Flare (pyrotechnic)
Overview
 
A flare, also sometimes called a fusee, is a type of pyrotechnic that produces a brilliant light or intense heat without an explosion
Explosion
An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...

. Flares are used for signalling, illumination, or defensive countermeasures in civilian and military applications. Flares may be ground pyrotechnics, projectile pyrotechnics, or parachute-suspended to provide maximum illumination time over a large area.
Encyclopedia
A flare, also sometimes called a fusee, is a type of pyrotechnic that produces a brilliant light or intense heat without an explosion
Explosion
An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...

. Flares are used for signalling, illumination, or defensive countermeasures in civilian and military applications. Flares may be ground pyrotechnics, projectile pyrotechnics, or parachute-suspended to provide maximum illumination time over a large area. Projectile pyrotechnics may be dropped from aircraft, fired from rocket or artillery
Artillery
Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...

, or deployed by flare gun
Flare gun
A flare gun is a firearm that launches flares. It is typically used for signalling, as distress signalling, at sea or from the ground to aircraft...

s or handheld percussive tubes.

Flares produce their light through the combustion
Combustion
Combustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species. The release of heat can result in the production of light in the form of either glowing or a flame...

 of a pyrotechnic composition
Pyrotechnic composition
A pyrotechnic composition is a substance or mixture of substances designed to produce an effect by heat, light, sound, gas or smoke or a combination of these, as a result of non-detonative self-sustaining exothermic chemical reactions...

. The ingredients are varied, but often based on strontium nitrate
Strontium nitrate
Strontium nitrate is an inorganic compound with the formula Sr2. This colourless solid is used as an colorant in pyrotechnics.- Preparation:Strontium nitrate is typically generated by the reaction of nitric acid on strontium carbonate.....

, potassium nitrate
Potassium nitrate
Potassium nitrate is a chemical compound with the formula KNO3. It is an ionic salt of potassium ions K+ and nitrate ions NO3−.It occurs as a mineral niter and is a natural solid source of nitrogen. Its common names include saltpetre , from medieval Latin sal petræ: "stone salt" or possibly "Salt...

, or potassium perchlorate
Potassium perchlorate
Potassium perchlorate is the inorganic salt with the chemical formula KClO4. Like other perchlorates, this salt is a strong oxidizer and potentially reacts with many organic substances...

 and mixed with a fuel such as charcoal
Charcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...

, sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

, sawdust
Sawdust
Sawdust is a by-product of cutting lumber with a saw, composed of fine particles of wood. It can present a hazard in manufacturing industries, especially in terms of its flammability....

, aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

, magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

, or a suitable polymeric resin. Flares may be colored by the inclusion of pyrotechnic colourants. Calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

 flares are used underwater to illuminate submerged objects.

Civilian use

In the civilian world, flares are commonly used as signals, and may be ignited on the ground or fired as an aerial signal from a pistol
Pistol
When distinguished as a subset of handguns, a pistol is a handgun with a chamber that is integral with the barrel, as opposed to a revolver, wherein the chamber is separate from the barrel as a revolving cylinder. Typically, pistols have an effective range of about 100 feet.-History:The pistol...

-like flare gun
Flare gun
A flare gun is a firearm that launches flares. It is typically used for signalling, as distress signalling, at sea or from the ground to aircraft...

, or launched from a self contained tube. Flares are commonly found in marine survival kits.

Maritime distress signal

A "rocket parachute flare or a hand flare showing a red light"..."indicates distress and need of assistance" at sea is one type of maritime distress signals. "The use or exhibition of any of the foregoing signals [as a hand flare showing a red light or rockets or shells, throwing red stars] except for the purpose of indicating distress and need of assistance and the use of other signals which may be confused with any of the above signals is prohibited." from the COLREGS ANNEX IV - Distress signals 1. (c), (i).

Other usage

Flares are routinely used in countries around Europe and South America, during football games, in order to aid the build-up of the atmosphere within the stadium. Hardcore supporter groups known as Ultras
Ultras
Ultras are a type of sports fans renowned for their fanatical support and elaborate displays. They are predominantly European followers of football teams...

, often light flares at the beginning of games, when their team has scored, or at the end of a game, if their team has won.

Fusee

Another type of flare is the fusee, which burns for 10–60 minutes with a bright red light. Fusees are commonly used to indicate obstacles or advise caution on roadways at night; in this usage they are also called highway flares, road flares, or ground flares. They are commonly found in roadside emergency kits.

Fusees are also known as railroad flares and are used to perform hand signals in rail transport
Rail transport
Rail transport is a means of conveyance of passengers and goods by way of wheeled vehicles running on rail tracks. In contrast to road transport, where vehicles merely run on a prepared surface, rail vehicles are also directionally guided by the tracks they run on...

 applications. Since they can be used only once, fusees nowadays are usually intended for emergency use (as opposed to the incandescent lanterns typically used during normal operating conditions). However, in the days before train radio communications, fusees were used to keep trains apart on un-signalled lines. A railroad fusee was timed to burn for ten minutes and quantities were dropped behind a train to ensure a safe spacing. If a following train encountered a burning fusee it was not to pass until the fusee burned out. Fusees made specifically for railroad use can be distinguished from highway fusees by a sharp steel spike at one end, used to embed the fusee upright in a wooden railroad tie
Railroad tie
A railroad tie/railway tie , or railway sleeper is a rectangular item used to support the rails in railroad tracks...

.

In forestry and firefighting, fusees are sometimes used in wildland fire suppression
Wildland fire suppression
Wildfire suppression refers to the firefighting tactics used to suppress wildfires. Firefighting efforts in wildland areas requires different techniques, equipment, and training from the more familiar structure fire fighting found in populated areas...

 and in the ignition of controlled burn
Controlled burn
Controlled or prescribed burning, also known as hazard reduction burning or Swailing is a technique sometimes used in forest management, farming, prairie restoration or greenhouse gas abatement. Fire is a natural part of both forest and grassland ecology and controlled fire can be a tool for...

s. They ignite at 191 °C (375.8 °F) and burn as hot as 1600 °C (2,912 °F). They are especially effective in igniting burnouts or backburns in very dry conditions, but not so effective when fuel conditions are moist. Since controlled burns are often done during relatively high humidity levels (on the grounds that they could not be safely contained during periods of very low humidity), the driptorch
Driptorch
A driptorch is a tool used in wildfire suppression, controlled burning, and other forestry applications to intentionally ignite fires.The driptorch consists of a canister for holding fuel with a handle attached to the side, a spout with a loop to prevent fire from entering the fuel canister, a...

 is more effective and more often used. Fusees are also commonly carried by wildland firefighter
Firefighter
Firefighters are rescuers extensively trained primarily to put out hazardous fires that threaten civilian populations and property, to rescue people from car incidents, collapsed and burning buildings and other such situations...

s for emergency use, to ignite an escape fire
Escape fire
An escape fire is a term used to describe the "backfire" or "backburn" set by Fireboss Wag Dodge at Mann Gulch to escape a primary fire burning inescapably towards him and his crew. Check Wiki definitions for "backfire" and "backburn," e.g...

  in surrounding fuels in case of being overrun by a fire if no other escape routes are available.

Calcium phosphide
Calcium phosphide
Calcium phosphide is a chemical is used in incendiary bombs. It has the appearance of red-brown crystalline powder or grey lumps, with melting point of 1600 °C. Its trade name is Photophor for the incendiary use or Polythanol for the use as rodenticide.It may be formed by reaction of the elements...

 is often used in naval flares, as in contact with water it liberates phosphine
Phosphine
Phosphine is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas. Pure phosphine is odourless, but technical grade samples have a highly unpleasant odor like garlic or rotting fish, due to the presence of substituted phosphine and diphosphine...

 which self-ignites in contact with air; it is often used together with calcium carbide
Calcium carbide
thumb|right|Calcium carbide.Calcium carbide is a chemical compound with the chemical formula of CaC2. The pure material is colorless, however pieces of technical grade calcium carbide are grey or brown and consist of only 80-85% of CaC2 . Because of presence of PH3, NH3, and H2S it has a...

 which releases acetylene
Acetylene
Acetylene is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in pure form and thus is usually handled as a solution.As an alkyne, acetylene is unsaturated because...

.

Air

A special variety of flare is used in military aircraft as a defensive countermeasure
Countermeasure
A countermeasure is a measure or action taken to counter or offset another one. As a general concept it implies precision, and is any technological or tactical solution or system designed to prevent an undesirable outcome in the process...

 against heat-seeking
Infrared homing
Infrared homing refers to a passive missile guidance system which uses the emission from a target of electromagnetic radiation in the infrared part of the spectrum to track and follow it. Missiles which use infrared seeking are often referred to as "heat-seekers", since infrared is just below the...

 missiles. These flares are usually discharged individually or in salvoes by the pilot or automatically by tail-warning devices, and are accompanied by vigorous evasive maneuvering. Since they are intended to deceive infrared missiles, these flares burn at temperatures of thousands of degrees, incandescing in the visible spectrum as well. Soids are floating flares that are effective only in the terminal phase of missiles with infrared signature seeker heads.

In 1922, a "landing flare" was an aerial candle attached to a parachute and used for landing an airplane in the dark. The flare burned for less than 4 minutes and the candle power was about 40,000.

Non-perchlorate flares

Many in-service colored signal flares and spectrally balanced decoy flares contain perchlorate oxidizers. Perchlorate, a type of salt in its solid form, dissolves and moves rapidly in groundwater and surface water. Even in low concentrations in drinking water supplies, perchlorate is known to inhibit the uptake of iodine by the thyroid gland. While there are currently no federal drinking water standards for perchlorate, some states have established public health goals, or action levels, and some are in the process of establishing state maximum contaminant levels. For example, the US Environmental Protection Agency have studied the impacts of perchlorate on the environment as well as drinking water. California has also issued guidance regarding perchlorate use.

Several states have enacted drinking water standard for perchlorate including Massachusetts in 2006. California's legislature enacted AB 826, the Perchlorate Contamination Prevention Act of 2003, requiring California's Department of Toxic Substance Control (DTSC) to adopt regulations specifying best management practices for perchlorate and perchlorate-containing substances. The Perchlorate Best Management Practices were adopted on December 31, 2005 and became operative on July 1, 2006. California issued drinking water standards in 2007. Several other states, including Arizona, Maryland, Nevada, New Mexico, New York, and Texas have established non-enforceable, advisory levels for perchlorate.

US courts have taken action regarding the use of perchlorate in manufacturing pyrotechnic devices such as flares. For example, in 2003, a federal district court in California found that Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) applied because perchlorate is ignitable and therefore a “characteristic” hazardous waste. (see Castaic Lake Water Agency v. Whittaker, 272 F. Supp. 2d 1053, 1059-61 (C.D. Cal. 2003)).

One example of perchlorate related problems was found at the Olin Flare Facility, Morgan Hill, California - Perchlorate contamination beneath a former flare manufacturing plant in California was first discovered in 2000, several years after the plant had closed. The plant had used potassium perchlorate as one of the ingredients during its 40 years of operation. By late 2003, the state of California and the Santa Clara Valley Water District had confirmed a groundwater plume currently extending over nine miles through residential and agricultural communities.

The Regional Water Quality Control Board and the Santa Clara Valley Water District have engaged in a major outreach effort that has received extensive press and community response. A well testing program is underway for approximately 1,200 residential, municipal, and agricultural wells in the area. Large ion exchange treatment units are operating in three public water supply systems that include seven municipal wells where perchlorate has been detected. The potentially responsible parties, Olin Corporation and Standard Fuse Incorporated, are supplying bottled water to nearly 800 households with private wells. The Regional Water Quality Control Board is overseeing potentially responsible party (PRP) cleanup efforts.

The U. S. Environmental Protection Agency's Richard Wilkin and colleagues, have conducted research on the use of pyrotechnic devices over bodies of water noting concerns over the effects of environmental perchlorate on human health and wildlife. Sources of perchlorate range from lightning and certain fertilizers to the perchlorate compounds in rocket fuel and explosives. Scientists long suspected community fireworks displays were another source, but few studies had been done on the topic. Wilkin's group has now established fireworks displays as a source of perchlorate contamination by analyzing water in an Oklahoma lake before and after fireworks displays in 2004, 2005 and 2006. Within 14 hours after the fireworks, perchlorate levels rose 24 to 1,028 times above background levels. Levels peaked about 24 hours after the display, and then decreased to the pre-fireworks background within 20- to 80 days. The study is detailed in the June 1, 2007 issue of the journal Environmental Science & Technology.

According to the May 2005 Government Accountability Office (GAO) Perchlorate Report, an EPA official has estimated about 10 million people may have been exposed to perchlorate through their drinking water. (See GAO Report — Perchlorate: A System to Track Sampling and Cleanup Results is Needed — Report to the Chairman, Dr. Adam Dierkers, Subcommittee on Environment and Hazardous Materials, Committee on Energy and Commerce, House of Representatives — May 2005). Accordingly, there is an urgent need to develop perchlorate-free compositions for pyrotechnic flare devices.

Some examples of efforts to create non-perchlorate flares include both spectrally balanced decoy and colored flare compositions which included nitrate or oxide oxidizers. Because nitrate oxidizers are less reactive than perchlorate oxidizers, high-energy fuels have used to compensate for this energy shortfall. Some of these high-energy fuels were produced using mechanical alloying technology.

See also

  • Very flare (WWI)
  • Flare gun
    Flare gun
    A flare gun is a firearm that launches flares. It is typically used for signalling, as distress signalling, at sea or from the ground to aircraft...

    , Flare (countermeasure)
    Flare (countermeasure)
    A flare is an aerial infrared countermeasure to counter an infrared homing surface-to-air missile or air-to-air missile. Flares are commonly composed of a pyrotechnic composition based on magnesium or another hot-burning metal, with burning temperature equal to or hotter than engine exhaust...

  • Other meanings of "fusee
    Fusee
    Used in antique spring-powered mechanical watches and clocks, a fusee is a cone-shaped pulley with a spiral groove around it, wound with a cord or chain which is attached to the mainspring barrel...

    "

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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