In
a hazardous environment like a petrochemical processing plant or an oil and gas
facility, failing to detect gas leaks can result in catastrophic events. That’s
why industries involved in processing, storing, manufacturing, and transporting
flammable materials rely on fire monitoring systems to prevent workplace fire
accidents.
Principles of Flame
Detection – How do they work?
Fires radiate over the entire spectrum
- Ultraviolet,
Visible and Infra-Red
High Intensity especially in IR (40kW for
standard fire [0.1 m2 n-heptane])
Low frequency radiation flicker, typically
1-10 Hz.
Environmental constraints & false alarm
sources help us select one technology over another……
Optical Flame Detector
Technologies
Optical
flame detectors provide the fastest detection of a flammable liquid or gaseous
fire
in the early ignition stage. Today’s optical flame detectors are offered in a
variety of dependable, flame sensing technologies as described below.
Ultraviolet (UV) flame detectors
provide dependable, ultra-highspeed detection to virtually all fires. In
general, they operate by counting the electron discharge from each UV photon.
Their sensitivity to radiation from welding, lightning, X-rays, and other
nuclear sources may limit them. They can also be adversely affected by airborne
contaminants.
Multi-Spectrum
Infrared flame detectors have the ideal combination of flame
sensitivity and false alarm
rejection. Most MultiSpectrum Infrared (MIR) optical flame
detectors utilize three sensors at
three different infrared wavelengths. Some MIR
detectors have sophisticated software
algorithms which provide the ability to ignore
modulated black bodies and other
non-fire sources in its field of view yet still retain its alarm capabilities.
Intelligent visual flame detection (iVFD) principle ensures maximum false
alarm immunity and eliminates sensitivity loss in the presence of modulated sunlight and black
body heat.
The detector operates ‘standalone’ or
can be integrated with an FM Approved control system. Detectors are typically
located throughout the installation to achieve specific detection coverage and
ensure that site performance requirements are met. Each detector can provide
live video images and fire alarm/fault signalling to the control equipment.
Each detector incorporates within a single unit an imaging device, digital
signal processing hardware, and firmware algorithms to process live video
images and recognise flame features
An Intelligent visual flame detection
(iVFD) is
- A flame detector designed to detect small fires.
- A flame detector designed to detect large fires.
- A flame detector designed to detect fires when sunny.
- A flame detector designed to detect fires when it is
raining.
Intelligent visual flame detectors (iVFD) consistently demonstrate the highest immunity to false alarms in areas where flare reflections and / or hot CO2 emissions may cause other technologies to false alarm.
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