 2008
The potential of an explosion in a high-risk environment is always a massive concern for those who work in such conditions. The combustible atmosphere of flammable gases, dust, and vapours means the prospect of an explosion being set off from the smallest source is a very real possibility. ATEX (atmosphere explosive) requirements are put in place to ensure nothing in the workplace has the potential to set off an explosion. In areas such as airports or large train stations, the sheer number of people who pass through the building poses a challenge in itself. It means that good, clear, alarm signals are need – especially when the vast majority of people will have no knowledge of the building layout or what different alarm sounds may mean. Therefore sirens, alarms, sounders and control panels are a vital safety feature in any high-risk environment and mustn’t react with the atmosphere the are operating in.
As Product Manager for MEDC Glynn Warren says, “it is vital that alarms or sirens are designed to ensure that they cannot ignite the very dangers they could be warning about.”
MEDC is a UK based company which was recently incorporated into a US based company called Cooper Industries. It provides a wide range of products for hazardous and non-hazardous environments and these are used in many varied industries. “We provide alarms, speakers, beacons, call points and indicators and are able to offer them to industrial areas across the world as they all conform to, not just the relevant European standards, but also to the North American equivalents and many others internationally.”
By covering so many regulations, including ATEX, MEDC is a popular choice particularly in offshore oil platforms and refineries; “In many industrial environments alarms and sounder systems must be able to work in hazardous conditions without the risk of igniting any combustible materials in the air,” Glynn notes. The audible sounder DB3 range is very popular in this area as well as the XB15 visual indicator. There is another benefit to the range by MEDC as Glynn points out; “Our products for marine, coastal and off-shore industries are made from glass reinforced polyester (GRP) so they don’t suffer from corrosion which is a major factor for industrial environments in such conditions.” The London Underground, rail networks and airports are also serviced with audible alarms and speakers from MEDC.
As noted, many areas such as airports or train stations have the problem whereby members of the general public are not be familiar with the layout of the building or alarm sounds specific to that building. As a result, voice sounders are becoming increasingly more common in such environments. By being able to communicate the nature of the situation and provide clear and concise directions, people can find their way out of a complex building quickly and safely.
Honeywell cover both the UK and US markets with its range called Notifier and these systems are installed in many international airports and large sporting arenas such as basketball and football stadiums as well as pharmaceutical plants and other similar environments. Peter Ebersold, Marketing Director for Honeywell, comments, “Facilities such as these have the potential for major fire hazards and so the need to evacuate quickly is vital. A voice evacuation system or a mass notification alert system will generate alert tones, pre-recorded messages or live messages that direct the occupants during the emergency.” The Notifier NFS2-3030 fire alarm control panel is frequently used in stadium environments and can also be networked together to protect a facility, such as an airport with a single system. The NFS2-3030 can also be integrated with the Notifier Onyx Digital Voice Command (DVC) system that both generates and distributes digital audio messages throughout a facility.
As with most safety technologies, alarms need to conform to relevant standards. “UL 864 is the standard that all manufacturers must meet before their products can be sold in the USA but it also extends to the Middle East and parts of Asia,” Peter explains, adding, “A system must be designed and installed to meet the requirements of NFPA 72, National Fire Alarm Code or the International Building Code, (IBC). As well as this there are often countries with their own installation codes.”
In airports and other mass transport structures the need for clear directional instructions is increased. Peter points out that in some cases alarms need to be individually tailored; “In an airport, for example, any messages played over the voice evacuation systems might need to give very specific instructions about where to exit the building, based on the occupants’ location. This requires a system with the capability to send alert tones or messages to very small areas of the airport.”
The presence of machinery in many factories and other industrial environments also brings in the prospect of high noise levels – and the likelihood many people would be using ear-defenders – so sound outputs often have to be louder than in commercial environments.
Fulleon is a company that offers products for all levels of industrial environments, addressing head-on the issue of being audible in extreme noise environments. The Asserta range has sound outputs of 110db and 120db that can be heard in extremely loud conditions. Fulleon has also expanded this range with a series of new Asserta Midi, Mini and Maxi alarms. The 110db Midi and 105db Mini were introduced to fill the need for lower output sounders while still providing very high levels of protection from harsher environments, explains Bob Choppen, Product Manager.
The Asserta range can be used for high-end industrial areas and is suitable for manufacturing environments. As Bob says, “These environments are usually extremely hostile places for equipment, with high levels of humidity, areas of wash-down and high levels of dust which can be corrosive, so the housings need to be robust and protected. Thus the Asserta range have high IP ratings, typically IP66.”
At the low-end there are Askari, Roshni and Solex Xenon beacons that cover general purpose and status indicator areas. Fulleon has also introduced a new range of traffic light style status indicators based on the Solista Maxi LED Beacon. This allows the user to select flash modes, colour options and power settings giving flexibility and reliability that ensures low running costs.
Klaxon Signals have just announced the launch of a new family of Sonos and Nexus voice sounders. The Sonos Voice Sounder is a fire alarm that combines a normal sounder with a synchronised voice message to reduce confusion during an active alarm. The Voice Enhanced sounders are available with either single or multi-message options for small-scale to large-scale installations.
Up to four messages can be transmitted on the multi-message sounders to provide information on “alert”, “evacuate” or “all clear” stages of an emergency, meaning workers or the public can be informed in detail of what needs to be done. Sara Mudalige, marketing executive, explains that a system which sends a specific message can help save time and possible lives, “Rather than having just a general sound it gives a detailed alarm as decided by the system when it detects a fire.”
The Sonos alarm can be used in industrial areas and the two variants are available with a choice of 32 tones, including all international standards.
Higher sound output
Klaxon Signals also provides a range of Nexus voice sounders for applications that require a higher sound output. A specialised variant of the Nexus voice sounder has been designed for the gas extinguishing systems market and comes with an interface controller that connects directly to the extinguishing control panel and sounder circuits, giving out the appropriate message and tone. As Sara explains there are several benefits of using a gas extinguishant system; “A system that releases a gas which reduces CO2 in the air helps stop the fire and avoids potential fire damage to telecom switch rooms or important documentation that might occur if normal sprinklers were used.”
Klaxon Signals sales director Stuart Mason notes that voice messages have been proven to improve evacuation response time through intelligible warnings, and as such the Nexus Voice Sounder is USB compatible, which means users can record and upload their own messages in WAV format, in-house, to provide highly specific warning messages.
Visual and combination warnings
In the great majority of commercial and industrial premises, the building’s fire system is the most likely method of warning about a potential threat to the occupants. The typical audible visual warning generated by the system alerts the occupants to the fact that there is an emergency, but doesn’t provide any help or guidance to show people the optimum escape route.
To address this important issue, KAC has introduced ExitPoint, a directional sound technology which, triggered by the fire system, instinctively attracts people towards its source in both good and poor visibility. Mark Thompson, business development manager, explains. “The units generate sound pulses of low, medium and high broadband noise that make it possible for people to identify accurately the location of the source. Directional sound is recognised by a primitive part of the human brain and because of this people are instinctively drawn to the noise. They can therefore be aurally directed to the nearest emergency exit, reducing evacuation times by up to 75 per cent in tests.”
ExitPoint operates at 24VDC, and has five user-selectable power settings so that it can be optimised to its installed environment. It is also available with an optional voice messaging capability that will reinforce the meaning of the tones to people, advising them that following the tones they are being led to the nearest emergency exit, further improving the effectiveness of the units in reducing evacuation times. Different tone combinations are also programmed into the unit that people instinctively recognise and follow. These combinations are designed to instruct occupants that they are nearing an exit, a stairway up or a stairway down.
The amount of industries that need to be covered means there are requirements for alarms for all types of environments. Cranford Controls provide a range of specific alarms – including an array of spatial sounders, room sounders and beacons – for different industrial areas. Charlotte Philo, marketing assistant, explains more, “Our alarms are discrete and compact and have loud sound output while only requiring low current consumptions. The sounder range can be used in various facilities including factories, hotels and many other hazardous areas.”
Charlotte explains some of the factors that must be considered when selecting alarms; “An effective sounder should have clear audibility and needs to be louder than the surrounding background noise. You should also consider any special requirements the sounder might need. For instance, do they need to be weatherproof, intrinsically safe or explosion proof?” Cranford Controls supply several Intrinsically Safe sounders that have ATEX approval while the VPR-DT and VSO manufactured sounders have LPCB approval and all products comply with the RoSHH and WEEE directives too. They will also be launching a new VSO combined platform sounder in the New Year which has a specifically designed lens to provide 360° light output.
In many environments a combination of beacon and sounder is the most suitable solution. Apollo Fire offers both these products, compliant with EN54 standards, and Rowland Davies, marketing services manager, explains why the two work so well together; “In many areas you often have people working against high background noise who might not hear a siren. But if there is a beacon as well they can see there is an emergency. It’s only relatively recently people have realised the potential, and importance, of the two together.”
Adjustable sound levels
There is also the fact that sirens need to operate at varying levels of noise – some higher than standard, some less so. Apollo Fire has recently launched a new Discovery Sounder Beacon Base that has adjustable sound levels.
The best thing about this system though, as Rowland notes, is that it can be tested and adjusted by just one person using a special “magnetic wand” that, when held close to the sounder, adjusts the sound levels to the desired volume. “It’s quite a sophisticated system and allows different areas of an environment to be covered with different sound levels.”
Abel Alarms provides fire protection solutions for many areas including industrial sites and national users with multiple outlets. Chris Norton, sales manager, explains the benefits of specific alarms, “In large public areas voice alarms in several languages can be necessary when you might have international travellers, while for people with impaired hearing visual fire warnings are required.
“The alarm systems are accredited to BAFE (British Approvals for Fire Equipment) Scheme SP203 by NSI (The National Security Inspectorate), in support of Government guidelines on fire protection issued for specific business areas and the British Standard 5839 provides positive recommendations.”
Guarding against unwanted alarms, sometimes caused by steam or burning toast, means choosing the correct fire detector to suit the environment is essential. As Chris points out; “Some applications demand a high degree of aesthetic consideration, so wire-free components operating on radio frequency may be the preferred choice, while in high value applications a system directly linked to fixed extinguishing installations to combat the fire would be preferable.”
As new buildings like King’s Cross St. Pancras International demonstrate, large scale buildings will always place high emphasis on design and aesthetics. But behind the scenes there are a range of companies able to provide safety solutions to a range of hazards.
With ATEX requirements in place to prevent the potential risk of explosions, manufacturers are able to ensure that their products can be used in some of the most hazardous areas to provide protection against the many dangers that exist in extreme industrial environments.