Grand Slam (bomb)
The Grand Slam was a 22,000 lb earthquake bomb used by RAF Bomber Command against strategic targets during the Second World War. Known as the Bomb, Medium Capacity, 22,000 lb, it was a scaled-up version of the Tallboy bomb and closer to the original size that the bombs' inventor, Barnes Wallis, had envisaged when he first developed his earthquake bomb idea, it was nicknamed "Ten ton Tess". It was the most powerful non-atomic aerial bomb used in combat until 2017, when a US GBU-43/B MOAB was used in a 2017 attack against ISIL forces in Afghanistan; when the success was proved, Wallis designed a yet more powerful weapon… This 22,000 lb bomb did not reach us before the spring of 1945, when we used it with great effect against viaducts or railways leading to the Ruhr and against several U-boat shelters. If it had been necessary, it would have been used against underground factories, preparations for attacking some of these were well advanced when the war ended. On 18 July 1943, work started on a larger version of the Tallboy bomb.
As with the original Tallboy, the Grand Slam's fins generated a stabilizing spin and the bomb had a thicker case than a conventional bomb, which allowed deeper penetration. Unlike the Tallboy, the Grand Slam was designed to penetrate concrete roofs, it was more effective against hardened targets than any existing bomb. After release from the Avro Lancaster B. Mk 1 bomber, the Grand Slam would reach near-supersonic speed, approaching 715 mph; when it hit, it would penetrate deep underground before detonating. The resulting explosion could cause the formation of a camouflet and shift the ground to undermine a target's foundation; the first Grand Slam was tested at the Ashley Range in the New Forest, on 13 March 1945. Like the Tallboy, after the hot molten Torpex was poured into the casing, the explosive took a month to cool and set. Therefore, the Grand Slam had a low consequent high value for each bomb; as a result, aircrews were told to land with their unused bombs on board rather than jettison them into the sea if a sortie was aborted.
By the end of the war, 42 Grand Slams had been dropped in active service:Bielefeld, 14 March 1945 The No. 617 Squadron RAF Avro Lancaster of Squadron Leader CC Calder dropped the first Grand Slam bomb from 11,965 ft on the Schildesche viaduct. A large section of the Bielefeld viaduct collapsed through the earthquake bomb effect of the Grand Slam and Tallboy bombs of No. 617 Squadron. No aircraft were lost. Arnsberg, 15 March 1945 Two aircraft of No. 617 Squadron RAF each carried a Grand Slam and 14 aircraft of No. 9 Squadron RAF carried Tallboy bombs to attack the railway viaduct in poor weather. One Grand Slam and 10 Tallboys were dropped, while one of the Lancasters was forced to bring its bomb back; the viaduct was not cut and no aircraft were lost. Arnsberg, 19 March 1945 19 Lancasters of No. 617 Squadron, six carrying Grand Slams, the remainder Tallboys, attacked the railway viaduct at Arnsberg. All Grand Slams blew a 40-foot gap in the viaduct; the standing structure was damaged. Arbergen, 21 March 1945 20 Lancasters of No. 617 Squadron, two carrying Grand Slams, the remainder Tallboys, attacked the railway bridge at Arbergen.
The Grand Slams landed off target due to heavy flak and aiming problems. One 617 Lancaster was lost. Nienburg, 22 March 1945 20 Lancasters of No. 617 Squadron, six carrying Grand Slams, the remainder Tallboys, attacked the railway bridge at Nienburg, between Bremen and Hanover. Five Grand Slams made the bridge was destroyed. Another five bombs were brought home by the squadron. Bremen, 23 March 1945 20 Lancasters of No. 617 Squadron, six carrying Grand Slams, the remainder Tallboys, attacked a railway bridge near Bremen. The Grand Slams appear to have landed too far from the target, brought down by a Tallboy. Author Jon Lake claims instead. Farge, 27 March 1945 20 Lancasters of No. 617 Squadron attacked the Valentin submarine pens, a huge, nearly-ready structure with a concrete roof up to 23 ft thick. Two Grand Slam bombs hit the pen, failing to penetrate a 14 ft 5 inches thick roof but causing large holes by exploding within the concrete. No aircraft were lost. Hamburg, 9 April 1945 17 aircraft of No. 617 Squadron, two with Grand Slams and the remainder with Tallboy bombs attacked the U-boat shelters.
The Grand Slams appear to have missed. No aircraft were lost. Heligoland, 19 April 1945 20 aircraft of No. 617 Squadron, six with Grand Slams and the remainder with Tallboy bombs, along with 16 aircraft from No. 9 Squadron, attacked coastal gun-batteries. No aircraft were lost. Beginning in March 1946, Project Ruby was a joint Anglo–American project to investigate the use of penetration bombs against protected, concrete targets; the target selected was the Valentin submarine pens near Bremen, rendered unusable and abandoned since 617 Squadron's attack on 27 March 1945. Grand Slams were carried by Lancasters from US Boeing B-29 Superfortress. Around 140 sorties were flown, testing a range of different bombs including the rocket-assisted Disney bomb. Five complete Grand Slam bombs are preserved and displayed in the United Kingdom at the RAF Museum, London. Main portions of these bombs, without their lightweight tails, can be seen at the Kelham Island Museum i
Aphrodite and Anvil were the World War II code names of United States Army Air Forces and United States Navy operations to use B-17 and PB4Y bombers as precision-guided munitions against bunkers and other hardened/reinforced enemy facilities, such as those targeted during Operation Crossbow. The plan called for B-17 aircraft, taken out of operational service to be loaded to capacity with explosives, flown by radio control into bomb-resistant fortifications such as German U-boat pens and V-weapon sites, it was hoped that it would match the British success with Tallboy and Grand Slam ground penetration bombs but the project was dangerous and unsuccessful. Of 14 missions flown, none resulted in the successful destruction of a target. Many aircraft lost control and crashed or were shot down by flak, many pilots were killed. However, a handful of aircraft scored near misses. One notable pilot death was that of Lt Joseph P. Kennedy, Jr. USNR, the elder brother of future US President John F. Kennedy.
The program ceased on January 27, 1945 when General Spaatz sent an urgent message to Doolittle: "Aphrodite babies must not be launched against the enemy until further orders". By late 1943, General Henry H. Arnold had directed Brigadier General Grandison Gardner's electronic engineers at Eglin Field, Florida, to outfit war-weary bombers with automatic pilots so that they could be remotely controlled; the plan was first proposed to Major General Jimmy Doolittle some time in 1944. Doolittle approved the plan for Operation Aphrodite on June 26, assigned the 3rd Bombardment Division with preparing and flying the drone aircraft, to be designated BQ-7. In the U. S. Navy's similar project, Operation Anvil, the drone was designated BQ-8. Final assignment of responsibility was given to the 562nd Bomb Squadron at RAF Honington in Suffolk. On July 6, 1944, the U. S. Navy Special Attack Unit was formed under ComAirLant, with Commander James A. Smith, Officer in Charge, for transfer without delay to Commander Fleet Air Wing 7 in Europe to attack German V-1 and V-2 sites with PB4Y-1s converted to assault drones.
Old Boeing B-17 Flying Fortress bombers were stripped of all normal combat armament and all other non-essential gear, relieving about 12,000 lb of weight. To allow easier exit when the pilot and co-pilot were to parachute out, the canopy was removed. Azon radio remote-control equipment was added, with two television cameras fitted in the cockpit to allow a view of both the ground and the main instrumentation panel to be transmitted back to an accompanying CQ-17'mothership'; the drone was loaded with explosives weighing more than twice that of a B-17's normal bomb payload. The British Torpex used for the purpose was itself 50% more powerful than TNT. A remote location in Norfolk, RAF Fersfield, was the launch site. RAF Woodbridge had been selected for its long runway, but the possibility of a damaged aircraft that diverted to Woodbridge for landings colliding with a loaded drone caused concerns; the remote control system was insufficient for safe takeoff, so each drone was taken aloft by a volunteer pilot and a volunteer flight engineer to an altitude of 2,000 ft for transfer of control to the CQ-17 operators.
After successful turnover of control of the drone, the two-man crew would arm the payload and parachute out of the cockpit. The'mothership' would direct the missile to the target; when the training program was complete, the 562nd Squadron had ten drones and four "motherships". Mistel Joseph P. Kennedy, Jr. Notes Further reading Gray, Edwin. Operation Aphrodite's B-17 "Smart Bomb". Aviation History
Beeswax is a natural wax produced by honey bees of the genus Apis. The wax is formed into scales by eight wax-producing glands in the abdominal segments of worker bees, which discard it in or at the hive; the hive workers collect and use it to form cells for honey storage and larval and pupal protection within the beehive. Chemically, beeswax consists of esters of fatty acids and various long-chain alcohols. Beeswax has been used since prehistory as the first plastic, as a lubricant and waterproofing agent, in lost wax casting of metals and glass, as a polish for wood and leather and for making candles, as an ingredient in cosmetics and as an artistic medium in encaustic painting. Beeswax is edible, having similar negligible toxicity to plant waxes, is approved for food use in most countries and in the European Union under the E number E901; the wax is formed by worker bees, which secrete it from eight wax-producing mirror glands on the inner sides of the sternites on abdominal segments 4 to 7.
The sizes of these wax glands depend on the age of the worker, after many daily flights, these glands begin to atrophy. The new wax is glass-clear and colorless, becoming opaque after mastication and adulteration with pollen by the hive worker bees, becoming progressively more yellow or brown by incorporation of pollen oils and propolis; the wax scales are about three millimetres across and 0.1 mm thick, about 1100 are required to make a gram of wax. Honey bees use the beeswax to build honeycomb cells in which their young are raised with honey and pollen cells being capped for storage. For the wax-making bees to secrete wax, the ambient temperature in the hive must be 33 to 36 °C; the amount of honey used by bees to produce wax has not been determined. The book, Beeswax Production, Harvesting and Products, suggests one kilogram of beeswax is used to store 22 kg honey. According to Whitcomb's 1946 experiment, 6.66 to 8.80 kg of honey yields one kilogram of wax. Another study estimated; when beekeepers extract the honey, they cut off the wax caps from each honeycomb cell with an uncapping knife or machine.
Its color varies from nearly white to brownish, but most a shade of yellow, depending on purity, the region, the type of flowers gathered by the bees. Wax from the brood comb of the honey bee hive tends to be darker than wax from the honeycomb. Impurities accumulate more in the brood comb. Due to the impurities, the wax must be rendered before further use; the leftovers are called slumgum. The wax may be clarified further by heating in water; as with petroleum waxes, it may be softened by dilution with mineral oil or vegetable oil to make it more workable at room temperature. Beeswax is a tough wax formed from a mixture of several chemical compounds. An approximate chemical formula for beeswax is C15H31COOC30H61, its main constituents are palmitate and oleate esters of long-chain aliphatic alcohols, with the ratio of triacontanyl palmitate CH329O-CO-14CH3 to cerotic acid CH324COOH, the two principal constituents, being 6:1. Beeswax can be classified into European and Oriental types; the saponification value is lower for European beeswax, higher for Oriental types.
Beeswax has a low melting point range of 62 to 64 °C. If beeswax is heated above 85 °C discoloration occurs; the flash point of beeswax is 204.4 °C. Density at 15 °C is 958 to 970 kg/m³; when natural beeswax is cold, it is brittle, its fracture dry and granular. At room temperature it is tenacious and it softens further at human body temperature; the specific gravity at 15 °C is from 0.958 to 0.975, that of melted wax at 98 to 99 °C compared with water at 15.5 °C is 0.822. Candle-making has long involved the use of beeswax, flammable, this material was traditionally prescribed for the making of the Paschal candle or "Easter candle". Beeswax candles are purported to be superior to other wax candles, because they burn brighter and longer, do not bend, burn "cleaner", it is further recommended for the making of other candles used in the liturgy of the Roman Catholic Church. Beeswax is the candle constituent of choice in the Orthodox Church. Refined beeswax plays a prominent role in art materials both as a binder in encaustic paint and as a stabilizer in oil paint to add body.
Beeswax is an ingredient in surgical bone wax, used during surgery to control bleeding from bone surfaces. Beeswax blended with pine rosin is used for waxing, can serve as an adhesive to attach reed plates to the structure inside a squeezebox, it can be used to make Cutler's resin, an adhesive used to glue handles onto cutlery knives. It is used in Eastern Europe in egg decoration. Beeswax is used by percussionists to make a surface on tambourines for thumb rolls, it can be used as a metal injection moulding binder component along with other polymeric binder materials. Beeswax was used in the manufacture of phonograph cylinders, it may still be used to seal formal legal or royal decree and academic parchments such as placing an awarding stamp imprimatur of the university upon completion of pos
A phlegmatized explosive is an explosive that has had an agent added to stabilize or desensitize it. Sometimes this is desirable either to improve the handling properties of an explosive or to reduce its sensitivity, brisance or detonation velocity. TNT explosive can itself be used to phlegmatize more sensitive explosives such as RDX, HMX or PETN. Other typical phlegmatizing agents include paraffin wax, paper or water; such agents will at least boil off easily. A small amount of phlegmatizing agent is used e.g. Composition B, which has 1% paraffin wax added, or the Russian RGO hand grenade which contains 90 grams of "A-IX-1" explosive, comprising 96% RDX and 4% paraffin wax by weight. Another example of use is the VS-50 antipersonnel mine, which contains an explosive filling of 43 grams of RDX, again phlegmatized by combining it with 10% paraffin wax by weight. Explosive compounds may exist in material states. For instance, nitroglycerin is an oily liquid. Phlegmatization of nitroglycerin allows it to be formed as a solid known as dynamite.
It allows the liquid, sensitive to shock, to be handled more vigorously
Not to be confused with the barbiturate amytal. Amatol is a explosive material made from a mixture of TNT and ammonium nitrate; the British name originates from the words toluene. Similar mixtures were known as Schneiderite in France. Amatol was used extensively during World War I and World War II as an explosive in military weapons such as aircraft bombs, depth charges, naval mines, it was replaced with alternative explosives such as composition B, tritonal. Amatol exploits synergy between TNT and ammonium nitrate. TNT is deficient in oxygen. Oxygen deficiency causes black smoke residue from a pure TNT explosion; the oxygen surplus of ammonium nitrate increases the energy release of TNT during detonation. Depending on the ratio of ingredients used, amatol leaves a residue of white or grey smoke after detonation. Amatol has a lower explosive velocity and correspondingly lower brisance than TNT but is cheaper because of the lower cost of ammonium nitrate. Amatol allowed supplies of TNT to be expanded with little reduction in the destructive power of the final product, so long as the amount of TNT in the mixture did not fall below 60%.
Mixtures containing as little as 20% TNT were for less demanding uses. TNT is 50% deficient in oxygen. Amatol is oxygen balanced and is therefore more effective than pure TNT when exploding underground or underwater. RDX has a negative oxygen balance. Unsophisticated cannery equipment can be adapted to amatol production. TNT is heated with steam or hot water until it melts, acquiring the physical characteristics of a syrup; the correct weight ratio of powdered ammonium nitrate is added and mixed in. Whilst this mixture is still in a molten state, it is poured into empty bomb casings and allowed to cool and solidify; the lowest grades of amatol could not be produced by casting molten TNT. Instead, flaked TNT was mixed with powdered ammonium nitrate and compressed or extruded; the colour of amatol ranges from off-white to yellow or pinkish brown, depending on the mixture used, remains soft for long periods of storage. It is hygroscopic, which complicates long-term storage. To prevent moisture problems, amatol charges were coated with a thin layer of pure molten TNT or alternatively bitumen.
Long-term storage was rare during wars because munitions charged with amatol were used soon after manufacture. Amatol should not be stored in containers made from copper or brass, as it can form unstable compounds sensitive to vibration. Pressed, it is insensitive but may be detonated by severe impact, whereas when cast, it is insensitive. Primary explosives such as mercury fulminate were used as a detonator, in combination with an explosive booster charge such as tetryl; the explosive charges hidden in HMS Campbeltown during the St. Nazaire Raid of 1942 contained amatol; the British X class midget submarines which planted explosive charges beneath the German battleship Tirpitz in September 1943 carried two "saddle charges" containing four tons of amatol. Warheads for the German V-1 flying bomb and V-2 rockets contained amatol. A derivative of amatol is amatex, consisting of 51% ammonium nitrate, 40% TNT, 9% RDX. Amatol is rare today, except in unexploded ordnance. A form of amatol exists under a different name — ammonite.
Ammonite is a civilian explosive comprising a 20/80 mixture of TNT and ammonium nitrate. It is used for quarrying or mining purposes, it is a popular civil engineering explosive in Eastern China. Because the proportion of TNT is lower than in its military counterpart, ammonite has much less destructive power. In general, a 30 kilogram charge of ammonite is equivalent to 20 kilograms of TNT. Amatol was the name given to a munitions factory and planned community built by the United States government in Mullica Township, New Jersey during World War I. After the war, the town was dismantled; the Atlantic City Speedway was built on part of the Amatol site in 1926. Ammonal Minol Hexanite RE factor "Amatol". A former World War I munitions factory, located in Mullica Township, NJ. Retrieved 2006-05-14
Hydrogen is a chemical element with symbol H and atomic number 1. With a standard atomic weight of 1.008, hydrogen is the lightest element in the periodic table. Hydrogen is the most abundant chemical substance in the Universe, constituting 75% of all baryonic mass. Non-remnant stars are composed of hydrogen in the plasma state; the most common isotope of hydrogen, termed protium, has no neutrons. The universal emergence of atomic hydrogen first occurred during the recombination epoch. At standard temperature and pressure, hydrogen is a colorless, tasteless, non-toxic, nonmetallic combustible diatomic gas with the molecular formula H2. Since hydrogen forms covalent compounds with most nonmetallic elements, most of the hydrogen on Earth exists in molecular forms such as water or organic compounds. Hydrogen plays a important role in acid–base reactions because most acid-base reactions involve the exchange of protons between soluble molecules. In ionic compounds, hydrogen can take the form of a negative charge when it is known as a hydride, or as a positively charged species denoted by the symbol H+.
The hydrogen cation is written as though composed of a bare proton, but in reality, hydrogen cations in ionic compounds are always more complex. As the only neutral atom for which the Schrödinger equation can be solved analytically, study of the energetics and bonding of the hydrogen atom has played a key role in the development of quantum mechanics. Hydrogen gas was first artificially produced in the early 16th century by the reaction of acids on metals. In 1766–81, Henry Cavendish was the first to recognize that hydrogen gas was a discrete substance, that it produces water when burned, the property for which it was named: in Greek, hydrogen means "water-former". Industrial production is from steam reforming natural gas, less from more energy-intensive methods such as the electrolysis of water. Most hydrogen is used near the site of its production, the two largest uses being fossil fuel processing and ammonia production for the fertilizer market. Hydrogen is a concern in metallurgy as it can embrittle many metals, complicating the design of pipelines and storage tanks.
Hydrogen gas is flammable and will burn in air at a wide range of concentrations between 4% and 75% by volume. The enthalpy of combustion is −286 kJ/mol: 2 H2 + O2 → 2 H2O + 572 kJ Hydrogen gas forms explosive mixtures with air in concentrations from 4–74% and with chlorine at 5–95%; the explosive reactions may be triggered by heat, or sunlight. The hydrogen autoignition temperature, the temperature of spontaneous ignition in air, is 500 °C. Pure hydrogen-oxygen flames emit ultraviolet light and with high oxygen mix are nearly invisible to the naked eye, as illustrated by the faint plume of the Space Shuttle Main Engine, compared to the visible plume of a Space Shuttle Solid Rocket Booster, which uses an ammonium perchlorate composite; the detection of a burning hydrogen leak may require a flame detector. Hydrogen flames in other conditions are blue; the destruction of the Hindenburg airship was a notorious example of hydrogen combustion and the cause is still debated. The visible orange flames in that incident were the result of a rich mixture of hydrogen to oxygen combined with carbon compounds from the airship skin.
H2 reacts with every oxidizing element. Hydrogen can react spontaneously and violently at room temperature with chlorine and fluorine to form the corresponding hydrogen halides, hydrogen chloride and hydrogen fluoride, which are potentially dangerous acids; the ground state energy level of the electron in a hydrogen atom is −13.6 eV, equivalent to an ultraviolet photon of 91 nm wavelength. The energy levels of hydrogen can be calculated accurately using the Bohr model of the atom, which conceptualizes the electron as "orbiting" the proton in analogy to the Earth's orbit of the Sun. However, the atomic electron and proton are held together by electromagnetic force, while planets and celestial objects are held by gravity; because of the discretization of angular momentum postulated in early quantum mechanics by Bohr, the electron in the Bohr model can only occupy certain allowed distances from the proton, therefore only certain allowed energies. A more accurate description of the hydrogen atom comes from a purely quantum mechanical treatment that uses the Schrödinger equation, Dirac equation or the Feynman path integral formulation to calculate the probability density of the electron around the proton.
The most complicated treatments allow for the small effects of special relativity and vacuum polarization. In the quantum mechanical treatment, the electron in a ground state hydrogen atom has no angular momentum at all—illustrating how the "planetary orbit" differs from electron motion. There exist two different spin isomers of hydrogen diatomic molecules that differ by the relative spin of their nuclei. In the orthohydrogen form, the spins of the two protons are parallel and form a triplet state with a molecular spin quantum number of 1. At standard temperature and pressure, hydrogen gas contains about 25% of the para form and 75% of the ortho form known as the "normal form"; the equilibrium ratio of orthohydrogen to parahydrogen depends on temperature, but because the ortho form is an excited state and has a higher energy
A powder is a dry, bulk solid composed of a large number of fine particles that may flow when shaken or tilted. Powders are a special sub-class of granular materials, although the terms powder and granular are sometimes used to distinguish separate classes of material. In particular, powders refer to those granular materials that have the finer grain sizes, that therefore have a greater tendency to form clumps when flowing. Granulars refers to the coarser granular materials. Many manufactured goods come in powder form, such as flour, ground coffee, powdered milk, copy machine toner, cosmetic powders, some pharmaceuticals. In nature, fine sand and snow, volcanic ash, the top layer of the lunar regolith are examples; because of their importance to industry and earth science, powders have been studied in great detail by chemical engineers, mechanical engineers, physicists and researchers in other disciplines. A powder can be compacted or loosened into a vastly larger range of bulk densities than can a coarser granular material.
When deposited by sprinkling, a powder may be light and fluffy. When vibrated or compressed it may become dense and lose its ability to flow; the bulk density of coarse sand, on the other hand, does not vary over an appreciable range. The clumping behavior of a powder arises because of the molecular Van der Waals force that causes individual grains to cling to one another; this force is present not just in sand and gravel, too. However, in such coarse granular materials the weight and the inertia of the individual grains are much larger than the weak Van der Waals forces, therefore the tiny clinging between grains does not have a dominant effect on the bulk behavior of the material. Only when the grains are small and lightweight does the Van der Waals force become predominant, causing the material to clump like a powder; the cross-over size between flow conditions and stick conditions can be determined by simple experimentation. Many other powder behaviors are common to all granular materials.
These include segregation, stratification and unjamming, loss of kinetic energy, frictional shearing and Reynolds' dilatancy. Powders are transported in the atmosphere differently from a coarse granular material. For one thing, tiny particles have little inertia compared to the drag force of the gas that surrounds them, so they tend to go with the flow instead of traveling in straight lines. For this reason, powders may be an inhalation hazard. Larger particles cannot weave through the body's defenses in the nose and sinus, but will strike and stick to the mucous membranes; the body moves the mucous out of the body to expel the particles. The smaller particles on the other hand can travel all the way to the lungs from which they cannot be expelled. Serious and sometimes fatal diseases such as silicosis are a result from working with certain powders without adequate respiratory protection. If powder particles are sufficiently small, they may become suspended in the atmosphere for a long time. Random motion of the air molecules and turbulence provide upward forces that may counteract the downward force of gravity.
Coarse granulars, on the other hand, are so heavy that they fall back to the ground. Once disturbed, dust may form huge dust storms that cross continents and oceans before settling back to the surface; this explains why there is little hazardous dust in the natural environment. Once aloft, the dust is likely to stay aloft until it meets water in the form of rain or a body of water, it sticks and is washed downstream to settle as mud deposits in a quiet lake or sea. When geological changes re-expose these deposits to the atmosphere, they may have cemented together to become mudstone, a type of rock. For comparison, the Moon has neither wind nor water, so its regolith contains dust but no mudstone; the cohesive forces between the particles tend to resist their becoming airborne, the motion of wind across the surface is less to disturb a low-lying dust particle than a larger sand grain that protrudes higher into the wind. Mechanical agitation such as vehicle traffic, digging or passing herds of animals is more effective than a steady wind at stirring up a powder.
The aerodynamic properties of powders are used to transport them in industrial applications. Pneumatic conveying is the transport of grains through a pipe by blowing gas. A gas fluidized bed is a container filled with a powder or granular substance, fluffed up by blowing gas upwardly through it; this is used for fluidized bed combustion, chemically reacting the gas with the powder.' Some powders may be dustier than others. The tendency of a powder to generate particles in the air under a given energy input is called "dustiness", it is an important powder property, relevant to powder aerosolization process. It has indications for human exposure to aerosolized particles and associated health risks at workplaces. Various dustiness testing methods have been established in research laboratories, in order to predict powder behaviors during aerosolization; these methods allow application of a wide range of energy inputs to powdered materials, which simulates different real-life scenarios. Many common powders made in industry are combustible.
Since powders have a high surface area, they can combust with explosive force once ignited. Facilities such as flour mills can be vulnerable to such explosions without proper dust mitigation efforts; some metals become dange