FIRE SAFETY & SECURITY
Quality fire detection systems also tend to feature innovative individual devices, which you won’t find in ranges at the bottom end of the market. You’d think these would come with a premium price attached but that’s not always the case; some of these could actually save you money. A Smoke Sensor with a built in sounder, for example, saves you the cost of buying two separate products i.e. the Sensor and a separate sounder product (base or wall mount sounder), plus it’s quicker to install and doesn’t require any additional wiring. Neither does it require a separate device address point. Nittan’s EV-PS Sensor with built in sounder, for example, could save at least 15/20 minutes per point to install when compared to fitting separate sounder products. When you are dealing with a large system, this becomes a significant saving. Of course, this solution has the added bonus of being more aesthetically pleasing.
Fit and Forget
So on to the second key point about the time and cost saving benefits of a quality fire detection system: reliability.
All commercial analogue addressable fire detection systems are based on a transmission protocol to enable the devices and panels on the system to communicate with each other. There are a number of different
BSEE
beam in the sensing chamber. However, instead of just using the standard Infra Red light, it also employs a second Blue LED to provide a more accurate measurement of particles within the chamber. By calculating the ratio of these light sources, which operate at different wavelengths, the detector can determine the particle size and thus distinguish between smoke and non-combustion products such as steam and dust. This technology is incorporated into Nittan’s Evolution EV-DP sensors. It reduces false alarms caused by steam, but the detector remains highly sensitive to combustion products to generate an alarm.
Supporting Cast
protocols used by manufacturers and all are most definitely not equal! The traditional protocol type commonly used in the fire industry, is square wave pulse based, but this comes with a number of issues including susceptibility to noise and interference plus limited information capacity. We find using a flexible Sine Wave, Frequency Shift Key (FSK) protocol to be superior as it has a uniquely high resistance to external noise and allows for substantial amounts of information to be transmitted back to the panel, but without global message collision thanks to the employment of delayed sequential response.
A quality protocol such as this will be capable of very high speed transmission, will not be affected by the number of devices on the loop and allow for more inputs / outputs, more controllable features and more type codes for devices. A quality fire detection system will also use sophisticated detection algorithms, combining extremely reliable fire detection together with a very high degree of protection against unwanted, false or spurious alarms; call them what you will, we all know false alarms are a serious pain point for customers and installers alike. Ultimately false alarms cost you time, money and reputation with repeat call backs eating into your profit margins and
unhappy end users doubting the efficacy of your installation. There’s no getting around it, cheap fire detection systems are far more likely to false alarm.
Of course, there are cases when even a quality system has the potential to false alarm. One of the biggest problems sensors face is steam. Put even a good quality sensor – or indeed a Multi Sensor – close to a source of steam such as a bathroom and it may false alarm. Investing in a Dual Optical detector however, will dramatically reduce the risk of false alarm and all the associated costs that go with it. A Dual Optical alarm is a single sensor type – optical - which ‘looks’ for smoke using a scattered light
Lastly, it may not seem that significant - until it’s too late, that is - but going down the quality route is far more likely to mean you are provided with a good level of technical support. So, if you do encounter a problem, it should be quick and easy to address. Cheap product generally comes with little or no support – in other words, you’re on your own!
So, in summary, if we consider the wider concept of system cost and factor in aspects such as installation time, long term reliability and ongoing product support, the decision to choose product from a quality fire detection manufacturer rather than go the “lowest cost” route is actually an easy one to justify.
Read the latest at:
www.bsee.co.uk
BUILDING SERVICES & ENVIRONMENTAL ENGINEER MAY 2020 17
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