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Series 7000 - General Description | ||||
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7000 SERIES HOME |
 Figure  1 |
Principles Infra-red emissions occur for all materials. The wave length spectrum and intensity of this IR depends on the material’s temperature, and for solid bodies is determined by the Laws of Physics formulated by Planck, Stefan, Boltzmann & Wien.
Figure 1 shows ‘black body’ IR emissions for passive material at various temperatures. Superimposed is the IR peak emission at 4.3um occurring on CO2 formation during the combustion of hydrocarbons. Other conditions, such as arc welding, provide different spectra, however, only flame provides significant IR energy over a narrow band centred on 4.3um, with virtually zero accumulative energy occurring in the long pass band above 5um. It is with an understanding of these criteria that the Patol Series 7000 infrared flame detection equipment has been designed. |
| Implementation & Performance The  detectors (7010 & 7011) have sensors, configured in pairs as channels, which generally respond to modulated infra-red in the range 1Hz to 10Hz, as is produced by flame flicker. Static background black body emissions are automatically rejected. The unit’s narrow band (4.2-4.7um) and wide band (>5um) filters, together with electronic analysis in relation to the various energy level parameters, enable the discrete channels to reject spurious and transient emissions from the local environment. The detectors do not react to visible light from the sun or local luminaires.
It is possible for certain conditions to ‘dazzle’ any particular detector channel. For example hot machinery rotating at 300 rpm could produce 5Hz IR modulation at 4.3um. Whilst the channel’s analytical circuit associated with the long pass detector will identify this as an erroneous signal and override an Alarm being raised, that channel is in effect blind for the duration of the condition. The detector incorporates timer functions that check the ability of the unit to be able to detect flame by all channels for at least a proportion of a defined monitoring period. If the local environment has prevailing IR conditions at sufficient level to effectively “blind” any one channel’s flame detection function over all of this period then a fault warning is signalled. The monitoring period is nominally set at 10s but can be adjusted to suit particular site conditions. The unit continuously checks itself. It will always provide a response to a flame condition, unless the site has problematical ambient conditions in which case an advanced fault warning will be registered. The 7010 & 7011 units have eight pairs of detectors, each pair operating as a discrete channel (alarm path). With this arrangement (figure 2) the overall field of view is sub-divided such as to more readily analyse & compute background emissions. The optical viewing field of each detector pair is 30º x 90º. The overall arrangement is such that the eight channels are mounted on a 22.5º rotational pattern which provides a 360º coverage. |
 Refering to Figure 2 above:-
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Aircraft Hangars Engine Test Bays Oil Refineries Turbine Halls Boiler Fronts Coal Stacks Recycling Plants Waste Handling & Tips Paint Spraying Areas Fuel Distribution Sites |
Application & Range The 7000 Series units are designed for long range monitoring of extensive locations for flame conditions. The unit is most applicable to situations where conventional building fire protection sensors can not be practically employed. With both open air sites and large enclosed areas, such as aircraft hangars or power stations, the normal rules regarding heat convection patterns, smoke stratification, and collection profiles at the ceiling are not applicable. This makes point heat and smoke detectors ineffective. Sites where there is a potential hazard due to volatile materials such as aviation fuel and PRB coal are particularly suitable for protection by Patol’s Series 7000 Flame Detectors.
The detectors have four basic sensitivity settings. Each of these levels has a ‘zoom’ option. Euro-Standard EN54-10 employs a 330 x 330 mm pan of ignited n-heptane for range classification. Based on this Figure 3 shows the typical range along the optical axis of the field of view as shown. The system is blind to both visible light from the sun or local luminaires, and black body emmissions from hot machinery etc. |
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Figure 3 |
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| Detector Locations & Zoning The exact location of the flame monitors, in order to adequately protect any particular site, is dependant on:- the space’s dimensions, the flame hazard (potential flame type/size), and the performance characteristics of the 7000 series flame detector.
The flame sensing units should be directed toward the centre of the protected area and ideally have a completely unobstructed view of all hazards. This is an un-usual site coverage for a single detector. The exact position and orientation of units must take into account obstructions to the field of view, and most applications will require two or more detectors for full coverage, even though some sub-areas will then be monitored by multiple devices. Figures 4 & 5 show a typical arrangement for an aircraft hangar. The area under the aircraft is a particular hazard. Thus the example shows detector placement at both high and low level to obviate obscuration by aircraft wings and body. With other applications, such as power station turbine halls or boiler areas, detector placement at both high and low level obviates obscuration by mezzanine floors and machinery. When the protected area is very large, as would be for as would be for multiple aircraft service facilities or multi-unit power stations, the overall space must be sub-divided into zones - each zone similar to that indicated in figures 4 & 5. A degree of overlap of zone boundaries should be employed to ensure effective coverage. If fire extinguishing media is to be automatically activated, all associated sub-areas/zones should have duplex coverage such that a “double knock” regime for “release” can be implemented. |
 Figure 4 
Figure 5
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Model 7010 Long Range Flame Detector |
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Model 7011 Long Range Flame Detector With Air Purging |
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7010 Data Sheet - PDF
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7011 Data Sheet - PDF
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PATOL LIMITED
- Rectory Road, Padworth Common, Berkshire, UK. Tel: 0118 9701701
Fax: 0118 9700700Email:- patol.limited@ntlworld.com
info@patol.co.uk |