Function Testing of a Flame Detector in Bright Sunlight using a Test Lamp
Flame Detectors are safety equipment, so they must be regularly function tested using a Test Lamp. Many Flame Detectors are used in outdoor applications and may be subject to bright sunlight. In bright sunlight it is difficult to align the light beam of the Test Lamp correctly. Sense-WARE | The Flame Detectors Company have a reflective ring around the window to enable convenient testing of the Flame Detector in bright sunlight.
Function testing of Flame Detectors with a Test Lamp, emitting a beam of visible light, may be difficult
if a Flame Detector is in an outdoor application with bright sunlight
In this section we explain how a Retro reflective Ring around the detector window is an essential feature when testing Flame Detectors. A Retro reflector is a device or surface that reflects light back to its source with minimum scattering. This works with a wide range of angle of incidence, unlike a flat mirror, which does this only if the mirror is exactly perpendicular to the wave front and having a zero angle of incidence. Being a directed surface, the Retro reflector’s reflection is brighter and superior than that of a diffuse reflector. Figure 1 illustrates the difference is between Retroreflection, Mirror reflection and Diffuse reflection.
That a Retrore flector reflects the light back to its source, makes this physical phenomenon extremely useful, enabling easy function testing of Flame Detectors in bright sunlight. During function testing, light reflected by the Retro reflector ring to the operator of the Test Lamp and is visible as a bright ring of light. This allows the operator of the Test Lamp to adjust the direction of the Test Lamp for maximum effect
Figure 1: Three types of Reflection
Light from the Test Lamp is sent back to the operator by the Retro reflector ring and is visible as a bright ring of light allowing the operator to know how to should align the Test Lamp for maximum effect.