Related media at Wikimedia Commons:
137-537: A self-contained breathing apparatus ( SCBA ) is a respirator worn to provide an autonomous supply of breathable gas in an atmosphere that is immediately dangerous to life or health from a gas cylinder . They are typically used in firefighting and industry. The term self-contained means that the SCBA is not dependent on a remote supply of breathing gas (e.g., through a long hose). They are sometimes called industrial breathing sets . Some types are also referred to as
274-446: A cascade storage system or from an air compressor brought to the scene. Escape SCBAs, also known as ESCBAs, come with hoods, are meant for escapes only, and are operated in continuous flow mode. Escape only SCBAs, designed for escape from IDLH situations, regardless of type, are usually limited to 3-10 minutes. 42 CFR 84 replaces the 30 CFR 11 respirator regulation used by NIOSH . As of 2001, quality assurance of SCBA harnesses
411-518: A compressed air breathing apparatus ( CABA ) or simply breathing apparatus ( BA ). Unofficial names include air pack , air tank , oxygen cylinder or simply pack , terms used mostly in firefighting . If designed for use under water, it is also known as a scuba set (self-contained underwater breathing apparatus). An open circuit SCBA typically has three main components: a high-pressure gas storage cylinder, (e.g., 2,216 to 5,500 psi (15,280 to 37,920 kPa ), about 150 to 374 atmospheres),
548-491: A precipitate of aluminium hydroxide , Al(OH) 3 , forms. This is useful for clarification of water, as the precipitate nucleates on suspended particles in the water, hence removing them. Increasing the pH even further leads to the hydroxide dissolving again as aluminate , [Al(H 2 O) 2 (OH) 4 ] , is formed. Aluminium hydroxide forms both salts and aluminates and dissolves in acid and alkali, as well as on fusion with acidic and basic oxides. This behavior of Al(OH) 3
685-525: A "less classical sound". This name persisted: although the -um spelling was occasionally used in Britain, the American scientific language used -ium from the start. Most scientists throughout the world used -ium in the 19th century; and it was entrenched in several other European languages, such as French , German , and Dutch . In 1828, an American lexicographer, Noah Webster , entered only
822-499: A Swedish chemist, Jöns Jacob Berzelius , in which the name aluminium is given to the element that would be synthesized from alum. (Another article in the same journal issue also refers to the metal whose oxide is the basis of sapphire , i.e. the same metal, as to aluminium .) A January 1811 summary of one of Davy's lectures at the Royal Society mentioned the name aluminium as a possibility. The next year, Davy published
959-645: A certification program for SCBA that are intended to be used in chemical, biological, radiological, and nuclear (CBRN) environments. Any SCBA supplied for use in Europe must comply with the requirements of the Personal Protective Equipment Directive (89/686/EEC). In practice this usually means that the SCBA must comply with the requirements of the European Standard EN 137:2006. This includes detailed requirements for
1096-561: A chemistry textbook in which he used the spelling aluminum . Both spellings have coexisted since. Their usage is currently regional: aluminum dominates in the United States and Canada; aluminium is prevalent in the rest of the English-speaking world. In 1812, British scientist Thomas Young wrote an anonymous review of Davy's book, in which he proposed the name aluminium instead of aluminum , which he thought had
1233-469: A device that 'permitted respiration in places where the atmosphere is charged with noxious gases, or vapors, smoke, or other impurities.' In the late 19th century, Miles Philips began using a "mundebinde" ("mouth bandage") of sterilized cloth which he refined by adapting a chloroform mask with two layers of cotton mull. In the winter of 1910, Wu was given instructions from the Foreign Office of
1370-522: A finely woven cloth dipped in water could protect sailors from a toxic weapon made of powder that he had designed. Alexander von Humboldt introduced a primitive respirator in 1799 when he worked as a mining engineer in Prussia. Julius Jeffreys first used the word "respirator" as a mask in 1836. In 1848, the first US patent for an air-purifying respirator was granted to Lewis P. Haslett for his 'Haslett's Lung Protector,' which filtered dust from
1507-530: A framed carrying harness. Escape SCBAs, also known as ESCBAs, come with hoods, are meant for escapes only, and are operated in continuous flow mode. A self-contained self-rescue device , SCSR, self-contained self-rescuer, or air pack is a type of closed-circuit SCBA with a portable oxygen source for providing breathable air when the surrounding atmosphere lacks oxygen or is contaminated with toxic gases, e.g. carbon monoxide . Self-rescuers are intended for use in environments such as coal mines where there
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#17327764102331644-479: A great affinity towards oxygen , forming a protective layer of oxide on the surface when exposed to air. Aluminium visually resembles silver , both in its color and in its great ability to reflect light. It is soft, nonmagnetic , and ductile . It has one stable isotope, Al, which is highly abundant, making aluminium the twelfth-most common element in the universe. The radioactivity of Al leads to it being used in radiometric dating . Chemically, aluminium
1781-484: A line of flow in the airstream come within one radius of a fiber and adhere to it; impaction , when larger particles unable to follow the curving contours of the airstream are forced to embed in one of the fibers directly; this increases with diminishing fiber separation and higher air flow velocity; by diffusion , where gas molecules collide with the smallest particles, especially those below 100 nm in diameter, which are thereby impeded and delayed in their path through
1918-697: A mask, and may use a bite-grip mouthpiece and nose clip instead. Alternatively, an escape respirator could be a time-limited self-contained breathing apparatus . For hazardous environments, like confined spaces , atmosphere-supplying respirators, like SCBAs , should be used. A wide range of industries use respirators including healthcare & pharmaceuticals, defense & public safety services (defense, firefighting & law enforcement), oil and gas industries, manufacturing (automotive, chemical, metal fabrication, food and beverage, wood working, paper and pulp), mining, construction, agriculture and forestry, cement production, power generation, painting, shipbuilding, and
2055-413: A pressure regulator, and a respiratory interface, which may be a mouthpiece, half mask or full-face mask, assembled and mounted on a framed carrying harness. A self-contained breathing apparatus may fall into one of three categories: open-circuit, closed-circuit, or continuous-flow. The closed-circuit type, also known as a rebreather, operates by filtering, supplementing, and recirculating exhaled gas. It
2192-441: A probable cause for it being soft with a low melting point and low electrical resistivity . Aluminium metal has an appearance ranging from silvery white to dull gray depending on its surface roughness . Aluminium mirrors are the most reflective of all metal mirrors for near ultraviolet and far infrared light. It is also one of the most reflective for light in the visible spectrum, nearly on par with silver in this respect, and
2329-683: A process termed passivation . Because of its general resistance to corrosion, aluminium is one of the few metals that retains silvery reflectance in finely powdered form, making it an important component of silver-colored paints. Aluminium is not attacked by oxidizing acids because of its passivation. This allows aluminium to be used to store reagents such as nitric acid , concentrated sulfuric acid , and some organic acids. In hot concentrated hydrochloric acid , aluminium reacts with water with evolution of hydrogen, and in aqueous sodium hydroxide or potassium hydroxide at room temperature to form aluminates —protective passivation under these conditions
2466-511: A pump or fan to constantly move air through a filter and supply purified air into a mask, helmet or hood. The history of protective respiratory equipment can be traced back as far as the first century, when Pliny the Elder ( c. 23 AD –79) described using animal bladder skins to protect workers in Roman mines from red lead oxide dust. In the 16th century, Leonardo da Vinci suggested that
2603-525: A refractory material, and in ceramics , as well as being the starting material for the electrolytic production of aluminium. Sapphire and ruby are impure corundum contaminated with trace amounts of other metals. The two main oxide-hydroxides, AlO(OH), are boehmite and diaspore . There are three main trihydroxides: bayerite , gibbsite , and nordstrandite , which differ in their crystalline structure ( polymorphs ). Many other intermediate and related structures are also known. Most are produced from ores by
2740-419: A respirator properly fits the face of someone who wears it. The fitting characteristic of a respirator is the ability of the mask to separate a worker's respiratory system from ambient air. A surgical mask is a loosely-placed, unsealed barrier, meant to stop droplets , and other liquid-borne particles from the mouth and nose that may contain pathogens . A surgical mask may not block all particles, due to
2877-582: A specific variant called a surgical respirator, which is both approved by NIOSH as a respirator and cleared by the Food and Drug Administration as a medical device similar to a surgical mask . These may also be labeled "Surgical N95", "medical respirators", or "healthcare respirators". The difference lies in the extra fluid-resistant layer outside, typically colored blue. In addition to 42 CFR 84, surgical N95s are regulated under FDA regulation 21 CFR 878.4040. Air-purifying respirators are respirators that draw in
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#17327764102333014-474: A stable noble gas configuration. Accordingly, the combined first three ionization energies of aluminium are far lower than the fourth ionization energy alone. Such an electron configuration is shared with the other well-characterized members of its group, boron , gallium , indium , and thallium ; it is also expected for nihonium . Aluminium can surrender its three outermost electrons in many chemical reactions (see below ). The electronegativity of aluminium
3151-469: A variety of industrial settings including mining , petrochemical , chemical , and nuclear industries . In some of the most hazardous conditions, SCBAs can be worn in conjunction with gas tight suits, which also aids in decontamination procedures. In the industrial setting, especially in confined spaces, a user will often be supplied air through a pressurized airline and will only carry compressed air cylinders for emergency escape and decontamination . In
3288-820: A variety of wet processes using acid and base. Heating the hydroxides leads to formation of corundum. These materials are of central importance to the production of aluminium and are themselves extremely useful. Some mixed oxide phases are also very useful, such as spinel (MgAl 2 O 4 ), Na-β-alumina (NaAl 11 O 17 ), and tricalcium aluminate (Ca 3 Al 2 O 6 , an important mineral phase in Portland cement ). The only stable chalcogenides under normal conditions are aluminium sulfide (Al 2 S 3 ), selenide (Al 2 Se 3 ), and telluride (Al 2 Te 3 ). All three are prepared by direct reaction of their elements at about 1,000 °C (1,800 °F) and quickly hydrolyze completely in water to yield aluminium hydroxide and
3425-575: A way of purifying bauxite to yield alumina, now known as the Bayer process , in 1889. Modern production of aluminium is based on the Bayer and Hall–Héroult processes. As large-scale production caused aluminium prices to drop, the metal became widely used in jewelry, eyeglass frames, optical instruments, tableware, and foil , and other everyday items in the 1890s and early 20th century. Aluminium's ability to form hard yet light alloys with other metals provided
3562-734: Is Al : while it was present along with stable Al in the interstellar medium from which the Solar System formed, having been produced by stellar nucleosynthesis as well, its half-life is only 717,000 years and therefore a detectable amount has not survived since the formation of the planet. However, minute traces of Al are produced from argon in the atmosphere by spallation caused by cosmic ray protons. The ratio of Al to Be has been used for radiodating of geological processes over 10 to 10 year time scales, in particular transport, deposition, sediment storage, burial times, and erosion. Most meteorite scientists believe that
3699-434: Is Al. Al was present in the early Solar System with abundance of 0.005% relative to Al but its half-life of 728,000 years is too short for any original nuclei to survive; Al is therefore extinct . Unlike for Al, hydrogen burning is the primary source of Al, with the nuclide emerging after a nucleus of Mg catches a free proton. However, the trace quantities of Al that do exist are the most common gamma ray emitter in
3836-407: Is paramagnetic and thus essentially unaffected by static magnetic fields. The high electrical conductivity, however, means that it is strongly affected by alternating magnetic fields through the induction of eddy currents . Aluminium combines characteristics of pre- and post-transition metals. Since it has few available electrons for metallic bonding, like its heavier group 13 congeners, it has
3973-483: Is 1.61 (Pauling scale). A free aluminium atom has a radius of 143 pm . With the three outermost electrons removed, the radius shrinks to 39 pm for a 4-coordinated atom or 53.5 pm for a 6-coordinated atom. At standard temperature and pressure , aluminium atoms (when not affected by atoms of other elements) form a face-centered cubic crystal system bound by metallic bonding provided by atoms' outermost electrons; hence aluminium (at these conditions)
4110-418: Is a post-transition metal in the boron group ; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state . The aluminium cation Al is small and highly charged ; as such, it has more polarizing power , and bonds formed by aluminium have a more covalent character. The strong affinity of aluminium for oxygen leads to the common occurrence of its oxides in nature. Aluminium
4247-548: Is a metal. This crystal system is shared by many other metals, such as lead and copper ; the size of a unit cell of aluminium is comparable to that of those other metals. The system, however, is not shared by the other members of its group: boron has ionization energies too high to allow metallization, thallium has a hexagonal close-packed structure, and gallium and indium have unusual structures that are not close-packed like those of aluminium and thallium. The few electrons that are available for metallic bonding in aluminium are
Self-contained breathing apparatus - Misplaced Pages Continue
4384-551: Is a risk of fire or explosion, and in a location where no external rescue may be available for some time – the wearer must make their own way to safety, or to some pre-equipped underground refuge. The main hazard here is from large quantities of carbon monoxide or whitedamp , often produced by an explosion of firedamp . In some industries, the hazard may be from anoxic asphyxia, or a lack of oxygen, rather than poisoning by something toxic. [REDACTED] Related media at Wikimedia Commons: The Hierarchy of Controls, noted as part of
4521-522: Is almost never found in the elemental state; instead it is found in oxides or silicates. Feldspars , the most common group of minerals in the Earth's crust, are aluminosilicates. Aluminium also occurs in the minerals beryl , cryolite , garnet , spinel , and turquoise . Impurities in Al 2 O 3 , such as chromium and iron , yield the gemstones ruby and sapphire , respectively. Native aluminium metal
4658-405: Is also easily machined and cast . Aluminium is an excellent thermal and electrical conductor , having around 60% the conductivity of copper , both thermal and electrical, while having only 30% of copper's density. Aluminium is capable of superconductivity , with a superconducting critical temperature of 1.2 kelvin and a critical magnetic field of about 100 gauss (10 milliteslas ). It
4795-404: Is also known as a scuba set (self-contained underwater breathing apparatus). An open circuit SCBA typically has three main components: a high-pressure gas storage cylinder, (e.g., 2,216 to 5,500 psi (15,280 to 37,920 kPa ), about 150 to 374 atmospheres), a pressure regulator, and a respiratory interface, which may be a mouthpiece, half mask or full-face mask, assembled and mounted on
4932-553: Is extremely rare and can only be found as a minor phase in low oxygen fugacity environments, such as the interiors of certain volcanoes. Native aluminium has been reported in cold seeps in the northeastern continental slope of the South China Sea . It is possible that these deposits resulted from bacterial reduction of tetrahydroxoaluminate Al(OH) 4 . Although aluminium is a common and widespread element, not all aluminium minerals are economically viable sources of
5069-438: Is found on Earth primarily in rocks in the crust , where it is the third-most abundant element , after oxygen and silicon , rather than in the mantle , and virtually never as the free metal . It is obtained industrially by mining bauxite , a sedimentary rock rich in aluminium minerals. The discovery of aluminium was announced in 1825 by Danish physicist Hans Christian Ørsted . The first industrial production of aluminium
5206-536: Is greatly reduced by aqueous salts, particularly in the presence of dissimilar metals. Aluminium reacts with most nonmetals upon heating, forming compounds such as aluminium nitride (AlN), aluminium sulfide (Al 2 S 3 ), and the aluminium halides (AlX 3 ). It also forms a wide range of intermetallic compounds involving metals from every group on the periodic table. The vast majority of compounds, including all aluminium-containing minerals and all commercially significant aluminium compounds, feature aluminium in
5343-492: Is in fact more basic than that of gallium. Aluminium also bears minor similarities to the metalloid boron in the same group: AlX 3 compounds are valence isoelectronic to BX 3 compounds (they have the same valence electronic structure), and both behave as Lewis acids and readily form adducts . Additionally, one of the main motifs of boron chemistry is regular icosahedral structures, and aluminium forms an important part of many icosahedral quasicrystal alloys, including
5480-500: Is negligible. Aqua regia also dissolves aluminium. Aluminium is corroded by dissolved chlorides , such as common sodium chloride , which is why household plumbing is never made from aluminium. The oxide layer on aluminium is also destroyed by contact with mercury due to amalgamation or with salts of some electropositive metals. As such, the strongest aluminium alloys are less corrosion-resistant due to galvanic reactions with alloyed copper , and aluminium's corrosion resistance
5617-521: Is not as important. It is a polymer with the formula (AlH 3 ) n , in contrast to the corresponding boron hydride that is a dimer with the formula (BH 3 ) 2 . Aluminium's per-particle abundance in the Solar System is 3.15 ppm (parts per million). It is the twelfth most abundant of all elements and third most abundant among the elements that have odd atomic numbers, after hydrogen and nitrogen. The only stable isotope of aluminium, Al,
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5754-420: Is not without cost. The weight of the unit and work of breathing affect the work capacity and agility of the wearer, and the full-face mask, while protecting the face and eyes from heat, smoke, and toxic gases, also reduces peripheral vision and awareness of the surroundings. The weight and harness straps may limit tidal volume, ventilation rate, and oxygen consumption, and heart rate may increase in comparison with
5891-416: Is quite soft and lacking in strength. In most applications various aluminium alloys are used instead because of their higher strength and hardness. The yield strength of pure aluminium is 7–11 MPa , while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium is ductile , with a percent elongation of 50-70%, and malleable allowing it to be easily drawn and extruded . It
6028-839: Is required. Labels have been updated to remove MSHA emblems from respirator labels, as MSHA is no longer involved in respirator approval except for respirators approved for mining. As a result, new SCBAs now have to specify whether the SCBA is "intended for mine use". SCBAs usually come with full-facepieces, but can also come with half-mask or mouthpiece in demand or pressure-demand mode, though use of mouthpieces are limited to escapes only, as of 1987. Hoods and helmets are limited to continuous flow mode only, and are also used in air-line respirators in addition to escape-only SCBAs. There are two major application areas for SCBA: firefighting , and industrial use in confined spaces. For SCBAs used in firefighting, manufacturers typically prioritize fire resistance and weight reduction over cost. SCBAs used by
6165-460: Is supplied at a rate which prevents ambient gas from reaching the nose or mouth during inhalation. Respirators can have half-face forms that cover the bottom half of the face including the nose and mouth, and full-face forms that cover the entire face. Half-face respirators are only effective in environments where the contaminants are not toxic to the eyes or facial area. An escape respirator may have no component that would normally be described as
6302-422: Is surrounded by six fluorine atoms in a distorted octahedral arrangement, with each fluorine atom being shared between the corners of two octahedra. Such {AlF 6 } units also exist in complex fluorides such as cryolite , Na 3 AlF 6 . AlF 3 melts at 1,290 °C (2,354 °F) and is made by reaction of aluminium oxide with hydrogen fluoride gas at 700 °C (1,300 °F). With heavier halides,
6439-547: Is termed amphoterism and is characteristic of weakly basic cations that form insoluble hydroxides and whose hydrated species can also donate their protons. One effect of this is that aluminium salts with weak acids are hydrolyzed in water to the aquated hydroxide and the corresponding nonmetal hydride: for example, aluminium sulfide yields hydrogen sulfide . However, some salts like aluminium carbonate exist in aqueous solution but are unstable as such; and only incomplete hydrolysis takes place for salts with strong acids, such as
6576-416: Is that of the preceding noble gas , whereas those of its heavier congeners gallium , indium , thallium , and nihonium also include a filled d-subshell and in some cases a filled f-subshell. Hence, the inner electrons of aluminium shield the valence electrons almost completely, unlike those of aluminium's heavier congeners. As such, aluminium is the most electropositive metal in its group, and its hydroxide
6713-433: Is the eighteenth most abundant nucleus in the universe. It is created almost entirely after fusion of carbon in massive stars that will later become Type II supernovas : this fusion creates Mg, which upon capturing free protons and neutrons, becomes aluminium. Some smaller quantities of Al are created in hydrogen burning shells of evolved stars, where Mg can capture free protons. Essentially all aluminium now in existence
6850-479: Is used when a longer-duration supply of breathing gas is needed, such as in mine rescue and in long tunnels , and going through passages too narrow for a big open-circuit air cylinder. Before open-circuit SCBA's were developed, most industrial breathing sets were rebreathers , such as the Siebe Gorman Proto , Siebe Gorman Savox , or Siebe Gorman Salvus . An example of modern rebreather SCBAs would be
6987-411: Is well tolerated by plants and animals. Because of the abundance of these salts, the potential for a biological role for them is of interest, and studies are ongoing. Of aluminium isotopes, only Al is stable. This situation is common for elements with an odd atomic number. It is the only primordial aluminium isotope, i.e. the only one that has existed on Earth in its current form since
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#17327764102337124-455: The Friedel–Crafts reactions . Aluminium trichloride has major industrial uses involving this reaction, such as in the manufacture of anthraquinones and styrene ; it is also often used as the precursor for many other aluminium compounds and as a reagent for converting nonmetal fluorides into the corresponding chlorides (a transhalogenation reaction ). Aluminium forms one stable oxide with
7261-475: The London Metal Exchange , the oldest industrial metal exchange in the world, in 1978. The output continued to grow: the annual production of aluminium exceeded 50,000,000 metric tons in 2013. The real price for aluminium declined from $ 14,000 per metric ton in 1900 to $ 2,340 in 1948 (in 1998 United States dollars). Extraction and processing costs were lowered over technological progress and
7398-600: The N95 respirator , which filters at least 95% of airborne particles but is not resistant to oil . Other categories filter 99% or 99.97% of particles, or have varying degrees of resistance to oil. In the European Union , European standard EN 143 defines the 'P' classes of particle filters that can be attached to a face mask, while European standard EN 149 defines classes of "filtering half masks" or "filtering facepieces", usually called FFP masks . According to 3M ,
7535-503: The Prevention Through Design initiative started by NIOSH with other standards bodies, is a set of guidelines emphasizing building in safety during design, as opposed to ad-hoc solutions like PPE, with multiple entities providing guidelines on how to implement safety during development outside of NIOSH-approved respirators. US Government entities currently and formerly involved in the regulation of respirators follow
7672-523: The SEFA . Duration of closed-circuit SCBAs is somewhere between 1-4 hours. A closed-circuit SCBA system is negative-pressure, increasing the risk of leaks. There are two types of closed-circuit SCBA according to NIOSH : To reduce pressure buildup from use, a pressure-relief valve with saliva trap is included. Closed-circuit SCBAs are also noticeably smaller than open-circuit ones. Self-contained self-rescue devices are also closed-circuit SCBAs, working on
7809-590: The air-purifying respirator , in which respirable air is obtained by filtering a contaminated atmosphere, and the air-supplied respirator , in which an alternate supply of breathable air is delivered. Within each category, different techniques are employed to reduce or eliminate noxious airborne contaminants. Air-purifying respirators range from relatively inexpensive, single-use, disposable face masks, known as filtering facepiece respirators , reusable models with replaceable cartridges called elastomeric respirators , to powered air-purifying respirators (PAPR), which use
7946-475: The aluminum spelling in his American Dictionary of the English Language . In the 1830s, the -um spelling gained usage in the United States; by the 1860s, it had become the more common spelling there outside science. In 1892, Hall used the -um spelling in his advertising handbill for his new electrolytic method of producing the metal, despite his constant use of the -ium spelling in all
8083-423: The chemical formula Al 2 O 3 , commonly called alumina . It can be found in nature in the mineral corundum , α-alumina; there is also a γ-alumina phase. Its crystalline form, corundum, is very hard ( Mohs hardness 9), has a high melting point of 2,045 °C (3,713 °F), has very low volatility, is chemically inert, and a good electrical insulator, it is often used in abrasives (such as toothpaste), as
8220-551: The interstellar gas ; if the original Al were still present, gamma ray maps of the Milky Way would be brighter. Overall, the Earth is about 1.59% aluminium by mass (seventh in abundance by mass). Aluminium occurs in greater proportion in the Earth's crust than in the universe at large. This is because aluminium easily forms the oxide and becomes bound into rocks and stays in the Earth's crust , while less reactive metals sink to
8357-526: The 5th century BCE. The ancients are known to have used alum as a dyeing mordant and for city defense. After the Crusades , alum, an indispensable good in the European fabric industry, was a subject of international commerce; it was imported to Europe from the eastern Mediterranean until the mid-15th century. The nature of alum remained unknown. Around 1530, Swiss physician Paracelsus suggested alum
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#17327764102338494-472: The Al–Zn–Mg class. Aluminium has a high chemical affinity to oxygen, which renders it suitable for use as a reducing agent in the thermite reaction. A fine powder of aluminium reacts explosively on contact with liquid oxygen ; under normal conditions, however, aluminium forms a thin oxide layer (~5 nm at room temperature) that protects the metal from further corrosion by oxygen, water, or dilute acid,
8631-555: The Chinese KN95, Australian / New Zealand P2, Korean 1st Class also referred to as KF94, and Japanese DS. Chemical cartridges and gas mask canisters remove gases, volatile organic compounds (VOCs), and other vapors from breathing air by adsorption , absorption , or chemisorption . A typical organic vapor respirator cartridge is a metal or plastic case containing from 25 to 40 grams of sorption media such as activated charcoal or certain resins . The service life of
8768-475: The Hierarchy of Controls, including OSHA and MSHA . However, some HOC implementations, notably MSHA's, have been criticized for allowing mining operators to skirt engineering control noncompliance by requiring miners to wear respirators instead if the permissible exposure limit (PEL) is exceeded, without work stoppages, breaking the hierarchy of engineering controls. Another concern was fraud related to
8905-565: The Imperial Qing court in Peking, to travel to Harbin to investigate an unknown disease that killed 99.9% of its victims. This was the beginning of the large pneumonic plague epidemic of Manchuria and Mongolia, which ultimately claimed 60,000 lives. The First World War brought about the first need for mass-produced gas masks on both sides because of extensive use of chemical weapons . The German army successfully used poison gas for
9042-482: The N95 standard, were enforced under a three-year transition period, ending on July 10, 1998. The standard for N95 respirators includes, but is not limited to, a filtration of at least 95% under a 0.3 micrometer 200 milligram test load of sodium chloride . Standards and specifications are also subject to change. Once 42 CFR 84 was in effect, MSHA, under a proposed rule change to 30 CFR 11, 70, and 71, would withdraw from
9179-506: The NIOSH Respirator Selection Logic, air-purifying respirators are recommended for concentrations of hazardous particulates or gases that are greater than the relevant occupational exposure limit but less than the immediately dangerous to life or health level and the manufacturer's maximum use concentration, subject to the respirator having a sufficient assigned protection factor . For substances hazardous to
9316-418: The SCBA is not dependent on a remote supply of breathing gas (e.g., through a long hose). They are sometimes called industrial breathing sets. Some types are also referred to as a compressed air breathing apparatus (CABA) or simply breathing apparatus (BA). Unofficial names include air pack , air tank , oxygen cylinder or simply pack , terms used mostly in firefighting . If designed for use under water, it
9453-585: The United States and Canada, SCBAs used in firefighting must meet guidelines established by the National Fire Protection Association , NFPA Standard 1981. If an SCBA is labeled as "1981 NFPA compliant", it is designed for firefighting. The current version of the standard was published in 2018. These standards are revised every five years. Similarly, the National Institute for Occupational Safety and Health (NIOSH) has
9590-418: The United States dollar, and alumina prices. The BRIC countries' combined share in primary production and primary consumption grew substantially in the first decade of the 21st century. China is accumulating an especially large share of the world's production thanks to an abundance of resources, cheap energy, and governmental stimuli; it also increased its consumption share from 2% in 1972 to 40% in 2010. In
9727-514: The United States, Western Europe, and Japan, most aluminium was consumed in transportation, engineering, construction, and packaging. In 2021, prices for industrial metals such as aluminium have soared to near-record levels as energy shortages in China drive up costs for electricity. The names aluminium and aluminum are derived from the word alumine , an obsolete term for alumina , the primary naturally occurring oxide of aluminium . Alumine
9864-607: The actual usable time of the SCBA. Air cylinders are made of aluminium , steel , or of a composite construction (usually glass or carbon-fiber wrapped.) The composite cylinders are the lightest in weight and are therefore preferred by fire departments (UK: fire and rescue services previously called fire brigades ), but they also have the shortest lifespan and must be taken out of service after 15 years. Air cylinders must be hydrostatically tested every 5 years. During extended operations, empty air cylinders can be quickly replaced with fresh ones and then refilled from larger tanks in
10001-439: The air using one-way clapper valves and a filter made of moistened wool or a similar porous substance. Hutson Hurd patented a cup-shaped mask in 1879 which became widespread in industrial use. Inventors in Europe included John Stenhouse , a Scottish chemist, who investigated the power of charcoal in its various forms, to capture and hold large volumes of gas. He built one of the first respirators able to remove toxic gases from
10138-494: The air, paving the way for activated charcoal to become the most widely used filter for respirators. Irish physicist John Tyndall took Stenhouse's mask, added a filter of cotton wool saturated with lime , glycerin , and charcoal, and in 1871 invented a 'fireman's respirator', a hood that filtered smoke and gas from air, which he exhibited at a meeting of the Royal Society in London in 1874. Also in 1874, Samuel Barton patented
10275-509: The airways through the inlet valves (negative pressure check) or exhalation valves (positive pressure check) while observing the flexing of the respirator or air leakage. Manufacturers have different methods for performing seal checks and wearers should consult the specific instructions for the model of respirator they are wearing. Some models of respirators or filter cartridges have special buttons or other mechanisms built into them to facilitate seal checks. A respirator fit test checks whether
10412-578: The aluminium atoms have tetrahedral four-coordination and the other half have trigonal bipyramidal five-coordination. Four pnictides – aluminium nitride (AlN), aluminium phosphide (AlP), aluminium arsenide (AlAs), and aluminium antimonide (AlSb) – are known. They are all III-V semiconductors isoelectronic to silicon and germanium , all of which but AlN have the zinc blende structure. All four can be made by high-temperature (and possibly high-pressure) direct reaction of their component elements. Aluminium alloys well with most other metals (with
10549-525: The approval process of rated respirators (outside of respirators used for mining). China normally makes 10 million masks per day, about half of the world production. During the COVID-19 pandemic , 2,500 factories were converted to produce 116 million daily. During the COVID-19 pandemic, people in the United States, and in a lot of countries in the world, were urged to make their own cloth masks due to
10686-404: The cartridge varies based, among other variables, on the carbon weight and molecular weight of the vapor and the cartridge media, the concentration of vapor in the atmosphere, the relative humidity of the atmosphere, and the breathing rate of the respirator wearer. When filter cartridges become saturated or particulate accumulation within them begins to restrict air flow, they must be changed. If
10823-436: The characteristic physical properties of a post-transition metal, with longer-than-expected interatomic distances. Furthermore, as Al is a small and highly charged cation, it is strongly polarizing and bonding in aluminium compounds tends towards covalency ; this behavior is similar to that of beryllium (Be ), and the two display an example of a diagonal relationship . The underlying core under aluminium's valence shell
10960-597: The concentration of harmful gases is immediately dangerous to life or health , in workplaces covered by the Occupational Safety and Health Act the US Occupational Safety and Health Administration specifies the use of air-supplied respirators except when intended solely for escape during emergencies. NIOSH also discourages their use under such conditions. Elastomeric respirators , also called reusable air-purifying respirators, seal to
11097-419: The coordination numbers are lower. The other trihalides are dimeric or polymeric with tetrahedral four-coordinate aluminium centers. Aluminium trichloride (AlCl 3 ) has a layered polymeric structure below its melting point of 192.4 °C (378 °F) but transforms on melting to Al 2 Cl 6 dimers. At higher temperatures those increasingly dissociate into trigonal planar AlCl 3 monomers similar to
11234-428: The core. In the Earth's crust, aluminium is the most abundant metallic element (8.23% by mass ) and the third most abundant of all elements (after oxygen and silicon). A large number of silicates in the Earth's crust contain aluminium. In contrast, the Earth's mantle is only 2.38% aluminium by mass. Aluminium also occurs in seawater at a concentration of 2 μg/kg. Because of its strong affinity for oxygen, aluminium
11371-414: The cylinder can be calculated from the volume, pressure and breathing rate of the user. The formula: volume (in liters) × pressure (in bars) / 40 (litres per minute) - 10 minutes (the 10 minutes is a safety margin, or reserve), so a 6-liter cylinder, of 300 bar, is 6 × 300 / 40 - 10 = 35 minutes working duration. The fitness and level of exertion of the wearer affect breathing rate, and result in variations of
11508-497: The energy released by the decay of Al was responsible for the melting and differentiation of some asteroids after their formation 4.55 billion years ago. The remaining isotopes of aluminium, with mass numbers ranging from 21 to 43, all have half-lives well under an hour. Three metastable states are known, all with half-lives under a minute. An aluminium atom has 13 electrons, arranged in an electron configuration of [ Ne ] 3s 3p , with three electrons beyond
11645-478: The exception of most alkali metals and group 13 metals) and over 150 intermetallics with other metals are known. Preparation involves heating fixed metals together in certain proportion, followed by gradual cooling and annealing . Bonding in them is predominantly metallic and the crystal structure primarily depends on efficiency of packing. There are few compounds with lower oxidation states. A few aluminium(I) compounds exist: AlF, AlCl, AlBr, and AlI exist in
11782-408: The eyes, a respirator equipped with a full facepiece, helmet, or hood is recommended. Air-purifying respirators are not effective during firefighting , in oxygen-deficient atmosphere , or in an unknown atmosphere; in these situations a self-contained breathing apparatus is recommended instead. Mechanical filters remove contaminants from air in several ways: interception when particles following
11919-477: The face or leaks around the skirt, the demand valve will free-flow. An open-circuit rescue or firefighting SCBA has a full-face mask , also called the face-piece, a demand regulator , air cylinder, pressure gauge, (sometimes with an integrated PASS device ), and a harness with adjustable shoulder straps and waist belt which lets it be worn on the back. The air cylinder is commonly 4 liter, 6 liter, or 6.8 liter, but other sizes are also available. The endurance of
12056-399: The face with elastomeric material, which may be a natural or synthetic rubber . They are generally reusable. Full-face versions of elastomeric respirators seal better and protect the eyes. These respirators do not purify the ambient air, but supply breathing gas from another source. The three types are the self contained breathing apparatus, in which a compressed air cylinder is worn by
12193-520: The fact that its nuclei are much lighter, while difference in the unit cell size does not compensate for this difference. The only lighter metals are the metals of groups 1 and 2 , which apart from beryllium and magnesium are too reactive for structural use (and beryllium is very toxic). Aluminium is not as strong or stiff as steel, but the low density makes up for this in the aerospace industry and for many other applications where light weight and relatively high strength are crucial. Pure aluminium
12330-555: The filter, increasing the probability that particles will be stopped by either of the previous two mechanisms; and by using an electrostatic charge that attracts and holds particles on the filter surface. There are many different filtration standards that vary by jurisdiction. In the United States , the National Institute for Occupational Safety and Health defines the categories of particulate filters according to their NIOSH air filtration rating . The most common of these are
12467-441: The filtering media in respirators made according to the following standards are similar to U.S. N95 or European FFP2 respirators, however, the construction of the respirators themselves, such as providing a proper seal to the face, varies considerably. (For example, US NIOSH -approved respirators never include earloops because they don't provide enough support to establish a reliable, airtight seal.) Standards for respirator filtration
12604-495: The fire service also incorporate other features such as a PASS (personal alert safety system), which is a device that emits a loud alarm should the firefighter manually activate it or remain motionless for a certain amount of time. Other features may include Bluetooth connection to voice amplifiers or portable radios, digital heads-up displays, built-in infrared cameras , ePAR (electronic personal accountability report) system, point of view video recording, and digital screens allowing
12741-530: The firefighter to more easily check their air supply. Every SCBA used in the fire service also comes with a vibralert system which alerts the firefighter as they get low on air and a UAC (universal air connection), which allows the firefighter to give or receive air to other SCBAs through a trans-fill line by equalizing the pressure in both SCBA cylinders. Some SCBAs also come with a buddy-breather setup which allows both firefighters to connect their SCBAs and breathe while connected to each other. SCBAs are also used in
12878-574: The first time against Allied troops at the Second Battle of Ypres , Belgium on April 22, 1915. An immediate response was cotton wool wrapped in muslin, issued to the troops by May 1. This was followed by the Black Veil Respirator , invented by John Scott Haldane , which was a cotton pad soaked in an absorbent solution which was secured over the mouth using black cotton veiling. Prior to the 1970s, respirator standards were under
13015-442: The formation of the planet. It is therefore a mononuclidic element and its standard atomic weight is virtually the same as that of the isotope. This makes aluminium very useful in nuclear magnetic resonance (NMR), as its single stable isotope has a high NMR sensitivity. The standard atomic weight of aluminium is low in comparison with many other metals. All other isotopes of aluminium are radioactive . The most stable of these
13152-730: The gas phase after explosion and in stellar absorption spectra. More thoroughly investigated are compounds of the formula R 4 Al 2 which contain an Al–Al bond and where R is a large organic ligand . A variety of compounds of empirical formula AlR 3 and AlR 1.5 Cl 1.5 exist. The aluminium trialkyls and triaryls are reactive, volatile, and colorless liquids or low-melting solids. They catch fire spontaneously in air and react with water, thus necessitating precautions when handling them. They often form dimers, unlike their boron analogues, but this tendency diminishes for branched-chain alkyls (e.g. Pr , Bu , Me 3 CCH 2 ); for example, triisobutylaluminium exists as an equilibrium mixture of
13289-453: The gaseous phase when the respective trihalide is heated with aluminium, and at cryogenic temperatures. A stable derivative of aluminium monoiodide is the cyclic adduct formed with triethylamine , Al 4 I 4 (NEt 3 ) 4 . Al 2 O and Al 2 S also exist but are very unstable. Very simple aluminium(II) compounds are invoked or observed in the reactions of Al metal with oxidants. For example, aluminium monoxide , AlO, has been detected in
13426-646: The halides, nitrate , and sulfate . For similar reasons, anhydrous aluminium salts cannot be made by heating their "hydrates": hydrated aluminium chloride is in fact not AlCl 3 ·6H 2 O but [Al(H 2 O) 6 ]Cl 3 , and the Al–O bonds are so strong that heating is not sufficient to break them and form Al–Cl bonds instead: All four trihalides are well known. Unlike the structures of the three heavier trihalides, aluminium fluoride (AlF 3 ) features six-coordinate aluminium, which explains its involatility and insolubility as well as high heat of formation . Each aluminium atom
13563-416: The inability to scrutinize engineering controls, unlike NIOSH-approved respirators, like the N95 , which can be fit tested by anyone, are subject to the scrutiny of NIOSH, and are trademarked and protected under US federal law. With regards to people complying with requirements to wear respirators, various papers note high respirator non-compliance across industries, with a survey noting non-compliance
13700-423: The lack of fit between the surface of the face mask and the face. The filtration efficiency of a surgical mask ranges between 10% and 90% for any given manufacturer, when measured using tests required for NIOSH certification. A study found that 80–100% of subjects failed an OSHA-accepted qualitative fit test, and a quantitative test showed between 12 and 25% leakage. Respirators used in healthcare are traditionally
13837-433: The low-pressure polymerization of ethene and propene . There are also some heterocyclic and cluster organoaluminium compounds involving Al–N bonds. The industrially most important aluminium hydride is lithium aluminium hydride (LiAlH 4 ), which is used as a reducing agent in organic chemistry . It can be produced from lithium hydride and aluminium trichloride . The simplest hydride, aluminium hydride or alane,
13974-529: The metal remained rare; its cost exceeded that of gold. The first industrial production of aluminium was established in 1856 by French chemist Henri Etienne Sainte-Claire Deville and companions. Deville had discovered that aluminium trichloride could be reduced by sodium, which was more convenient and less expensive than potassium, which Wöhler had used. Even then, aluminium was still not of great purity and produced aluminium differed in properties by sample. Because of its electricity-conducting capacity, aluminium
14111-655: The metal to be isolated from alum was alumium , which Davy suggested in an 1808 article on his electrochemical research, published in Philosophical Transactions of the Royal Society . It appeared that the name was created from the English word alum and the Latin suffix -ium ; but it was customary then to give elements names originating in Latin, so this name was not adopted universally. This name
14248-465: The metal with many uses at the time. During World War I , major governments demanded large shipments of aluminium for light strong airframes; during World War II , demand by major governments for aviation was even higher. By the mid-20th century, aluminium had become a part of everyday life and an essential component of housewares. In 1954, production of aluminium surpassed that of copper , historically second in production only to iron, making it
14385-491: The metal. Almost all metallic aluminium is produced from the ore bauxite (AlO x (OH) 3–2 x ). Bauxite occurs as a weathering product of low iron and silica bedrock in tropical climatic conditions. In 2017, most bauxite was mined in Australia, China, Guinea, and India. The history of aluminium has been shaped by usage of alum . The first written record of alum, made by Greek historian Herodotus , dates back to
14522-485: The monomer and dimer. These dimers, such as trimethylaluminium (Al 2 Me 6 ), usually feature tetrahedral Al centers formed by dimerization with some alkyl group bridging between both aluminium atoms. They are hard acids and react readily with ligands, forming adducts. In industry, they are mostly used in alkene insertion reactions, as discovered by Karl Ziegler , most importantly in "growth reactions" that form long-chain unbranched primary alkenes and alcohols, and in
14659-506: The most produced non-ferrous metal . During the mid-20th century, aluminium emerged as a civil engineering material, with building applications in both basic construction and interior finish work, and increasingly being used in military engineering, for both airplanes and land armor vehicle engines. Earth's first artificial satellite , launched in 1957, consisted of two separate aluminium semi-spheres joined and all subsequent space vehicles have used aluminium to some extent. The aluminium can
14796-614: The next decade, the -um spelling dominated American usage. In 1925, the American Chemical Society adopted this spelling. The International Union of Pure and Applied Chemistry (IUPAC) adopted aluminium as the standard international name for the element in 1990. In 1993, they recognized aluminum as an acceptable variant; the most recent 2005 edition of the IUPAC nomenclature of inorganic chemistry also acknowledges this spelling. IUPAC official publications use
14933-407: The oxidation state 3+. The coordination number of such compounds varies, but generally Al is either six- or four-coordinate. Almost all compounds of aluminium(III) are colorless. In aqueous solution, Al exists as the hexaaqua cation [Al(H 2 O) 6 ] , which has an approximate K a of 10 . Such solutions are acidic as this cation can act as a proton donor and progressively hydrolyze until
15070-460: The patents he filed between 1886 and 1903. It is unknown whether this spelling was introduced by mistake or intentionally, but Hall preferred aluminum since its introduction because it resembled platinum , the name of a prestigious metal. By 1890, both spellings had been common in the United States, the -ium spelling being slightly more common; by 1895, the situation had reversed; by 1900, aluminum had become twice as common as aluminium ; in
15207-454: The performance of the SCBA, the marking required, and the information to be provided to the user. Two classes of SCBA are recognised, Type 1 for industrial use and Type 2 for firefighting. Any SCBA conforming to this standard will have been verified to reliably operate and protect the user from -30 °C to +60 °C under a wide range of severe simulated operational conditions. SCBA is intended to be personal protective equipment, but its use
15344-402: The periodic fit test that is performed by specially trained personnel using testing equipment. Filtering facepiece respirators are typically checked by cupping the hands over the facepiece while exhaling (positive pressure check) or inhaling (negative pressure check) and observing any air leakage around the facepiece. Elastomeric respirators are checked in a similar manner, except the wearer blocks
15481-414: The pressure from storage pressure of up to more than 300 bar to about 10 bar for supply to the second stage on the mask, which further reduces it to just above atmospheric pressure via a demand valve when the pressure drops on inhalation. A positive pressure mask has the demand valve set to close when the pressure inside the mask is slightly above the external ambient pressure, so when the mask is removed from
15618-608: The purview of the US Bureau of Mines (USBM). An example of an early respirator standard, Type A, established in 1926, was intended to protect against mechanically generated dusts produced in mines. These standards were intended to obviate miner deaths, noted to have reached 3,243 by 1907. However, prior to the Hawks Nest Tunnel Disaster , these standards were merely advisory, as the USBM had no enforcement power at
15755-536: The requirements for the correct use of respirators are not always met. Experts note that in practice it is difficult to achieve elimination of occupational morbidity with the help of respirators: Aluminium Aluminium (or aluminum in North American English ) is a chemical element ; it has symbol Al and atomic number 13. Aluminium has a density lower than that of other common metals , about one-third that of steel . It has
15892-423: The respective hydrogen chalcogenide . As aluminium is a small atom relative to these chalcogens, these have four-coordinate tetrahedral aluminium with various polymorphs having structures related to wurtzite , with two-thirds of the possible metal sites occupied either in an orderly (α) or random (β) fashion; the sulfide also has a γ form related to γ-alumina, and an unusual high-temperature hexagonal form where half
16029-531: The same exercise levels without the equipment. Shoulder harness straps of heavy SCBA can reduce free motion of the thorax which affects breathing. [REDACTED] Related media at Wikimedia Commons: [REDACTED] Texts on Wikisource: Respirator A respirator is a device designed to protect the wearer from inhaling hazardous atmospheres including lead fumes , vapors , gases and particulate matter such as dusts and airborne pathogens such as viruses . There are two main categories of respirators:
16166-927: The same principles, being designed for emergency use in mines, and lasting about one hour. An open-circuit SCBA does not recirculate air; it instead allows respired air to be exhausted outside. While 30 CFR 11 does not restrict the gas that can be used (although compressed air is usually chosen), use of compressed oxygen is not allowed due to the system's exposure to outside air. Duration is usually limited to 30-60 minutes. There are two types of open-circuit SCBA according to NIOSH: NIOSH emphasizes that facepieces between both SCBA types cannot be interchanged, but certain SCBAs can be switched to both 'demand' and 'pressure-demand' operation. However, both modes require different training. Open-circuit industrial breathing sets are filled with filtered, compressed air. Typical open-circuit systems have two stage regulators. The first stage reduces
16303-485: The scale of the economies. However, the need to exploit lower-grade poorer quality deposits and the use of fast increasing input costs (above all, energy) increased the net cost of aluminium; the real price began to grow in the 1970s with the rise of energy cost. Production moved from the industrialized countries to countries where production was cheaper. Production costs in the late 20th century changed because of advances in technology, lower energy prices, exchange rates of
16440-408: The structure of BCl 3 . Aluminium tribromide and aluminium triiodide form Al 2 X 6 dimers in all three phases and hence do not show such significant changes of properties upon phase change. These materials are prepared by treating aluminium with the halogen. The aluminium trihalides form many addition compounds or complexes; their Lewis acidic nature makes them useful as catalysts for
16577-436: The surrounding air and purify it before it is breathed (unlike air-supplying respirators, which are sealed systems, with no air intake, like those used underwater). Air-purifying respirators filter particulates, gases, and vapors from the air, and may be negative-pressure respirators driven by the wearer's inhalation and exhalation, or positive-pressure units such as powered air-purifying respirators (PAPRs). According to
16714-403: The textile industry. Respirators require user training in order to provide proper protection. Each time a wearer dons a respirator, they must perform a seal check to be sure that they have an airtight seal to the face so that air does not leak around the edges of the respirator. (PAPR respirators may not require this because they don't necessarily seal to the face.) This check is different than
16851-502: The time. After the disaster, an explicit approval program was established in 1934, along with the introduction of combination Type A/B/C respirator ratings, corresponding to Dusts/Fumes/Mists respectively, with Type D blocking all three, under 30 CFR 14 Schedule 21. In the 1970s, the successor to the United States Bureau of Mines and NIOSH developed standards for single-use respirators, and the first single-use respirator
16988-536: The two therefore look similar. Aluminium is also good at reflecting solar radiation , although prolonged exposure to sunlight in air adds wear to the surface of the metal; this may be prevented if aluminium is anodized , which adds a protective layer of oxide on the surface. The density of aluminium is 2.70 g/cm , about 1/3 that of steel, much lower than other commonly encountered metals, making aluminium parts easily identifiable through their lightness. Aluminium's low density compared to most other metals arises from
17125-470: The wearer; the supplied air respirators, where a hose supplies air from a stationary source; and combination supplied-air respirators, with an emergency backup tank. A self-contained breathing apparatus (SCBA) is a respirator worn to provide an autonomous supply of breathable gas in an atmosphere that is immediately dangerous to life or health from a gas cylinder . They are typically used in firefighting and industry. The term self-contained means that
17262-410: The widespread shortage of commercial masks. All respirators have some type of facepiece held to the wearer's head with straps, a cloth harness, or some other method. Facepieces come in many different styles and sizes to accommodate all types of face shapes. A full facepiece covers the mouth, nose and eyes and if sealed, is sealed round the perimeter of the face. Unsealed versions may be used when air
17399-421: Was a crucial strategic resource for aviation . In 1954, aluminium became the most produced non-ferrous metal , surpassing copper . In the 21st century, most aluminium was consumed in transportation, engineering, construction, and packaging in the United States, Western Europe, and Japan. Despite its prevalence in the environment, no living organism is known to metabolize aluminium salts , but this aluminium
17536-461: Was a salt of an earth of alum. In 1595, German doctor and chemist Andreas Libavius experimentally confirmed this. In 1722, German chemist Friedrich Hoffmann announced his belief that the base of alum was a distinct earth. In 1754, German chemist Andreas Sigismund Marggraf synthesized alumina by boiling clay in sulfuric acid and subsequently adding potash . Attempts to produce aluminium date back to 1760. The first successful attempt, however,
17673-494: Was borrowed from French, which in turn derived it from alumen , the classical Latin name for alum , the mineral from which it was collected. The Latin word alumen stems from the Proto-Indo-European root *alu- meaning "bitter" or "beer". British chemist Humphry Davy , who performed a number of experiments aimed to isolate the metal, is credited as the person who named the element. The first name proposed for
17810-422: Was completed in 1824 by Danish physicist and chemist Hans Christian Ørsted . He reacted anhydrous aluminium chloride with potassium amalgam , yielding a lump of metal looking similar to tin. He presented his results and demonstrated a sample of the new metal in 1825. In 1827, German chemist Friedrich Wöhler repeated Ørsted's experiments but did not identify any aluminium. (The reason for this inconsistency
17947-496: Was criticized by contemporary chemists from France, Germany, and Sweden, who insisted the metal should be named for the oxide, alumina, from which it would be isolated. The English name alum does not come directly from Latin, whereas alumine / alumina obviously comes from the Latin word alumen (upon declension , alumen changes to alumin- ). One example was Essai sur la Nomenclature chimique (July 1811), written in French by
18084-576: Was developed by 3M and approved in 1972. 3M used a melt blowing process that it had developed decades prior and used in products such as ready-made ribbon bows and bra cups; its use in a wide array of products had been pioneered by designer Sara Little Turnbull . Historically, respirators in the US had generally been approved by MESA / MSHA / NIOSH under federal regulation 30 CFR 11. On July 10, 1995, in response to respirators exhibiting "low initial efficiency levels", new 42 CFR 84 standards, including
18221-660: Was due in large part due to discomfort from temperature increases along the face, and a large amount of respondents also noting the social unacceptability of provided N95 respirators during the survey. For reasons like mishandling, ill-fitting respirators and lack of training, the Hierarchy of Controls dictates respirators be evaluated last while other controls exist and are working. Alternative controls like hazard elimination , administrative controls , and engineering controls like ventilation are less likely to fail due to user discomfort or error. A U.S. Department of Labor study showed that in almost 40 thousand American enterprises,
18358-571: Was initiated by French chemist Henri Étienne Sainte-Claire Deville in 1856. Aluminium became much more available to the public with the Hall–Héroult process developed independently by French engineer Paul Héroult and American engineer Charles Martin Hall in 1886, and the mass production of aluminium led to its extensive use in industry and everyday life. In the First and Second World Wars, aluminium
18495-418: Was invented in 1956 and employed as a storage for drinks in 1958. Throughout the 20th century, the production of aluminium rose rapidly: while the world production of aluminium in 1900 was 6,800 metric tons, the annual production first exceeded 100,000 metric tons in 1916; 1,000,000 tons in 1941; 10,000,000 tons in 1971. In the 1970s, the increased demand for aluminium made it an exchange commodity; it entered
18632-433: Was only discovered in 1921.) He conducted a similar experiment in the same year by mixing anhydrous aluminium chloride with potassium and produced a powder of aluminium. In 1845, he was able to produce small pieces of the metal and described some physical properties of this metal. For many years thereafter, Wöhler was credited as the discoverer of aluminium. As Wöhler's method could not yield great quantities of aluminium,
18769-580: Was used as the cap of the Washington Monument , completed in 1885. The tallest building in the world at the time, the non-corroding metal cap was intended to serve as a lightning rod peak. The first industrial large-scale production method was independently developed in 1886 by French engineer Paul Héroult and American engineer Charles Martin Hall ; it is now known as the Hall–Héroult process . The Hall–Héroult process converts alumina into metal. Austrian chemist Carl Joseph Bayer discovered
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