MSA’s Guide to Selecting the Right Detector for Your Application

INNOVATION IN employing scientific disciplines (IR) bands. Figure 2 schematically such as physical chemistry, shows a typical FLAME DETECTION physics, electro-optics, emission spectrum where UV and electromagnetic physics, IR spectral bands are "highlighted" ndustries involved in electromagnetic spectral analysis to show the spectral ranges that Imanufacturing, processing, and thermodynamics. This Guide are usually selected for existing storing or transportation of describes an innovative approach flame detectors. flammable material are constantly to flame spectral analysis that has in need of reliable and fast led to the development of a The flame spectral response fire detection systems. unique multipurpose -type pattern, being unique, allows It is evident that the smaller the (IR) flame detector. several spectral ranges to be fire, when detected, the easier it employed in the various detection is to extinguish. In this respect, BACKGROUND FOR devices. Flame detectors usually fire detection systems, especially utilize optical sensors working at optical flame detectors, are the FIRE DETECTION specific spectral ranges (usually most powerful apparatus in fire narrow band) that record the fire scenario can be analyzed fighting due to their ability to incoming radiation at the selected by several approaches, remotely detect a small fire from A wavelengths. The signals recorded a long distance. depending on the monitored by the sensor are then analyzed parameters such as fuel according to a predetermined It may seem simple and straight consumption, oxygen/air technique that includes one or forward to design a sensitive consumption, heat evolving or more of the following: optical flame detector by utilizing chemical reactions taking place in (UV), Infrared (IR) or a the vaporized fuel zone. Figure 1 1. Flickering frequency combination of UV/IR sensors. describes the anatomy of a analysis However, these detectors often hydrocarbon fire where the 2. Threshold energy signal operate in industrial environments vaporized fuel is dispersed in the comparison which contain many radiation surrounding atmosphere where it 3. Mathematical correlation sources that could impair detector immediately reacts with oxygen between several signals performance and even cause and the flame chemical chain 4. Comparison techniques false alarms. Moreover, many reaction takes place to give off (Ration, AND gate, OR gate applications require flame gaseous products such as CO2, techniques) detectors to withstand harsh H2O, HC - (unburned environmental conditions and still hydrocarbon molecules), C 5. Correlation to memorized maintain their entire envelope of (Soot), CO. Fire detection spectral analysis performance. technologies throughout the years Detection devices using several of have relied on these factors for the above-mentioned techniques Most applications for optical flame the developing detection devices. detectors are "High Risk - High promise to be most reliable with Value", that require detectors to OPTICAL FLAME respect to detection sensitivity be designed, qualified and versus immunity to false alarms. manufactured according to DETECTION sophisticated and advanced Four major families of optical methods to ensure the installed he energy radiated from a fire detectors have emerged in the product is reliable. Tserves as a major factor in it's last 20 years. detection analysis. 30% - 40% of 1. UV Detectors These requirements have this energy is dissipated in the 2. IR Detectors accelerated the technology race form of electromagnetic radiation to research and develop new at various spectral ranges, such as 3. UV/IR Detectors approaches to fire detection Ultraviolet (UV), visible, infrared 4. IR/IR Detectors Guide to Selecting the Right Flame Detector for Your Application

AnatomyAnatomy ofof aa FirFiree

Figure 1. Guide to Selecting the Right Flame Detector for Your Application

Each of these detector families The occurrence of random UV mathematical techniques are uses one or several of the radiation from sources such as employed. The most accepted are parameter analyses listed , arc welding, radiation flickering analysis and narrow previously, and employ the most and solar radiation (which are not band IR threshold signals advanced optical sensors at the absorbed by the atmosphere due processed in the IR 4.1um-4.6um specific spectral wavelengths. to holes in the layer and wavelengths. These IR detectors However, each family of detectors solar bursts) cause false alarms are still subject to false alarms is recommended for use only in in UV detectors. caused by blackbody radiation specific applications. These (heaters, incandescent lamps, applications are usually IR FLAME halogen lamps plus others). determined by evaluating to what DETECTION extent false alarms caused by In order to minimize or eliminate false alarms, dual wavelength environmental stimulus could nfrared radiation is present in technology has been adopted for create major problems. most (as can be seen I optical flame detection. UV FLAME from Fig 2). The flame temperature, its mass of hot This dual wavelength technology DETECTION gases (fire products), emit a has two major branches: specific spectral pattern that can he UV spectral band, because be easily reorganized by 1. UV/IR Spectral Bands Tof shortwave characteristics, employing IR sensor technology. 2. IR/IR Spectral Bands is absorbed in the surrounding atmosphere by air, , dust, However, the flames are not the In recent years dual spectral gases and various organic only source of IR radiation and detection was considered the materials. Hence UV radiation any hot surface such as ovens, most advanced method to cope dispersed in the atmosphere, lamps, incandescent halogen with false alarms. especially at wavelengths shorter lamps, furnaces, solar radiation, than 300 nm (the solar blind emit IR radiation which coincides UV/IR FLAME spectral band), is being absorbed with the flame IR radiation DETECTION by the surrounding atmosphere wavelengths. and will not create false alarms on he dual spectrum UV/IR these flame detectors. UV DUAL WAVELENGTH Ttechnology employs a solar detectors based on this technology DETECTION blind UV sensor, with a high signal are detecting flames at high speed to noise ratio and a narrow band (3-4 milliseconds) due to the UV n order to discern the flames' IR sensor. The UV sensor itself is high energy radiation emitted by I"spectral signature" from other a good fire detector but is easily and explosions at the instant IR source spectral signatures, activated by alarm stimuli such as of their ignition. various parameter analysis and welding, lightning, Xrays and solar

Figure 2. Guide to Selecting the Right Flame Detector for Your Application spikes. To prevent false alarms channel, thus impairing its ability caused by these sources, the IR to detect a fire. ¥ Flickering analysis sensing channel was added. The ¥ Radiation intensity IR spectral channel has a spectral Further discrimination relating to above a certain threshold the percentage of time each signal signature characteristic to fire in The ratio between both signals is present using "windows" where ¥ addition to the fire's UV flame received at the 2 sensors detector spectral signature and the UV signals are counted together serve as a reliable continuously, enable elimination of Since most of these dual IR detector for most mid-range strong signals not emitted by detectors use the 4.3um sensor as applications. Even this advanced actual fires. Comparable their main channel for has limitations, since techniques using "AND-gate" recognition (where the CO2 each type of fire has its own methods, process the UV and IR emission peak exists), they suffer specific ratio of UV to IR output. signals received by both sensors from atmospheric attenuation, in the detector, thus ensuring the especially on long range detection For example, a flame accuracy of these detectors. applications. generates a high amount of UV radiation with very little IR, while a IR/IR FLAME ADVANCED coal fire generates little UV DETECTION radiation and a high amount of IR TECHNIQUES FOR radiation. Since the dual UV/IR nother dual wavelength FLAME SPECTRAL detector combines both signals to Atechnology combines two ANALYSIS an “AND-gate", there could be a narrow spectral ranges in the near fire that will not be detected. To IR spectral band. Since the ach of the previously ensure the reliability of the fire hydrocarbon flames emit energy of described detection methods signal, a discriminating circuit E a continuous nature in the near IR has drawbacks. It is evident that compares the UV radiation (0.9um - 3.0um) and a unique classic fire analysis methods are threshold signal, the IR threshold peak at the 4.3um -4.5um (caused insufficient for some applications. signal, and their ratio, as well as by the hot CO fire product) these The development of electro-optic their flickering mode. 2 features are the "heart" of most technology enables advanced dual IR detectors. Common dual The fire alarm is confirmed only techniques for performing deeper IR flame detectors employ two when all parameters satisfy the and more comprehensive spectral narrow bands 0.9um and 4.3um, detection mathematical algorithm. analysis. for fire signal analysis. In industrial environments the The spectrum of flame radiation sources for false alarms are Another approach to dual IR measured by the detector is variant, including UV radiating detection technology has influenced by the distance sources such as: welding, emerged in recent years, where a between the detector and the fire electrical arcs, lightning (high fire's main spectral characteristic and by the concentration of the voltage coronas), torches (in the feature at 4.3um -4.5um is CO2 gas in the atmosphere. petrochemical industry), solar analyzed thoroughly. spikes, and IR radiating sources Two factors limit the detection (heaters, incandescent lamps, The basis to this analysis is the range of dual IR detectors: halogen lamps, etc). Since these "differential spectral" approach false alarms affect both UV and IR where two spectral ranges are 1. The fires radiation intensity channels, certain scenarios may analyzed. One spectral range is strongly decreases as the occur where a false fire stimulus is emitted strongly by the fire while distance increases around present, i.e.: when an IR source the second spectral range is the 3.3um peak. The input () and a UV source emitted weakly by the surrounding. signal received by the sensor (welding) are present at once. The ratio between these two is very weak (the more CO2 signals provides a substantial in the atmosphere, the higher In certain detectors, a serious mathematical tool for fire signal absorption of this problem may occur when a strong processing. This type of IR wavelength and the lower the UV source (welding) is present detector senses the radiation at signal received). This could and a fire ignites. The strong UV these two channels and processes be omitted and not signal blocks the detector's logic the input signals based on the recognized as fire by dual from comparison with the IR following parameters: IR/IR type detectors. Guide to Selecting the Right Flame Detector for Your Application

2. The ratio between the 4.3um a fire at a distance greater than a improvement of this IR analysis spectral band and the few meters is not significantly technique enables the accurate second IR channel (the distinguishable from their internal detection of a hidden fire background 4.9um spectral noise,requiring sophisticated (smoldering fire) where the band), approaches equality mathematical techniques for proper radiating flames are hidden, but (1:1) and ceases to be signal recognition. the hot mass of CO2 gases are typical to the ratio existing emitted and therefore detected. in fires. In summary, the dual IR fire detection technology, although Using correlation techniques where suitable in some indoor and limited Once the ratio approaches 1:1, the each IR channel is auto-correlated algorithm processing the fire outdoor short range applications, to a pre-determined value and signals gives a no-fire signal, even have serious limitations that further, (using the ratio between though a fire may occur at that prevent the application of this the specific IR channels), very moment. technology to long-range fire detection. discrimination between fire and The first limiting factor may be false-alarm stimuli is possible. reduced by choosing a sensor with To resolve some of these limiting a wide band spectral range. This factors, a unique approach has CONCLUSIONS will enhance the input signal, but been introduced into the fire will not solve the problem detector market. Its scientific ptical flame detectors have discussed in the second limiting background can be described as Oexisted for over 20 years. factor (2). The ratio between the follows: Through the years there have two IR channels becomes equal been developments of these Most fire radiation is due to hot for a long distance fire in the case detectors by combining various CO and H O molecules that are of high concentration of CO in the 2 2 sensors and employing new logic 2 the main combustion products. In atmosphere. This criteria, when and mathematical techniques. this novel approach, the fire is employed in IR/IR fire detectors, considered an alternating infrared MSA’s FlameGard¨ IR3 Flame makes the distinction between source that emits strongly at the Detector is the new generation in flames and false alarm sources CO emission band and weakly at 2 flame detection, offering high (electrical heaters) virtually the background emission band. impossible. Most of the IR sources (considered sensitivity as well as immunity to IR false-alarm stimuli) including false alarms. To address both limitations, the , incandescent and halogen use of a narrow-band, spectral lamps, arc discharge, electrical With the introduction of the filter is suggested. The use of this 3 heaters, etc., do not possess this FlameGard IR Flame Detector narrow spectral band sensor in unique spectral feature. with its extended range, fewer addition to the second IR channel, detectors are required to cover an provides a typical fire ratio at Three spectral wavelength bands area. longer distances. Once the proper have been selected for this flame spectral band is selected, the detection technique: For example, when laying out limiting flame detector factor for detection for an oil or gas loading the detection range is no longer The mathematical relation between facility in the past, 4 or 5 the atmospheric attenuation, but the three (or more) sensors, detectors per bay were required. the sensitivity of the specific detecting the specific wavelengths With the FlameGard IR3 detector, sensor. of IR radiation, is typical to each IR only 2 to 3 detectors per bay source for distinguishing between would be required. This results in If the input signal is not significantly a fire scenario and interfering IR substantial savings on the cost of greater than the internal noise of stimuli. Each IR source has its own the sensor, the ratio and measured IR spectral signature and gives a equipment, while at the same intensity are not reliable as fire different signal ratio at the three time providing the same indicators. IR sensors currently sources. protection. available on the market have low ratios between input signal and Taking into consideration the ratio In the case of train loading, the internal noise. between the three IR channels, a number of detectors required fire can be singularly detected with could also be cut substantially For these sensors, the signal from almost no false alarms. Further with the new FlameGard IR3. Guide to Selecting the Right Flame Detector for Your Application

Charts and Graphs

Maximum Distances from Detector to Potential Fires Type of Fire 30FT. 40FT. 50FT. 100FT. 200FT.

1 SQ.FT. Gasoline All models All models All models U; I I 1 SQ.FT. Diesel All models U; I U; I I I 11 SQ.FT. n-Heptane All models All models All models U; I I 1 SQ.FT. Alcohol All models U; I U; I I I 4 SQ.FT. JP4/JP8 All models All models All models All models I Comparison Between Various Types of Flame Detectors Technology Advantages Disadvantages Applications

Infrared (IR) High speed. Moderate Affected by temperature. Subject Indoors sensitivity. Manual self-test. to false alarms. IR sources. Low cost. Ultraviolet (UV) Highest speed.High sensitivity. Affected by UV sources. Subject Indoors Automatic self-test. Low cost. to false alarms. Blinded by thick smoke. Moderate cost. Dual Detector High speed. High sensitivity. Affected by specific UV/IR. Ratio Outdoors/ (UV/IR) Low false alarm rate. Automatic created by false stimuli. Affected by Indoors self-test. thick smoke. Moderate Cost. Dual Detector Moderate speed. Moderate Limited operation by temperature Outdoors/ (IR/IR) sensitivity. Low false alarm rate. range. Affected by IR sources. Indoors Moderate cost. Triple IR High speed. Highest sensitivity. Moderate cost. Outdoors/ Lowest false alarm rate. Indoors Automatic self-test. Recommended Flame Detectors for Various Fire Scenarios For These Types of Potential Fire Hazards...

Gasoline Paints Alcohol Hydrogen Plastic JP4/JP8 Solvents Wood Oils Methane Paper Diesel CFC’s

Possible False Alarm Sources Present Use These Detectors:

Arc welding UV/IR*, IR3 UV/IR*, IR3 UV/IR*, IR3 UV/IR*, IR3 UV/IR*, IR3

X-rays UV/IR* UV/IR* UV/IR* UV/IR* UV/IR* (for maintenance properties) IR3 IR3 IR3 IR3 IR3

Hot surfaces UV.UV/IR UV, UV/IR UV, UV/IR UV, UV/IR UV, UV/IR High temperatures IR3 IR3 IR3 IR3 IR3

Background

Incandescent light UV**, UV/IR UV**, UV/IR UV, UV/IR UV, UV/IR UV, UV/IR Fluorescent light IR3 IR3 IR3 IR3

Halon lighting- w/glass UV**, UV/IR UV**, UV/IR UV**, UV/IR UV, UV/IR UV, UV/IR Halon lighting- w/o glass IR3 IR3 IR3 IR3

Mercury lamps UV/IR UV/IR UV/IR UV/IR UV/IR Flash lamps IR3 IR3 IR3 IR3 IR3

*Model UV/IR only. **For indoor applications only. Guide to Selecting the Right Flame Detector for Your Application

FlameGard® Models* and Characteristics Detection Range 1Ft. x 1FT. Model Type Pan Fire Response Time Description

U UV 50FT. 0.5 second nominal Fast response UV detector

U UV 50FT. 0.5 second nominal As above with automatic or manual built-in test for verifying lens cleanliness and electric operation. Indoor operations.

I UV/IR 50FT. 1 second nominal Dual UV/IR indoor and outdoor applications.

I UV/IR 50FT. 2 seconds nominal As above with automatic or manual test for verifying lens cleanliness and electric operation. Indoor and outdoor applications.

IR3 IR3 200FT. 5 seconds Extended detection range alarms. Automatic or manual bit 4-20mA interface. 4 SQ.FT. JP4 1 second Optional RS85 interface. Adjustable time Fuel at 100FT. delay up to 30 seconds.

*All models are explosion-proof and approved by FM/CENELEC/CSA. Typical Layouts Single Plane Industrial Application Hangar

Underwing coverage using 4 FlameGard IR3 flame detectors.

Sensitivity: 10’ x 10’.

Oil tank installation with floating roof.

Overwing Protection

Hangar detector coverage using 8 FlameGard IR3 flame detectors. Double coverage.

Sensitivity: 1’ x 1’ pan fire at 200 feet. If you would like MSA to generate a suggested layout, please FAX us at (412) 776-3280 with the outline dimensions showing clearly any

Laying Out the Area to be Protected

1. Draw a floor plan of the area for which detection is to be provided. Use graph paper if possible and fill in the outline measurements. 2. Locate detectors within and around the potential hazard area so at least one detector has an unobstructed view of every location within the hazard area. Use the distance charts in this guide, taking into account the type of fire that is likely to occur. 3. For example, in an aircraft hangar, the most likely fire would occur in a spill underneath the aircraft. Therefore, detectors should be lookin underneath the aircraft wings. In a warehouse application where chemicals are being stored in racks, the entire volume should be covered, taking care not to have non-burning obstructions within the detector’s field of view. 4. If performance criteria have been established, define the minimum size fire to be detected (i.e.1FT. pan fire at 50FT.). Then use the chart provided in this guide to determine the distance from the potential source of fire to where the detector(s) can be located. (Remember, the larger the area the detector can cover, the fewer the detectors required for your application.)

SCALE=1 FT.

Note: This bulletin contains only a general description of the MSA FlameGard Mine Safety Appliances Company Flame Detectors. While uses and performance capabilities are described, In U.S, 1-800-MSA-INST or FAX (724) 776-3280 under no circumstances should the product be used except by qualified, In Canada, 1-800-267-0672 or FAX (416) 663-5908 trained personnel, and not until the instructions, labels or other literature accompanying the product have been carefully read and understood and the Elsewhere, MSA International, (412) 967-3228 or FAX (412) 967-3373 precautions therein set forth followed. Only they contain the complete and detailed information concerning this product. Instrument Division: P.O. Box 427, Pittsburgh, PA 15230 U.S.A.

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