Hybrid wireless fire detection has become increasingly popular over the last few years. It refers to the design, specification, and installation of a fire detection system that comprises hardwired, analog, addressable technology alongside wireless-based equipment.
Modern hybrid wireless systems deliver fully intelligent field device integration, allowing analog values, device addresses, and type codes to be transmitted to a system’s control panel. Wireless units can be installed and the devices added to an existing system simply by using an appropriate translator module.
In its early days this technology was derided for its unreliability, but these issues have been addressed, and it is now seen as the ideal solution for buildings where traditional fire detection is not deemed suitable.
It is precisely this type of application where hybrid wireless systems are particularly beneficial, so the answer is a resounding yes.
For architects and others involved in the renovation of listed buildings, the challenges posed by fire detection system provision can be difficult to overcome due to the types of materials used in such properties, as well as the regulations concerning structural change and rewiring. In these circumstances, hybrid wireless fire detection is the only realistic option.
However, hybrid wireless systems are also suitable for other environments, and we are seeing them successfully used in temporary structures in hospitals and educational establishments, as well as buildings that are spread across a site, such as exterior classrooms. Also, in buildings where asbestos is present, it offers an ideal way to keep occupants safe without disturbing this potentially lethal material.
Wireless technology isn’t suitable for every application. For instance, one disadvantage of a hybrid wireless system that should be considered is that signal strengths are affected by different structural media. For instance in a historical building with 5-meter-thick walls or in a modern mobile unit consisting of a metallic structure, obtaining the required signal strengths can prove difficult. However, even in these environments wireless protection can normally still be achieved, but a great deal more consideration should be given.
With regard to the technology itself, in some circumstances signal times with regard to cause-and-effect capabilities can be a problem. Also, there are the dynamic capabilities of sounder tones to consider. Wired systems can have more than 50 different tones that can be used to signify different things, whereas a wireless system will usually only operate on a single set tone.
Since March 2011 all wireless fire detection systems have to comply with EN 54-25, which is now the common standard across Europe and the main reference point for this technology.
It was established to ensure that wireless and hybrid wireless fire detection systems provide the same level of protection as their hardwired counterparts. EN 54-25 specifies the requirements for how these systems operate, such as bi-directional communication, redundancy through dual battery back-up, minimum battery life, improved fault monitoring, and defined product testing procedures.
Each device must be marked with the number of the standard, the name of the manufacturer, the model, a CE mark, and the notified product certification body number. Any systems that do not have all of these marks should be avoided, and it is also a good idea to seek evidence of third-party testing.
Being able to ensure that this technology will work within a building requires a radio site survey. It is perhaps the most important element of any wireless installation process and must be thorough and comprehensive, as much of the subsequent configuration will depend on the results.
It’s always preferable to do this physically by visiting the site, but in situations where a system has to be designed “off paper” as part of a tender, there are some good software packages around that can help configure the right specification.
A word of warning though — carrying out a site survey can be a time-consuming process and can typically take a full day or more to complete, depending on the building. This means lots of invested time at the tender stage or at the beginning of a job, so make sure that it’s a cost that you factor in.
The main pitfall to avoid is carrying out a radio site survey when a building is empty or not being used in its normal manner.
Customers often ask surveyors to attend a site during quiet periods or other downtime. This is especially common in schools and other educational establishments, where such an activity might be more convenient during school holidays. However, this should be avoided, as it does not give a true representation of the obstacles faced by wireless signals on a day-to-day basis.
The structure of the building, including doors and windows, as well as people and the electronic devices that they use — mobile phones, computers, machinery, third-party radio equipment, etc. — can potentially have a significant impact on the ability of signals to operate at full strength and can drastically affect the tolerance of values. Therefore, it is always advisable to carry out the survey when it is fully occupied.
My advice is to look for the worst-case scenario and design accordingly, by building in sufficient levels of redundancy, in particular when you are considering the quantity of radio transmitters/receivers.
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I am interested in learning more about these wireless devices like what band do they fall in and what communication methods they use, can you recommend anywhere I could look to learn more about them? Have any studies been conducted about the affects of interference from other devices on these devices? I am interested to see how it handles that sort of thing.
I have read your article and I am interested to know if there is ready demand for your device and how can we one for trial
This is an interesting article that begins to address some of the misconceptions about wireless/hybrid fire detection systems. Over many years of development wireless has been gaining acceptance across many business sectors. This started with the difficult and challenging applications where wireless was chosen as a traditional wired system could not be installed however this has now changed fundamentally. With the introduction of EN54 Pt 25 in 2010, a Pan European initiative, manufacturers of wireless systems must now have compliant and certified products to meet this exacting standard which has changed the landscape completely. Additionally 868MHz is now the harmonised… Read more »
EN54-25 do not limit the frequency used for radio fire alarm communication, but most fire alarm manufacturers select exactly 868MHz. We know that in UK and Europe, 4G(LTE) is already fact. Also we know about interference between 868MHz and 4G. What will happen with all installed wireless systems at 868MHz when 4G cells of mobile operators start working? Isn’t it better to use higher frequencies for this kind of applications – 2,4GHz or 5 GHz. This bands are also occupied from CCTV cameras and Wi-Fi routers, but this radio influences can be limited much easier than the 4G. Any time… Read more »
The frequencies suggested in the last post, 2,4GHz and 5 GHz, would result in inferior signal propagation for the same output power. These are heavily congested bands which would incur quite significant local interference issues from Wi-Fi enabled devices and thus are totally unsuitable for any life safety product. We at EMS have already addressed any perceived issues around 4G and 868MHz and have published a document and would highlight the following extract: “As a leading UK developer of wireless technology EMS has already carried out extensive investigations and testing to determine the impact of 4G on our FireCell and other… Read more »