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55-453: Not to be confused with Demag . Demak is on the north coast of Central Java province, on the island of Java, Indonesia. Demak, Demak , modern-day large town Demak Sultanate , sixteenth century sultanate Demak Regency , modern-day regency around the town [REDACTED] Topics referred to by the same term This disambiguation page lists articles about distinct geographical locations with

110-502: A compressor will not function unless fitted with features such as stationary vanes with variable angles (known as variable inlet guide vanes and variable stators), the ability to allow some air to escape part-way along the compressor (known as interstage bleed) and being split into more than one rotating assembly (known as twin spools, for example). Axial compressors can have high efficiencies; around 90% polytropic at their design conditions. However, they are relatively expensive, requiring

165-453: A consortium of Siemens and Bosch. Siemens and Bosch then divested the different units between them and the Demag units became a part of Siemens. These were Demag plastics technology (with Krauss-Maffei), Demag compressor technology and Demag conveyor technology, which included the Demag mobile cranes and the crane manufacturer Gottwald. In the autumn of 2001, Siemens sold the core activities of

220-654: A crankshaft. They can be either stationary or portable, can be single or multi-staged, and can be driven by electric motors or internal combustion engines. Small reciprocating compressors from 5 to 30  horsepower (hp) are commonly seen in automotive applications and are typically for intermittent duty. Larger reciprocating compressors well over 1,000 hp (750 kW) are commonly found in large industrial and petroleum applications. Discharge pressures can range from low pressure to very high pressure (>18000 psi or 124 MPa). In certain applications, such as air compression, multi-stage double-acting compressors are said to be

275-444: A hermetic and semi-hermetic is that there is no route for the gas to leak out of the system. The main advantages of open compressors is that they can be driven by any motive power source, allowing the most appropriate motor to be selected for the application, or even non-electric power sources such as an internal combustion engine or steam turbine , and secondly the motor of an open compressor can be serviced without opening any part of

330-450: A hermetic or semi-hermetic system can sit unused for years, and can usually be started up again at any time without requiring maintenance or experiencing any loss of system pressure. Even well lubricated seals will leak a small amount of gas over time, particularly if the refrigeration gasses are soluble in the lubricating oil, but if the seals are well manufactured and maintained this loss is very low. The disadvantage of hermetic compressors

385-425: A large number of components, tight tolerances and high quality materials. Axial compressors are used in medium to large gas turbine engines, natural gas pumping stations, and some chemical plants. Compressors used in refrigeration systems must exhibit near-zero leakage to avoid the loss of the refrigerant if they are to function for years without service. This necessitates the use of very effective seals, or even

440-423: A positive displacement compressor is one that operates by drawing in a discrete volume of gas from its inlet then forcing that gas to exit via the compressor's outlet. The increase in the pressure of the gas is due, at least in part, to the compressor pumping it at a mass flow rate which cannot pass through the outlet at the lower pressure and density of the inlet. Reciprocating compressors use pistons driven by

495-410: A pump is to pressurize and transport liquids. The main and important types of gas compressors are illustrated and discussed below: A positive displacement compressor is a system that compresses the air by the displacement of a mechanical linkage reducing the volume (since the reduction in volume due to a piston in thermodynamics is considered as positive displacement of the piston). Put another way,

550-1053: A rotating disk or impeller in a shaped housing to force the gas to the rim of the impeller, increasing the velocity of the gas. A diffuser (divergent duct) section converts the velocity energy to pressure energy. They are primarily used for continuous, stationary service in industries such as oil refineries , chemical and petrochemical plants and natural gas processing plants. Their application can be from 100 horsepower (75 kW) to thousands of horsepower. With multiple staging, they can achieve high output pressures greater than 1,000 psi (6.9 MPa). This type of compressor, along with screw compressors, are extensively used in large refrigeration and air conditioning systems. Magnetic bearing (magnetically levitated) and air bearing centrifugal compressors exist. Many large snowmaking operations (like ski resorts ) use this type of compressor. They are also used in internal combustion engines as superchargers and turbochargers . Centrifugal compressors are used in small gas turbine engines or as

605-574: A world leader in the manufacturing of injection moulding machines. In 1973 the ownership of Demag was assumed by the Mannesmann group, based in Düsseldorf . In 1983 Mannesmann-Demag AG and Wean United, Inc. of Pittsburgh , United States, founded a daughter company to produce steel working equipment, Mannesmann Demag Wean Co. A joint venture with the Japanese manufacturer Komatsu led to spinning off of

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660-522: Is a reciprocating compressor with the piston being the rotor of a linear motor. This type of compressor can compress a wide range of gases, including refrigerant, hydrogen, and natural gas. Because of this, it finds use in a wide range of applications in many different industries and can be designed to a wide range of capacities, by varying size, number of cylinders, and cylinder unloading. However, it suffers from higher losses due to clearance volumes, resistance due to discharge and suction valves, weighs more,

715-430: Is a specific type of gas compressor. Many compressors can be staged, that is, the gas is compressed several times in steps or stages, to increase discharge pressure. Often, the second stage is physically smaller than the primary stage, to accommodate the already compressed gas without reducing its pressure. Each stage further compresses the gas and increases its pressure and also temperature (if inter cooling between stages

770-423: Is difficult to maintain due to having a large number of moving parts, and it has inherent vibration. An ionic liquid piston compressor , ionic compressor or ionic liquid piston pump is a hydrogen compressor based on an ionic liquid piston instead of a metal piston as in a piston-metal diaphragm compressor . Rotary screw compressors use two meshed rotating positive-displacement helical screws to force

825-457: Is higher than the output pressure of the compressor. This can cause gases to flow back and forth between the compressor and whatever is connected to its discharge line, causing oscillations. Diagonal or mixed-flow compressors are similar to centrifugal compressors, but have a radial and axial velocity component at the exit from the rotor. The diffuser is often used to turn diagonal flow to an axial rather than radial direction. Comparative to

880-406: Is higher, require highly precise CNC machining, the impeller needs to rotate at high speeds making small compressors impractical, and surging becomes more likely. Surging is gas flow reversal, meaning that the gas goes from the discharge to the suction side, which can cause serious damage, specially in the compressor bearings and its drive shaft. It is caused by a pressure on the discharge side that

935-432: Is less efficient than other compressor types due to losses from the clearance volume. A scroll compressor , also known as scroll pump and scroll vacuum pump , uses two interleaved spiral-like vanes to pump or compress fluids such as liquids and gases . The vane geometry may be involute , archimedean spiral , or hybrid curves. They operate more smoothly, quietly, and reliably than other types of compressors in

990-436: Is not used). Compressors are similar to pumps : both increase the pressure on a fluid (such as a gas) and both can transport the fluid through a pipe . The main distinction is that the focus of a compressor is to change the density or volume of the fluid, which is mostly only achievable on gases. Gases are compressible, while liquids are relatively incompressible, so compressors are rarely used for liquids. The main action of

1045-469: Is that the motor drive cannot be repaired or maintained, and the entire compressor must be replaced if a motor fails. A further disadvantage is that burnt-out windings can contaminate the whole systems, thereby requiring the system to be entirely pumped down and the gas replaced (This can also happen in semi hermetic compressors where the motor operates in the refrigerant). Typically, hermetic compressors are used in low-cost factory-assembled consumer goods where

1100-486: Is the most important or one of the most important factors to consider when designing a refrigeration or air conditioning system. This type of compressor was used as the supercharger on Volkswagen G60 and G40 engines in the early 1990s. When compared with reciprocating and rolling piston compressors, scroll compressors are more reliable since they have fewer components and have a simpler structure, are more efficient since they have no clearance volume nor valves, and possess

1155-794: The Berlin Staaken plant. During the buildup to, and during World War II, Demag-designed halftrack military vehicles, both in unarmored "artillery tractor" models in the late 1930s, the basis for the powertrain of their armored Sd.Kfz. 250 , which itself played an important role during the war, with just over 6,600 built by Demag and their subcontractors. In 1954, Demag developed their first hydraulic excavators. Demag would soon expand into construction machines, vehicle cranes, moving and conveying engineering (workshop crane and control devices), steel mill technology (complete metallurgical plants, in particular continuous casting equipment), compressors , and compressed air engineering. The company also became

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1210-515: The Demag brand name in 2021. In 2017 Konecranes from Finland purchases the MHPS division from Terex. In addition to becoming again a European owned company, Konecranes also revives the Demag name as the MHPS becomes the Demag Cranes & Components Gmbh Gas compressor A compressor is a mechanical device that increases the pressure of a gas by reducing its volume . An air compressor

1265-446: The advantages both of surging less and not vibrating so much. But, when compared with screw and centrifugal compressors, scroll compressors have lower efficiencies and smaller capacities. A diaphragm compressor (also known as a membrane compressor ) is a variant of the conventional reciprocating compressor. The compression of gas occurs by the movement of a flexible membrane, instead of an intake element. The back-and-forth movement of

1320-441: The air drier, and the selection of air drier is always 1.5 times volumetric delivery of the compressor. Designs with a single screw or three screws instead of two exist. Screw compressors have fewer moving components, larger capacity, less vibration and surging, can operate at variable speeds, and typically have higher efficiency. Small sizes or low rotor speeds are not practical due to inherent leaks caused by clearance between

1375-649: The biggest crane building company in Germany employing 250-300 people. The company was a manufacturer of industrial cranes that included types like, bridge cranes , hoist (device) , overhead cranes , Gantry crane to name a few. In 1910 came the hour of the Deutsche Maschinenfabrik in Duisburg – known worldwide by its telegram abbreviation Demag (now Demag Cranes & Components GmbH ). In 1973 The Mannesmann group assumed ownership of Demag. The Demag company

1430-415: The clearance volume between the piston and the compressor casing, it's 40% to 50% smaller and lighter for a given capacity (which can impact material and shipping costs when used in a product), causes less vibration, has fewer components and is more reliable than a reciprocating compressor. But its structure does not allow capacities beyond 5 refrigeration tons, is less reliable than other compressor types, and

1485-407: The compression cavities or screws and compressor housing. They depend on fine machining tolerances to avoid high leakage losses and are prone to damage if operated incorrectly or poorly serviced. Rotary vane compressors consist of a rotor with a number of blades inserted in radial slots in the rotor. The rotor is mounted offset in a larger housing that is either circular or a more complex shape. As

1540-509: The conventional centrifugal compressor (of the same stage pressure ratio), the value of the speed of the mixed flow compressor is 1.5 times larger. Axial compressors are dynamic rotating compressors that use arrays of fan-like airfoils to progressively compress a fluid. They are used where high flow rates or a compact design are required. The arrays of airfoils are set in rows, usually as pairs: one rotating and one stationary. The rotating airfoils, also known as blades or rotors , accelerate

1595-408: The cost of repair and labor is high compared to the value of the device, and it would be more economical to just purchase a new device or compressor. Semi-hermetic compressors are used in mid-sized to large refrigeration and air conditioning systems, where it is cheaper to repair and/or refurbish the compressor compared to the price of a new one. A hermetic compressor is simpler and cheaper to build than

1650-506: The elimination of all seals and openings to form a hermetic system. These compressors are often described as being either hermetic , open , or semi-hermetic , to describe how the compressor is enclosed and how the motor drive is situated in relation to the gas or vapor being compressed. Some compressors outside of refrigeration service may also be hermetically sealed to some extent, typically when handling toxic, polluting, or expensive gasses, with most non-refrigeration applications being in

1705-520: The final compression stage of medium-sized gas turbines. Centrifugal compressors are the largest available compressors, offer higher efficiencies under partial loads, may be oil-free when using air or magnetic bearings which increases the heat transfer coefficient in evaporators and condensers, weigh up to 90% less and occupy 50% less space than reciprocating compressors, are reliable and cost less to maintain since less components are exposed to wear, and only generate minimal vibration. But, their initial cost

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1760-409: The fluid. The stationary airfoils, also known as stators or vanes, decelerate and redirect the flow direction of the fluid, preparing it for the rotor blades of the next stage. Axial compressors are almost always multi-staged, with the cross-sectional area of the gas passage diminishing along the compressor to maintain an optimum axial Mach number . Beyond about 5 stages or a 4:1 design pressure ratio

1815-478: The former Demag (Demag Cranes & Components, Gottwald and MPM) to Kohlberg Kravis Roberts (KKR). Those that remained were restructured and became part of the new company focus for future growth. For example parts of the conveying engineering activities remained with Siemens under the name Dematic . In 2002 Siemens sold the Demag Mobile Cranes division, which has not been a part of the package sold to KKR,

1870-665: The gas into a smaller space. These are usually used for continuous operation in commercial and industrial applications and may be either stationary or portable. Their application can be from 3 horsepower (2.2 kW) to over 1,200 horsepower (890 kW) and from low pressure to moderately high pressure (>1,200 psi or 8.3 MPa). The classifications of rotary screw compressors vary based on stages, cooling methods, and drive types among others. Rotary screw compressors are commercially produced in Oil Flooded, Water Flooded and Dry type. The efficiency of rotary compressors depends on

1925-430: The injection moulding manufacturing was merged with that of Krauss-Maffei , which had itself been acquired by Mannesmann from 1989, to form Mannesmann Demag Krauss Maffei and formed part of Mannesmann Atecs (for Advanced Technologies), a holding company for all of Mannesmann's non-telecom activities. Krauss Maffei's general equipment manufacturing and defence portions later passed to Linke/Hoffmann/Busch. The holding company

1980-521: The large-scale excavation operations and their renaming as Komatsu Mining. The steel and rolling mill technology division, based in Duisburg , was spun off to Schloemann-Siemag (SMS) and continues today under the name SMS group. The compressor division was sold in 1996 to CompAir, which was then part of the British Siebe/Invensys group, but has since become an independent company. Later (1999),

2035-677: The lower volume range. Often, one of the scrolls is fixed, while the other orbits eccentrically without rotating, thereby trapping and pumping or compressing pockets of fluid between the scrolls. Due to minimum clearance volume between the fixed scroll and the orbiting scroll, these compressors have a very high volumetric efficiency . These compressors are extensively used in air conditioning and refrigeration because they are lighter, smaller and have fewer moving parts than reciprocating compressors and they are also more reliable. They are more expensive though, so peltier coolers or rotary and reciprocating compressors may be used in applications where cost

2090-427: The membrane is driven by a rod and a crankshaft mechanism. Only the membrane and the compressor box come in contact with the gas being compressed. The degree of flexing and the material constituting the diaphragm affects the maintenance life of the equipment. Generally stiff metal diaphragms may only displace a few cubic centimeters of volume because the metal cannot endure large degrees of flexing without cracking, but

2145-549: The most efficient compressors available, and are typically larger, and more costly than comparable rotary units. Another type of reciprocating compressor, usually employed in automotive cabin air conditioning systems, is the swash plate or wobble plate compressor, which uses pistons moved by a swash plate mounted on a shaft (see axial piston pump ). Household, home workshop, and smaller job site compressors are typically reciprocating compressors 1.5 hp (1.1 kW) or less with an attached receiver tank. A linear compressor

2200-413: The necessary volumetric efficiency to achieve pressures up to about 13 bar (1,300 kPa; 190 psi) in a single stage. A rotary vane compressor is well suited to electric motor drive and is significantly quieter in operation than the equivalent piston compressor. Rotary vane compressors can have mechanical efficiencies of about 90%. The Rolling piston in a rolling piston style compressor plays

2255-544: The part of a partition between the vane and the rotor. Rolling piston forces gas against a stationary vane. 2 of these compressors can be mounted on the same shaft to increase capacity and reduce vibration and noise. A design without a spring is known as a swing compressor. In refrigeration and air conditioning, this type of compressor is also known as a rotary compressor, with rotary screw compressors being also known simply as screw compressors. It offers higher efficiency than reciprocating compressors due to less losses from

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2310-432: The petrochemical industry. In hermetic and most semi-hermetic compressors, the compressor and motor driving the compressor are integrated, and operate within the pressurized gas envelope of the system. The motor is designed to operate in, and be cooled by, the refrigerant gas being compressed. Open compressors have an external motor driving a shaft that passes through the body of the compressor and rely on rotary seals around

2365-427: The refrigerant system. An open pressurized system such as an automobile air conditioner can be more susceptible to leak its operating gases. Open systems rely on lubricant in the system to splash on pump components and seals. If it is not operated frequently enough, the lubricant on the seals slowly evaporates, and then the seals begin to leak until the system is no longer functional and must be recharged. By comparison,

2420-494: The right depicts a three-stage diaphragm compressor used to compress hydrogen gas to 6,000 psi (41 MPa) for use in a prototype compressed hydrogen and compressed natural gas (CNG) fueling station built in downtown Phoenix, Arizona by the Arizona Public Service company (an electric utilities company). Reciprocating compressors were used to compress the natural gas . The reciprocating natural gas compressor

2475-691: The rotor turns, blades slide in and out of the slots keeping contact with the outer wall of the housing. Thus, a series of increasing and decreasing volumes is created by the rotating blades. Rotary vane compressors are, with piston compressors one of the oldest of compressor technologies. With suitable port connections, the devices may be either a compressor or a vacuum pump. They can be either stationary or portable, can be single or multi-staged, and can be driven by electric motors or internal combustion engines. Dry vane machines are used at relatively low pressures (e.g., 2 bar or 200 kPa or 29 psi) for bulk material movement while oil-injected machines have

2530-559: The same name. If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Demak&oldid=977055372 " Category : Place name disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Demag The roots of Demag date back prior to its formation, but became Märkische Maschinenbau-Anstalt, Ludwig A.-G in 1906 as

2585-427: The shaft to retain the internal pressure. The difference between the hermetic and semi-hermetic, is that the hermetic uses a one-piece welded steel casing that cannot be opened for repair; if the hermetic fails it is simply replaced with an entire new unit. A semi-hermetic uses a large cast metal shell with gasketed covers with screws that can be opened to replace motor and compressor components. The primary advantage of

2640-447: The stiffness of a metal diaphragm allows it to pump at high pressures. Rubber or silicone diaphragms are capable of enduring deep pumping strokes of very high flexion, but their low strength limits their use to low-pressure applications, and they need to be replaced as plastic embrittlement occurs. Diaphragm compressors are used for hydrogen and compressed natural gas ( CNG ) as well as in a number of other applications. The photograph on

2695-721: The takeover of Demag when it purchased 82% of the shares of Demag Cranes Ag. Demag became the Terex Material Handling & Port Solutions (MHPS) division. In 2008 KRR sold MPM to Sumitomo Heavy Industries and is known today as Sumitomo (SHI) Demag. In 2019 Terex decided to sell the Mobile Cranes division to the Japan based Tadano and it became the Tadano Demag Gmbh. In 2020 Tadano Demag Gmbh filed for insolvency. Surviving restructuring Tadano announced that it will drop

2750-519: The water. The weight of falling water compresses the air in the top of the chamber. A submerged outlet from the chamber allows water to flow to the surface at a lower height than the intake. An outlet in the roof of the chamber supplies the compressed air to the surface. A facility on this principle was built on the Montreal River at Ragged Shutes near Cobalt, Ontario in 1910 and supplied 5,000 horsepower to nearby mines. Centrifugal compressors use

2805-459: Was developed by Sertco . The prototype alternative fueling station was built in compliance with all of the prevailing safety, environmental and building codes in Phoenix to demonstrate that such fueling stations could be built in urban areas. Also known as a trompe . A mixture of air and water generated through turbulence is allowed to fall into a subterranean chamber where the air separates from

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2860-721: Was formed finally 1910 in Duisburg through the union of the Märkische Maschinenbau-Anstalt L. Stuckenholz AG , the Duisburg Mechanical Engineering AG , and the Benrath Machine Works GmbH . The Märkische Maschinenbau-Anstalt L. Stuckenholz AG traces back to the machine factory Mechanische Werkstätten Harkort & Co. , founded 1819 in Wetter an der Ruhr , already beginning the manufacturing of cranes in 1840. In 1908, they designed what

2915-401: Was later named Mannesmann Plastics Machinery or MPM, with primary divisions Demag Plastics and Krauss-Maffei. In February 2000 Mannesmann was taken over by Vodafone . All of Mannesmann's industrial activities, which had been combined under Atecs (meaning Advanced Technologies) holding company in order to strategically separate mobile communications and industrial activities, were divested to

2970-492: Was sold to US based company Terex . KKR initiated a major reorganization of the Demag Crane & Components organization, including a refocused effort of their product lines. The production and general company focus changed to Overhead cranes , hoists , Gantry cranes , and Portal cranes under the name Gottwald . In 2006 KKR combined Demag Cranes and Gottwald under Demag Cranes Ag and went public. in 2011 Terex completed

3025-523: Was then the world's largest floating crane, built for Harland & Wolff in Belfast , which would be used for the building of the passenger liners RMS Olympic and RMS Titanic . Starting in 1925, Demag also manufactured excavators . They expanded to manufacture locomotives and railroad cars . During the Second World War , armoured fighting vehicles (in particular Bergepanther ) were built in

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