1.
Valve Corporation
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Valve Corporation is an American video game developer and digital distribution company headquartered in Bellevue, Washington. The company is known for the Half-Life, Counter-Strike, Portal, Day of Defeat, Team Fortress, Left 4 Dead, and Dota 2 games, Valve was founded in 1996 as a limited liability company by former Microsoft employees Gabe Newell and Mike Harrington. Their debut product, the PC first-person shooter Half-Life, was released in 1998 to critical acclaim and commercial success, in 2004, Valve launched Steam alongside the critically acclaimed Half-Life 2. By 2011, over half of digital PC game sales were through Steam, in 2015, Valve entered the game hardware market with the Steam Machine, a line of prebuilt gaming computers running SteamOS, a Valve-developed fork of the Debian operating system. Valve was founded by former longtime Microsoft employees Gabe Newell and Mike Harrington on August 24,1996, as Valve L. L. C. based in Kirkland, Harrington left the company in 2000. After incorporation in April 2003, it moved from its location to Bellevue, Washington. In 2010, the office was moved again to a location in Bellevue. In 2016, Valve signed a lease in the Lincoln Square complex in downtown Bellevue. After securing a license to the Quake engine through the help of friend Michael Abrash of id Software in late 1996, Newell, originally planned for release in late 1997, Half-Life launched on November 19,1998. Valve acquired TF Software Pty. Ltd. the makers of the Team Fortress mod for Quake, the Team Fortress Classic mod, essentially a port of the original Team Fortress mod for Quake, was released for Half-Life in 1999. Gearbox contributed much after the release of Half-Life, after the success of Half-Life, the team worked on mods, spin-offs, and sequels, including Half-Life 2. All current Valve games are built on its Source engine, the company has developed six game series, Half-Life, Team Fortress, Portal, Counter-Strike, Left 4 Dead and Day of Defeat. Valve is noted for its support of its games modding community, most prominently, Counter-Strike, Team Fortress, Valve has branched out with this tradition to continue developing Dota 2 as the standalone sequel to the Warcraft III mod. Each of these began as a third-party mod that Valve purchased and developed into a full game. They also distribute community mods on Steam, Valve announced the Source 2 engine in March 2015, later porting the entirety of Dota 2 to the engine in September of that year. Valve has grown both in scope and commercial value, on January 10,2008, Valve announced the acquisition of Turtle Rock Studios. On April 8,2010, Valve won The Escapist Magazines March Mayhem tournament for the best developer of 2010, beating out Zynga in the semi-finals, in 2012, the company acquired Star Filled Studios, a two-man gaming company to open a San Francisco office. In August 2013, however, Valve ended the operation when it was decided there was little benefit coming from the arrangement
2.
Vacuum tube
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In electronics, a vacuum tube, an electron tube, or just a tube, or valve, is a device that controls electric current between electrodes in an evacuated container. Vacuum tubes mostly rely on thermionic emission of electrons from a hot filament or a cathode heated by the filament and this type is called a thermionic tube or thermionic valve. A phototube, however, achieves electron emission through the photoelectric effect, the simplest vacuum tube, the diode, contains only a heater, a heated electron-emitting cathode, and a plate. Current can only flow in one direction through the device between the two electrodes, as electrons emitted by the travel through the tube and are collected by the anode. Adding one or more control grids within the tube allows the current between the cathode and anode to be controlled by the voltage on the grid or grids, Tubes with grids can be used for many purposes, including amplification, rectification, switching, oscillation, and display. In the 1940s the invention of devices made it possible to produce solid-state devices, which are smaller, more efficient, more reliable, more durable. Hence, from the mid-1950s solid-state devices such as transistors gradually replaced tubes, the cathode-ray tube remained the basis for televisions and video monitors until superseded in the 21st century. However, there are still a few applications for which tubes are preferred to semiconductors, for example, the used in microwave ovens. One classification of vacuum tubes is by the number of active electrodes, a device with two active elements is a diode, usually used for rectification. Devices with three elements are used for amplification and switching. Additional electrodes create tetrodes, pentodes, and so forth, which have additional functions made possible by the additional controllable electrodes. X-ray tubes are vacuum tubes. Phototubes and photomultipliers rely on electron flow through a vacuum, though in those cases electron emission from the cathode depends on energy from photons rather than thermionic emission, since these sorts of vacuum tubes have functions other than electronic amplification and rectification they are described in their own articles. A vacuum tube consists of two or more electrodes in a vacuum inside an airtight enclosure, most tubes have glass envelopes, though ceramic and metal envelopes have been used. The electrodes are attached to leads which pass through the envelope via an airtight seal, Tubes were a frequent cause of failure in electronic equipment, and consumers were expected to be able to replace tubes themselves. In addition to the terminals, some tubes had an electrode terminating at a top cap. The principal reason for doing this was to avoid leakage resistance through the tube base, the bases were commonly made with phenolic insulation which performs poorly as an insulator in humid conditions. There was even a design that had two top cap connections
3.
Handle
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A handle is a part of, or attachment to, an object that can be moved or used by hand. The design of type of handle involves substantial ergonomic issues. Handles for tools are an important part of their function, enabling the user to exploit the tools to maximum effect, the three nearly universal requirements of are, Sufficient strength to support the object, or to otherwise transmit the force involved in the task the handle serves. Sufficient length to permit the hand or hands gripping it to exert that force. Sufficiently small circumference to permit the hand or hands to surround it far enough to grip it as solidly as needed to exert that force. Other requirements may apply to specific handles, A sheath or coating on the handle that provides friction against the hand, designs such as recessed car-door handles, reducing the chance of accidental operation, or simply the inconvenience of snagging the handle. Sufficient circumference to distribute the force comfortably and safely over the hand, design to thwart unwanted access, for example, by children or thieves. In these cases many of the requirements may have reduced importance. For example, a child-proof doorknob can be difficult for even an adult to use, one major category of handles are pull handles, where one or more hands grip the handle or handles, and exert force to shorten the distance between the hands and their corresponding shoulders. The three criteria stated above are universal for pull handles, many pull handles are for lifting, mostly on objects to be carried. Horizontal pull handles are widespread, including drawer pulls, handles on latchless doors, the inside controls for opening car doors from inside are usually pull handles, although their function of permitting the door to be pushed open is accomplished by an internal unlatching linkage. Pull handles are also a frequent host of common door handle bacteria such as e-coli, some throwing motions, as in a track-and-field hammer throw, involve pulling on a handle against centrifugal force, in the course of accelerating the thrown object by forcing it into circular motion. Another category of hand-operated device requires grasping and rotating the hand and either the arm or the whole arm. When the grip required is a fist grip, as with a handle that has an arm rather than a knob to twist
4.
Slurry
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A slurry is a thin sloppy mud or cement or, in extended use, any fluid mixture of a pulverized solid with a liquid, often used as a convenient way of handling solids in bulk. Slurries behave in ways like thick fluids, flowing under gravity but are also capable of being pumped if not too thick. It contains large amount of catalyst, in form of sediments hence the denomination of slurry. C, a General Theory of the Hydraulic Transport of Solids in Full Suspension Ravelet, F. Bakir, F. Khelladi, S. Rey, R. Experimental study of transport of large particles in horizontal pipes. Ming, G. Ruixiang, L. Fusheng, N. Liqun, X. Hydraulic Transport of Coarse Gravel—A Laboratory Investigation Into Flow Resistance
5.
Piping and plumbing fitting
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A fitting is used in pipe systems to connect straight pipe or tubing sections, adapt to different sizes or shapes and for other purposes, such as regulating fluid flow. Tubing is sometimes used for piping, especially that flexible enough to be supplied in coiled form. Fittings require money, time, materials and tools to install, valves are technically fittings, but are usually discussed separately. Standard codes are followed when designing a piping system and these codes specify requirements for materials and components, design, fabrication, assembly, erection, examination, inspection and testing of piping. The material with which a pipe is manufactured is often the basis for choosing a pipe, brass or bronze fittings are common in copper piping and plumbing systems. Fire hazards, earthquake resistance and other factors influence the choice of fitting materials. Gaskets are mechanical seals, usually ring-shaped, which seal flange joints, gaskets vary by construction, materials and features. Commonly used gaskets are non-metallic, spiral-wound and ring-joint, non-metallic gaskets are used with flat- or raised-face flanges. Spiral-wound gaskets are used with raised-face flanges, and ring-joint gaskets are used with ring-type joint flanges, stress develops between an RTJ gasket and the flange groove when the gasket is bolted to a flange, leading to plastic deformation of the gasket. Piping or tubing is usually inserted into fittings to make connections, connectors are assigned a gender, abbreviated M or F. An example of this is a 3/4-inch female adapter NPT, which would have a male connection of the same size. This section discusses fittings primarily used in pressurized piping systems, though there is overlap with fittings for low-pressure or non-pressurized systems. Specialized fittings for the latter setups are discussed in the next major subsection, an elbow is installed between two lengths of pipe to allow a change of direction, usually a 90° or 45° angle,22. 5° elbows are also available. The ends may be machined for butt welding, threaded, or socketed, when the ends differ in size, it is known as a reducing elbow. A 90º elbow, also known as a 90 bend,90 ell or quarter bend, attaches readily to plastic, copper, cast iron, steel, and lead, other available materials include silicone, rubber compounds, galvanized steel, and nylon. It is primarily used to connect hoses to valves, water pumps, elbows are also categorized by length. The radius of curvature of a long-radius elbow is 1.5 times the pipe diameter, short elbows, widely available, are typically used in pressurized systems, and in physically tight locations. Long elbows are used in low-pressure gravity-fed systems and other applications where low turbulence and they are available in acrylonitrile butadiene styrene, polyvinyl chloride, chlorinated polyvinyl chloride, and copper, and are used in DWV systems, sewage, and central vacuum systems
6.
Check valve
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A check valve, clack valve, non-return valve or one-way valve is a valve that normally allows fluid to flow through it in only one direction. Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for fluid to leave, there are various types of check valves used in a wide variety of applications. Check valves are often part of household items. Although they are available in a range of sizes and costs, check valves generally are very small, simple. Check valves work automatically and most are not controlled by a person or any control, accordingly. The bodies of most check valves are made of plastic or metal, an important concept in check valves is the cracking pressure which is the minimum upstream pressure at which the valve will operate. Typically the check valve is designed for and can therefore be specified for a specific cracking pressure, heart valves are essentially inlet and outlet check valves for the heart ventricles, since the ventricles act as pumps. Cracking pressure — the inlet pressure at which the first indication of flow occurs, reseal pressure — the pressure at which there is no indication of flow. In some ball check valves, the ball is spring-loaded to help keep it shut, for those designs without a spring, reverse flow is required to move the ball toward the seat and create a seal. The interior surface of the seats of ball check valves are more or less conically-tapered to guide the ball into the seat. Ball check valves are often small, simple, and cheap. They are commonly used in liquid or gel minipump dispenser spigots, spray devices, some rubber bulbs for pumping air, etc. manual air pumps and some other pumps, and refillable dispensing syringes. Although the balls are most often made of metal, they can be made of other materials, high pressure HPLC pumps and similar applications commonly use small inlet and outlet ball check valves with both balls and seats made of artificial ruby, for both hardness and chemical resistance. After prolonged use, such check valves can eventually wear out or the seat can develop a crack, there are similar check valves where the disc is not a ball, but some other shape, such as a poppet energized by a spring. Ball check valves should not be confused with ball valves, which is a different type of valve in which a ball acts as a rotor to stop or direct flow. A diaphragm check valve uses a rubber diaphragm positioned to create a normally-closed valve. Pressure on the side must be greater than the pressure on the downstream side by a certain amount, known as the pressure differential. Once positive pressure stops, the diaphragm automatically flexes back to its closed position
7.
Control valve
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A control valve is a valve used to control fluid flow by varying the size of the flow passage as directed by a signal from a controller. This enables the control of flow rate and the consequential control of process quantities such as pressure, temperature. In automatic control terminology a control valve is termed a final control element, the opening or closing of automatic control valves is usually done by electrical, hydraulic or pneumatic actuators. Normally with a valve, which can be set to any position between fully open and fully closed, valve positioners are used to ensure the valve attains the desired degree of opening. The pneumatic control signals are based on a pressure range of 3-15psi, or more commonly now. The HART, Fieldbus Foundation, and Profibus are the most common protocols, an automatic control valve consists of three main parts in which each part exist in several types and designs, Valve actuator - which moves the valves modulating element, such as ball or butterfly. Valve positioner - Which ensures the valve has reached the degree of opening. This overcomes the problems of friction and wear, Valve body - in which the modulating element, a plug, globe, ball or butterfly, is contained. Taking the example of a valve, there are two control actions possible, Air or current to open - The flow restriction decreases with increased control signal value. Air or current to close - The flow restriction increases with increased control signal value. There can also be failure to safety modes, Air or control signal failure to close - On failure of compressed air to the actuator, the valve closes under spring pressure or by backup power. Air or control signal failure to open - On failure of compressed air to actuator, the modes of failure operation are requirements of the failure to safety process control specification of the plant. In the case of cooling water it may be to open. As the pneumatic operation of valves, compared to motorised operation, has cost and reliability advantages and these are usually located locally to the control valve and convert 4-20 mA to 3-15 psi (or. This signal is fed to the valve actuator or more commonly. This is a controller with a pneumatic nozzle and flapper arrangement. As a mechanical linkage is used for this, the positioner has to be mounted on the valve body, a positioner also allows the use of higher air pressures for valve actuation, which is particularly useful with cylinder type valve actuators. With the development of cheap industrial micro-processors, smart valve positioners have become available since the mid-1980s and are popular for new installations
8.
Pressure
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Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the relative to the ambient pressure. Various units are used to express pressure, Pressure may also be expressed in terms of standard atmospheric pressure, the atmosphere is equal to this pressure and the torr is defined as 1⁄760 of this. Manometric units such as the centimetre of water, millimetre of mercury, Pressure is the amount of force acting per unit area. The symbol for it is p or P, the IUPAC recommendation for pressure is a lower-case p. However, upper-case P is widely used. The usage of P vs p depends upon the field in one is working, on the nearby presence of other symbols for quantities such as power and momentum. Mathematically, p = F A where, p is the pressure, F is the normal force and it relates the vector surface element with the normal force acting on it. It is incorrect to say the pressure is directed in such or such direction, the pressure, as a scalar, has no direction. The force given by the relationship to the quantity has a direction. If we change the orientation of the element, the direction of the normal force changes accordingly. Pressure is distributed to solid boundaries or across arbitrary sections of normal to these boundaries or sections at every point. It is a parameter in thermodynamics, and it is conjugate to volume. The SI unit for pressure is the pascal, equal to one newton per square metre and this name for the unit was added in 1971, before that, pressure in SI was expressed simply in newtons per square metre. Other units of pressure, such as pounds per square inch, the CGS unit of pressure is the barye, equal to 1 dyn·cm−2 or 0.1 Pa. Pressure is sometimes expressed in grams-force or kilograms-force per square centimetre, but using the names kilogram, gram, kilogram-force, or gram-force as units of force is expressly forbidden in SI. The technical atmosphere is 1 kgf/cm2, since a system under pressure has potential to perform work on its surroundings, pressure is a measure of potential energy stored per unit volume. It is therefore related to density and may be expressed in units such as joules per cubic metre. Similar pressures are given in kilopascals in most other fields, where the prefix is rarely used
9.
Fluid dynamics
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In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids. It has several subdisciplines, including aerodynamics and hydrodynamics, before the twentieth century, hydrodynamics was synonymous with fluid dynamics. This is still reflected in names of some fluid dynamics topics, like magnetohydrodynamics and hydrodynamic stability, the foundational axioms of fluid dynamics are the conservation laws, specifically, conservation of mass, conservation of linear momentum, and conservation of energy. These are based on mechanics and are modified in quantum mechanics. They are expressed using the Reynolds transport theorem, in addition to the above, fluids are assumed to obey the continuum assumption. Fluids are composed of molecules that collide with one another and solid objects, however, the continuum assumption assumes that fluids are continuous, rather than discrete. The fact that the fluid is made up of molecules is ignored. The unsimplified equations do not have a general solution, so they are primarily of use in Computational Fluid Dynamics. The equations can be simplified in a number of ways, all of which make them easier to solve, some of the simplifications allow some simple fluid dynamics problems to be solved in closed form. Three conservation laws are used to solve fluid dynamics problems, the conservation laws may be applied to a region of the flow called a control volume. A control volume is a volume in space through which fluid is assumed to flow. The integral formulations of the laws are used to describe the change of mass, momentum. Mass continuity, The rate of change of fluid mass inside a control volume must be equal to the net rate of flow into the volume. Mass flow into the system is accounted as positive, and since the vector to the surface is opposite the sense of flow into the system the term is negated. The first term on the right is the net rate at which momentum is convected into the volume, the second term on the right is the force due to pressure on the volumes surfaces. The first two terms on the right are negated since momentum entering the system is accounted as positive, the third term on the right is the net acceleration of the mass within the volume due to any body forces. Surface forces, such as forces, are represented by F surf. The following is the form of the momentum conservation equation
10.
Automation
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Some processes have been completely automated. The biggest benefit of automation is that it saves labor, however, it is used to save energy and materials and to improve quality, accuracy. The term automation, inspired by the word automatic, was not widely used before 1947. It was during this time industry was rapidly adopting feedback controllers. Automation has been achieved by means including mechanical, hydraulic, pneumatic, electrical, electronic devices and computers. Complicated systems, such as factories, airplanes and ships typically use all these combined techniques. Fundamentally, there are two types of control loop, open loop control, and closed loop control, in open loop control, the control action from the controller is independent of the process output. A good example of this is a central heating boiler controlled only by a timer, so heat is applied for a constant time. In closed loop control, the action from the controller is dependent on the process output. A closed loop controller therefore has a loop which ensures the controller exerts a control action to give a process output the same as the Reference input or set point. For this reason, closed loop controllers are also called feedback controllers, the theoretical basis of closed loop automation is control theory. The control action is the form of the output action. One of the simplest types of control is on-off control, an example is the thermostat used on household appliances which either opens or closes an electrical contact. Sequence control, in which a sequence of discrete operations is performed. An elevator control system is an example of sequence control, a proportional–integral–derivative controller is a control loop feedback mechanism widely used in industrial control systems. Sequential control may be either to a sequence or to a logical one that will perform different actions depending on various system states. An example of an adjustable but otherwise fixed sequence is a timer on a lawn sprinkler, States refer to the various conditions that can occur in a use or sequence scenario of the system. An example is an elevator, which uses logic based on the state to perform certain actions in response to its state
11.
Irrigation
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Irrigation is the method in which a controlled amount of water is supplied to plants at regular intervals for agriculture. It is used to assist in the growing of crops, maintenance of landscapes. Additionally, irrigation also has a few uses in crop production. In contrast, agriculture that only on direct rainfall is referred to as rain-fed or dry land farming. Irrigation systems are used for dust suppression, disposal of sewage. Irrigation is often studied together with drainage, which is the natural or artificial removal of surface and sub-surface water from a given area, Irrigation has been a central feature of agriculture for over 5,000 years and is the product of many cultures. Historically, it was the basis for economies and societies across the globe, archaeological investigation has found evidence of irrigation where the natural rainfall was insufficient to support crops for rainfed agriculture. Ancient Egyptians practiced Basin irrigation using the flooding of the Nile to inundate land plots which had surrounded by dykes. The flood water was held until the sediment had settled before the surplus was returned to the watercourse. The Ancient Nubians developed a form of irrigation by using a device called a sakia. Irrigation began in Nubia some time between the third and second millennium BCE and it largely depended upon the flood waters that would flow through the Nile River and other rivers in what is now the Sudan. In sub-Saharan Africa irrigation reached the Niger River region cultures and civilizations by the first or second millennium BCE and was based on wet season flooding, terrace irrigation is evidenced in pre-Columbian America, early Syria, India, and China. These canals are the earliest record of irrigation in the New World, traces of a canal possibly dating from the 5th millennium BCE were found under the 4th millennium canal. Large scale agriculture was practiced and a network of canals was used for the purpose of irrigation. Ancient Persia as far back as the 6th millennium BCE, where barley was grown in areas where the rainfall was insufficient to support such a crop. The Qanats, developed in ancient Persia in about 800 BCE, are among the oldest known irrigation methods still in use today and they are now found in Asia, the Middle East and North Africa. The system comprises a network of wells and gently sloping tunnels driven into the sides of cliffs. The noria, a wheel with clay pots around the rim powered by the flow of the stream, was first brought into use at about this time
12.
Plumbing
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Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, valves, plumbing fixtures, tanks, heating and cooling, waste removal, and potable water delivery are among the most common uses for plumbing, but it is not limited to these applications. The word derives from the Latin for lead, plumbum, as the first effective pipes used in the Roman era were lead pipes, in the developed world, plumbing infrastructure is critical to public health and sanitation. Boilermakers and pipefitters are not plumbers, although they work with piping as part of their trade, standardized earthen plumbing pipes with broad flanges making use of asphalt for preventing leakages appeared in the urban settlements of the Indus Valley Civilization by 2700 B. C. The Romans used lead pipe inscriptions to prevent water theft, Plumbing reached its early apex in ancient Rome, which saw the introduction of expansive systems of aqueducts, tile wastewater removal, and widespread use of lead pipes. With the Fall of Rome both water supply and sanitation stagnated—or regressed—for well over 1,000 years, improvement was very slow, with little effective progress made until the growth of modern densely populated cities in the 1800s. During this period, public authorities began pressing for better waste disposal systems to be installed. Earlier, the disposal system had merely consisted of collecting waste. Eventually the development of separate, underground water and sewage systems eliminated open sewage ditches, most large cities today pipe solid wastes to sewage treatment plants in order to separate and partially purify the water, before emptying into streams or other bodies of water. For potable water use, galvanized iron piping was commonplace in the United States from the late 1800s until around 1960, after that period, copper piping took over, first soft copper with flared fittings, then with rigid copper tubing utilizing soldered fittings. The use of lead for potable water declined sharply after World War II because of increased awareness of the dangers of lead poisoning, at this time, copper piping was introduced as a better and safer alternative to lead pipes. e. Heating and cooling systems utilizing water to transport thermal energy, as in district heating systems, a water pipe is a pipe or tube, frequently made of plastic or metal, that carries pressurized and treated fresh water to a building, as well as inside the building. For many centuries, lead was the material for water pipes. This was a source of lead-related health problems in the years before the hazards of ingesting lead were fully understood, among these were stillbirths. Lead water pipes were still used in the early 20th century. In addition, lead-tin alloy solder was commonly used to join copper pipes, despite the Romans common use of lead pipes, their aqueducts rarely poisoned people. Unlike other parts of the world where lead pipes cause poisoning, what often causes confusion is the large amount of evidence of widespread lead poisoning, particularly amongst those who would have had easy access to piped water. This was a result of lead being used in cookware and as an additive to processed food and drink
13.
Tap (valve)
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A tap is a valve controlling the release of a liquid or gas. Tap is used in the British Isles and most of the Commonwealth for any type of valve, particularly the fittings that control water supply to bathtubs. Faucet is the most common term in the US, similar in use to tap in British English, spigot is used by professionals in the trade, and typically refers to an outdoor fixture. Silcock, same as spigot, referring to a cock that penetrates a foundation sill, wall hydrant, same as spigot Tap generally refers to a beer tap, though also appears as a descriptor in tap water. In kitchens and bathrooms, mixer taps are commonly used, in this case, hot and cold water from the two valves is mixed before reaching the outlet, allowing the water to emerge at any temperature between that of the hot and cold water supplies. Mixer taps were invented by Thomas Campbell of Saint John, New Brunswick and this helps avoid scalding or uncomfortable chilling as other water loads occur. Rather than two valves, mixer taps frequently use a single, more complex, valve controlled by a single handle. The handle moves up and down to control the amount of water flow, especially for baths and showers, the latest designs are thermostatic mixing valves that do this using a built-in thermostat, and can be mechanical or electronic. There are also faucets with color LEDs to show the temperature of the water, if separate taps are fitted, it may not be immediately clear which tap is hot and which is cold. The hot tap generally has a red indicator while the cold tap generally has a blue or green indicator, in the United States, the taps are frequently also labeled with an H or C. Note that in countries with Romance languages, the letters C for hot and this can create confusion when English speakers visit these countries or vice versa. Mixer taps may have a stripe or arrows indicating which side will give hot. In most countries, there is an arrangement of hot/cold taps. For example, in the United States and many other countries, many installations exist where this standard has been ignored. Mis-assembly of some single-valve mixer taps will exchange hot and cold if the fixture has been plumbed correctly. Most handles on homes are connected to the shaft and fastened down with a screw. This teeth and cog system is used on most modern faucets. Although most of the time a key is on industrial and commercial applications
14.
Tap water
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Tap water is water supplied to a tap. Its uses include drinking, washing, cooking, and the flushing of toilets, Tap water became common in many regions during the 20th century, and is now lacking mainly among people in poverty, especially in developing countries. Tap water is often assumed to be drinking water, especially in developed countries. Usually it is potable, although water quality problems are not rare, household water purification methods such as water filters, boiling, or distillation can be used when tap waters potability is doubted. The application of technologies involved in providing water to homes, businesses. Publicly available treated water has historically been associated with increases in life expectancy. Water-borne diseases are vastly reduced by proper sewage and fresh water availability, specific chemical compounds are often taken out of tap water during the treatment process to adjust the pH or remove contaminants, and chlorine may be added to kill biological toxins. Local geological conditions affecting groundwater are determining factors for the presence of metal ions. Tap water remains susceptible to biological or chemical contamination, in the event of contamination deemed dangerous to public health, government officials typically issue an advisory regarding water consumption. In the case of contamination, residents are usually advised to boil their water before consumption or to use bottled water as an alternative. In the case of contamination, residents may be advised to refrain from consuming tap water entirely until the matter is resolved. In many areas a compound of fluoride is added to tap water in an effort to improve health among the public. In some communities fluoridation remains a controversial issue and this supply may come from several possible sources. Municipal water supply Water wells Processed water from creeks, streams, rivers, lakes, rainwater, domestic water systems have been evolving since people first located their homes near a running water supply, such as a stream or river. The water flow also allowed sending waste water away from the residences, modern indoor plumbing delivers clean, safe, potable water to each service point in the distribution system. It is important that the water not be contaminated by the waste water side of the process system. Historically, this contamination of drinking water has been the largest killer of humans, Tap water can sometimes appear cloudy, often mistaken for mineral impurities in the water. It is usually caused by air coming out of solution due to change in temperature or pressure
15.
Washing machine
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A washing machine is a machine used to wash laundry, such as clothing and sheets. The term is applied to machines that use water as opposed to dry cleaning or ultrasonic cleaners. Laundry detergent is used to clean clothes, and is sold in either powdered or liquid form. Laundering by hand involves soaking, beating, scrubbing, and rinsing dirty textiles, Water for the laundry would be hand carried, heated on a fire for washing, then poured into the tub. That made the warm soapy water precious, it would be reused, first to wash the least soiled clothing, removal of soap and water from the clothing after washing was originally a separate process. First, soap would be rinsed out with clear water, after rinsing, the soaking wet clothing would be formed into a roll and twisted by hand to extract water. The entire process often occupied an entire day of hard work, Clothes washer technology developed as a way to reduce the manual labor spent, providing an open basin or sealed container with paddles or fingers to automatically agitate the clothing. The earliest machines were hand-operated and constructed from wood, while later machines made of metal permitted a fire to burn below the washtub, the earliest special-purpose mechanical washing device was the washboard, invented in 1797 by Nathaniel Briggs of New Hampshire. By the mid-1850s steam-driven commercial laundry machinery were on sale in the UK, technological advances in machinery for commercial and institutional washers proceeded faster than domestic washer design for several decades, especially in the UK. In the United States there was emphasis on developing machines for washing at home, though machines for commercial laundry services were widely used in the late 19th. The rotary washing machine was patented by Hamilton Smith in 1858, as electricity was not commonly available until at least 1930, some early washing machines were operated by a low-speed, single-cylinder hit-and-miss gasoline engine. After the items were washed and rinsed, water had to be removed by twisting, to help reduce this labor, the wringer/mangle machine was developed. As implied by the term mangle, these machines were quite dangerous, especially if powered. A users fingers, hand, arm, or hair could become entangled in the laundry being squeezed, resulting in injuries, unwary bystanders, such as children, could also be caught. Safer mechanisms were developed over time, and the more hazardous designs were eventually outlawed, the mangle used two rollers under spring tension to squeeze water out of clothing and household linen. Each laundry item would be fed through the wringer separately, the first wringers were hand-cranked, but were eventually included as a powered attachment above the washer tub. The wringer would be swung over the wash tub so that extracted wash water would fall back into the tub to be reused for the next load, the modern process of water removal by spinning did not come into use until electric motors were developed. Spinning requires a constant high-speed power source, and was originally done in a device known as an extractor
16.
Dishwasher
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A dishwasher is a mechanical device for cleaning dishware and cutlery. A mix of water and dishwasher detergent is pumped to one or more rotating spray arms, once the wash is finished, the water is drained, more hot water is pumped in and a rinse cycle begins. After the rinse cycle finishes and the water is drained, the dishes are dried using one of several drying methods, typically a rinse aid is used to eliminate water spots for streak-free dishes and glassware resulting from hard water or other reasons. In addition to units, industrial dishwashers are available for use in commercial establishments such as hotels and restaurants. Users operate dishwashers by scraping food from dirty dishes, loading them into the dishwasher racks, adding dishwasher detergent, turning on the device, dishwasher use starts with installation as an appliance. Most home users fix their dishwashers in one place, such as under a countertop, the user scrapes dishes clean, such as by pushing uneaten food from a plate into a waste container as food waste. From the early 2010s, manufacturers have designed consumer dishwashers for use without pre-rinsing or pre-washing, Dishwashers are designed to hold different dishes in different places. For the most common installed two-rack consumer style of dishwasher, the user loads cups, bowls, eating utensils go in the bottom rack into a container, with pointed ends down for safety. Some dishwashers have a rack for utensils. Heavier dishes go on the rack, with large pots facing downward toward the spray nozzle. After the dishwasher is loaded, the user puts dishwasher detergent into the machine, contemporary dishwashers use sensors to determine how much washing is required, and when they finish, will provide clean dishes. Dishwashers and the used in dishwashers are not designed for use with some materials. The washing cycles heat and chemicals can harm kitchen knives and non-stick surface pans, detergents have their own usage restrictions, including not being safe for cleaning various materials like wood or certain metals. The first reports of a mechanical dishwashing device are of an 1850 patent in the United States by Joel Houghton for a hand-powered wood device and this device was made of wood and was cranked by hand while water sprayed onto the dishes. This device was both slow and unreliable, another patent was granted to L. A. Alexander in 1865 that was similar to the first but featured a hand-cranked rack system. Neither device was practical or widely accepted, cochranes inspiration was her frustration at the damage to her good china that occurred when her servants handled it during cleaning. Europes first domestic dishwasher with a motor was invented and manufactured by Miele in 1929. In the United Kingdom, William Howard Livens invented a small, drying elements were even added to his design in 1940
17.
Hot water system
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Water heating is a thermodynamic process that uses an energy source to heat water above its initial temperature. Typical domestic uses of hot water include cooking, cleaning, bathing, in industry, hot water and water heated to steam have many uses. Domestically, water is heated in vessels known as water heaters, kettles, cauldrons, pots. These metal vessels that heat a batch of water do not produce a supply of heated water at a preset temperature. Rarely, hot water occurs naturally, usually from natural hot springs, the temperature varies with the consumption rate, becoming cooler as flow increases. Appliances that provide a supply of hot water are called water heaters, hot water heaters, hot water tanks, boilers, heat exchangers, geysers. These names depend on region, and whether they heat potable or non-potable water, are in domestic or industrial use, in domestic installations, potable water heated for uses other than space heating is also called domestic hot water. Fossil fuels, or solid fuels are used for heating water. These may be consumed directly or may produce electricity that, in turn, electricity to heat water may also come from any other electrical source, such as nuclear power or renewable energy. Densely populated urban areas of some countries provide district heating of hot water and this is especially the case in Scandinavia and Finland. District heating systems supply energy for heating and space heating from waste heat from industries, power plants, incinerators, geothermal heating. Actual heating of tap water is performed in heat exchangers at the consumers premises, generally the consumer has no in-building backup system, due to the expected high availability of district heating systems. Hot water used for space heating may be heated by fossil fuels in a boiler and this is common practice in the US, especially when warm-air space heating is usually employed. Typical sizes for household use range from 75 to 400 liters and these may use electricity, natural gas, propane, heating oil, solar, or other energy sources. Natural gas heaters are most popular in the US and most European countries, since the gas is often conveniently piped throughout cities and towns and currently is the cheapest to use. In the United States, typical natural gas water heaters for households without unusual needs are 40 or 50 US gallons with a burner rated at 34,000 to 40,000 BTU/hour, some models offer High Efficiency and Ultra Low NOx emissions. In North America, these vessels are called hot water tanks, and may incorporate an electrical resistance heater, where hot-water space heating boilers are installed, domestic hot water cylinders are usually heated indirectly by primary water from the boiler, or by an electric immersion heater. In the UK these vessels are called indirect cylinders, or direct cylinders, additionally, if these cylinders form part of a sealed system, providing mains-pressure hot water, they are known as unvented cylinders
18.
Poppet valve
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A poppet valve is a valve typically used to control the timing and quantity of gas or vapour flow into an engine. It consists of a hole, usually round or oval, the portion of the hole where the plug meets with it is referred to as the seat or valve seat. The shaft guides the plug portion by sliding through a valve guide, in exhaust applications a pressure differential helps to seal the valve and in intake valves a pressure differential helps open it. Poppet valves date from at least the 1770s, when James Watt used them on his steam engines, the word poppet shares etymology with puppet, it is from the Middle English popet, from Middle French poupette, which is a diminutive of poupée. The use of the poppet to describe a valve comes from the same word applied to marionettes. In the past, puppet valve was a synonym for poppet valve, however, the main advantage of the poppet valve is that it has no movement on the seat, thus requiring no lubrication. In most cases it is beneficial to have a balanced poppet in a direct-acting valve, less force is needed to move the poppet because all forces on the poppet are nullified by equal and opposite forces. However, they are most well known for their use in combustion and steam engines. Presta and Schrader valves used on pneumatic tyres are examples of poppet valves, the Presta valve has no spring and relies on a pressure differential for opening and closing while being inflated. Poppet valves are employed extensively in the launching of torpedoes from submarines, poppet valves are used in most piston engines to open and close the intake and exhaust ports in the cylinder head. The valve is usually a disk of metal with a long rod known as the valve stem attached to one side. The stem is used to push down on the valve to open it, at high revolutions per minute, the inertia of the spring means it cannot respond quickly enough to return the valve to its seat between cycles, leading to valve float. The engine normally operates the valves by pushing on the stems with cams, the shape and position of the cam determines the valve lift and when and how quickly the valve is opened. The cams are normally placed on a camshaft which is then geared to the crankshaft. On high-performance engines, the camshaft is movable and the cams have a height so, by axially moving the camshaft in relation with the engine RPM. For certain applications the valve stem and disk are made of different steel alloys, or the stem may be hollow and filled with sodium to improve heat transport. Although a better conductor, an aluminium cylinder head requires steel valve seat inserts. Such a condition occurs when changing gear, five valve designs are also in use
19.
Vein
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Veins are blood vessels that carry blood toward the heart. Most veins carry deoxygenated blood from the back to the heart, exceptions are the pulmonary and umbilical veins. In contrast to veins, arteries carry blood away from the heart, veins are less muscular than arteries and are often closer to the skin. There are valves in most veins to prevent backflow, veins are present throughout the body as tubes that carry blood back to the heart. Veins are classified in a number of ways, including superficial vs. deep, pulmonary vs. systemic, superficial veins are those closer to the surface of the body, and have no corresponding arteries. Deep veins are deeper in the body and have corresponding arteries, perforator veins drain from the superficial to the deep veins. These are usually referred to in the limbs and feet. Communicating veins are veins that directly connect superficial veins to deep veins, pulmonary veins are a set of veins that deliver oxygenated blood from the lungs to the heart. Systemic veins drain the tissues of the body and deliver deoxygenated blood to the heart, most veins are equipped with valves to prevent blood flowing in the reverse direction. Veins appear blue because the subcutaneous fat absorbs low-frequency light, permitting only the highly energetic blue wavelengths to penetrate through to the dark vein and reflect back to the viewer. The colour of a vein can be affected by the characteristics of a skin, how much oxygen is being carried in the blood. When a vein is drained of blood and removed from an organism, the largest veins in the human body are the venae cavae. These are two large veins which enter the right atrium of the heart from above and below. The superior vena cava carries blood from the arms and head to the atrium of the heart, while the inferior vena cava carries blood from the legs. The inferior vena cava is retroperitoneal and runs to the right, large veins feed into these two veins, and smaller veins into these. Together this forms the venous system, whilst the main veins hold a relatively constant position, the position of veins person to person can display quite a lot of variation. The pulmonary veins carry relatively oxygenated blood from the lungs to the heart, the superior and inferior venae cavae carry relatively deoxygenated blood from the upper and lower systemic circulations, respectively. The portal venous system is a series of veins or venules that directly connect two capillary beds, examples of such systems include the hepatic portal vein and hypophyseal portal system
20.
Heart valve
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A heart valve normally allows blood to flow in only one direction through the heart. The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart, a heart valve opens or closes incumbent on differential blood pressure on each side. The four main valves in the heart are, The two atrioventricular valves, the valve, and the tricuspid valve, which are between the upper chambers and the lower chambers. The two semilunar valves, the valve and the pulmonary valve, which are in the arteries leaving the heart. The mitral valve and the valve are in the left heart, the tricuspid valve. There are also the coronary sinus and the inferior vena cava valves, the heart valves and the chambers are lined with endocardium. Heart valves separate the atria from the ventricles, or the ventricles from a blood vessel, heart valves are situated around the fibrous rings of the cardiac skeleton. The valves incorporate leaflets or cusps, which are pushed open to allow blood flow, the mitral valve has two cusps, whereas the others have three. There are nodules at the tips of the cusps that make the seal tighter, the pulmonary valve has left, right, and anterior cusps. The aortic valve has left, right, and posterior cusps, the tricuspid valve has anterior, posterior, and septal cusps, and the mitral valve has just anterior and posterior cusps. These are the mitral and tricuspid valves, which are situated between the atria and the ventricles and prevent backflow from the ventricles into the atria during systole and they are anchored to the walls of the ventricles by chordae tendineae, which prevent the valves from inverting. The chordae tendineae are attached to muscles that cause tension to better hold the valve. Together, the muscles and the chordae tendineae are known as the subvalvular apparatus. The function of the apparatus is to keep the valves from prolapsing into the atria when they close. The subvalvular apparatus has no effect on the opening and closure of the valves, however, the peculiar insertion of chords on the leaflet free margin, however, provides systolic stress sharing between chords according to their different thickness. The closure of the AV valves is heard as lub, the first heart sound, the closure of the SL valves is heard as dub, the second heart sound. The mitral valve is called the bicuspid valve because it contains two leaflets or cusps. The mitral valve gets its name from the resemblance to a bishops mitre and it is on the left side of the heart and allows the blood to flow from the left atrium into the left ventricle
21.
Pump
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A pump is a device that moves fluids, or sometimes slurries, by mechanical action. Pumps can be classified into three groups according to the method they use to move the fluid, direct lift, displacement. Pumps operate by some mechanism, and consume energy to mechanical work by moving the fluid. Pumps operate via many energy sources, including operation, electricity, engines, or wind power, come in many sizes. Single stage pump - When in an only one impeller is revolving then it is called single stage pump. Double/ Multi stage pump - When in a two or more than two impellers are revolving then it is called double/ multi stage pump. In biology, many different types of chemical and bio-mechanical pumps have evolved, mechanical pumps may be submerged in the fluid they are pumping or be placed external to the fluid. Pumps can be classified by their method of displacement into positive displacement pumps, impulse pumps, velocity pumps, gravity pumps, steam pumps, there are two basic types of pumps, positive displacement and centrifugal. Although axial-flow pumps are classified as a separate type, they have essentially the same operating principles as centrifugal pumps. A positive displacement pump makes a move by trapping a fixed amount. Some positive displacement pumps use a cavity on the suction side. Liquid flows into the pump as the cavity on the suction side expands, the volume is constant through each cycle of operation. Positive displacement pumps, unlike centrifugal or roto-dynamic pumps, theoretically can produce the flow at a given speed no matter what the discharge pressure. Thus, positive displacement pumps are constant flow machines, however, a slight increase in internal leakage as the pressure increases prevents a truly constant flow rate. A positive displacement pump must not operate against a closed valve on the side of the pump. A relief or safety valve on the side of the positive displacement pump is therefore necessary. The relief valve can be internal or external, the pump manufacturer normally has the option to supply internal relief or safety valves. The internal valve is only used as a safety precaution
22.
Lever
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A lever is a machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum. A lever is a body capable of rotating on a point on itself. On the basis of the location of fulcrum, load and effort and it is one of the six simple machines identified by Renaissance scientists. A lever amplifies an input force to provide an output force. The ratio of the force to the input force is the mechanical advantage of the lever. The word lever entered English about 1300 from Old French, in which the word was levier and this sprang from the stem of the verb lever, meaning to raise. The verb, in turn, goes back to the Latin levare, itself from the adjective levis, the words primary origin is the Proto-Indo-European stem legwh-, meaning light, easy or nimble, among other things. The PIE stem also gave rise to the English word light, the earliest remaining writings regarding levers date from the 3rd century BC and were provided by Archimedes. Give me a place to stand, and I shall move the Earth with it is a remark of Archimedes who formally stated the correct mathematical principle of levers. The distance required to do this might be exemplified in astronomical terms as the distance to the Circinus galaxy - about 9 million light years. It is assumed that in ancient Egypt, constructors used the lever to move, a lever is a beam connected to ground by a hinge, or pivot, called a fulcrum. The ideal lever does not dissipate or store energy, which there is no friction in the hinge or bending in the beam. This is known as the law of the lever, the mechanical advantage of a lever can be determined by considering the balance of moments or torque, T, about the fulcrum. T1 = F1 a, T2 = F2 b where F1 is the force to the lever. The distances a and b are the distances between the forces and the fulcrum. Since the moments of torque must be balanced, T1 = T2, the mechanical advantage of the lever is the ratio of output force to input force, M A = F2 F1 = a b. Levers are classified by the positions of the fulcrum, effort. It is common to call the force the effort and the output force the load or the resistance
23.
Temperature
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A temperature is an objective comparative measurement of hot or cold. It is measured by a thermometer, several scales and units exist for measuring temperature, the most common being Celsius, Fahrenheit, and, especially in science, Kelvin. Absolute zero is denoted as 0 K on the Kelvin scale, −273.15 °C on the Celsius scale, the kinetic theory offers a valuable but limited account of the behavior of the materials of macroscopic bodies, especially of fluids. Temperature is important in all fields of science including physics, geology, chemistry, atmospheric sciences, medicine. The Celsius scale is used for temperature measurements in most of the world. Because of the 100 degree interval, it is called a centigrade scale.15, the United States commonly uses the Fahrenheit scale, on which water freezes at 32°F and boils at 212°F at sea-level atmospheric pressure. Many scientific measurements use the Kelvin temperature scale, named in honor of the Scottish physicist who first defined it and it is a thermodynamic or absolute temperature scale. Its zero point, 0K, is defined to coincide with the coldest physically-possible temperature and its degrees are defined through thermodynamics. The temperature of zero occurs at 0K = −273. 15°C. For historical reasons, the triple point temperature of water is fixed at 273.16 units of the measurement increment, Temperature is one of the principal quantities in the study of thermodynamics. There is a variety of kinds of temperature scale and it may be convenient to classify them as empirically and theoretically based. Empirical temperature scales are historically older, while theoretically based scales arose in the middle of the nineteenth century, empirically based temperature scales rely directly on measurements of simple physical properties of materials. For example, the length of a column of mercury, confined in a capillary tube, is dependent largely on temperature. Such scales are only within convenient ranges of temperature. For example, above the point of mercury, a mercury-in-glass thermometer is impracticable. A material is of no use as a thermometer near one of its phase-change temperatures, in spite of these restrictions, most generally used practical thermometers are of the empirically based kind. Especially, it was used for calorimetry, which contributed greatly to the discovery of thermodynamics, nevertheless, empirical thermometry has serious drawbacks when judged as a basis for theoretical physics. Theoretically based temperature scales are based directly on theoretical arguments, especially those of thermodynamics, kinetic theory and they rely on theoretical properties of idealized devices and materials
24.
Piston
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A piston is a component of reciprocating engines, reciprocating pumps, gas compressors and pneumatic cylinders, among other similar mechanisms. It is the component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder, in some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder wall. An internal combustion engine is acted upon by the pressure of the combustion gases in the combustion chamber space at the top of the cylinder. This force then acts downwards through the rod and onto the crankshaft. The connecting rod is attached to the piston by a swivelling gudgeon pin and this pin is mounted within the piston, unlike the steam engine, there is no piston rod or crosshead. The pin itself is of hardened steel and is fixed in the piston, a few designs use a fully floating design that is loose in both components. All pins must be prevented from moving sideways and the ends of the pin digging into the cylinder wall, gas sealing is achieved by the use of piston rings. These are a number of iron rings, fitted loosely into grooves in the piston. The rings are split at a point in the rim, allowing them to press against the cylinder with a light spring pressure. Two types of ring are used, the rings have solid faces and provide gas sealing, lower rings have narrow edges. There are many proprietary and detail design features associated with piston rings, pistons are cast from aluminium alloys. For better strength and fatigue life, some racing pistons may be forged instead, early pistons were of cast iron, but there were obvious benefits for engine balancing if a lighter alloy could be used. To produce pistons that could survive engine combustion temperatures, it was necessary to develop new alloys such as Y alloy and Hiduminium, a few early gas engines had double-acting cylinders, but otherwise effectively all internal combustion engine pistons are single-acting. During World War II, the US submarine Pompano was fitted with a prototype of the infamously unreliable H. O. R, although compact, for use in a cramped submarine, this design of engine was not repeated. Media related to Internal combustion engine pistons at Wikimedia Commons Trunk pistons are long relative to their diameter and they act both as a piston and cylindrical crosshead. As the connecting rod is angled for much of its rotation, a longer piston helps to support this
25.
Safety valve
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A safety valve is a valve that acts as a fail-safe in a thermal-hydraulics plant. Pilot-operated relief valves are a type of pressure safety valve. Safety valves were first developed for use on steam boilers during the Industrial Revolution, early boilers operating without them were prone to explosion. Vacuum safety valves are used to prevent a tank from collapsing while it is being emptied, when sizing a vacuum safety valve, the calculation method is not defined in any norm, particularly in the hot CIP / cold water scenario, but some manufacturers have developed sizing simulations. The earliest and simplest safety valve was used on a 1679 steam digester and utilized a weight to retain the steam pressure, however, on the Stockton and Darlington Railway, the safety valve tended to go off when the engine hit a bump in the track. A valve less sensitive to sudden accelerations used a spring to contain the steam pressure and this dangerous practice was sometimes used to marginally increase the performance of a steam engine. In 1856, John Ramsbottom invented a tamper-proof spring safety valve that became universal on railways, Safety valves also evolved to protect equipment such as pressure vessels and heat exchangers. The term safety valve should be limited to compressible fluid applications, the two general types of protection encountered in industry are thermal protection and flow protection. Flow protection is characterized by safety valves that are larger than those mounted for thermal protection. They are generally sized for use in situations where significant quantities of gas or high volumes of liquid must be discharged in order to protect the integrity of the vessel or pipeline. This protection can alternatively be achieved by installing a high integrity pressure protection system, Relief valve, an automatic system that is actuated by the static pressure in a liquid-filled vessel. It specifically opens proportionally with increasing pressure, Safety valve, an automatic system that relieves the static pressure on a gas. It usually opens completely, accompanied by a popping sound, Safety relief valve, an automatic system that relieves by static pressure on both gas and liquid. Pilot-operated safety relief valve, a system that relieves on remote command from a pilot. Low pressure safety valve, a system that relieves static pressure on a gas. Used when the difference between the pressure and the ambient atmospheric pressure is small. Vacuum pressure safety valve, a system that relieves static pressure on a gas. Used when the difference between the vessel pressure and the ambient pressure is small, negative and near to atmospheric pressure
26.
Boiler
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A boiler is a closed vessel in which water or other fluid is heated. The fluid does not necessarily boil, the heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, central heating, boiler-based power generation, cooking, and sanitation. The pressure vessel of a boiler is usually made of steel, stainless steel, especially of the austenitic types, is not used in wetted parts of boilers due to corrosion and stress corrosion cracking. In live steam models, copper or brass is used because it is more easily fabricated in smaller size boilers. For much of the Victorian age of steam, the material used for boilermaking was the highest grade of wrought iron. In the 20th century, design practice instead moved towards the use of steel, which is stronger and cheaper, with welded construction, which is quicker and requires less labour. It should be noted, however, that wrought iron boilers corrode far slower than their steel counterparts. This makes the longevity of older wrought-iron boilers far superior to those of welded steel boilers, cast iron may be used for the heating vessel of domestic water heaters. Although such heaters are usually termed boilers in some countries, their purpose is usually to produce hot water, not steam, the brittleness of cast iron makes it impractical for high-pressure steam boilers. The source of heat for a boiler is combustion of any of several fuels, such as wood, coal, oil, electric steam boilers use resistance- or immersion-type heating elements. Nuclear fission is used as a heat source for generating steam, either directly or, in most cases. Heat recovery steam generators use the heat rejected from other such as gas turbine. 18th century Haycock boilers generally produced and stored large volumes of very low-pressure steam and these could burn wood or most often, coal. Flued boiler with one or two large flues—an early type or forerunner of fire-tube boiler, fire-tube boiler, Here, water partially fills a boiler barrel with a small volume left above to accommodate the steam. This is the type of boiler used in nearly all steam locomotives, the heat source is inside a furnace or firebox that has to be kept permanently surrounded by the water in order to maintain the temperature of the heating surface below the boiling point. Fire-tube boilers usually have a low rate of steam production. Fire-tube boilers mostly burn solid fuels, but are adaptable to those of the liquid or gas variety. Water-tube boiler, In this type, tubes filled with water are arranged inside a furnace in a number of possible configurations and this type generally gives high steam production rates, but less storage capacity than the above
27.
Actuator
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An actuator is a component of a machine that is responsible for moving or controlling a mechanism or system. An actuator requires a signal and a source of energy. The control signal is low energy and may be electric voltage or current, pneumatic or hydraulic pressure. The supplied main energy source may be current, hydraulic fluid pressure. When the control signal is received, the actuator responds by converting the energy into mechanical motion, an actuator is the mechanism by which a control system acts upon an environment. The control system can be simple, software-based, a human, the history of the pneumatic actuation system and the hydraulic actuation system dates to around the time of World War II. A hydraulic actuator consists of cylinder or fluid motor that uses hydraulic power to mechanical operation. The mechanical motion gives an output in terms of linear, rotatory or oscillatory motion, as liquids are nearly impossible to compress, a hydraulic actuator can exert a large force. The drawback of this approach is its limited acceleration, the hydraulic cylinder consists of a hollow cylindrical tube along which a piston can slide. The term single acting is used when the pressure is applied to just one side of the piston. The piston can move in one direction, a spring being frequently used to give the piston a return stroke. The term double acting is used when pressure is applied on each side of the piston, a pneumatic actuator converts energy formed by vacuum or compressed air at high pressure into either linear or rotary motion. Pneumatic energy is desirable for main engine controls because it can respond in starting and stopping as the power source does not need to be stored in reserve for operation. Pneumatic actuators enable considerable forces to be produced relatively small pressure changes. These forces are used with valves to move diaphragms to affect the flow of liquid through the valve. An electric actuator is powered by a motor that converts electrical energy into mechanical torque, the electrical energy is used to actuate equipment such as multi-turn valves. It is one of the cleanest and most readily available forms of actuator because it does not directly involve oil or other fossil fuels, actuators which can be actuated by applying thermal or magnetic energy have been used in commercial applications. They tend to be compact, lightweight, economical and with high power density and these actuators use shape memory materials, such as shape memory alloys or magnetic shape-memory alloys
28.
US dollars
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The United States dollar is the official currency of the United States and its insular territories per the United States Constitution. It is divided into 100 smaller cent units, the circulating paper money consists of Federal Reserve Notes that are denominated in United States dollars. The U. S. dollar was originally commodity money of silver as enacted by the Coinage Act of 1792 which determined the dollar to be 371 4/16 grain pure or 416 grain standard silver, the currency most used in international transactions, it is the worlds primary reserve currency. Several countries use it as their currency, and in many others it is the de facto currency. Besides the United States, it is used as the sole currency in two British Overseas Territories in the Caribbean, the British Virgin Islands and Turks and Caicos Islands. A few countries use the Federal Reserve Notes for paper money, while the country mints its own coins, or also accepts U. S. coins that can be used as payment in U. S. dollars. After Nixon shock of 1971, USD became fiat currency, Article I, Section 8 of the U. S. Constitution provides that the Congress has the power To coin money, laws implementing this power are currently codified at 31 U. S. C. Section 5112 prescribes the forms in which the United States dollars should be issued and these coins are both designated in Section 5112 as legal tender in payment of debts. The Sacagawea dollar is one example of the copper alloy dollar, the pure silver dollar is known as the American Silver Eagle. Section 5112 also provides for the minting and issuance of other coins and these other coins are more fully described in Coins of the United States dollar. The Constitution provides that a regular Statement and Account of the Receipts and that provision of the Constitution is made specific by Section 331 of Title 31 of the United States Code. The sums of money reported in the Statements are currently being expressed in U. S. dollars, the U. S. dollar may therefore be described as the unit of account of the United States. The word dollar is one of the words in the first paragraph of Section 9 of Article I of the Constitution, there, dollars is a reference to the Spanish milled dollar, a coin that had a monetary value of 8 Spanish units of currency, or reales. In 1792 the U. S. Congress passed a Coinage Act, Section 20 of the act provided, That the money of account of the United States shall be expressed in dollars, or units. And that all accounts in the offices and all proceedings in the courts of the United States shall be kept and had in conformity to this regulation. In other words, this act designated the United States dollar as the unit of currency of the United States, unlike the Spanish milled dollar the U. S. dollar is based upon a decimal system of values. Both one-dollar coins and notes are produced today, although the form is significantly more common
29.
Inch
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The inch is a unit of length in the imperial and United States customary systems of measurement now formally equal to 1⁄36 yard but usually understood as 1⁄12 of a foot. Derived from the Roman uncia, inch is also used to translate related units in other measurement systems. The English word inch was a borrowing from Latin uncia not present in other Germanic languages. The vowel change from Latin /u/ to English /ɪ/ is known as umlaut, the consonant change from the Latin /k/ to English /tʃ/ or /ʃ/ is palatalisation. Both were features of Old English phonology, inch is cognate with ounce, whose separate pronunciation and spelling reflect its reborrowing in Middle English from Anglo-Norman unce and ounce. In many other European languages, the word for inch is the same as or derived from the word for thumb, the inch is a commonly used customary unit of length in the United States, Canada, and the United Kingdom. It is also used in Japan for electronic parts, especially display screens, for example, three feet two inches can be written as 3′ 2″. Paragraph LXVII sets out the fine for wounds of various depths, one inch, one shilling, an Anglo-Saxon unit of length was the barleycorn. After 1066,1 inch was equal to 3 barleycorns, which continued to be its legal definition for several centuries, similar definitions are recorded in both English and Welsh medieval law tracts. One, dating from the first half of the 10th century, is contained in the Laws of Hywel Dda which superseded those of Dyfnwal, both definitions, as recorded in Ancient Laws and Institutes of Wales, are that three lengths of a barleycorn is the inch. However, the oldest surviving manuscripts date from the early 14th century, john Bouvier similarly recorded in his 1843 law dictionary that the barleycorn was the fundamental measure. He noted that this process would not perfectly recover the standard, before the adoption of the international yard and pound, various definitions were in use. In the United Kingdom and most countries of the British Commonwealth, the United States adopted the conversion factor 1 metre =39.37 inches by an act in 1866. In 1930, the British Standards Institution adopted an inch of exactly 25.4 mm, the American Standards Association followed suit in 1933. By 1935, industry in 16 countries had adopted the industrial inch as it came to be known, in 1946, the Commonwealth Science Congress recommended a yard of exactly 0.9144 metres for adoption throughout the British Commonwealth. This was adopted by Canada in 1951, the United States on 1 July 1959, Australia in 1961, effective 1 January 1964, and the United Kingdom in 1963, effective on 1 January 1964. The new standards gave an inch of exactly 25.4 mm,1.7 millionths of a longer than the old imperial inch and 2 millionths of an inch shorter than the old US inch. The United States retains the 1/39. 37-metre definition for survey purposes and this is approximately 1/8-inch in a mile
30.
Aerosol can
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Aerosol spray is a type of dispensing system which creates an aerosol mist of liquid particles. This is used with a can or bottle that contains a payload, when the containers valve is opened, the payload is forced out of a small hole and emerges as an aerosol or mist. As propellant expands to drive out the payload, only some propellant evaporates inside the can to maintain a constant pressure, outside the can, the droplets of propellant evaporate rapidly, leaving the payload suspended as very fine particles or droplets. Typical payload liquids dispensed in this way are insecticides, deodorants and paints, an atomizer is a similar device that is pressurised by a hand-operated pump rather than by stored propellant. The concepts of aerosol probably go as far back as 1790, the first aerosol spray can patent was granted in Oslo in 1927 to Erik Rotheim, a Norwegian chemical engineer, and a United States patent was granted for the invention in 1931. The patent rights were sold to a United States company for 100,000 Norwegian kroner, the Norwegian Postal Service, Posten Norge, celebrated the invention by issuing a stamp in 1998. In 1939, American Julian S. Kahn received a patent for a spray can. Kahns idea was to mix cream and a propellant from two sources to make whipped cream at home — not a true aerosol in that sense, moreover, in 1949, he disclaimed his first four claims, which were the foundation of his following patent claims. It was not until 1941 that the spray can was first put to good use by Americans Lyle Goodhue and William Sullivan. Their design of a spray can dubbed the bug bomb, is the ancestor of many popular commercial spray products. In 1948, three companies were granted licenses by the United States government to manufacture aerosols, two of the three companies, Chase Products Company and Claire Manufacturing, still manufacture aerosols to this day. The crimp-on valve, used to control the spray in low-pressure aerosols was developed in 1949 by Bronx machine shop proprietor Robert H. Abplanalp. In 1974, Drs. Frank Sherwood Rowland and Mario J. Molina proposed that chlorofluorocarbons, used as propellants in aerosol sprays, contributed to the depletion of Earths ozone layer. In response to this theory, the U. S. Congress passed amendments to the Clean Air Act in 1977 authorizing the Environmental Protection Agency to regulate the presence of CFCs in the atmosphere. The United Nations Environment Programme called for ozone layer research that same year, in 1985, Joe Farman, Brian G. Gardiner, and Jon Shanklin published the first scientific paper detailing the hole in the ozone layer. That same year, the Vienna Convention was signed in response to the UNs authorization, two years later, the Montreal Protocol, which regulated the production of CFCs was formally signed. It came into effect in 1989, the U. S. formally phased out CFCs in 1995. Usually the gas is the vapor of a liquid with boiling point slightly lower than room temperature and this means that inside the pressurized can, the vapor can exist in equilibrium with its bulk liquid at a pressure that is higher than atmospheric pressure, but not dangerously high
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Hydraulics
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Hydraulics is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids or fluids. At a very basic level, hydraulics is the version of pneumatics. Fluid mechanics provides the foundation for hydraulics, which focuses on the applied engineering using the properties of fluids. In fluid power, hydraulics are used for the generation, control, hydraulic topics range through some parts of science and most of engineering modules, and cover concepts such as pipe flow, dam design, fluidics and fluid control circuitry, pumps. The principles of hydraulics are in use naturally in the body within the heart. Free surface hydraulics is the branch of hydraulics dealing with surface flow, such as occurring in rivers, canals, lakes, estuaries. Its sub-field open channel flow studies the flow in open channels, the word hydraulics originates from the Greek word ὑδραυλικός which in turn originates from ὕδωρ and αὐλός. Early uses of water power date back to Mesopotamia and ancient Egypt, other early examples of water power include the Qanat system in ancient Persia and the Turpan water system in ancient Central Asia. The Greeks constructed sophisticated water and hydraulic power systems, an example is the construction by Eupalinos, under a public contract, of a watering channel for Samos, the Tunnel of Eupalinos. An early example of the usage of hydraulic wheel, probably the earliest in Europe, is the Perachora wheel, notable is the construction of the first hydraulic automata by Ctesibius and Hero of Alexandria. Hero describes a number of working machines using hydraulic power, such as the force pump, in ancient China there was Sunshu Ao, Ximen Bao, Du Shi, Zhang Heng, and Ma Jun, while medieval China had Su Song and Shen Kuo. Du Shi employed a waterwheel to power the bellows of a blast furnace producing cast iron, Zhang Heng was the first to employ hydraulics to provide motive power in rotating an armillary sphere for astronomical observation. In ancient Sri Lanka, hydraulics were used in the ancient kingdoms of Anuradhapura. The discovery of the principle of the tower, or valve pit. By the first century AD, several irrigation works had been completed. The coral on the rock at the site includes cisterns for collecting water. They were among the first to use of the siphon to carry water across valleys. They used lead widely in plumbing systems for domestic and public supply, hydraulic mining was used in the gold-fields of northern Spain, which was conquered by Augustus in 25 BC
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Pneumatics
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Pneumatics is a branch of engineering that makes use of gas or pressurized air. Pneumatic systems used in industry are commonly powered by compressed air or compressed inert gases, a centrally located and electrically powered compressor powers cylinders, air motors, and other pneumatic devices. A pneumatic system controlled through manual or automatic solenoid valves is selected when it provides a lower cost, more flexible, pneumatics also has applications in dentistry, construction, mining, and other areas. Pneumatic systems in fixed installations, such as factories, use compressed air because a sustainable supply can be made by compressing atmospheric air, the air usually has moisture removed, and a small quantity of oil is added at the compressor to prevent corrosion and lubricate mechanical components. Factory-plumbed pneumatic-power users need not worry about poisonous leakage, as the gas is usually just air, smaller or stand-alone systems can use other compressed gases that present an asphyxiation hazard, such as nitrogen—often referred to as OFN when supplied in cylinders. Any compressed gas other than air is an asphyxiation hazard—including nitrogen, compressed oxygen would not asphyxiate, but is not used in pneumatically-powered devices because it is a fire hazard, more expensive, and offers no performance advantage over air. Carbon dioxide is an asphyxiant and can be a hazard if vented improperly. The origins of pneumatics can be traced back to the first century when ancient Greek mathematician Hero of Alexandria wrote about his inventions powered by steam or the wind, german physicist Otto von Guericke went a little further. He invented the pump, a device that can draw out air or gas from the attached vessel. He demonstrated the vacuum pump to separate the pairs of copper hemispheres using air pressures, the field of pneumatics has changed considerably over the years. It has moved from small handheld devices to large machines with multiple parts that serve different functions, both pneumatics and hydraulics are applications of fluid power. Pneumatics uses an easily compressible gas such as air or a suitable pure gas—while hydraulics uses relatively incompressible liquid media such as oil, most industrial pneumatic applications use pressures of about 80 to 100 pounds per square inch. Hydraulics applications commonly use from 1,000 to 5,000 psi, simplicity of design and control—Machines are easily designed using standard cylinders and other components, and operate via simple on-off control. Reliability—Pneumatic systems generally have long operating lives and require little maintenance, because gas is compressible, equipment is less subject to shock damage. Gas absorbs excessive force, whereas fluid in hydraulics directly transfers force, compressed gas can be stored, so machines still run for a while if electrical power is lost. Safety—There is a low chance of fire compared to hydraulic oil. Newer machines are usually overload safe, liquid does not absorb any of the supplied energy. Capable of moving much higher loads and providing much higher due to the incompressibility
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Solenoid valve
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A solenoid valve is an electromechanically operated valve. Multiple solenoid valves can be placed together on a manifold, solenoid valves are the most frequently used control elements in fluidics. Their tasks are to shut off, release, dose, distribute or mix fluids and they are found in many application areas. Solenoids offer fast and safe switching, high reliability, long life, good medium compatibility of the materials used, low control power. Besides the plunger-type actuator which is used most frequently, pivoted-armature actuators, there are many valve design variations. Ordinary valves can have ports and fluid paths. A 2-way valve, for example, has 2 ports, if the valve is open, then the two ports are connected and fluid may flow between the ports, if the valve is closed, then ports are isolated. If the valve is open when the solenoid is not energized, similarly, if the valve is closed when the solenoid is not energized, then the valve is termed normally closed. There are also 3-way and more complicated designs, a 3-way valve has 3 ports, it connects one port to either of the two other ports. Solenoid valves are also characterized by how they operate, a small solenoid can generate a limited force. If that force is sufficient to open and close the valve, a typical solenoid force might be 15 N. An application might be a low pressure gas with a small orifice diameter, when high pressures and large orifices are encountered, then high forces are required. To generate those forces, an internally piloted solenoid valve design may be possible, in such a design, the line pressure is used to generate the high valve forces, a small solenoid controls how the line pressure is used. Internally piloted valves are used in dishwashers and irrigation systems where the fluid is water, the pressure might be 80 pounds per square inch, in some solenoid valves the solenoid acts directly on the main valve. Others use a small, complete solenoid valve, known as a pilot, while the second type is actually a solenoid valve combined with a pneumatically actuated valve, they are sold and packaged as a single unit referred to as a solenoid valve. Piloted valves require much less power to control, but they are noticeably slower, a direct acting solenoid valve typically operates in 5 to 10 milliseconds. The operation time of a piloted valve depends on its size, power consumption and supply requirements of the solenoid vary with application, being primarily determined by fluid pressure and line diameter. For example, a popular 3/4150 psi sprinkler valve, intended for 24 VAC residential systems, has an inrush of 7.2 VA
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Electric motor
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An electric motor is an electrical machine that converts electrical energy into mechanical energy. The reverse of this is the conversion of energy into electrical energy and is done by an electric generator. In normal motoring mode, most electric motors operate through the interaction between an electric motors magnetic field and winding currents to generate force within the motor, small motors may be found in electric watches. General-purpose motors with highly standardized dimensions and characteristics provide convenient mechanical power for industrial use, the largest of electric motors are used for ship propulsion, pipeline compression and pumped-storage applications with ratings reaching 100 megawatts. Electric motors may be classified by electric power source type, internal construction, application, type of motion output, perhaps the first electric motors were simple electrostatic devices created by the Scottish monk Andrew Gordon in the 1740s. The theoretical principle behind production of force by the interactions of an electric current. The conversion of energy into mechanical energy by electromagnetic means was demonstrated by the British scientist Michael Faraday in 1821. A free-hanging wire was dipped into a pool of mercury, on which a permanent magnet was placed, when a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a close circular magnetic field around the wire. This motor is often demonstrated in experiments, brine substituting for toxic mercury. Though Barlows wheel was a refinement to this Faraday demonstration. In 1827, Hungarian physicist Ányos Jedlik started experimenting with electromagnetic coils, after Jedlik solved the technical problems of the continuous rotation with the invention of the commutator, he called his early devices electromagnetic self-rotors. Although they were used only for instructional purposes, in 1828 Jedlik demonstrated the first device to contain the three components of practical DC motors, the stator, rotor and commutator. The device employed no permanent magnets, as the fields of both the stationary and revolving components were produced solely by the currents flowing through their windings. His motor set a record which was improved only four years later in September 1838 by Jacobi himself. His second motor was powerful enough to drive a boat with 14 people across a wide river and it was not until 1839/40 that other developers worldwide managed to build motors of similar and later also of higher performance. The first commutator DC electric motor capable of turning machinery was invented by the British scientist William Sturgeon in 1832, following Sturgeons work, a commutator-type direct-current electric motor made with the intention of commercial use was built by the American inventor Thomas Davenport, which he patented in 1837. The motors ran at up to 600 revolutions per minute, and powered machine tools, due to the high cost of primary battery power, the motors were commercially unsuccessful and Davenport went bankrupt. Several inventors followed Sturgeon in the development of DC motors but all encountered the same battery power cost issues, no electricity distribution had been developed at the time
35.
Globe valve
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A globe valve, different from ball valve, is a type of valve used for regulating flow in a pipeline, consisting of a movable disk-type element and a stationary ring seat in a generally spherical body. Globe valves are named for their body shape with the two halves of the body being separated by an internal baffle. This has an opening that forms a seat onto which a plug can be screwed in to close the valve. The plug is called a disc or disk. In globe valves, the plug is connected to a stem which is operated by screw action using a handwheel in manual valves, typically, automated globe valves use smooth stems rather than threaded and are opened and closed by an actuator assembly. Although globe valves in the past had the bodies which gave them their name. However, the term globe valve is often used for valves that have such an internal mechanism. It contains all of the internal parts that will come in contact with the substance being controlled by the valve. The bonnet is connected to the body and provides the containment of the fluid, gas, globe valves are typically two-port valves, although three port valves are also produced mostly in straight-flow configuration. Ports are openings in the body for fluid flowing in or out, the two ports may be oriented straight across from each other or anywhere on the body, or oriented at an angle. Globe valves with ports at such an angle are called angle globe valves, globe valves are mainly used for corrosive or high viscous fluids which solidify at room temperature. This is because straight valves are designed so that the pipe is in line with the inlet pipe. In the case of angle valves, the pipe is directed towards the bottom. This allows the fluid to drain off, in turn, this prevents clogging and/or corrosion of the valve components over a period of time. A globe valve can also have a body in the shape of a Y and this will allow the construction of the valve to be straight at the bottom as opposed to the conventional pot type construction in case of other valves. This will again allow the fluid to pass through without difficulty, the bonnet provides a leakproof closure for the valve body. The threaded section of the stem goes through a hole with matching threads in the bonnet, globe valves may have a screw-in, union, or bolted bonnet. Screw-in bonnet is the simplest bonnet, offering a durable, pressure-tight seal, union bonnet is suitable for applications requiring frequent inspection or cleaning
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Casing (borehole)
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Casing is large diameter pipe that is assembled and inserted into a recently drilled section of a borehole and typically held in place with cement. Casing that is cemented in place, aids the process in several ways. Prevent unstable upper formations from caving in and sticking the drill string or forming large caverns, provides a strong upper foundation to use high-density drilling fluid to continue drilling deeper. Isolates different zones, that may have different pressures or fluids - known as zonal isolation, seals off high pressure zones from the surface, avoiding potential for a blowout Prevents fluid loss into or contamination of production zones. Provides a smooth internal bore for installing production equipment and this decision is often based on subsurface data such as formation pressures, strengths, and makeup, and is balanced against the cost objectives and desired drilling strategy. With the casing set depths determined, hole sizes and casing sizes must follow, the hole drilled for each casing string must be large enough to easily fit the casing inside it, allowing room for cement between the outside of the casing and the hole. Also, the diameter of the first casing string must be large enough to fit the second bit that will continue drilling. Thus, each casing string will have a smaller diameter. The inside diameter of the casing string must accommodate the production tubing and associated hardware such as packers, gas lift mandrels. Casing design for each size is done by calculating the worst conditions that may be faced during drilling, mechanical properties of designed pipes such as collapse resistance, burst pressure, and axial tensile strength must be sufficient for the worst conditions. Casing strings are supported by casing hangers that are set in the wellhead, the wellhead usually is installed on top of the first casing string after it has been cemented in place. Typically, a well contains multiple intervals of casing successively placed within the casing run. It can normally vary from such as 18 to 30. The purpose of surface casing is to isolate freshwater zones so that they are not contaminated during drilling, surface casing is the most strictly regulated due to these environmental concerns, which can include regulation of casing depth and cement quality. A typical size of surface casing is 13⅜ inches, casing placement is selected so that the hydrostatic pressure of the drilling fluid remains at a pressure level that is between formation pore pressures and fracture pressures. In order to reduce cost, a liner may be used which extends just above the shoe of the previous casing interval and it may typically be 7, although many liners match the diameter of the production tubing. Few wells actually produce through casing, since producing fluids can corrode steel or form deposits such as asphaltenes or paraffin waxes, production tubing is therefore installed inside the last casing string and the tubing annulus is usually sealed at the bottom of the tubing by a packer. Tubing is easier to remove for maintenance, replacement, or for various types of workover operations and it is significantly lighter than casing and does not require a drilling rig to run in and out of hole, smaller service rigs are used for this purpose
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Stem (bicycle part)
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The stem is the component on a bicycle that connects the handlebars to the steerer tube of the bicycle fork. Threadless, the stem clamps around the tube, which is not threaded. Somewhat counterintuitively, the term threadless derives not from whether the stem itself is threaded, Quill stems require a threaded headset of specific length for each bicycle model. Threadless stems require an unthreaded steerer tube, which may vary in length for each bicycle model. With the advent of threadless stems, manufacturers no longer need to provide a range of threaded forks for a given model, the steerer tubes are then cut to length to fit upon installation. Unthreaded forks often require less labor to swap than threaded forks, the older of the two handlebar stem styles, quill types have been largely displaced as the industry standard on sport bikes. However, they remain standard on the majority of utility bikes, regardless of price, as well as on less expensive sport bikes and higher-end retro bikes. The quill stem fits down into the inside of the top of the steerer tube to be held in place internally via either a wedge and bolt or a cone-shaped expander nut. With a quill stem, the tube does not protrude above the headset. The quill stem requires a fork that extends up through the headset. Threadless stems, the newer of the two styles, are popular and have displaced quill stems as the industry standard on sport bikes. Threadless stems feature a design where the stem clamps around the outside of the top of the fork steerer tube that protrudes above the headset. Threadless stems are commonly available in lengths up to about 130 millimeters, with threadless stems, a star-nut is driven down into the threadless steerer tube and held in place by two barbed flanges. The top cap bolts into, and pulls against, the star-nut, special adaptors may allow a threaded fork to receive a threadless stem. Threadless stems allow for the carbon fiber or aluminum alloy steerer tubes. Threadless stems can be changed with an allen wrench. The threadless stems centering can be adjusted without disturbing the handlebar height, threadless stems avoid the internal binding or seizing possible with a quill stems wedge or cone bolt. Quill advantages, Quill stems offer the ability to make adjustments to handlebar height
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Metal
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A metal is a material that is typically hard, opaque, shiny, and has good electrical and thermal conductivity. Metals are generally malleable—that is, they can be hammered or pressed permanently out of shape without breaking or cracking—as well as fusible and ductile, about 91 of the 118 elements in the periodic table are metals, the others are nonmetals or metalloids. Some elements appear in both metallic and non-metallic forms, astrophysicists use the term metal to collectively describe all elements other than hydrogen and helium, the simplest two, in a star. The star fuses smaller atoms, mostly hydrogen and helium, to larger ones over its lifetime. In that sense, the metallicity of an object is the proportion of its matter made up of all chemical elements. Many elements and compounds that are not normally classified as metals become metallic under high pressures, the atoms of metallic substances are typically arranged in one of three common crystal structures, namely body-centered cubic, face-centered cubic, and hexagonal close-packed. In bcc, each atom is positioned at the center of a cube of eight others, in fcc and hcp, each atom is surrounded by twelve others, but the stacking of the layers differs. Some metals adopt different structures depending on the temperature, atoms of metals readily lose their outer shell electrons, resulting in a free flowing cloud of electrons within their otherwise solid arrangement. This provides the ability of metallic substances to easily transmit heat, while this flow of electrons occurs, the solid characteristic of the metal is produced by electrostatic interactions between each atom and the electron cloud. This type of bond is called a metallic bond, Metals are usually inclined to form cations through electron loss, reacting with oxygen in the air to form oxides over various timescales. Examples,4 Na + O2 →2 Na2O2 Ca + O2 →2 CaO4 Al +3 O2 →2 Al2O3, the transition metals are slower to oxidize because they form a passivating layer of oxide that protects the interior. Others, like palladium, platinum and gold, do not react with the atmosphere at all, some metals form a barrier layer of oxide on their surface which cannot be penetrated by further oxygen molecules and thus retain their shiny appearance and good conductivity for many decades. The oxides of metals are generally basic, as opposed to those of nonmetals, exceptions are largely oxides with very high oxidation states such as CrO3, Mn2O7, and OsO4, which have strictly acidic reactions. Painting, anodizing or plating metals are good ways to prevent their corrosion, however, a more reactive metal in the electrochemical series must be chosen for coating, especially when chipping of the coating is expected. Water and the two form an electrochemical cell, and if the coating is less reactive than the coatee. Metals in general have high conductivity, high thermal conductivity. Typically they are malleable and ductile, deforming under stress without cleaving, in terms of optical properties, metals are shiny and lustrous. Sheets of metal beyond a few micrometres in thickness appear opaque, although most metals have higher densities than most nonmetals, there is wide variation in their densities, lithium being the least dense solid element and osmium the densest
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Plastic
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Plastic is a material consisting of any of a wide range of synthetic or semi-synthetic organic compounds that are malleable and can be molded into solid objects. Plastics are typically organic polymers of high mass, but they often contain other substances. They are usually synthetic, most commonly derived from petrochemicals, due to their relatively low cost, ease of manufacture, versatility, and imperviousness to water, plastics are used in an enormous and expanding range of products, from paper clips to spaceships. They have already displaced many traditional materials, such as wood, stone, horn and bone, leather, paper, metal, glass, and ceramic, in most of their former uses. In developed countries, about a third of plastic is used in packaging, other uses include automobiles, furniture, and toys. In the developing world, the ratios may be different - for example, the worlds first fully synthetic plastic was bakelite, invented in New York in 1907 by Leo Baekeland who coined the term plastics. Toward the end of the century, one approach to this problem was met with wide efforts toward recycling, the word plastic is derived from the Greek πλαστικός meaning capable of being shaped or molded, from πλαστός meaning molded. The common word plastic should not be confused with the technical adjective plastic, used for insulating parts in electrical fixtures, paper laminated products, thermally insulation foams. Problems include the probability of moldings naturally being dark colors, One of the most expensive commercial polymers. It forms the basis of artistic and commercial acrylic paints when suspended in water with the use of other agents, polytetrafluoroethylene – Heat-resistant, low-friction coatings, used in things like non-stick surfaces for frying pans, plumbers tape and water slides. It is more known as Teflon. Urea-formaldehyde – One of the aminoplasts and used as an alternative to phenolics. Used as an adhesive and electrical switch housings. Early plastics were bio-derived materials such as egg and blood proteins, in 1600 BC, Mesoamericans used natural rubber for balls, bands, and figurines. Treated cattle horns were used as windows for lanterns in the Middle Ages, materials that mimicked the properties of horns were developed by treating milk-proteins with lye. In the 1800s, as industrial chemistry developed during the Industrial Revolution, the development of plastics also accelerated with Charles Goodyears discovery of vulcanization to thermoset materials derived from natural rubber. Parkesine is considered the first man-made plastic, the plastic material was patented by Alexander Parkes, In Birmingham, UK in 1856. It was unveiled at the 1862 Great International Exhibition in London, parkesine won a bronze medal at the 1862 Worlds fair in London
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Brass
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Brass is a metal alloy made of copper and zinc, the proportions of zinc and copper can be varied to create a range of brasses with varying properties. It is an alloy, atoms of the two constituents may replace each other within the same crystal structure. By comparison, bronze is principally an alloy of copper and tin, however, bronze and brass may also include small proportions of a range of other elements including arsenic, phosphorus, aluminium, manganese, and silicon. The term is applied to a variety of brasses. Modern practice in museums and archaeology increasingly avoids both terms for objects in favour of the all-embracing copper alloy. It is also used in zippers, Brass is often used in situations in which it is important that sparks not be struck, such as in fittings and tools used near flammable or explosive materials. Brass has higher malleability than bronze or zinc, the relatively low melting point of brass and its flow characteristics make it a relatively easy material to cast. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard, the density of brass is 8.4 to 8.73 grams per cubic centimetre. Today, almost 90% of all alloys are recycled. Because brass is not ferromagnetic, it can be separated from ferrous scrap by passing the scrap near a powerful magnet, Brass scrap is collected and transported to the foundry where it is melted and recast into billets. Billets are heated and extruded into the form and size. The general softness of brass means that it can often be machined without the use of cutting fluid, aluminium makes brass stronger and more corrosion-resistant. Aluminium also causes a highly beneficial hard layer of oxide to be formed on the surface that is thin, transparent. Tin has an effect and finds its use especially in seawater applications. Combinations of iron, aluminium, silicon and manganese make brass wear and tear resistant, to enhance the machinability of brass, lead is often added in concentrations of around 2%. Since lead has a melting point than the other constituents of the brass. The pattern the globules form on the surface of the brass increases the available surface area which in turn affects the degree of leaching. In addition, cutting operations can smear the lead globules over the surface and these effects can lead to significant lead leaching from brasses of comparatively low lead content
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Bronze
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These additions produce a range of alloys that may be harder than copper alone, or have other useful properties, such as stiffness, ductility, or machinability. The archeological period where bronze was the hardest metal in use is known as the Bronze Age. In the ancient Near East this began with the rise of Sumer in the 4th millennium BC, with India and China starting to use bronze around the same time, everywhere it gradually spread across regions. The Bronze Age was followed by the Iron Age starting from about 1300 BC and reaching most of Eurasia by about 500 BC, the discovery of bronze enabled people to create metal objects which were harder and more durable than previously possible. Bronze tools, weapons, armor, and building such as decorative tiles were harder and more durable than their stone. It was only later that tin was used, becoming the major ingredient of bronze in the late 3rd millennium BC. Tin bronze was superior to arsenic bronze in that the process could be more easily controlled. Also, unlike arsenic, metallic tin and fumes from tin refining are not toxic, the earliest tin-alloy bronze dates to 4500 BCE in a Vinča culture site in Pločnik. Other early examples date to the late 4th millennium BC in Africa, Susa and some ancient sites in China, Luristan, ores of copper and the far rarer tin are not often found together, so serious bronze work has always involved trade. Tin sources and trade in ancient times had a influence on the development of cultures. In Europe, a source of tin was the British deposits of ore in Cornwall. In many parts of the world, large hoards of bronze artefacts are found, suggesting that bronze also represented a store of value, in Europe, large hoards of bronze tools, typically socketed axes, are found, which mostly show no signs of wear. With Chinese ritual bronzes, which are documented in the inscriptions they carry and from other sources and these were made in enormous quantities for elite burials, and also used by the living for ritual offerings. Pure iron is soft, and the process of beating and folding sponge iron to wrought iron removes from the metal carbon. Careful control of the alloying and tempering eventually allowed for wrought iron with properties comparable to modern steel, Bronze was still used during the Iron Age, and has continued in use for many purposes to the modern day. Among other advantages, it does not rust, the weaker wrought iron was found to be sufficiently strong for many uses. Archaeologists suspect that a disruption of the tin trade precipitated the transition. The population migrations around 1200–1100 BC reduced the shipping of tin around the Mediterranean, limiting supplies, there are many different bronze alloys, but typically modern bronze is 88% copper and 12% tin
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Gunmetal
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Gunmetal, also known as red brass in the United States, is a type of bronze – an alloy of copper, tin and zinc. Proportions vary by source, but 88% copper, 8-10% tin, originally used chiefly for making guns, it was eventually superseded in this department by steel. It has a strength of 221 to 310 MPa, a specific gravity of 8.7, a density 8,719 kg/m3, a Brinell hardness of 65 to 74. Gunmetal ingot is a related alloy where the zinc is replaced by 2% lead, modified gunmetal contains lead in addition to the zinc, it is typically composed of 86% copper,9. 5% tin,2. 5% lead and 2% zinc. It is used for gears and bearings, U. S. Government bronze specification G C90500 is composed of 88% copper, 10% tin and 2% zinc. G bronze contains 88% copper, 8% tin and 4% zinc, U. S. Government bronze specification H is composed of 83% copper, 14% tin, 3% zinc and 0. 8% phosphorus. Red brass is used to produce pipes, valves and plumbing fixtures and is considered to offer a mixture of corrosion resistance, strength. It typically contains 85% copper, 5% tin, 5% lead, copper Alloy C23000, which is also known as red brass, contains 84-86% copper,0. 05% each iron and lead, with the balance being zinc. Gunmetal can also mean steel treated to simulate gunmetal bronze, bushings made of this metal are used in machinery. The Victoria Cross, Britains highest award for valour, is traditionally made using gunmetal from a cannon captured at the Siege of Sevastopol during the Crimean War. Gunmetal as a colour is different to the reddish alloy of the same name described above. It is a shade of grey that has a purplish tinge
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Cast iron
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Cast iron is a group of iron-carbon alloys with a carbon content greater than 2%. Its usefulness derives from its low melting temperature. Carbon ranging from 1. 8–4 wt%, and silicon 1–3 wt% are the main alloying elements of cast iron, Iron alloys with less carbon content are known as steel. While this technically makes the Fe–C–Si system ternary, the principle of cast iron solidification can be understood from the simpler binary iron–carbon phase diagram, cast iron tends to be brittle, except for malleable cast irons. It is resistant to destruction and weakening by oxidation, the earliest cast iron artefacts date to the 5th century BC, and were discovered by archaeologists in what is now Jiangsu in China. Cast iron was used in ancient China for warfare, agriculture, during the 15th century, cast iron became utilized for artillery in Burgundy, France, and in England during the Reformation. The first cast iron bridge was built during the 1770s by Abraham Darby III, cast iron is also used in the construction of buildings. Cast iron is made by re-melting pig iron, often along with quantities of iron, steel, limestone, carbon. Phosphorus and sulfur may be burnt out of the iron, but this also burns out the carbon. Depending on the application, carbon and silicon content are adjusted to the desired levels, other elements are then added to the melt before the final form is produced by casting. Cast iron is melted in a special type of blast furnace known as a cupola. After melting is complete, the molten cast iron is poured into a furnace or ladle. Cast irons properties are changed by adding various alloying elements, or alloyants, next to carbon, silicon is the most important alloyant because it forces carbon out of solution. A low percentage of silicon allows carbon to remain in solution forming iron carbide, a high percentage of silicon forces carbon out of solution forming graphite and the production of grey cast iron. Other alloying agents, manganese, chromium, molybdenum, titanium and vanadium counteracts silicon, promotes the retention of carbon, nickel and copper increase strength, and machinability, but do not change the amount of graphite formed. The carbon in the form of graphite results in an iron, reduces shrinkage, lowers strength. Sulfur, largely a contaminant when present, forms iron sulfide, the problem with sulfur is that it makes molten cast iron viscous, which causes defects. To counter the effects of sulfur, manganese is added because the two form into manganese sulfide instead of iron sulfide, the manganese sulfide is lighter than the melt so it tends to float out of the melt and into the slag
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Steel
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Steel is an alloy of iron and other elements, primarily carbon, that is widely used in construction and other applications because of its high tensile strength and low cost. Steels base metal is iron, which is able to take on two forms, body centered cubic and face centered cubic, depending on its temperature. It is the interaction of those allotropes with the elements, primarily carbon. In the body-centred cubic arrangement, there is an atom in the centre of each cube. Carbon, other elements, and inclusions within iron act as hardening agents that prevent the movement of dislocations that otherwise occur in the lattices of iron atoms. The carbon in steel alloys may contribute up to 2. 1% of its weight. Steels strength compared to pure iron is possible at the expense of irons ductility. With the invention of the Bessemer process in the mid-19th century and this was followed by Siemens-Martin process and then Gilchrist-Thomas process that refined the quality of steel. With their introductions, mild steel replaced wrought iron, further refinements in the process, such as basic oxygen steelmaking, largely replaced earlier methods by further lowering the cost of production and increasing the quality of the product. Today, steel is one of the most common materials in the world and it is a major component in buildings, infrastructure, tools, ships, automobiles, machines, appliances, and weapons. Modern steel is generally identified by various grades defined by assorted standards organizations, the noun steel originates from the Proto-Germanic adjective stakhlijan, which is related to stakhla. The carbon content of steel is between 0. 002% and 2. 1% by weight for plain iron–carbon alloys and these values vary depending on alloying elements such as manganese, chromium, nickel, iron, tungsten, carbon and so on. Basically, steel is an alloy that does not undergo eutectic reaction. In contrast, cast iron does undergo eutectic reaction, too little carbon content leaves iron quite soft, ductile, and weak. Carbon contents higher than those of steel make an alloy, commonly called pig iron, while iron alloyed with carbon is called carbon steel, alloy steel is steel to which other alloying elements have been intentionally added to modify the characteristics of steel. Common alloying elements include, manganese, nickel, chromium, molybdenum, boron, titanium, vanadium, tungsten, cobalt, and niobium. Additional elements are important in steel, phosphorus, sulfur, silicon, and traces of oxygen, nitrogen, and copper. Alloys with a higher than 2. 1% carbon content, depending on other element content, cast iron is not malleable even when hot, but it can be formed by casting as it has a lower melting point than steel and good castability properties
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