Sierra Monitor’s high performance flame detector products are
variations of the most commonly used type, the optical flame detector. Optical
flame detectors are designed to perform in the harshest environmental
conditions and connect directly to alarm control panels. We provide a full line
of industrial flame detectors designed to meet the needs of fire and safety
professionals. Our optical flame detection systems feature single, dual, and
tri-spectrum designs to provide a wide range of capabilities.
Selecting the right flame detector for your application depends on several factors: the nature of the fire, the size of the area to be protected, environmental conditions, detector capabilities and limitations, and other concerns must be considered.
UV (Ultraviolet) Flame Detectors
UV (ultraviolet) flame detectors can detect open flames, fires,
and explosions within 3 to 4 milliseconds, as these sources emit UV radiation
at the instant of ignition. UV flame detectors identify radiation in
wavelengths between approximately 180 and 260 nanometers, and are designed to
ignore sources of natural, incidental background radiation such as sunlight.
However, false alarms can sometimes be triggered by other sources, such as
electrical arc welding and halogen or quartz lighting. Many UV flame detector
models integrate a 2 to 3 second time delay to reduce false alarms.
UV flame detection systems can detect hydrocarbon-based fuel
and gas fires, invisible hydrogen flames, and fires fed by both organic and
inorganic sources. Because nearly every possible source of flame or fire
radiates UV light, UV flame detectors are a good all-around choice.
Sierra Monitor’s UV flame detectors detect hydrocarbon-based
fuel and gas fires, invisible hydrogen flames, and fires from hydrides,
ammonia, silane, and other organic sources.
IR (Infrared) Flame Detectors
IR (infrared) flame detectors monitor the heat radiation generated by fire and open flames, with a response time of roughly 3 to 5 seconds. Working within the infrared spectral band, these flame detection systems have a sensitivity range between approximately 4.3 to 4.4 micrometers. This range covers the resonance frequency of Carbon Dioxide (CO2), which is generated in large amounts by the burning of hydrocarbon materials such as wood and fossil fuels. Hot CO2 gases from fires produce a peak in total radiation emission, as well as a specific spectral pattern in the infrared range, both of which are easily detectable by IR flame detectors.
Incidental background thermal radiation and nearby hot surfaces
can sometimes trigger false alarms in infrared flame detection systems. Ambient
CO2 in air filters, IR radiation from sunlight, and many other sources could
cause false alarms. Special programming algorithms designed to recognize the
flicker frequency of flames (from one to 20 Hz) are often implemented, thus
reducing false alarms caused by heat radiation from hot machinery or other
A variation of these devices, called triple IR (IR3) flame
detectors, compares three specific infrared wavelength bands and their relative
ratios. Typically, this includes one sensor which detects radiation in the 4.4
micrometer range, with the other two sensors reading reference bands above and
below that level. This gives IR3 flame detection systems the ability to better
distinguish between CO2-emitting flames and non-flame IR sources, providing far
greater accuracy and minimizing false alarms.
Sierra Monitor’s IR flame detectors detect hydrocarbon and
hydrogen flames, fires fed by hydrocarbon-based fuels, gas fires, and other
similar sources of flame. Different IR models with the highest immunities to
false alarms can detect even the smallest of fires at distances ranging up to
215 feet away.
UV & IR Flame Detectors
UV & IR (UV/IR) flame detectors compare threshold signals
from ultraviolet and infrared spectrums. Signals from both sensors are analyzed
for intensity, frequency, and duration; this helps these systems better
recognize different types of flame signatures and leads to fewer false alarms.
Simultaneous detection of radiant energy in both sensors will trigger the
system’s alarm. Response times can be as fast as 150 milliseconds, though a
three second range is more typical.
Different models of UV & IR flame detectors put varying
emphasis on one technology over the other. Most UV/IR flame detection systems
operate on infrared wavelengths between 2.5 and 4.5 micrometers, and can detect
radiant energy in the short wave range of both ultraviolet and infrared
spectrums. These flame detectors can detect hydrocarbon-based fuel and gas
fires, hydrogen and hydroxyl fires, hydrocarbon fires, metal fires, and
inorganic fires. Detection ranges varies from model to model.
Sierra Monitor carries different UV/IR flame detectors suitable
for different situations, such as an industrial setting or a manufacturing wet