![Wien - Anti-Akademikerball-Demo der Offensive gegen rechts - IIIb](https://upload.wikimedia.org/wikipedia/commons/7/70/Wien_-_Anti-Akademikerball-Demo_der_Offensive_gegen_rechts_-_IIIb.jpg)
A flare, also sometimes called a fusée, fusee, or bengala in some Latin-speaking countries, is a type of
pyrotechnic
Pyrotechnics is the science and craft of creating such things as fireworks, safety matches, oxygen candles, explosive bolts and other fasteners, parts of automotive airbags, as well as gas-pressure blasting in mining, quarrying, and demolition. ...
that produces a bright light or intense heat without an
explosion
An explosion is a rapid expansion in volume associated with an extreme outward release of energy, usually with the generation of high temperatures and release of high-pressure gases. Supersonic explosions created by high explosives are known ...
. Flares are used for distress signaling, illumination, or defensive
countermeasures
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. The fi ...
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 is a class of heavy military ranged weapons that launch munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during siege ...
, or deployed by
flare gun
A flare gun, also known as a Very pistol or signal pistol, is a large-bore handgun that discharges flares, blanks and smoke. The flare gun is typically used to produce a distress signal.
Types
The most common type of flare gun is a Very (som ...
s or handheld percussive tubes.
History
The earliest recorded use of gunpowder for signaling purposes was the 'signal bomb' used by the Chinese
Song Dynasty
The Song dynasty (; ; 960–1279) was an imperial dynasty of China that began in 960 and lasted until 1279. The dynasty was founded by Emperor Taizu of Song following his usurpation of the throne of the Later Zhou. The Song conquered the rest ...
(960–1279) as the Mongol-led
Yuan Dynasty
The Yuan dynasty (), officially the Great Yuan (; xng, , , literally "Great Yuan State"), was a Mongol-led imperial dynasty of China and a successor state to the Mongol Empire after its division. It was established by Kublai, the fifth ...
(1271–1368) besieged
Yangzhou
Yangzhou, postal romanization Yangchow, is a prefecture-level city in central Jiangsu Province (Suzhong), East China. Sitting on the north bank of the Yangtze, it borders the provincial capital Nanjing to the southwest, Huai'an to the north, Yan ...
in 1276.
These soft-shelled bombs, timed to explode in midair, were used to send messages to a detachment of troops far in the distance. Another mention of the signal bomb appears in a text dating from 1293 requesting their collection from those still stored in
Zhejiang
Zhejiang ( or , ; , also romanized as Chekiang) is an eastern, coastal province of the People's Republic of China. Its capital and largest city is Hangzhou, and other notable cities include Ningbo and Wenzhou. Zhejiang is bordered by Jiang ...
.
A signal gun appears in Korea by 1600. The ''Wu I Thu Phu Thung Chih'' or ''Illustrated Military Encyclopedia'', written in 1791, depicts a signal gun in an illustration.
Civilian use
![26](https://upload.wikimedia.org/wikipedia/commons/0/0f/26.5mm_Flare_Gun.jpg)
In the civilian world, flares are commonly used as signals, and may be ignited on the ground, fired as an aerial signal from a
pistol
A pistol is a handgun, more specifically one with the chamber integral to its gun barrel, though in common usage the two terms are often used interchangeably. The English word was introduced in , when early handguns were produced in Europe, an ...
-like
flare gun
A flare gun, also known as a Very pistol or signal pistol, is a large-bore handgun that discharges flares, blanks and smoke. The flare gun is typically used to produce a distress signal.
Types
The most common type of flare gun is a Very (som ...
, or launched from a self-contained tube. Flares are commonly found in marine
survival kit
A survival kit is a package of basic tools and supplies prepared as an aid to survival in an emergency. Civil and military aircraft, lifeboats, and spacecraft are equipped with survival kits.
Survival kits, in a variety of sizes, contain supp ...
s.
Maritime distress signal
Red flares, either sent as a rocket or held in the hand, are widely recognized as a maritime distress signal.
The
International Convention for the Safety of Life at Sea
The International Convention for the Safety of Life at Sea (SOLAS) is an international maritime treaty that sets minimum safety standards in the construction, equipment and operation of merchant ships. The International Maritime Organization ...
(SOLAS) has standards for visual signals, including both handheld and aerial flares. Handheld flares must burn for at least one minute at an average
luminosity
Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a st ...
of 15,000
candela
The candela ( or ; symbol: cd) is the unit of luminous intensity in the International System of Units (SI). It measures luminous power per unit solid angle emitted by a light source in a particular direction. Luminous intensity is analogous to ...
s, while aerial flares must burn for at least 40 seconds with a 30,000-candela average luminosity. Both should burn in a bright red color. Nations that are members of SOLAS require vessels to carry visual signals on board.
Fusee
![Flare 0](https://upload.wikimedia.org/wikipedia/commons/7/7c/Flare_0.jpg)
Another type of flare is the ''fusee'', which burns for 5–60 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 commonly used to perform hand signals in
rail transport
Rail transport (also known as train transport) is a means of transport that transfers passengers and goods on wheeled vehicles running on rails, which are incorporated in tracks. In contrast to road transport, where the vehicles run on a p ...
applications. Since they can be used only once, fusees nowadays are usually intended for emergency use (as opposed to the lanterns typically used during normal operating conditions). However, in the days before train radio communications, fusees were used to keep trains apart in
dark territory
Dark territory is a term used in the North American railroad industry to describe a section of running track not controlled by signals. Train movements in dark territory were previously handled by timetable and train order operation, but since t ...
. A railroad fusee was timed to burn for 10 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
A railroad tie, crosstie (American English), railway tie (Canadian English) or railway sleeper (Australian and British English) is a rectangular support for the rails in railroad tracks. Generally laid perpendicular to the rails, ties transfer ...
.
In forestry and firefighting, fusees are sometimes used in
wildfire suppression
Wildfire suppression is a range of firefighting tactics used to suppress wildfires. Firefighting efforts in wild land areas require different techniques, equipment, and training from the more familiar structure fire fighting found in populated ...
and in the ignition of
controlled burn
A controlled or prescribed burn, also known as hazard reduction burning, backfire, swailing, or a burn-off, is a fire set intentionally for purposes of forest management, farming, prairie restoration or greenhouse gas abatement. A control ...
s. They ignite at and burn as hot as . 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
A driptorch is a tool used in wildfire suppression, controlled burning, and other forestry applications to intentionally ignite fires by dripping flaming fuel onto the ground.
Description
The driptorch consists of a canister for holding fuel w ...
is more effective and more often used. Fusees are also commonly carried by
wildland
Wilderness or wildlands (usually in the plural), are natural environments on Earth that have not been significantly modified by human activity or any nonurbanized land not under extensive agricultural cultivation. The term has traditionally re ...
firefighter
A firefighter is a first responder and rescuer extensively trained in firefighting, primarily to extinguish hazardous fires that threaten life, property, and the environment as well as to rescue people and in some cases or jurisdictions also ...
s for emergency use, to ignite an
escape fire
An escape fire is a fire lit to clear an area of vegetation in the face of an approaching wildfire when no escape exists. Approximately 40-percent of all wildfire deaths are caused by such fire entrapments, or what are sometimes called "burnovers" ...
in surrounding fuels in case of being overrun by a fire if no other escape routes are available.
Calcium phosphide
Calcium phosphide (CP) is the inorganic compound with the formula Ca3P2. It is one of several phosphides of calcium, being described as the salt-like material composed of Ca2+ and P3−. Other, more exotic calcium phosphides have the formula CaP, ...
is often used in naval flares, as in contact with water it liberates
phosphine
Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula , classed as a pnictogen hydride. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like rotting ...
which self ignites in contact with air; it is often used together with
calcium carbide
Calcium carbide, also known as calcium acetylide, is a chemical compound with the chemical formula of Ca C2. Its main use industrially is in the production of acetylene and calcium cyanamide.
The pure material is colorless, while pieces of tec ...
which releases
acetylene
Acetylene (systematic name: ethyne) is the chemical compound with the formula and structure . 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 its pure ...
.
Law enforcement also may use flares (either propped on a biped or laid flat) to signal traffic hazards or that a road is blocked, often as a more visible replacement for traffic cones.
Law enforcement in the United States usually use
magnesium
Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...
-based flares that last from 15–30 minutes.
Military use
Maritime signal flare
In 1859,
Martha Coston
Martha Jane Coston (December 12, 1826 – July 9, 1904) was an American inventor and businesswoman who invented the Coston Flare (pyrotechnic), flare, a device for signaling at sea, and the owner of the Coston Manufacturing Company.
Early life
Sh ...
patented the Coston flare based on early work by her deceased husband Benjamin Franklin Coston. It was used extensively by the
US Navy
The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage of ...
during the Civil War and by the
United States Life-Saving Service
The United States Life-Saving ServiceDespite the lack of hyphen in its insignia, the agency itself is hyphenated in government documents including: and was a United States government agency that grew out of private and local humanitarian effort ...
(the precursor to the
US Coast Guard
The United States Coast Guard (USCG) is the maritime security, search and rescue, and law enforcement service branch of the United States Armed Forces and one of the country's eight uniformed services. The service is a maritime, military, multi ...
) to signal to other ships and to shore.
Illumination
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 four minutes and the
candlepower
Candlepower (abbreviated as cp or CP) is a unit of measurement for luminous intensity. It expresses levels of light intensity relative to the light emitted by a candle of specific size and constituents. The historical candlepower is equal to 0.981 ...
was about 40,000
lumens.
Countermeasure
A special variety of flares is used in military aircraft as a defensive
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. The fi ...
against
heat-seeking
Infrared homing is a passive weapon guidance system which uses the infrared (IR) light emission from a target to track and follow it seamlessly. Missiles which use infrared seeking are often referred to as "heat-seekers" since infrared is radi ...
missiles. These flares are usually discharged individually or in salvos 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.
Tripflares
Flares connected to
tripwire
A tripwire is a passive triggering mechanism. Typically, a wire or cord is attached to a device for detecting or reacting to physical movement.
Military applications
Such tripwires may be attached to one or more mines – especially fragme ...
s are used to guard an area against infiltration. The flare begins burning when the tripwire is triggered, providing both alarm and illumination.
Regulation
Under the
UN hazard number system, pyrotechnic flares are designated class 1.4 explosives.
Several U.S. states, including California and Massachusetts, have begun regulating levels of potassium perchlorate, which can be unsafe at certain levels in drinking water. Contaminated drinking water can lead to such symptoms as gastric irritation, nausea, vomiting, fever, skin rashes, and even fatal
aplastic anemia
Aplastic anemia is a cancer in which the body fails to make blood cells in sufficient numbers. Blood cells are produced in the bone marrow by stem cells that reside there. Aplastic anemia causes a deficiency of all blood cell types: red blood ...
(a reduction in all types of blood cells).
Chemistry
Flares produce their light through the
combustion
Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combusti ...
of a
pyrotechnic composition
A pyrotechnic composition is a substance or mixture of substances designed to produce an effect by heat, light, sound, gas/smoke or a combination of these, as a result of non-detonative self-sustaining exothermic reaction, exothermic chemical reac ...
. The ingredients are varied, but often based on
strontium nitrate
Strontium nitrate is an inorganic compound composed of the elements strontium, nitrogen and oxygen with the formula Sr( NO3)2. This colorless solid is used as a red colorant and oxidizer in pyrotechnics.
Preparation
Strontium nitrate is typical ...
,
potassium nitrate
Potassium nitrate is a chemical compound with the chemical formula . This alkali metal nitrate salt is also known as Indian saltpetre (large deposits of which were historically mined in India). It is an ionic salt of potassium ions K+ and nitrat ...
, or
potassium perchlorate
Potassium perchlorate is the inorganic salt with the chemical formula K Cl O4. Like other perchlorates, this salt is a strong oxidizer although it usually reacts very slowly with organic substances. This, usually obtained as a colorless, crysta ...
and mixed with a fuel such as
charcoal
Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, cal ...
,
sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
,
sawdust
Sawdust (or wood dust) is a by-product or waste product of woodworking operations such as sawing, sanding, milling, planing, and routing. It is composed of small chippings of wood. These operations can be performed by woodworking machinery, ...
,
aluminium
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
,
magnesium
Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...
, or a suitable
polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
ic
resin
In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on natu ...
. Flares may be colored by the inclusion of
pyrotechnic colorant
A pyrotechnic colorant is a chemical compound which causes a flame to burn with a particular color. These are used to create the colors in pyrotechnic compositions like fireworks and colored fires. The color-producing species are usually create ...
s.
Calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...
flares are used underwater to illuminate submerged objects.
Perchlorate flare health issues
Many in-service colored signal flares and spectrally balanced
decoy flares contain
perchlorate
A perchlorate is a chemical compound containing the perchlorate ion, . The majority of perchlorates are commercially produced salts. They are mainly used as oxidizers for pyrotechnic devices and to control static electricity in food packaging. Per ...
oxidizers. Perchlorate, a type of
salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...
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
Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...
by the
thyroid gland
The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobe (anatomy), lobes. The lower two thirds of the lobes are connected by a thin band of Connective tissue, tissue cal ...
. While there are currently no US federal
drinking water standard
Drinking water quality standards describes the quality parameter#Environmental science, parameters set for drinking water. Despite the truth that every human on this planet needs drinking water to survive and that water may contain many water poll ...
s 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
The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...
has studied the impacts of perchlorate on the environment as well as drinking water. California has also issued guidance regarding perchlorate use.
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 the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) applied because perchlorate is ignitable and therefore a “characteristic”
hazardous waste
Hazardous waste is waste that has substantial or potential threats to public health or the environment. Hazardous waste is a type of dangerous goods. They usually have one or more of the following hazardous traits: ignitability, reactivity, co ...
.
See also
*
*
*
*
References
Further reading
*
External links
*
{{Artificial light sources
Association football culture
Chinese inventions
Distress signals
Emergency communication
Gunpowder
Incendiary weapons
Lighting
Maritime safety
Missile countermeasures
Pyrotechnics
Military history of the Song dynasty
Wildfire suppression equipment
Military history of the Yuan dynasty