Flame Detectors

Technical:

Flame detectors are optical equipment used to detect the flames of a fire, as their name suggests. Unlike smoke detectors, which sound an alarm after smoke from a fire has reached them (which can sometimes take several minutes), or sprinkler systems, which work to extinguish fires after they've grown large enough to trigger the sprinkler's mechanism (which can also take minutes), flame detectors can detect the presence of fire almost at the instant of ignition. Smoke detectors and sprinkler systems are useful in limiting the damage of caused by already-burning fires; flame detection systems can help prevent fire damage by alerting personnel of a fire before it gets out of control.
Flame detectors are important for the safety of personnel, equipment, and structures, and are highly useful for companies in hazardous process and manufacturing industries, such as oil and gas refinement. Countless flammable materials are used every day in industrial processes, such as alcohols, solvents, gasoline, propane, and wood and paper products, among many others.
• Optical Flame Detectors:
  There are three basic types of flame detection systems: optical flame detectors, which use optical sensors to detect flames; ionization flame detectors, which use current flow in the flames themselves to detect their presence; and thermocouple flame detectors, which use thermal sensors for detection.
• UV 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.
• IR 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 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 the air filters IR radiation from sunlight and many other sources that could cause false alarms, though direct sunlight does reduce IR flame detectors' sensitivity. 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 sources. A variation of these devices, called triple IR flame detectors (or IR3 flame detectors), compare 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.
• UV & IR Flame Detectors:
  UV & IR flame detectors (or UV/IR flame detectors) compare threshold signals from the 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; through the 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 the 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; however, this range varies from model to model.
  
• 1.Digital, analog and relay outputs for reliable status information across a range of communication formats.
• 2.Power-on self-test and frequent sensor self-test ensure system integrity and correct operation
• 3.Continuous monitoring of optical path for obstruction or reduced transmission
• 4.Industry standard for remote alarm and fault indication ensures reliability and consistency
• 5.Status LED for easy viewing of operating status
• 6.Explosion-proof package for operation in hazardous environments