VIEW Detection

products / fire detection and alarm

VIEW Detection

 

 

Our VIEW laser system is ideal for critical applications where even a trace of undetected smoke is unacceptable or where high air flows can make traditional smoke sensors inadequate. VIEW provides the very early warning, individual point indication, total supervision and simplified maintenance available only from hard wired, intelligent technology.

The result is the security of knowing you'll receive the earliest possible warning and location of smoke without the supervision and maintenance drawbacks of alternatives like air sampling systems.

Why VIEW?

  • Superior stability resulting from over two million hours of false alarm-free testing.
  • Adjustable sensitivity of pre-alarm and alarm levels from .07%/m to 3.2%/m obscuration provides the appropriate response in even the most critical applications.
  • Cooperative detection algorithms let VIEW sensors operate in a group mode, enhancing response time and stability while helping overcome smoke dilution in high air flow applications.
  • Dual LED design for 360 degree viewing of intuitive two-colour LEDs (blink green for normal, steady red for alarm) makes point identification and status recognition simple.
  • VIEW sensors can be intermixed with other sensors on the same loop to custom-match detection to risk without redundant controls.
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    A Quantum Leap in Smoke Detection Technology


VIEW is a revolutionary advance in early warning smoke detection technology, VIEW is the 'Very Intelligent Early Warning system'.

The VIEW system was developed in response to the demand for high sensitivity, highly reliable, cost effective detection for critical, high value applications such as clean rooms, hospitals, telephone switching rooms, computer rooms and museums.

The VIEW system comprises three elements, a revolutionary new laser detector, advanced software algorithms and an intelligent control panel. The three elements work together to provide extremely sensitive smoke detection with exceptionally high false alarm immunity.

Laser Detector


The laser detector shares the same low profile moulding as other smoke detectors. It is therefore base compatible with other Notifier intelligent detectors and externally looks the same. However, once the cover is removed the difference becomes apparent.

The laser detector incorporates an extremely bright laser diode and integral lens that focuses the light beam to a very small point near the receiving photo sensor. The light then passes into a light trap and is absorbed. The photo sensor is activated by a scattering of smoke particles in this narrow light beam.

In a typical optical or photoelectric detector the light beam given off by the LED is very wide and can (and normally does) reflect off chamber walls into the photo sensor. When dust accumulates in the detector the chamber walls change in colour from flat black to grey. With the laser detector the concentrated light beam does not touch the walls, it is therefore much less susceptible to dust accumulation.

Smoke scatters light in all directions and in a typical optical detector, only a small portion of that scattered light reaches the photo sensor itself. In the laser detector a special mirror reflects and concentrates most of the scattered light into the photo sensor. This is one of the reasons why the laser detector is much more sensitive than a standard detector.

Compared to smoke, airborne dust particles are very large and very sparse. Since they are in motion and the illuminated volume is very small, pulsing the laser every few seconds ensures that the occasional dust particle cannot remain in the light beam for more than one or two samples. This transient signal from dust is the key to the dust discrimination performed by VIEW.

The laser diode combined with the special lens and mirror optics allows the laser detector to achieve a signal to noise ratio that is much higher than traditional optical detectors. The features detailed above, coupled with the software algorithms allow differentiation between dust and smoke particles. Because of these factors the laser detector can be set to extremely high sensitivity, yet can reject false signals caused by larger airborne particles such as dust, lint and small insects.

Software Algorithms


It is clearly not acceptable to develop a highly sensitive system which will continuously false alarm. Therefore, in addition to the laser detector design, advanced software algorithms have been developed to provide immunity to false alarm causes.

The software algorithms used are known as AWACS which is an acronym for 'Advanced Warning Addressable Combustion Sensing' The AWACS software has a number of features to ensure optimum performance and minimal false alarm potential.

Drift Compensation and Smoothing -

 

Drift compensation allows the system to identify and compensate for long term changes. This allows the detector to retain its original ability to detect smoke, and resist false alarms, even as dust accumulates.

Smoothing filters are also provided by software to remove transient noise signals, usually caused by electrical interference. Different smoothing algorithms are used depending on the sensitivity of each detector.

Dust Rejection and Lint Trap


By using a pulsing laser diode in the detector a series of readings are given back from each laser detector, The software allows the analysis of a series of pulses rather than a single reading to reject signals given by transient dust or lint. entering the chamber. The software also allows the readings from one detector to be compared to others to further allow false alarm rejection.

Sensitivity Adjust


Nine different sensitivity levels are provided for alarm, a further nine levels are provided for pre-alarm. The levels can be set manually, or can change automatically between day and night.

Co-operating Multidetector Sensing


One of the unique features of the VIEW system is its ability for each detector to involve adjacent detectors in its analogue alarm decision. This should not be confused with 'double knock' or 'coincidence' detection where an AND function is applied to the 100% alarm condition of 2 or more detectors before making decisions. Co-operating multidetector sensing goes beyond that and has two main benefits.

Firstly, it may be used to reject certain false alarm phenomena. If a detector sees a sudden large increase in analogue value it can look at adjacent detectors to monitor their values. If they do not see the sudden change then it helps to confirm a fault rather than a fire condition.
Secondly a faster response to a real fire is possible using co-operating multidetector sensing. As part of the AWACS algorithm, signals from adjacent detectors are statistically combined to reach a common signal. Therefore VIEW can indicate an alarm condition before the signal from any one detector is itself above the alarm threshold.

Intelligent Panel


One of the major advantages with VIEW over other early warning smoke systems is that the laser detectors are connected to the same loop as other analogue devices wired from the intelligent panel, Notifier panels have the ability to control 99 detectors and 99 modules (callpoints I/O's etc.) per loop with up to a 2km loop length. Therefore, there is no need to install 2 completely different systems and link them together. The VIEW system is completely integrated within the analogue fire detection and alarm system.

Applications


The VIEW system is designed for early warning applications in relatively clean environments. Although it certainly will give adequate warning of a fire to building occupants, its primary role is to give advanced warning of smouldering fires in areas of high value property, so that a fire can be extinguished before serious damage or lengthy interruption of service occurs.

Today the most effective way of covering these applications is generally considered to be by use of an aspiration system. An aspiration system comprises a photo detector, aspiration pump and a pipe network.

Pipework is run around the protected area with sample holes drilled at strategic locations. The pipework is linked to the control unit, which draws samples of air in via the aspiration pump, the air sample is then passed through a filter and into the detector. The detector typically has a pre-alarm and an alarm level which give signals to a fire detection panel to raise the alarm.

In tests carried out, the VIEW system has given better or comparable responses to fires, compared to aspiration systems.

The VIEW system also has additional features. An aspiration system can tell you that there is a fire within the covered area and depending on the system, possibly which sample pipe has sampled the smoke. The VIEW system is addressable and so it is possible to see which specific detector(s) have gone into alarm, this helps find the true source of the fire much more quickly. This is particularly important as sometimes there is no/little visible smoke to identify the source of fire.

Aspiration systems monitor airflow through the pipework and if a section of pipe is removed or there is a blockage within the pipe or filter this will result in a fault.

VIEW supervises every component on the system, with wiring and detectors tested every few seconds. Early warning of potential problems can also be identified to allow preventive maintenance. This, coupled with the fact that it is an all electronic system with no moving parts or filters means that maintenance costs are significantly lower.

As VIEW is part of an integrated fire detection and alarm system, there are no links between different systems. Through panel programming individual laser detectors can trigger sounders and plant shutdown without delay.

The fact that VIEW is part of the fire detection system opens up many new applications that could not be considered for early warning detection before.

Within a building such as an office block where there is a small computer room with high value equipment in it, it may not be feasible to install a complete aspiration system in this area. However, two or more laser detectors could be installed in the area on the standard fire system loop wiring giving the area the highly sensitive detection, which is required, at minimal cost.

The VIEW system greatly reduces the lifetime costs of early warning systems, relative to aspiration technology commonly used today. The lifetime cost of the system having three main elements: equipment cost, installation cost and maintenance cost.

VIEW Tests


Comprehensive tests have been carried out both in the USA and in Europe to prove the performance of the VIEW system. To give some form of comparison, the systems have generally been tested at premises such as telephone switching rooms, which already have aspiration type systems installed.

The tests in the USA and Europe were witnessed by representatives from major telecommunications companies, research organisations, leading specifying engineering firms and major approvals organisations. These independent witnesses participated in the test planning, giving recommendations for system design and fire placement etc.

The test results (which are available) show the VIEW systems ability to rapidly detect fires, activating in advance of aspiration technology in most cases. In some scenarios, VIEW detected low levels of smoke, which were unreported by the aspirating systems.

The following is an example of one of the VIEW system tests in the switch room of a major European Telecommunications Company.

The facility was ventilated via ceiling grills over the equipment and air-handling units on one side of the room.

An aspirating system was installed with pipework at ceiling levels and across the AHU inlets. All pipework was connected to a single aspirating detector unit. VIEW laser detectors were installed near most (but not all) sampling holes in the pipework.

The control panel running the VIEW system was connected to a computer logging the results, also all tests and responses were timed using stopwatches.

'Test' fires were based on BS6266 : 1992 passing high current through 1m length of 0.078 sq mm of PVC insulated wire. This produces a controlled amount of smoke, simulating an electrical short circuit.

The test fires generated some visible smoke, which was quickly dissipated due to the room ventilation. The VIEW laser detectors close to the test fires consistently went into pre alarm very quickly and then full alarm. I was amazed at the response the system gave with such a small amount of smoke. The aspiration system registered small amounts of smoke on most tests and did go into an alert or pre-alarm condition on some of the tests.

Test Conclusion


The VIEW system, when properly installed meets the requirements of BS6266 for telecommunications equipment facilities, even at less than maximum sensitivity settings.

The VIEW system performance is equal or superior to aspiration technology used in the test sites.

The VIEW system consistently located the fire with 'downwind' detectors near the fire source activating first. This ability to approximately locate the fire is a major advantage compared to aspiration technology. Low energy electrical faults can create a very small quantity of smoke and without this address information the fires could be extremely difficult to locate.

VIEW - The future of fire detection?


The revolutionary new VIEW system with laser detector technology, advanced software algorithms and intelligent panel functionality could change the way we think about fire detection. It is a quantum leap in advanced detection technology, which should give specifiers of systems solutions to some difficult problems. It is a viable alternative to aspiration technology in many applications and opens up many other opportunities, which previously were not possible.