Novar GmbH: improvements in fire detection. When looking at the catalogues of manufacturers in the field of technical fire detection, it becomes obvious that for fire detectors alone, there is already a vast selection of variants with a multitude of different features. It is almost impossible to produce one detector which is equally sensitive to all fire characteristics. However, there are now products on the market which are getting closer to making this a reality.

Smoke gas detectors react to combustion gases such as carbon monoxide (CO). Heat detectors sound their alarm whenever the surrounding temperature exceeds a predefined maximum value or increases unusually quickly within a certain time span. Flame detectors react to the features of flames.

Smoke detectors use different physical effects for the recognition of smoke. The most common variant here is the optical one. It works according to the so-called scattered light principle. Should smoke particles enter the detector’s optical chamber, a ray of light emitted by an LED is diffused by these particles. Part of this diffused light then falls upon a lightsensitive sensor and the smoke detector’s alarm is triggered.

Ionization smoke detectors work with a radioactive emitter. This type of detector is only used in special cases due to strict regulations involved. Moreover there are special detectors for specific areas of use such as line heat detectors and/or line smoke detectors or aspirating smoke detectors.

Research is being carried out concerning biosensors: for example the Fire-colored Beetle has an ‘infrared organ’ which possesses thermosensitive sensors able to locate changes in temperature which are emitted by forest fires – even across extraordinarily long distances of approximately 60 km!

Different fire detectors on the market today are already rather sophisticated due to the progress made in the area of microprocessor technology, yet there is still room for development. One decisive criterion concerning fire detection is the resistance to disturbance signals. False alarms are caused by exhaust from internal combustion engines, cigarette smoke or steam.

By evaluating different characteristics in so-called multi-sensor detectors (OT, OTG, O²T) a reduced sensitivity to such false variables can be achieved. Innovative technology for optical detectors has been using a blue light-emitting diode instead of the usual infrared LED for quite some time now.

The Calming Effect of Blue

In 2006, the Japanese scientist Shuji Nakamura received the Millennium Technology Award. At one million dollars, it is the highest paying award in technology research worldwide. The jury honored Nakamura’s achievements in the development of blue light-emitting diodes and laser diodes. Such blue LEDs also form the basis for the IQ8Quad OTblue fire detector.

This is a multi-criterion detector which uses the combination of an optical and a heat sensor in order to reduce the rate of false alarms. In order to evaluate the usage of blue LEDs being used here, one needs to understand the technical background. One manufacturer who was supposedly dealing with the topic in a professional way unknowingly disqualified themselves publically by usingincorrect and somewhat ignorant counterarguments.

The statement “If we need such a detector, then we’ll also build one with orange light,” seems to experts like a spiteful reaction due to lack of knowledge on the subject, even overlooking the fact that it should actually read “orange-colored light”. All this when the color blue is supposed to have a calming effect on our nervous system, not an upsetting one.

A Short Excursion into the Technology

In the theory of diffusion, there is the concept of the Rayleigh scattering (or Rayleigh diffusion), which states that a diffused light yield of a much higher degree can be achieved if the wave length is respectively smaller. Therefore, the usage of blue LEDs offers a significant advantage for aerosol sizes which are smaller than the respective wave length.

A blue LED might have a significantly smaller yield of light than a red one, yet what seems like a shortcoming at first glance is actually an advantage since the diffused light signal of blue light is approximately 10 to 15 times higher than that of a red LED. It is also possible to work with a higher transmitting current. A higher transmitting current can additionally be worked with here so that the end result is a significantly more sensitive diffused light sensor compared to using red light.

The IQ8Quad OTblue fire detector uses this technology and received an award for the “Most Innovative Product” at the MIPS, the largest international exhibition for security and fire fighting in Russia.

Apart from the VdS certification and the certification in France, the detector also holds the Polish CNBOP certification. The test fires implemented here are carried out in accordance with the EN standard and are even more demanding than the fire tests done by the VdS. The detector is the only product worldwide which has passed all standardized test fires without Ionization element.

Moreover, it also poses an interesting alternative for specialized planners in the area of heating, air-condition and ventilation since it is also used in air duct detectors. The advantages for the optical heat detector with a blue LED are therefore obvious: despite completely avoiding radioactive material, it fully covers the sensitivity area thus far reserved for ionization detectors.

It even detects very small aerosols with a consistently high degree of sensitivity and also even contributes to protecting the environment. All of this makes it attractive product indeed, and not only for countries, in which the use of I-detectors is forbidden.

From Simple Detector to All-rounder

In addition to quick and reliable fire detection, the significance of being able to carry out a timely alarm and evacuation today is increasing more and more. There are already fire detectors which also offer possibilities for alarms such as the optical function of a flasher, the acoustic alarm of an alarm sounder and the functionality of a voice alarm, apart from the detection itself. These alarms are regarded as being true allrounders.

Contact:

Eveline Kolanek
Novar GmbH
Esser by Honeywell, Neuss, Germany
Tel.: +49 2137 17 527
 Fax: +49 2137 172313
info@esser-systems.com
www.esser-systems.com