Oldham SharpEye NP40IGB, Руководство пользователя, Страница: 10 / 50

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1.3 Features and Benefits
•
Detection Range: Up to 215 ft (65m) for a 1 ft
2
(0.1m
2
) n-heptane fire.
•
Ultra High Immunity to False Alarms.
•
Advanced Digital Processing of the Dynamic Characteristics of Fire: Flickering,
threshold correlation and ratio.
•
Multi IR Channels: Between 3-5 microns
•
Field Programmable Sensitivity: Four ranges to avoid zone crossover.
•
Built In Test (BIT): Manual and Automatic (see Built-In-Test (BIT) on page 19).
•
Heated Window: Prevents effects of icing, snow, condensation.
•
Electrical Interface:
•
Dry contact relays
•
Communication network RS-485
•
0-20mA output
•
HART Protocol: Communication protocol (see HART Protocol on page 12).
•
EExde: Integral junction box for easy wiring.
•
SIL-2: TÜV approved.
•
Hazardous Area Certification: ATEX, IECEx, FM, CSA.
•
EN54-10: Approved by LPCB (BRE, UK).
1.4 Principles of Operation
1.4.1 Hydrocarbon Fire Detection
The SharpEye 40/40I detector is designed to detect flames in which carbon dioxide (CO
2
)
is produced in the combustion process. These include all hydrocarbon flames, as well as
other types of flames and burning materials such as wood or alcohol.
The detector’s principle of operation is based on patented IR3 technology. This
technology identifies the unique spectral signature that hot CO
2
has in the infrared (IR),
namely a peak of the intensity at wavelengths 4.2 to 4.7µ.
The origina l IR3 technique (such as implemented in the SharpEye 20/20I flame detector)
utilizes three infrared sensors, each sensitive to its own wavelength range. The first sensor
is sensitive to wavelengths within the emission peak of hot CO
2
. The other two sensors are
sensitive to wavelengths above and below this peak. In the event of fire, the signal
measured in the first sensor is significantly higher than those measured in the other two
sensors. In order to issue a fire alarm, the detector requires that this occurs, as well as
other conditions (for example, radiation is flickering in frequencies typical of flames). If
exposed to non-fire radiation sources, the specific conditions required does not occur, and
the detector does not react.
The SharpEye 40/40I further includes an additional IR sensor, sensitive to a different band
within the emission peak of hot CO
2
. The signal of this sensor is compared to those of the
other three. This increases sensitivity for some types of flames. (For example, gas flames).
1.4.2 Heated Optics
The SharpEye 40/40 Flame Detectors use heated optics. The heater increases the
temperature of the optical surface by 5-8°F (~3-5°C) above the ambient temperature to
improve performance in icing, condensation and snow conditions.