Applications for IR
³
Flame Detectors
IR
³
Flame Detectors are used when detection is required to be unaffected by convection
currents, draughts or wind; tolerant of fumes, vapours, steam, dust and mist; responsive to a
flame more than 25m away and fast reacting.
Typical applications examples are:
• agriculture – grain and malt processing, animal feed manufacture
• aircraft hangars
• automotive industry – spray booths, parts manufacture
• chipboard and MDF manufacture
• power plants
• printing
• transformer stations
Applications and locations to avoid:
• ambient temperatures above 55°C (continuous)
• sunlight falling directly onto IR optics
• exposure to severe rain and ice
• flickering or moving hot objects
• flood or spot lighting falling directly on IR optics
• large amounts of flickering reflections
• large IR sources above 200°C – heaters, burners, flare stacks
• microwave ovens and dryers
• obstructions to field of view
Table 1
Sensor window contamination
Contaminant
Typical percentage of
normal response
Water spray
75
Steam
75
Smoke
75
Oil film
86
Salt water film
86
Dry salt deposits
86
Functional testing
When polled by a compatible panel or test set, the IR
³
Flame Detector, in quiescent condi-
tion, should return an analogue value of 25 and input bits set to ‘0’.
When output bit 2 is set to logic 1 on two or more consecutive pollings, the red LED on the
flame detector will illuminate.
When output bit 1 is set to 1 on two or more consecutive pollings the flame detector will
perform a self test. It does this by causing internal LEDs to flicker in the field of view of the
flame detector, thus simulating the behavior of flames.
When output bit 0 is set to 1 on two or more consecutive pollings the IR
³
Flame Detector will
switch on a remote LED.
Finally, provided it is safe to do so, carry out a flame test using a flickering flame source,
such as a portable bunsen burner. A still, non-flickering flame will not produce a response
from the detector.
Maintenance Guide
The IR
³
Flame Detector is designed to give years of trouble-free operation with minimal
attention. However the periodic maintenance steps listed below are essential to maintain
reliable fire protection.
1. Inform all appropriate personnel of intention to work on the flame detector.
2. Disable any automatic systems that may be activated by the flame detector if not
required as part of the maintenance check.
Alarms Extinguishers Control
Audio/Visual
Gas systems
Plant stops
Auto diallers
Water sprays
Dampers/doors
3. Check that the flame detector’s control panel is functioning correctly and shows no
faults.
4. Inspect the detector viewing window for any build-up of dust or other contaminants
on the optical surface. If necessary clean the optical surface with a cotton wipe and
commercial liquid glass cleaner and wipe clean.
The detector specification for performance is with a clean optical sensor window.
Contaminants like dust, oil and paint will reduce sensitivity.
5. Ensure the detector still has a clear line of sight of the area it is protecting and no
obstacles obstruct its view.
6. Check that the detector is securely fitted.
7. Visually check the exterior of the detector for any mechanical or corrosive damage.
8. Test the operation of the detector with either a portable flame sensor test unit or if
practical a flickering yellow flame.
9. Reinstate any automatic system disabled during maintenance.
10. Inform all appropriate personnel on completion of the maintenance work and if
necessary record this work.
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