Ultraviolet flame detectors are designed to respond to optical radiation in the ultraviolet wavelengths (wavelengths below 4,000 Angstrom∗, usually in the 2800 – 3000 Angstrom range) primarily emitted by higher intensity flames.
One drawback is that solar radiation can extend to as low 2900 Angstrom, while the detector must be able to respond to fire induced optical radiation below 2900 Angstrom.
Most detectors manufactured are effective in discriminating between solar and fire induced radiation. These detectors are normally applied where the detector can be located reasonably close to the expected ignition source and the background can be protected from other sources of ultraviolet radiation.
One notable application for UV detectors is for use in explosion suppression systems. UV flame detectors are essentially solid state devices employing silicon carbide, aluminum nitride, or gas filled tubes that measure the flame component wavelength range between 0.17 – 0.30 microns∗∗ which are insensitive to both sunlight and artificial light.a