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63-438: She had one torpedo tube (and two torpedoes ) and an air regeneration system. Her hull shape, propeller, periscope, torpedo launcher and cruciform external controls anticipated later designs. Her underwater speed was 3 knots (5.6 km/h; 3.5 mph). With fully charged batteries, she was the fastest submarine yet built, with underwater performance levels (except for range) that matched those of First World War U-boats for

126-447: A drain cleaner . Worldwide production in 2022 was approximately 83 million tons. Pure sodium hydroxide is a colorless crystalline solid that melts at 318 °C (604 °F) without decomposition and boils at 1,388 °C (2,530 °F). It is highly soluble in water, with a lower solubility in polar solvents such as ethanol and methanol . Sodium hydroxide is insoluble in ether and other non-polar solvents. Similar to

189-556: A primary standard because it is hygroscopic and absorbs carbon dioxide from air. Sodium hydroxide also reacts with acidic oxides , such as sulfur dioxide . Such reactions are often used to " scrub " harmful acidic gases (like SO 2 and H 2 S ) produced in the burning of coal and thus prevent their release into the atmosphere. For example, Glass reacts slowly with aqueous sodium hydroxide solutions at ambient temperatures to form soluble silicates . Because of this, glass joints and stopcocks exposed to sodium hydroxide have

252-524: A characteristic viscosity , 78 m Pa ·s, that is much greater than that of water (1.0 mPa·s) and near that of olive oil (85 mPa·s) at room temperature. The viscosity of aqueous NaOH , as with any liquid chemical, is inversely related to its temperature, i.e., its viscosity decreases as temperature increases, and vice versa. The viscosity of sodium hydroxide solutions plays a direct role in its application as well as its storage. Sodium hydroxide can form several hydrates NaOH· n H 2 O , which result in

315-458: A clear solution of Na 2 ZnO 2 or Na 2 PbO 2 . Aluminium hydroxide is used as a gelatinous flocculant to filter out particulate matter in water treatment . Aluminium hydroxide is prepared at the treatment plant from aluminium sulfate by reacting it with sodium hydroxide or bicarbonate. Sodium hydroxide can be used for the base-driven hydrolysis of esters (also called saponification ), amides and alkyl halides . However,

378-540: A complex solubility diagram that was described in detail by Spencer Umfreville Pickering in 1893. The known hydrates and the approximate ranges of temperature and concentration (mass percent of NaOH) of their saturated water solutions are: Early reports refer to hydrates with n = 0.5 or n = 2/3, but later careful investigations failed to confirm their existence. The only hydrates with stable melting points are NaOH·H 2 O (65.10 °C) and NaOH·3.5H 2 O (15.38 °C). The other hydrates, except

441-401: A fact that angered Isaac Peral. The simulated night attack was successful. The staff that evaluated the trials of the submarine submitted a report, considering its speed and range insufficient, and being especially critical about the failure of the submarine during the daylight attack and its electric motors. However, overall the report was positive, and a second submarine was ordered, again under

504-431: A liquid solution. Even the n = 3.5 hydrate is difficult to crystallize, because the solution supercools so much that other hydrates become more stable. A hot water solution containing 73.1% (mass) of NaOH is a eutectic that solidifies at about 62.63 °C as an intimate mix of anhydrous and monohydrate crystals. A second stable eutectic composition is 45.4% (mass) of NaOH, that solidifies at about 4.9 °C into

567-407: A liquid with 35.7% NaOH and density 1.392 g/cm , and therefore floats on it like ice on water. However, at about 4.9 °C it may instead melt incongruously into a mixture of solid NaOH·3.5H 2 O and a liquid solution. The β form of the tetrahydrate is metastable, and often transforms spontaneously to the α form when cooled below −20 °C. Once initiated, the exothermic transformation

630-749: A man who worked for drug cartels admitted disposing of over 300 bodies with it. Sodium hydroxide is a dangerous chemical due to its ability to hydrolyze protein. If a dilute solution is spilled on the skin, burns may result if the area is not washed thoroughly and for several minutes with running water. Splashes in the eye can be more serious and can lead to blindness. Strong bases attack aluminium . Sodium hydroxide reacts with aluminium and water to release hydrogen gas. The aluminium takes an oxygen atom from sodium hydroxide, which in turn takes an oxygen atom from water, and releases two hydrogen atoms. The reaction thus produces hydrogen gas and sodium aluminate . In this reaction, sodium hydroxide acts as an agent to make

693-413: A maximum depth of 30 meters in trials. On 25 June 1890 Peral made two simulated engagements on the cruiser Cristóbal Colón , one at day and other at night. At the daylight trial the submarine was unable to attack the cruiser, as the optical turret was spotted less than 1,000 yards (910 m) away from the cruiser, which had 200 civilian and military guests who obviously expected to see the submarine,

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756-514: A means of charging batteries while underway, such as an internal combustion engine, thus had a very limited endurance and range. In June 1890, Peral's submarine launched a torpedo while submerged. It was also the first submarine to incorporate a fully reliable underwater navigation system. However, conservatives in the Spanish naval hierarchy terminated the project despite two years of successful tests. Her operational abilities have led some to call her

819-495: A mixture of crystals of the dihydrate and of the 3.5-hydrate. The third stable eutectic has 18.4% (mass) of NaOH. It solidifies at about −28.7 °C as a mixture of water ice and the heptahydrate NaOH·7H 2 O . When solutions with less than 18.4% NaOH are cooled, water ice crystallizes first, leaving the NaOH in solution. The α form of the tetrahydrate has density 1.33 g/cm . It melts congruously at 7.55 °C into

882-400: A new development of the water ram expulsion system, which ejects the torpedo with water pressure to avoid acoustic detection. Sodium hydroxide Sodium hydroxide , also known as lye and caustic soda , is an inorganic compound with the formula NaOH . It is a white solid ionic compound consisting of sodium cations Na and hydroxide anions OH . Sodium hydroxide

945-433: A single shaft. The submarine Peral began in 1887 had a length of more than 22 m (72 ft), a beam of 2.87 m (9.4 ft), a draft of 2.76 m (9.1 ft), two 30 shp (22 kW) electric motors geared to twin screws , and a displacement of 77 tons surfaced and 85 submerged. Air regeneration in the interior of the submarine was accomplished by an auxiliary 6 hp (4 kW) engine, which passed

1008-456: A specific type of torpedo, while submarine torpedo tubes are general-purpose launchers, and are often also capable of deploying mines and cruise missiles . Most modern launchers are standardized on a 12.75-inch (324 mm) diameter for light torpedoes (deck mounted aboard ship) or a 21-inch (533 mm) diameter for heavy torpedoes (underwater tubes), although torpedoes of other classes and diameters have been used. A submarine torpedo tube

1071-435: A storage capacity of 8 tons, and were used to stabilize the submarine. In order to navigate, Peral used a bronze magnetic needle installed in the ceiling of the turret. The design avoided any electrical interference. He also devised a periscope , a fixed tube on the turret; by using a series of prisms, it projected the outside world to within the submarine. The engine-cooling system consisted of forcing compressed air stored in

1134-491: A tendency to "freeze". Flasks and glass-lined chemical reactors are damaged by long exposure to hot sodium hydroxide, which also frosts the glass. Sodium hydroxide does not attack iron at room temperature, since iron does not have amphoteric properties (i.e., it only dissolves in acid, not base). Nevertheless, at high temperatures (e.g. above 500 °C), iron can react endothermically with sodium hydroxide to form iron(III) oxide , sodium metal, and hydrogen gas. This

1197-545: A torpedo loading system, but safety is paramount. There are various manual and hydraulic handling systems for loading torpedoes into the tubes. Prior to the Ohio class , US SSBNs utilized manual block and tackle which took about 15 minutes to load a tube. SSNs prior to the Seawolf class used a hydraulic system that was much faster and safer in conditions where the ship needed to maneuver. The German Type 212 submarine uses

1260-457: A very short period, before her batteries began to drain. For example, the SM ; U-9 , a pre-war German U-boat built in 1908, had an underwater speed of 8.1 knots (15.0 km/h; 9.3 mph), and an underwater range of 150 km (81 nmi) at 5.8 knots (10.7 km/h; 6.7 mph), before having to resurface to recharge her batteries. Although advanced in many ways, Peral lacked

1323-457: Is a highly corrosive base and alkali that decomposes lipids and proteins at ambient temperatures and may cause severe chemical burns . It is highly soluble in water , and readily absorbs moisture and carbon dioxide from the air . It forms a series of hydrates NaOH· n H 2 O . The monohydrate NaOH·H 2 O crystallizes from water solutions between 12.3 and 61.8 °C. The commercially available "sodium hydroxide"

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1386-422: Is a more complex mechanism than a torpedo tube on a surface ship, because the tube has to accomplish the function of moving the torpedo from the normal atmospheric pressure within the submarine into the sea at the ambient pressure of the water around the submarine. Thus a submarine torpedo tube operates on the principle of an airlock . The diagram illustrates the operation of a submarine torpedo tube. The diagram

1449-429: Is complete in a few minutes, with a 6.5% increase in volume of the solid. The β form can be crystallized from supercooled solutions at −26 °C, and melts partially at −1.83 °C. The "sodium hydroxide" of commerce is often the monohydrate (density 1.829 g/cm ). Physical data in technical literature may refer to this form, rather than the anhydrous compound. NaOH and its monohydrate form orthorhombic crystals with

1512-416: Is cooled, the monohydrate normally starts to crystallize (at about 22 °C) before the dihydrate. However, the solution can easily be supercooled down to −15 °C, at which point it may quickly crystallize as the dihydrate. When heated, the solid dihydrate might melt directly into a solution at 13.35 °C; however, once the temperature exceeds 12.58 °C it often decomposes into solid monohydrate and

1575-562: Is due to the lower enthalpy of formation of iron(III) oxide (−824.2 kJ/mol) compared to sodium hydroxide (−500 kJ/mol) and positive entropy change of the reaction, which implies spontaneity at high temperatures ( ΔST > ΔH , ΔG < 0 ) and non-spontaneity at low temperatures ( ΔST < ΔH , ΔG > 0 ). Consider the following reaction between molten sodium hydroxide and finely divided iron filings: A few transition metals , however, may react quite vigorously with sodium hydroxide under milder conditions. In 1986, an aluminium road tanker in

1638-466: Is formed is toxic and difficult to deal with, and the process is banned in many countries because of this. In 2006, Trafigura used the process and then dumped the waste in Ivory Coast . Other common uses of sodium hydroxide include: Sodium hydroxide is also widely used in pulping of wood for making paper or regenerated fibers. Along with sodium sulfide , sodium hydroxide is a key component of

1701-499: Is given by: This reaction can be useful in etching , removing anodizing, or converting a polished surface to a satin-like finish, but without further passivation such as anodizing or alodining the surface may become degraded, either under normal use or in severe atmospheric conditions. In the Bayer process , sodium hydroxide is used in the refining of alumina containing ores ( bauxite ) to produce alumina ( aluminium oxide ) which

1764-462: Is industrially produced, first as a 32% solution, and then evaporated to a 50% solution by variations of the electrolytic chloralkali process . Chlorine gas is also produced in this process. Solid sodium hydroxide is obtained from this solution by the evaporation of water. Solid sodium hydroxide is most commonly sold as flakes, prills , and cast blocks. In 2022, world production was estimated at 83 million dry tonnes of sodium hydroxide, and demand

1827-432: Is often this monohydrate, and published data may refer to it instead of the anhydrous compound. As one of the simplest hydroxides, sodium hydroxide is frequently used alongside neutral water and acidic hydrochloric acid to demonstrate the pH scale to chemistry students. Sodium hydroxide is used in many industries: in the making of wood pulp and paper , textiles , drinking water , soaps and detergents , and as

1890-409: Is somewhat simplified but does show the working of a submarine torpedo launch. A torpedo tube has a considerable number of interlocks for safety reasons. For example, an interlock prevents the breech door and muzzle door from opening at the same time. The submarine torpedo launch sequence is, in simplified form: Spare torpedoes are stored behind the tube in racks. Speed is a desirable feature of

1953-465: Is the raw material used to produce aluminium via the electrolytic Hall-Héroult process . Since the alumina is amphoteric , it dissolves in the sodium hydroxide, leaving impurities less soluble at high pH such as iron oxides behind in the form of a highly alkaline red mud . Other amphoteric metals are zinc and lead which dissolve in concentrated sodium hydroxide solutions to give sodium zincate and sodium plumbate respectively. Sodium hydroxide

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2016-409: Is used in many scenarios where it is desirable to increase the alkalinity of a mixture, or to neutralize acids. For example, in the petroleum industry, sodium hydroxide is used as an additive in drilling mud to increase alkalinity in bentonite mud systems, to increase the mud viscosity , and to neutralize any acid gas (such as hydrogen sulfide and carbon dioxide ) which may be encountered in

2079-463: The Peral ' s trials started, consisting of handling and surface navigation. On 7 August that year, the submarine submerged for the first time up to the turret; 18 days later fired the first trial torpedo (without warhead); on 5 December submerged to 7.5 m; on 25 December passed the first non-static dive test, sailing at a steady depth of 9.5 meters; and, in 1890 sailed underwater for one hour, reaching

2142-460: The Solvay process in the late 19th century. The conversion of sodium carbonate to sodium hydroxide was superseded entirely by the chloralkali process , which produces sodium hydroxide in a single process. Sodium hydroxide is also produced by combining pure sodium metal with water. The byproducts are hydrogen gas and heat, often resulting in a flame. This reaction is commonly used for demonstrating

2205-472: The chloralkali process . Historically, sodium hydroxide was produced by treating sodium carbonate with calcium hydroxide (slaked lime) in a metathesis reaction which takes advantage of the fact that sodium hydroxide is soluble, while calcium carbonate is not. This process was called causticizing. The sodium carbonate for this reaction was produced by the Leblanc process in the early 19th century, or

2268-578: The geological formation as drilling progresses. Another use is in salt spray testing where pH needs to be regulated. Sodium hydroxide is used with hydrochloric acid to balance pH. The resultant salt, NaCl, is the corrosive agent used in the standard neutral pH salt spray test. Poor quality crude oil can be treated with sodium hydroxide to remove sulfurous impurities in a process known as caustic washing . Sodium hydroxide reacts with weak acids such as hydrogen sulfide and mercaptans to yield non-volatile sodium salts, which can be removed. The waste which

2331-545: The La Carraca yard where it was built. On 11 November 1890 a decree set the end of the projects of underwater navigation in the Spanish Navy. Similar figures of performance were only attained about a decade later in other countries. The speed and endurance of the Peral attained World War I standards (in terms of underwater, battery-powered sailing). In 1890 Peral was withdrawn from service, equipment removed, and

2394-629: The Spanish navy staff. He wrote a letter to the Spanish naval minister, Vice Admiral Pezuela y Lobo, in September, 1885. Pezuela called Peral to Madrid to have a personal interview with him. After the interview Pezuela agreed to finance Peral's preliminary studies in Cádiz with an initial budget of 5,000 pesetas , before launching a program to build a full-scale submarine. The first study consisted of human breath test in an enclosure for several hours. A room of 58 m (620 sq ft) square meters

2457-593: The UK was mistakenly used to transport 25% sodium hydroxide solution, causing pressurization of the contents and damage to tankers. The pressurization is due to the hydrogen gas which is produced in the reaction between sodium hydroxide and aluminium: Unlike sodium hydroxide, which is soluble, the hydroxides of most transition metals are insoluble, and therefore sodium hydroxide can be used to precipitate transition metal hydroxides. The following colours are observed: Zinc and lead salts dissolve in excess sodium hydroxide to give

2520-480: The air through a sodium hydroxide purifier to eliminate CO 2 exhaled by the crew. In addition, the pump injected oxygen when needed. The same engine which circulated air also drove the bailing pump. The submarine dived by means of the "depth's device" which drove two shafts of vertical axes located at both ends of the hull, moved by two 4 hp (3 kW) electrical motors to submerge or surface, and to maintain horizontal stability submerged. The ballast tanks had

2583-399: The boat again depended on battery charge level; Peral calculated his original submarine could reach 132 nmi (152 mi; 244 km) at a speed of 6 kn (11 km/h; 6.9 mph). With no means of charging batteries while underway, such as an internal combustion engine, endurance and range were limited. One of the original features of Peral was an underwater lamp, which enabled

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2646-405: The corresponding salts. For example, when sodium hydroxide reacts with hydrochloric acid , sodium chloride is formed: In general, such neutralization reactions are represented by one simple net ionic equation: This type of reaction with a strong acid releases heat, and hence is exothermic . Such acid–base reactions can also be used for titrations . However, sodium hydroxide is not used as

2709-425: The crew to search the sea bottom. The searchlight had a range of 150 m (490 ft). The submarine was single-hulled, and the ballast tanks were located at the bottom of the hull, underneath the torpedo tube. This single torpedo tube was the only weapon in the submarine, with two watertight doors on each end so the submarine could launch a torpedo submerged. Mechanisms used for reloading were simple and fast, and

2772-411: The direction of Isaac Peral but also managed by several naval departments. Peral designed a 30-meter submarine of 130 tons, under the condition of choosing the yard where the submarine would be built and the choosing the team to build it. These conditions were not accepted by the authorities, who considered this a refusal by Peral to build the submarine. Finally they ordered Peral to return the submarine to

2835-404: The end of the stages. In a similar fashion, sodium hydroxide is used to digest tissues, as in a process that was used with farm animals at one time. This process involved placing a carcass into a sealed chamber, then adding a mixture of sodium hydroxide and water (which breaks the chemical bonds that keep the flesh intact). This eventually turns the body into a liquid with a dark brown color, and

2898-535: The first U-boat. Peral was withdrawn from service in 1890 and is now preserved at the Cartagena Naval Museum . Peral was first conceived on 20 September 1884, when Lieutenant Isaac Peral y Caballero wrote a paper which would become his Proyecto de Torpedero Submarino ("Project for a submarine torpedo boat "). After several studies and experiments, and having gained support from his superiors and fellow officers, Peral exposed his idea to

2961-552: The hull and the electric engine. He authorized Peral to carry out all the modifications that he thought worthwhile, granting him 25,000 pesetas. On 5 March 1887, Peral communicated that the electric motor or "depth's device", as he called it, was ready. On 17 March, the Commander in Chief of Cadiz, Florencio Montojo, who headed the technical committee overseeing the machine, requested budgeting for Peral's submarine. On 25 April 1887,

3024-466: The hull stored at La Carraca Arsenal. In 1913 her demolition was ordered but this was not carried out. In 1929, Admiral Mateo García de los Reyes , first commander of the Spanish submarine forces, managed to reclaim the hull and towed it to Cartagena , putting it ashore at the submarine base. In 1965 the authorities of Cartagena succeeded in moving the hull to the Plaza de los Héroes de Cavite. In 2002

3087-505: The hydration of sulfuric acid, dissolution of solid sodium hydroxide in water is a highly exothermic reaction where a large amount of heat is liberated, posing a threat to safety through the possibility of splashing. The resulting solution is usually colorless and odorless. As with other alkaline solutions, it feels slippery with skin contact due to the process of saponification that occurs between NaOH and natural skin oils. Concentrated (50%) aqueous solutions of sodium hydroxide have

3150-535: The limited solubility of sodium hydroxide in organic solvents means that the more soluble potassium hydroxide (KOH) is often preferred. Touching a sodium hydroxide solution with bare hands, while not recommended, produces a slippery feeling. This happens because oils on the skin such as sebum are converted to soap. Despite solubility in propylene glycol it is unlikely to replace water in saponification due to propylene glycol's primary reaction with fat before reaction between sodium hydroxide and fat. Sodium hydroxide

3213-431: The metastable ones NaOH·3H 2 O and NaOH·4H 2 O (β) can be crystallized from solutions of the proper composition, as listed above. However, solutions of NaOH can be easily supercooled by many degrees, which allows the formation of hydrates (including the metastable ones) from solutions with different concentrations. For example, when a solution of NaOH and water with 1:2 mole ratio (52.6% NaOH by mass)

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3276-422: The only solids that remain are bone hulls, which can be crushed between one's fingertips. Sodium hydroxide is frequently used in the process of decomposing roadkill dumped in landfills by animal disposal contractors. Due to its availability and low cost, it has been used by criminals to dispose of corpses. Italian serial killer Leonarda Cianciulli used this chemical to turn dead bodies into soap. In Mexico,

3339-516: The reactivity of alkali metals in academic environments; however, it is not used commercially aside from a reaction within the mercury cell chloralkali process where sodium amalgam is reacted with water. Sodium hydroxide is a popular strong base used in industry. Sodium hydroxide is used in the manufacture of sodium salts and detergents, pH regulation, and organic synthesis. In bulk, it is most often handled as an aqueous solution , since solutions are cheaper and easier to handle. Sodium hydroxide

3402-473: The rest remained for a total of five hours, and the test was considered a total success. On 21 July 1886, the new Navy Minister, rear-admiral Beranger, decided that the project would be reviewed by the Centro Técnico de la Armada (Naval Technical Center), under the responsibility of Admiral Antequera. He considered a more complete study of the actuator necessary before undertaking the construction of

3465-506: The solution alkaline, which aluminium can dissolve in. Sodium aluminate is an inorganic chemical that is used as an effective source of aluminium hydroxide for many industrial and technical applications. Pure sodium aluminate (anhydrous) is a white crystalline solid having a formula variously given as NaAlO 2 , Na 3 AlO 3 , Na[Al(OH) 4 ] , Na 2 O·Al 2 O 3 or Na 2 Al 2 O 4 . Formation of sodium tetrahydroxoaluminate(III) or hydrated sodium aluminate

3528-560: The space groups Cmcm ( oS8 ) and Pbca (oP24), respectively. The monohydrate cell dimensions are a = 1.1825, b = 0.6213, c = 0.6069 nm . The atoms are arranged in a hydrargillite -like layer structure, with each sodium atom surrounded by six oxygen atoms, three each from hydroxide ions and three from water molecules. The hydrogen atoms of the hydroxyls form strong bonds with oxygen atoms within each O layer. Adjacent O layers are held together by hydrogen bonds between water molecules. Sodium hydroxide reacts with protic acids to produce water and

3591-479: The submarine had three reserves. This was almost identical to the torpedo launchers used in submarines since then. In order to avoid expenses, the torpedoes Peral launched during the trials were borrowed from torpedo boats, two from Retamosa and one from Barceló . The Peral was launched on 8 September 1888, sixteen days before another pioneering electric submarine, the French Gymnote . On 6 March 1889

3654-576: The submarine over the engines, and though the original project had needed 430 accumulators, the final project installed 613 with a weight of 50 kg (110 lb). The total weight of the batteries was around 30 tons. The top speed varied with the charge of the batteries. With one-quarter charge, the submarine was able to reach 4.7 kn (8.7 km/h; 5.4 mph), one-half 6.9 kn (12.8 km/h; 7.9 mph), three-quarters 8.9 kn (16.5 km/h; 10.2 mph), knots, completely charged 10.9 kn (20.2 km/h; 12.5 mph). The range of

3717-441: The submarine's construction was finally approved by the government; the keel was laid down on La Carraca on 7 October, although work did not start until two weeks later. Nevertheless, the submarine had already undergone a number of modifications: Peral's original 1885 model conceived of a 61-ton submarine, 18.8 m (62 ft) long, with a beam of 2.52 m (8.3 ft) and a single 40 shp (30 kW) electric motor for

3780-399: The white liquor solution used to separate lignin from cellulose fibers in the kraft process . It also plays a key role in several later stages of the process of bleaching the brown pulp resulting from the pulping process. These stages include oxygen delignification, oxidative extraction, and simple extraction, all of which require a strong alkaline environment with a pH > 10.5 at

3843-719: Was estimated at 51 million tonnes. In 1998, total world production was around 45 million tonnes . North America and Asia each contributed around 14 million tonnes, while Europe produced around 10 million tonnes. In the United States, the major producer of sodium hydroxide is Olin , which has annual production around 5.7 million tonnes from sites at Freeport, Texas ; Plaquemine, Louisiana ; St. Gabriel, Louisiana ; McIntosh, Alabama ; Charleston, Tennessee ; Niagara Falls, New York ; and Bécancour, Canada . Other major US producers include Oxychem , Westlake , Shintek, and Formosa . All of these companies use

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3906-577: Was moved to the Paseo Alfonso XII, in front of the port of Cartagena . In 2013, Peral was restored and moved to the Cartagena Naval Museum . Torpedo tube A torpedo tube is a cylindrical device for launching torpedoes . There are two main types of torpedo tube: underwater tubes fitted to submarines and some surface ships, and deck-mounted units (also referred to as torpedo launchers ) installed aboard surface vessels. Deck-mounted torpedo launchers are usually designed for

3969-417: Was used, with an air storage cell, loaded to 79 atmospheres and a storage capacity of 0.5 m. In addition to instruments to measure the temperature and moisture, there was a tube to re-oxygenate the air supply to the crew through a 4 mm (0.16 in) waterproof cloak and three water buckets to maintain the moisture. Six people locked themselves inside the room; one had to leave an hour and quarter later, but

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