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Vacuum – Nothing but Pressure
By Mike Tuohey, Sales & Marketing Communications Manager, Piab USA Inc. Vacuum – nothing but pressure According to the dictionary, vacuum is a space completely empty of substance. Yet, in engineering, vacuum is employed for a number of tasks. So, how can nothing be utilized to do something? Well, without pressure it wouldn’t work. Vacuum is an ideal and elusive state, and from a practical point of view it is perhaps not necessary to use this theoretical term, once a hot topic among philosophers in ancient Greece, especially since most modern thinkers agree that a complete or perfect vacuum does not exist. Even if all matter could be removed from a volume, it would still not be empty due to dark energy, rays, neutrinos and other phenomena in quantum physics. However, in particle physics, the vacuum state is considered the basic state of matter. In applied physics and engineering, on the other hand, it is probably more helpful to view vacuum as a negative pressure, as this is the force that can be harnessed to do work. The pressure controlled by a vacuum pump can be a powerful force. In a vacuum system, it is the differential between the atmospheric pressure and the vacuum (negative) pressure that creates the ability to lift, hold, move, and perform many types of work. Atmospheric pressure – the pressure we’re all under Atmospheric pressure is the pressure of the weight of the air above us. A cross section of a column of air, measured from sea level to the top of the atmosphere, would exert a pressure of approximately 14.7 pounds per square inch (psi). -
11 Fluid Statics
CHAPTER 11 | FLUID STATICS 357 11 FLUID STATICS Figure 11.1 The fluid essential to all life has a beauty of its own. It also helps support the weight of this swimmer. (credit: Terren, Wikimedia Commons) Learning Objectives 11.1. What Is a Fluid? • State the common phases of matter. • Explain the physical characteristics of solids, liquids, and gases. • Describe the arrangement of atoms in solids, liquids, and gases. 11.2. Density • Define density. • Calculate the mass of a reservoir from its density. • Compare and contrast the densities of various substances. 11.3. Pressure • Define pressure. • Explain the relationship between pressure and force. • Calculate force given pressure and area. 11.4. Variation of Pressure with Depth in a Fluid • Define pressure in terms of weight. • Explain the variation of pressure with depth in a fluid. • Calculate density given pressure and altitude. 11.5. Pascal’s Principle • Define pressure. • State Pascal’s principle. • Understand applications of Pascal’s principle. • Derive relationships between forces in a hydraulic system. 11.6. Gauge Pressure, Absolute Pressure, and Pressure Measurement • Define gauge pressure and absolute pressure. • Understand the working of aneroid and open-tube barometers. 11.7. Archimedes’ Principle • Define buoyant force. • State Archimedes’ principle. • Understand why objects float or sink. • Understand the relationship between density and Archimedes’ principle. 11.8. Cohesion and Adhesion in Liquids: Surface Tension and Capillary Action • Understand cohesive and adhesive forces. • Define surface tension. • Understand capillary action. 11.9. Pressures in the Body • Explain the concept of pressure the in human body. • Explain systolic and diastolic blood pressures. • Describe pressures in the eye, lungs, spinal column, bladder, and skeletal system. -
Pressure, Its Units of Measure and Pressure References
_______________ White Paper Pressure, Its Units of Measure and Pressure References Viatran Phone: 1‐716‐629‐3800 3829 Forest Parkway Fax: 1‐716‐693‐9162 Suite 500 [email protected] Wheatfield, NY 14120 www.viatran.com This technical note is a summary reference on the nature of pressure, some common units of measure and pressure references. Read this and you won’t have to wait for the movie! PRESSURE Gas and liquid molecules are in constant, random motion called “Brownian” motion. The average speed of these molecules increases with increasing temperature. When a gas or liquid molecule collides with a surface, momentum is imparted into the surface. If the molecule is heavy or moving fast, more momentum is imparted. All of the collisions that occur over a given area combine to result in a force. The force per unit area defines the pressure of the gas or liquid. If we add more gas or liquid to a constant volume, then the number of collisions must increase, and therefore pressure must increase. If the gas inside the chamber is heated, the gas molecules will speed up, impact with more momentum and pressure increases. Pressure and temperature therefore are related (see table at right). The lowest pressure possible in nature occurs when there are no molecules at all. At this point, no collisions exist. This condition is known as a pure vacuum, or the absence of all matter. It is also possible to cool a liquid or gas until all molecular motion ceases. This extremely cold temperature is called “absolute zero”, which is -459.4° F. -
Pressure Measuring Instruments
testo-312-2-3-4-P01 21.08.2012 08:49 Seite 1 We measure it. Pressure measuring instruments For gas and water installers testo 312-2 HPA testo 312-3 testo 312-4 BAR °C www.testo.com testo-312-2-3-4-P02 23.11.2011 14:37 Seite 2 testo 312-2 / testo 312-3 We measure it. Pressure meters for gas and water fitters Use the testo 312-2 fine pressure measuring instrument to testo 312-2 check flue gas draught, differential pressure in the combustion chamber compared with ambient pressure testo 312-2, fine pressure measuring or gas flow pressure with high instrument up to 40/200 hPa, DVGW approval, incl. alarm display, battery and resolution. Fine pressures with a resolution of 0.01 hPa can calibration protocol be measured in the range from 0 to 40 hPa. Part no. 0632 0313 DVGW approval according to TRGI for pressure settings and pressure tests on a gas boiler. • Switchable precision range with a high resolution • Alarm display when user-defined limit values are • Compensation of measurement fluctuations caused by exceeded temperature • Clear display with time The versatile pressure measuring instrument testo 312-3 testo 312-3 supports load and gas-rightness tests on gas and water pipelines up to 6000 hPa (6 bar) quickly and reliably. testo 312-3 versatile pressure meter up to Everything you need to inspect gas and water pipe 300/600 hPa, DVGW approval, incl. alarm display, battery and calibration protocol installations: with the electronic pressure measuring instrument testo 312-3, pressure- and gas-tightness can be tested. -
China's Place in Philology: an Attempt to Show That the Languages of Europe and Asia Have a Common Origin
CHARLES WILLIAM WASON COLLECTION CHINA AND THE CHINESE THE GIFT Of CHARLES WILLIAM WASON CLASS OF IB76 1918 Cornell University Library P 201.E23 China's place in phiiologyian attempt toI iPii 3 1924 023 345 758 CHmi'S PLACE m PHILOLOGY. Cornell University Library The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924023345758 PLACE IN PHILOLOGY; AN ATTEMPT' TO SHOW THAT THE LANGUAGES OP EUROPE AND ASIA HAVE A COMMON OKIGIIS". BY JOSEPH EDKINS, B.A., of the London Missionary Society, Peking; Honorary Member of the Asiatic Societies of London and Shanghai, and of the Ethnological Society of France, LONDON: TRtJBNEE & CO., 8 aito 60, PATEENOSTER ROV. 1871. All rights reserved. ft WftSffVv PlOl "aitd the whole eaeth was op one langtta&e, and of ONE SPEECH."—Genesis xi. 1. "god hath made of one blood axl nations of men foe to dwell on all the face of the eaeth, and hath detee- MINED the ITMTIS BEFOEE APPOINTED, AND THE BOUNDS OP THEIS HABITATION." ^Acts Xvil. 26. *AW* & ju€V AiQionas fiereKlaOe tij\(J6* i6j/ras, AiOioiras, rol Si^^a SeSafarat effxarot av8p&Vf Ol fiiv ivffofievov Tireplovos, oi S' avdv-rof. Horn. Od. A. 22. TO THE DIRECTORS OF THE LONDON MISSIONAEY SOCIETY, IN EECOGNITION OP THE AID THEY HAVE RENDERED TO EELIGION AND USEFUL LEAENINO, BY THE RESEARCHES OP THEIR MISSIONARIES INTO THE LANGUAOES, PHILOSOPHY, CUSTOMS, AND RELIGIOUS BELIEFS, OP VARIOUS HEATHEN NATIONS, ESPECIALLY IN AFRICA, POLYNESIA, INDIA, AND CHINA, t THIS WORK IS RESPECTFULLY DEDICATED. -
Heat Treating of Aluminum Alloys
ASM Handbook, Volume 4: Heat Treating Copyright © 1991 ASM International® ASM Handbook Committee, p 841-879 All rights reserved. DOI: 10.1361/asmhba0001205 www.asminternational.org Heat Treating of Aluminum Alloys HEAT TREATING in its broadest sense, • Aluminum-copper-magnesium systems The mechanism of strengthening from refers to any of the heating and cooling (magnesium intensifies precipitation) precipitation involves the formation of co- operations that are performed for the pur- • Aluminum-magnesium-silicon systems herent clusters of solute atoms (that is, the pose of changing the mechanical properties, with strengthening from Mg2Si solute atoms have collected into a cluster the metallurgical structure, or the residual • Aluminum-zinc-magnesium systems with but still have the same crystal structure as stress state of a metal product. When the strengthening from MgZn2 the solvent phase). This causes a great deal term is applied to aluminum alloys, howev- • Aluminum-zinc-magnesium-copper sys- of strain because of mismatch in size be- er, its use frequently is restricted to the tems tween the solvent and solute atoms. Conse- specific operations' employed to increase quently, the presence of the precipitate par- strength and hardness of the precipitation- The general requirement for precipitation ticles, and even more importantly the strain hardenable wrought and cast alloys. These strengthening of supersaturated solid solu- fields in the matrix surrounding the coher- usually are referred to as the "heat-treat- tions involves the formation of finely dis- ent particles, provide higher strength by able" alloys to distinguish them from those persed precipitates during aging heat treat- obstructing and retarding the movement of alloys in which no significant strengthening ments (which may include either natural aging dislocations. -
Introduction to the Principles of Vacuum Physics
1 INTRODUCTION TO THE PRINCIPLES OF VACUUM PHYSICS Niels Marquardt Institute for Accelerator Physics and Synchrotron Radiation, University of Dortmund, 44221 Dortmund, Germany Abstract Vacuum physics is the necessary condition for scientific research and modern high technology. In this introduction to the physics and technology of vacuum the basic concepts of a gas composed of atoms and molecules are presented. These gas particles are contained in a partially empty volume forming the vacuum. The fundamentals of vacuum, molecular density, pressure, velocity distribution, mean free path, particle velocity, conductivity, temperature and gas flow are discussed. 1. INTRODUCTION — DEFINITION, HISTORY AND APPLICATIONS OF VACUUM The word "vacuum" comes from the Latin "vacua", which means "empty". However, there does not exist a totally empty space in nature, there is no "ideal vacuum". Vacuum is only a partially empty space, where some of the air and other gases have been removed from a gas containing volume ("gas" comes from the Greek word "chaos" = infinite, empty space). In other words, vacuum means any volume containing less gas particles, atoms and molecules (a lower particle density and gas pressure), than there are in the surrounding outside atmosphere. Accordingly, vacuum is the gaseous environment at pressures below atmosphere. Since the times of the famous Greek philosophers, Demokritos (460-370 B.C.) and his teacher Leukippos (5th century B.C.), one is discussing the concept of vacuum and is speculating whether there might exist an absolutely empty space, in contrast to the matter of countless numbers of indivisible atoms forming the universe. It was Aristotle (384-322 B.C.), who claimed that nature is afraid of total emptiness and that there is an insurmountable "horror vacui". -
Comac Medical NLSP2 Thefo
Issue May/14 No.2 Copyright © 2014 Comac Medical. All rights reserved Dear Colleagues, The Newsletter Special Edition No.2 is dedicated to the 1150 years of the Moravian Mission of Saints Cyril and Methodius and 1150 years of the official declaration of Christianity as state religion in Bulgaria by Tsar Boris I and imposition of official policy of literacy due to the emergence of the fourth sacral language in Europe. We are proudly presenting: • PUBLISHED BY COMAC-MEDICAL • ~Page I~ SS. CIRYL AND METHODIUS AND THE BULGARIAN ALPHABET By rescuing the creation of Cyril and Methodius, Bulgaria has earned the admiration and respect of not only the Slav peoples but of all other peoples in the world and these attitudes will not cease till mankind keeps implying real meaning in notions like progress, culture “and humanity. Bulgaria has not only saved the great creation of Cyril and Methodius from complete obliteration but within its territories it also developed, enriched and perfected this priceless heritage (...) Bulgaria became a living hearth of vigorous cultural activity while, back then, many other people were enslaved by ignorance and obscurity (…) Тhe language “ of this first hayday of Slavonic literature and culture was not other but Old Bulgarian. This language survived all attempts by foreign invaders for eradication thanks to the firmness of the Bulgarian people, to its determination to preserve what is Bulgarian, especially the Bulgarian language which has often been endangered but has never been subjugated… -Prof. Roger Bernard, French Slavist Those who think of Bulgaria as a kind of a new state (…), those who have heard of the Balkans only as the “powder keg of Europe”, those cannot remember that “Bulgaria was once a powerful kingdom and an active player in the big politics of medieval Europe. -
Case File Copy
NTS 31493 NASA CR-121221 CASE FILE COPY CHARACTERIZATION OF THE MECHANICAL AND PHYSICAL PROPERTIES OF TD-NiCr (Ni-20Cr-2ThO2) ALLOY SHEET by L. J. Fritz, W. P. Koster, and R. E. Taylor* METCUT RESEARCH ASSOCIATES INC. *THERMOPHYSICAL PROPERTIES RESEARCH CENTER prepared for NATIONAL AERONAUTICS AND SPACE ADMINISTRATION NASA Lewis Research Center Contract NAS3-15558 1 Report No. 2. Government Accession No. 3. Recipient's Catalog No. NASA CR- 12 1221 4. Title and Subtitle 5. Report Date Characterization of the Mechanical and Physical Properties of TD-NiCr (Ni-20Cr-2ThO2 ) Alloy 6. Performing Organization Code Sheet 7. Authof(s) 8. Performing Organization Report No. L. J. Fritz- W. P. Koster, and R. E. Taylor 10. Work Unit No. 9. Performing Organization Name and Address Metcut Research Associates Inc. 11. Contract or Grant No. 3980 Rosslyn Drive NAS3-15558 Cincinnati, OH 45209 13. Type of Report and Period Covered 12. Sponsoring Agency Name and Address National Aeronautics and Space Administration 14. Sponsoring Agency Code Washington, D.C. 20546 15. Supplementary Notes Project Manager, John D. Whittenberger, Materials and Structures Division, NASA Lewis Research Center, Cleveland, OH 16. Abstract Sheets of TD-NiCr processed using techniques developed to produce uniform material were tested to supply mechanical and physical property data. Two heats each of 0. 025 and 0. 051 cm thick sheet were tested. Mechanical properties evaluated included tensile, modulus of elasticity, Poisson's Ratio, compression, creep-rupture, creep strength, bearing strength, shear strength, sharp notch and fatigue strength. Test temperatures covered the range from ambient to 1589K. Physical properties were also studied as a function of temperature. -
THE HOT-CATHODE DISCHARGE in HELIUM by Michael A. Gusinow A
The hot-cathode discharge in helium Item Type text; Thesis-Reproduction (electronic) Authors Gusinow, Michael Allen, 1939- Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 02/10/2021 14:07:46 Link to Item http://hdl.handle.net/10150/319504 THE HOT-CATHODE DISCHARGE IN HELIUM by Michael A. Gusinow A Thesis Submitted to the Faculty of the DEPARTMENT OF ELECTRICAL ENGINEERING In Partial Fulfillment of the Requirements For the Degree of MASTER OF SCIENCE In the Graduate College THE UNIVERSITY OF ARIZONA 1963 STATEMENT BY AUTHOR This thesis has been submitted in partial fulfillment of re quirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to bor rowers under rules of the Library. Brief quotations from this thesis are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in their judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author. SIGNED APPROVAL BY THESIS DIRECTOR This thesis has been approved on the date shown below: / Date Associate Professor of Electrical Engineering ii ACKNOWLEDGMENTS The author wishes to express his appreciation to Dr. -
Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles
Designation: B 221 – 05a Standard Specification for Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes1 This standard is issued under the fixed designation B 221; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense. 1. Scope* B211 Specification for Aluminum and Aluminum-Alloy 1.1 This specification2 covers aluminum and aluminum- Bar, Rod, and Wire alloy extruded bar, rod, wire, profile, and tube in the aluminum B 241/B 241M Specification for Aluminum and Aluminum- alloys (Note 1) and tempers shown in Table 2. Alloy Seamless Pipe and Seamless Extruded Tube B 429 Specification for Aluminum-Alloy Extruded Struc- NOTE 1—Throughout this specification, the use of the term alloy in the tural Pipe and Tube general sense includes aluminum as well as aluminum alloy. B 557 Test Methods of Tension Testing Wrought and Cast NOTE 2—For rolled or cold-finished bar and rod refer to Specification B211, for drawn tube, Specification B 210, for structural pipe and tube, Aluminum- and Magnesium-Alloy Products Specification B 429, and for seamless pipe and tube, Specification B 594 Practice for Ultrasonic Inspection of Aluminum- B 241/B 241M. Alloy Wrought Products for Aerospace Applications 1.2 Alloy and temper designations are in accordance with B 660 Practices for Packaging/Packing of Aluminum and ANSI H35.1. -
Machining of Aluminum and Aluminum Alloys / 763
ASM Handbook, Volume 16: Machining Copyright © 1989 ASM International® ASM Handbook Committee, p 761-804 All rights reserved. DOI: 10.1361/asmhba0002184 www.asminternational.org MachJning of Aluminum and AlumJnum Alloys ALUMINUM ALLOYS can be ma- -r.. _ . lul Tools with small rake angles can normally chined rapidly and economically. Because be used with little danger of burring the part ," ,' ,,'7.,','_ ' , '~: £,~ " ~ ! f / "' " of their complex metallurgical structure, or of developing buildup on the cutting their machining characteristics are superior ,, A edges of tools. Alloys having silicon as the to those of pure aluminum. major alloying element require tools with The microconstituents present in alumi- larger rake angles, and they are more eco- num alloys have important effects on ma- nomically machined at lower speeds and chining characteristics. Nonabrasive con- feeds. stituents have a beneficial effect, and ,o IIR Wrought Alloys. Most wrought alumi- insoluble abrasive constituents exert a det- num alloys have excellent machining char- rimental effect on tool life and surface qual- acteristics; several are well suited to multi- ity. Constituents that are insoluble but soft B pie-operation machining. A thorough and nonabrasive are beneficial because they e,,{' , understanding of tool designs and machin- assist in chip breakage; such constituents s,~ ,.t ing practices is essential for full utilization are purposely added in formulating high- of the free-machining qualities of aluminum strength free-cutting alloys for processing in alloys. high-speed automatic bar and chucking ma- Strain-hardenable alloys (including chines. " ~ ~p /"~ commercially pure aluminum) contain no In general, the softer ailoys~and, to a alloying elements that would render them lesser extent, some of the harder al- c • o c hardenable by solution heat treatment and ,p loys--are likely to form a built-up edge on precipitation, but they can be strengthened the cutting lip of the tool.