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Control Valves
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 direct control of flow rate and the consequential control of process quantities such as pressure, temperature, and liquid level. In automatic control terminology, a control valve is termed a "final control element". Operation The opening or closing of automatic control valves is usually done by electrical, hydraulic or pneumatic actuators. Normally with a modulating 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. Air-actuated valves are commonly used because of their simplicity, as they only require a compressed air supply, whereas electrically operated valves require additional cabling and switch gear, and hydraulically actuated valves required high pressure supply and return lines for the hydraulic fluid. The p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valve
A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings, but are usually discussed as a separate category. In an open valve, fluid flows in a direction from higher pressure to lower pressure. The word is derived from the Latin ''valva'', the moving part of a door, in turn from ''volvere'', to turn, roll. The simplest, and very ancient, valve is simply a freely hinged flap which swings down to obstruct fluid (gas or liquid) flow in one direction, but is pushed up by the flow itself when the flow is moving in the opposite direction. This is called a check valve, as it prevents or "checks" the flow in one direction. Modern control valves may regulate pressure or flow downstream and operate on sophisticated automation systems. Valves have many uses, including controlling water for irrigation, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HVAC
Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. "Refrigeration" is sometimes added to the field's abbreviation as HVAC&R or HVACR, or "ventilation" is dropped, as in HACR (as in the designation of HACR-rated circuit breakers). HVAC is an important part of residential structures such as single family homes, apartment buildings, hotels, and senior living facilities; medium to large industrial and office buildings such as skyscrapers and hospitals; vehicles such as cars, trains, airplanes, ships and submarines; and in marine environments, where safe and Sick building syndrome, healthy building conditions are regulated with respect to temperature and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vena Contracta
Vena contracta is the point in a fluid stream where the diameter of the stream is the least, and fluid velocity is at its maximum, such as in the case of a stream issuing out of a nozzle (orifice). (Evangelista Torricelli, 1643). It is a place where the cross section area is minimum. The maximum contraction takes place at a section slightly downstream of the orifice, where the jet is more or less horizontal. The effect is also observed in flow from a tank into a pipe, or a sudden contraction in pipe diameter. Streamlines will converge just downstream of the diameter change, and a region of separated flow occurs from the sharp corner of the diameter change and extends past the vena contracta. Formation of vena contracta can be seen in the venturimeter. Explanation The reason for this phenomenon is that fluid streamlines cannot abruptly change direction. In the case of both the free jet and the sudden pipe diameter change, the streamlines are unable to closely follow the sharp a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loop Performance
Loop performance in control engineering indicates the performance of control loops, such as a regulatory PID loop. Performance refers to the accuracy of a control system's ability to track (output) the desired signals to regulate the plant process variables in the most beneficial and optimised way, without delay or overshoot. Importance Regulatory control loops are critical in automated manufacturing and utility industries like refining, paper and chemicals manufacturing, power generation, among others. They are used to control a particular parameter within a process. The parameter that is being controlled could be temperature, pressure, flow or level of some process. For example, temperature controllers are used in boilers which are used in production of gasoline. Software There are many software applications that help in measuring and analysing the performance of control loops in industrial plants. Benchmarking Benchmarking is the practice of comparing business processes and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fail-safe
In engineering, a fail-safe is a design feature or practice that in the event of a specific type of failure, inherently responds in a way that will cause minimal or no harm to other equipment, to the environment or to people. Unlike inherent safety to a particular hazard, a system being "fail-safe" does not mean that failure is impossible or improbable, but rather that the system's design prevents or mitigates unsafe consequences of the system's failure. That is, if and when a "fail-safe" system fails, it remains at least as safe as it was before the failure. Since many types of failure are possible, failure mode and effects analysis is used to examine failure situations and recommend safety design and procedures. Some systems can never be made fail-safe, as continuous availability is needed. Redundancy, fault tolerance, or contingency plans are used for these situations (e.g. multiple independently controlled and fuel-fed engines). Examples Mechanical or physical Examples inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pl Control Valve
PL, P.L., Pl, or .pl may refer to: Businesses and organizations Government and political * Partit Laburista, a Maltese political party * Liberal Party (Brazil, 2006), a Brazilian political party * Liberal Party (Moldova), a Moldovan political party * Liberal Party (Rwanda), a Rwandan political party * Parlamentarische Linke, a parliamentary caucus in Germany * Patriotic League (Bosnia and Herzegovina) (Bosnian: ''Patriotska Liga''), a military organisation of the Republic of Bosnia and Herzegovina * Philippine Legislature, a legislature that existed in the Philippines from 1907 to 1935 * Progressive Labor Party (United States), a United States communist party Sports leagues * Premier League, the top English association football league * Pacific League, one of the two leagues in Japan's Nippon Professional Baseball * Pioneer Baseball League, a Rookie league in Minor League Baseball * Pioneer Football League, NCAA FCS conference Other businesses and organizations * Airstars Airw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smart Current Loop Positioner
Smart or SMART may refer to: Arts and entertainment * ''Smart'' (Hey! Say! JUMP album), 2014 * Smart (Hotels.com), former mascot of Hotels.com * ''Smart'' (Sleeper album), 1995 debut album by Sleeper * ''SMart'', a children's television series about art on CBBC Businesses and brands * S-Mart, a Mexican grocery store chain * SMART (advertising agency), an Australian company * SmartCell, a network operator in Nepal * Smart Communications, a cellular service provider in the Philippines * Smart Technologies, a company providing group collaboration tools * Smart Telecom, a network operator in the Republic of Ireland * Smart (cigarette), an Austrian brand * Smart (drink), a brand of fruit-flavored soda produced by The Coca-Cola Company for Mainland China Computing * Smart device, an electronic device connected to other devices or networks wirelessly * Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.), a standard used in computer storage devices * SMART Informat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analogue Control Loop Evolution
Analog or analogue may refer to: Computing and electronics * Analog signal, in which information is encoded in a continuous variable ** Analog device, an apparatus that operates on analog signals *** Analog electronics, circuits which use analog signals **** Analog computer, a computer that uses analog signals ** Analog recording, information recorded using an analog signal * Functional analog (electronic), a system that fulfills the same function as another * Structural analog (electronic), a system that has the same structure as another Entertainment Albums and songs * ''Analog'' (album), an album by Eureka Farm * "Analog" (song), a song by Tyler, The Creator, featuring Hodgy Beats, from ''Goblin'' * ''Analogue'' (album), a 2005 album by A-ha ** "Analogue" (All I Want), the title track of the 2005 album by A-ha Books and magazines * ''Analog Science Fiction and Fact'', a science-fiction magazine * ''ANALOG Computing'', a 1981–1989 magazine about Atari computers * '' An ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fieldbus
Fieldbus is the name of a family of industrial computer networks used for real-time distributed control. Fieldbus profiles are standardized by the International Electrotechnical Commission (IEC) as IEC 61784/61158. A complex automated industrial system is typically structured in hierarchical levels as a distributed control system (DCS). In this hierarchy the upper levels for production managements are linked to the direct control level of programmable logic controllers (PLC) via a non-time-critical communications system (e.g. Ethernet). The fieldbus links the PLCs of the direct control level to the components in the plant of the field level such as sensors, actuators, electric motors, console lights, switches, valves and contactors and replaces the direct connections via current loops or digital I/O signals. The requirement for a fieldbus are therefore time-critical and cost sensitive. Since the new millennium a number of fieldbuses based on Real-time Ethernet have been establish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Highway Addressable Remote Transducer Protocol
The HART Communication Protocol (Highway Addressable Remote Transducer) is a hybrid analog+digital industrial automation open protocol. Its most notable advantage is that it can communicate over legacy 4–20 mA analog instrumentation current loops, sharing the pair of wires used by the analog-only host systems. HART is widely used in process and instrumentation systems ranging from small automation applications up to highly sophisticated industrial applications. According to Emerson,Emerson ''https://web.archive.org/web/20181107104043/https://www.automation.com/automation-news/industry/emerson-proves-advancements-in-eddl-electronic-device-description-language-technology'', rev. 2005-04-14 due to the huge installation base of 4–20 mA systems throughout the world, the HART Protocol is one of the most popular industrial protocols today. HART protocol has made a good transition protocol for users who wished to use the legacy 4–20 mA signals, but wanted to implement a "smart" protoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4-20mA
In electrical signalling an analog current loop is used where a device must be monitored or controlled remotely over a pair of conductors. Only one current level can be present at any time. A major application of current loops is the industry de facto standard 4–20 mA current loop for process control applications, where they are extensively used to carry signals from process instrumentation to PID controllers, SCADA systems, and programmable logic controllers (PLCs). They are also used to transmit controller outputs to the modulating field devices such as control valves. These loops have the advantages of simplicity and noise immunity, and have a large international user and equipment supplier base. Some 4–20 mA field devices can be powered by the current loop itself, removing the need for separate power supplies, and the "smart" HART protocol uses the loop for communications between field devices and controllers. Various automation protocols may replace analog cur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
