The Roots blower is one example of a vacuum pump

A vacuum pump is a pump that removes gas molecules from a sealed volume in order to leave behind a partial vacuum. The vacuum pump was invented in 1650 by Otto von Guericke. Image File history File links Rotary_piston_pump. ... Image File history File links Rotary_piston_pump. ... A Roots Blower refers to a specific design of positive displacement vacuum pump”. // General description The term derives from the Roots brothers who invented the rotary lobe pump more than a century ago. ... This article is about a mechanical device. ... Look up Vacuum in Wiktionary, the free dictionary. ... Otto von Guericke Otto von Guericke (originally spelled Gericke) [] (November 20, 1602 – May 11, 1686 (Julian calendar); November 30, 1602 – May 21, 1686 (Gregorian calendar)) was a German scientist, inventor, and politician. ...

Types

Pumps can be broadly categorized according to three techniques:^[1]

• Positive displacement pumps use a mechanism to repeatedly expand a cavity, allow gases to flow in from the chamber, seal off the cavity, and exhaust it to the atmosphere.
• Momentum transfer pumps, also called molecular pumps, use high speed jets of dense fluid or high speed rotating blades to knock gaseous molecules out of the chamber.
• Entrapment pumps capture gases in a solid or absorbed state. This includes cryopumps, getters, and ion pumps.

Positive displacement pumps are the most effective for low vacuums, but their high backstream flows through mechanical seals generally limit their usefulness in high vacuums. Momentum transfer pumps in series with positive displacement pumps are the most common configuration used to achieve high vacuums, but they stall at low vacuums. (Hence the need for a positive displacement pump in series.) Entrapment pumps can be added to reach ultrahigh vacuums, but they have a maximum operational time since they do not exhaust materials. They periodically saturate and require regeneration, which usually means bringing the system back up to higher pressures and temperatures. The available operational time is usually unacceptably short in low and high vacuums, thus limiting their use to ultrahigh vacuums. Pumps also differ in details like manufacturing tolerances, sealing material, pressure, flow, admission or no admission of oil vapor, service intervals, reliability, tolerance to dust, tolerance to chemicals, tolerance to liquids and vibration. A cryopump is a vacuum pump that traps gases and vapours by condensing them on a cold surface. ... This article is about electronics. ... Image:Ion pump2. ...

Performance measures

• Pumping speed refers to the volume flow rate of a pump at its inlet, often measured in litres per second, cubic feet per minute, or cubic metre per hour. Because of compression, the volume flow rate at the outlet will always be much lower than at the inlet. Momentum transfer and entrapment pumps are more effective on some gases than others, so the pumping speed can be simultaneously different for each of the gases being pumped, and the average pumping speed will vary depending on the chemical composition of the gases remaining in the chamber.
• Throughput refers to the pumping speed multiplied by the gas pressure at the inlet, and is measured in units such as torr-litres/second. At a constant temperature, throughput is proportional to the number of molecules being pumped per unit time, and therefore to the mass flow rate of the pump. (Think pV=nRT) When discussing a leak, backstreaming or outgassing, throughput refers to the volume leak rate multiplied by the pressure at the vacuum side of the leak, so the leak throughput can be compared to the pump throughput.

Positive displacement and momentum transfer pumps have a constant volume flow rate, (pumping speed,) but as the chamber's pressure drops, this volume contains less and less mass. So although the pumping speed remains constant, the throughput and mass flow rate drop exponentially. Meanwhile, the leakage, evaporation, sublimation and backstreaming rates produce a constant throughput into the system. When the pump's mass flow drops to the same level as the mass flows into the chamber, the system asymptotically approaches a constant pressure called the base pressure. This article is about pressure in the physical sciences. ... Mass flow rate is the movement of mass per time. ...

Evaporation and sublimation into a vacuum is called outgassing, and the most common source is water absorbed by materials in the chamber. If the dominant mass flow into the vacuum system is chamber leakage or outgassing of materials under vacuum, then the vacuum can be improved simply by installing bigger pumps with a higher volume flow rate. However, there is a point where backstream leakage through the pump and outgassing of the pump oils become the dominant mass flows into the chamber. In this situation, the vacuum will approach the pump's ultimate pressure - the best vacuum that this type of pump can achieve under ideal conditions. Adding more pumps in parallel or bigger pumps of the same type can still improve the pump-down speed, but they will not reduce the base pressure below ultimate. Better pumping technologies must be used to go beyond this barrier. “Vaporization” redirects here. ... This article does not cite any references or sources. ... Outgassing (sometimes called Offgassing, particularly when in reference to indoor air quality) is the slow release of a gas that was trapped, frozen, absorbed or adsorbed in some material. ...

Positive displacement

The manual water pump draws water up from a well by creating a vacuum that water rushes in to fill. In a sense, it acts to evacuate the well, although the high leakage rate of dirt prevents a high quality vacuum from being maintained for any length of time.

Mechanism of a scroll pump

Fluids cannot be pulled, so it is technically impossible to create a vacuum by suction. Suction is the movement of fluids into a vacuum under the effect of a higher external pressure, but the vacuum has to be created first. The easiest way to create an artificial vacuum is to expand the volume of a container. For example, the diaphragm muscle expands the chest cavity, which causes the volume of the lungs to increase. This expansion reduces the pressure and creates a partial vacuum, which is soon filled by air pushed in by atmospheric pressure. Image File history File links L-Pumpe2. ... Image File history File links L-Pumpe2. ... Image File history File links Two_moving_spirals_scroll_pump. ... In the anatomy of mammals, the diaphragm is a shelf of muscle extending across the bottom of the ribcage. ...

To continue evacuating a chamber indefinitely without requiring infinite growth, a compartment of the vacuum can be repeatedly closed off, exhausted, and expanded again. This is the principle behind positive displacement pumps, like the manual water pump for example. Inside the pump, a mechanism expands a small sealed cavity to create a deep vacuum. Because of the pressure differential, some fluid from the chamber (or the well, in our example) is pushed into the pump's small cavity. The pump's cavity is then sealed from the chamber, opened to the atmosphere, and squeezed back to a minute size.

More sophisticated systems are used for most industrial applications, but the basic principle of cyclic volume removal is the same:

• Rotary vane pump, the most common
• Diaphragm pump, zero oil contamination
• Liquid ring pump
• Piston pump, cheapest
• Scroll pump, highest speed dry pump
• Screw pump (10 Pa)
• Wankel pump
• External vane pump
• Roots blower, also called a booster pump, has highest pumping speeds but low compression ratio
• Multistage Roots pump that combine several stages providing high pumping speed with better compression ratio
• Toepler pump

The base pressure of a rubber- and plastic-sealed piston pump system is typically 1 to 50 kPa, while a scroll pump might reach 10 Pa (when new) and a rotary vane oil pump with a clean and empty metallic chamber can easily achieve 0.1 Pa. A rotary vane pump is a positive displacement pump that consists of variable-length, tensioned vanes mounted to a rotor that rotates inside of a cavity. ... A diaphragm pump is a positive displacement pump that uses a combination of the reciprocating action of a rubber or teflon diaphragm and suitable non-return check valves to pump a fluid. ... A liquid ring pump is a rotating positive displacement pump. ... A scroll compressor uses two interleaved spiral-shaped scrolls to compress a fluid. ... Dr. Felix Heinrich Wankel (August 13, 1902–October 9, 1988) was the German inventor of the Wankel engine. ... A Roots Blower refers to a specific design of positive displacement vacuum pump”. // General description The term derives from the Roots brothers who invented the rotary lobe pump more than a century ago. ... This does not cite any references or sources. ... For other uses, see Plastic (disambiguation). ...

A positive displacement vacuum pump moves the same volume of gas with each cycle, so its pumping speed is constant until it is overcome by backstreaming. For other uses, see Volume (disambiguation). ...

Momentum transfer

A cutaway view of a turbomolecular high vacuum pump

In a momentum transfer pump, gas molecules are accelerated from the vacuum side to the exhaust side (which is usually maintained at a reduced pressure by a positive displacement pump). Momentum transfer pumping is only possible below pressures of about 1 kPa. Matter flows differently at different pressures based on the laws of fluid dynamics. At atmospheric pressure and mild vacuums, molecules interact with each other and push on their neighboring molecules in what is known as viscous flow. When the distance between the molecules increases, the molecules interact with the walls of the chamber more often than the other molecules, and molecular pumping becomes more effective than positive displacement pumping. This regime is generally called high vacuum. Image File history File links Cut_through_turbomolecular_pump. ... Image File history File links Cut_through_turbomolecular_pump. ... Fluid dynamics is the sub-discipline of fluid mechanics dealing with fluids (liquids and gases) in motion. ...

Molecular pumps sweep out a larger area than mechanical pumps, and do so more frequently, making them capable of much higher pumping speeds. They do this at the expense of the seal between the vacuum and their exhaust. Since there is no seal, a small pressure at the exhaust can easily force flow backstream through the pump; this is called stall. In high vacuum, however, pressure gradients have little effect on fluid flows, and molecular pumps can attain their full potential.

The two main types of molecular pumps are the diffusion pump and the turbomolecular pump. Both types of pumps blow out gas molecules that diffuse into the pump. Diffusion pumps blow out molecules with jets of oil, while turbomolecular pumps use high speed fans. Both of these pumps will stall and fail to pump if exhausted directly to atmospheric pressure, so they must be exhausted to a lower grade vacuum created by a mechanical pump. Diffusion pumps are a type of vacuum pump designed to achieve better vacuum pressures than possible by use of mechanical pumps alone. ... Interior view of a turbomolecular pump Turbomolecular pumps is a form of turbopump used to obtain and maintain high vacuum. ...

As with positive displacement pumps, the base pressure will be reached when leakage, outgassing, and backstreaming equal the pump speed, but now minimizing leakage and outgassing to a level comparable to backstreaming becomes much more difficult.

• Diffusion pump
• Turbomolecular pump

Diffusion pumps are a type of vacuum pump designed to achieve better vacuum pressures than possible by use of mechanical pumps alone. ... Interior view of a turbomolecular pump Turbomolecular pumps is a form of turbopump used to obtain and maintain high vacuum. ...

Entrapment

Entrapment pumps may be cryopumps, which use cold temperatures to condense gases to a solid or absorbed state, chemical pumps, which react with gases to produce a solid residue, or ionization pumps, which use strong electrical fields to ionize gases and propel the ions into a solid substrate. A cryomodule uses cryopumping. A cryopump is a vacuum pump that traps gases and vapours by condensing them on a cold surface. ... Cryogenics is the study of very low temperatures or the production of the same, and is often confused with cryobiology, the study of the effect of low temperatures on organisms, or the study of cryopreservation. ... Image:Ion pump2. ... A cryomodule is that section, or sections of a linear particle accelerator composed of superconducting niobium cavities used in a linear accelerator, or linac. ...

• Ion pump
• Cryopump
• Sorption pump
• Non-evaporative getter

Image:Ion pump2. ... A cryopump is a vacuum pump that traps gases and vapours by condensing them on a cold surface. ... The Sorption pump is a kind of pump used in ultra high vacuum experiments, for example in surface physics in order to obtain low pressures so that experiments can take place. ... This article is about electronics. ...

Other pump types

Venturi vacuum pump (aspirator) (10 to 30 kPa) A copper aspirator. ...

• Rotary Vane

Steam ejector (vacuum depends on the number of stages, but can be very low) A steam ejector is a device which uses high pressure steam to create a vacuum. ...

Techniques

Vacuum pumps are combined with chambers and operational procedures into a wide variety of vacuum systems. Sometimes more than one pump will be used (in series or in parallel) in a single application. A partial vacuum, or rough vacuum, can be created using a positive displacement pump that transports a gas load from an inlet port to an outlet (exhaust) port. Because of their mechanical limitations, such pumps can only achieve a fairly crude partial vacuum. To achieve a more-perfect vacuum, other techniques must then be used, typically in series (usually following an initial fast "pump down" using a positive displacement pump). Some examples might be use of an oil sealed rotary vane pump backing a diffusion pump, or a dry scroll pump backing a turbomolecular pump. There are other combinations depending on the vacuum quality desired. Electrical circuit components can be connected together in one of two ways: series or parallel. ... Electrical circuit components can be connected together in one of two ways: series or parallel. ...

Achieving truly high vacuum is difficult because all of the materials exposed to the vacuum must be carefully evaluated for their outgassing and vapor pressure properties. For example, oils, greases, rubber, or plastic used to form gaskets and seals must not boil off when exposed to the vacuum, or the gases they produce would prevent the creation of the desired degree of vacuum. Often, all of the surfaces exposed to the vacuum must be baked at high temperature to drive off adsorbed gases. Outgassing (sometimes called Offgassing, particularly when in reference to indoor air quality) is the slow release of a gas that was trapped, frozen, absorbed or adsorbed in some material. ... Vapor pressure is the pressure of a vapor in equilibrium with its non-vapor phases. ... Grease is a lubricant of higher initial viscosity than oil, consisting originally of a calcium, sodium or lithium soap jelly emulsified with mineral oil. ... This does not cite any references or sources. ... For other uses, see Plastic (disambiguation). ... Some seals and gaskets 1. ... Compression seal example A mechanical seal is a device which helps join systems or mechanisms together by preventing leakage (e. ... Italic text This article is about the boiling point of liquids. ... Adsorption is a process that occurs when a gas or liquid solute accumulates on the surface of a solid or, more rarely, a liquid (adsorbent), forming a molecular or atomic film (the adsorbate). ...

Outgassing can also be reduced simply by desiccation prior to vacuum pumping. High vacuum systems generally require metal chambers with metal O-ring seals such as Klein flanges or ISO flanges. The system must be clean and free of organic matter to minimize outgassing. All materials, solid or liquid, have a small vapour pressure, and their outgassing becomes important when the vacuum pressure falls below this vapour pressure. As a result, many materials that work well in low vacuums, such as epoxy, will become a problematic source of outgassing when attempting to achieve high vacuums. With these standard precautions, vacuums of 1 mPa are easily achieved with off-the-shelf molecular pumps. With careful design and operation, 1 µPa is possible. Desiccation is the state of extreme dryness, or the process of extreme drying. ... In chemistry, epoxy or polyepoxide is a thermosetting epoxide polymer that cures (polymerizes and crosslinks) when mixed with a catalyzing agent or hardener. Most common epoxy resins are produced from a reaction between epichlorohydrin and bisphenol-A. The first commercial attempts to prepare resins from epichlorohydrin occurred in 1927 in...

Several types of pumps may be used in sequence or in parallel. In a typical pumpdown sequence, a positive displacement pump would be used to remove most of the gas from a chamber, starting from atmosphere (760 Torr, 101 kPa) to 25 Torr (3 kPa). Then a sorption pump would be used to bring the pressure down to 10^-4 Torr (10 mPa). A cryopump or turbomolecular pump would be used to bring the pressure further down to 10^-8 Torr (1 µPa). An additional ion pump can be started below 10^-6 Torr to remove gases which are not adequately handled by a cryopump or turbo pump, such as helium or hydrogen. For other uses, see Helium (disambiguation). ... This article is about the chemistry of hydrogen. ...

Ultra high vacuum generally requires custom-built equipment, strict operational procedures, and a fair amount of trial-and-error. Ultra-high vacuum systems are usually made of stainless steel with metal-gasketed conflat flanges. The system is usually baked, preferably under vacuum, to temporarily raise the vapour pressure of all outgassing materials in the system and boil them off. If necessary, this outgassing of the system can also be performed at room temperature, but this takes much more time. Once the bulk of the outgassing materials are boiled off and evacuated, the system may be cooled to lower vapour pressures and minimize residual outgassing during actual operation. Some systems are cooled well below room temperature by liquid nitrogen to shut down residual outgassing and simultaneously cryopump the system. Ultra high vacuum (UHV) is the regime characterised by pressures lower than about 10−7 pascal or 100 nanopascals (~10−9 torr). ... The 630 foot (192 m) high, stainless-clad (type 304) Gateway Arch defines St. ... A tank of liquid nitrogen, used to supply a cryogenic freezer (for storing laboratory samples at a temperature of about -150 Celsius). ...

In ultra-high vacuum systems, some very odd leakage paths and outgassing sources must be considered. The water absorption of aluminium and palladium becomes an unacceptable source of outgassing, and even the absorptivity of hard metals such as stainless steel or titanium must be considered. Some oils and greases will boil off in extreme vacuums. The porosity of the metallic chamber walls may have to be considered, and the grain direction of the metallic flanges should be parallel to the flange face. Aluminum redirects here. ... For other uses, see Palladium (disambiguation). ... General Name, symbol, number titanium, Ti, 22 Chemical series transition metals Group, period, block 4, 4, d Appearance silvery metallic Standard atomic weight 47. ...

The impact of molecular size must be considered. Smaller molecules can leak in more easily and are more easily absorbed by certain materials, and molecular pumps are less effective at pumping gases with lower molecular weights. A system may be able to evacuate nitrogen, (the main component of air,) to the desired vacuum, but the chamber could still be full of residual atmospheric hydrogen and helium. Vessels lined with a highly gas-permeable material such as palladium (which is a high-capacity hydrogen sponge) create special outgassing problems. For other uses, see Palladium (disambiguation). ... This article is about the chemistry of hydrogen. ...

Uses of vacuum pumps

Vacuum pumps are used in many industrial and scientific processes including:

• The production of most types of electric lamps, vacuum tubes, and CRTs where the device is either left evacuated or re-filled with a specific gas or gas mixture
• Semiconductor processing, notably ion implantation, dry etch and PVD, ALD, PECVD and CVD deposition and soon in photolithography
• Electron microscopy
• Medical processes that require suction
• Medical applications such as such Radiotherapy, Radiosurgery, Radiopharmacy
• Analytical instrumentation to analyse gas, liquid, solid, surface and bio materials
• Mass spectrometers to create an ultra high vacuum between the ion source and the detector
• Vacuum Coating for decoration, for durability, for energy saving
• Glass coating for low e glass
• Hard coating for engine (as in Formula One)
• Opthalmic coating
• Trash compactor
• Vacuum engineering
• even in sewage system see EN1091:1997 standards

Vacuum may be used to power mechanical devices. In diesel-engined automobiles, a pump fitted on the engine (usually on the camshaft) is used to produce vacuum. In gasoline-powered automobiles, instead, vacuum is obtained as a side-effect of the operation of the engine and the flow restriction created by the throttle plate. This vacuum may then be used to power: Not to be confused with lightning. ... Structure of a vacuum tube diode Structure of a vacuum tube triode In electronics, a vacuum tube, electron tube, or (outside North America) thermionic valve or just valve, is a device used to amplify, switch or modify a signal by controlling the movement of electrons in an evacuated space. ... Cathode ray tube employing electromagnetic focus and deflection Cutaway rendering of a color CRT: 1. ... A semiconductor is a solid whose electrical conductivity is in between that of a conductor and that of an insulator, and can be controlled over a wide range, either permanently or dynamically. ... Ion implantation is a materials engineering process by which ions of a material can be implanted into another solid, thereby changing the physical properties of the solid. ... An electron microscope is a type of microscope that uses electrons as a way to illuminate and create an image of a specimen. ... Mass spectrometry is a technique for separating ions by their mass-to-charge (m/z) ratios. ... Vacuum engineering deals with technological processes and equipment that use vacuum to achieve better results than those run under atmospheric pressure. ... This article is about the fuel. ... For the fictional characters of the same name, see Camshaft (Transformers). ... Petrol redirects here. ... “Car” and “Cars” redirect here. ... In an engine, the throttle is the mechanism by which the engines power is increased or decreased. ...

• The booster for the power brakes
• Motors that move dampers in the ventilation system
• The throttle driver in the cruise control servomechanism
• Controlling other devices (such as turbo geometry, EGR, etc.)

In an aircraft, the vacuum source is often used to power gyroscopes in the various flight instruments. To prevent the complete loss of instrumentation in the event of an electrical failure, the instrument panel is deliberately designed with certain instruments powered by electricity and other instruments powered by the vacuum source. A zone damper is a specific type of damper used to control the flow of air in an HVAC heating or cooling system. ... In an engine, the throttle is the mechanism by which the engines power is increased or decreased. ... Cruise control (sometimes known as speed control or Autocruise) is a system to automatically control the speed of an automobile. ... Small R/C servo mechanism 1. ... Flying machine redirects here. ... A gyroscope For other uses, see Gyroscope (disambiguation). ... Electricity (from New Latin Ä“lectricus, amberlike) is a general term for a variety of phenomena resulting from the presence and flow of electric charge. ...

History of the vacuum pump

The vacuum pump was invented by Otto von Guericke. Image File history File links No higher resolution available. ... Otto von Guericke Otto von Guericke (originally spelled Gericke) [] (November 20, 1602 – May 11, 1686 (Julian calendar); November 30, 1602 – May 21, 1686 (Gregorian calendar)) was a German scientist, inventor, and politician. ...

Nikola Tesla designed the apparatus, imaged to the right, that contains a Sprengel pump to create a high degree of exhaustion. Nikola Tesla (1856-1943)[1] was a world-renowned Serbian inventor, physicist, mechanical engineer and electrical engineer. ...

Hazards

Old vacuum-pump oils that were produced before circa 1980 often contain a mixture of several different dangerous polychlorinated biphenyls (PCBs), which are highly toxic, carcinogenic, persistent organic pollutants.^[2][3] “PCB” redirects here. ... Toxic redirects here, but this is also the name of a song by Britney Spears; see Toxic (song) Look up toxic and toxicity in Wiktionary, the free dictionary. ... In pathology, a carcinogen is any substance or agent that promotes cancer. ... Persistent organic pollutants (POPs) are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. ...

See also

• An Experiment on a Bird in the Air Pump
• Vacuum engineering
• Vacuum flange

An Experiment on a Bird in the Air Pump is a 1768 oil-on-canvas painting by Joseph Wright of Derby, part of a series of candlelit scenes that Wright painted during the 1760s. ... Vacuum engineering deals with technological processes and equipment that use vacuum to achieve better results than those run under atmospheric pressure. ... A vacuum flange is a flange at the end of a tube used to connect vacuum containing vessels, tubing and vacuum pumps to each other. ...

References

1. ^ Van Atta, C. M.; and M. Hablanian (1991). "Vacuum and Vacuum Technology". Encyclopedia of Physics (Second Edition). Ed. Rita G. Lerner and George L. Trigg. VCH Publishers Inc.. pp. 1330-1333. ISBN 3-527-26954-1. 
2. ^ Martin G Broadhurst (October 1972). "Use and Replaceability of Polychlorinated Biphenyls". Environmental Health Perspectives 2: 81-102. doi:10.2307/3428101. 
3. ^ C J McDonald and R E Tourangeau (1986). PCBs: Question and Answer Guide Concerning Polychlorinated Biphenyls. Government of Canada: Environment Canada Department. ISBN 0-662-14595-X. Retrieved on 2007-11-07. 

A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 311th day of the year (312th in leap years) in the Gregorian calendar. ...

External links

• Instructables: Make a Manual Vacuum Pump for Under $20 by Converting a Bicycle Pump