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1、 CGA P-92008 THE INERT GASES: ARGON, NITROGEN, AND HELIUM FOURTH EDITION COMPRESSED GAS ASSOCIATION, INC. 4221 Walney Road, 5th Floor Chantilly, VA 20151 Phone: 703-788-2700 FAX: 703-961-1831 E-mail: PAGE ii COMPRESSED GAS ASSOCIATION, INC. CGA P-92008 PLEASE NOTE: The information contained in this
2、 document was obtained from sources believed to be reliable and is based on technical information and experience currently available from members of the Compressed Gas Association, Inc. and others. However, the Association or its members, jointly or severally, make no guarantee of the results and as
3、sume no liability or responsibility in connection with the information or suggestions herein contained. Moreover, it should not be assumed that every acceptable commodity grade, test or safety procedure or method, precaution, equipment or device is contained within, or that abnormal or unusual circu
4、mstances may not warrant or suggest further requirements or additional procedure. This document is subject to periodic review, and users are cautioned to obtain the latest edition. The Associa- tion invites comments and suggestions for consideration. In connection with such review, any such comments
5、 or suggestions will be fully reviewed by the Association after giving the party, upon request, a reasonable op- portunity to be heard. Proposed changes may be submitted via the Internet at our web site, . This document should not be confused with Federal, state, provincial, or municipal specificati
6、ons or regulations; insurance requirements; or national safety codes. While the Association recommends reference to or use of this document by government agencies and others, this document is purely voluntary and not binding. A listing of all publications, audiovisual programs, safety and technical
7、bulletins, and safety posters is available via the Internet at our website at . For more information contact CGA at Phone: 703-788-2700, ext. 799. E-mail: . Work Item 06-005 Atmospheric Gases and Equipment Committee NOTETechnical changes from the previous edition are underlined. FOURTH EDITION: 2008
8、 THIRD EDITION: 2001 SECOND EDITION: 1992 FIRST EDITION: 1980 2008 The Compressed Gas Association, Inc. All rights reserved. All materials contained in this work are protected by United States and international copyright laws. No part of this work may be reproduced or transmitted in any form or by a
9、ny means, electronic or mechanical including photocopying, recording, or any informa- tion storage and retrieval system without permission in writing from The Compressed Gas Association, Inc. All requests for permission to reproduce material from this work should be directed to The Compressed Gas As
10、sociation, Inc., 4221 Walney Road, Suite 500, Chantilly VA 20151. You may not alter or remove any trademark, copyright or other notice from this work. CGA P-92008 COMPRESSED GAS ASSOCIATION, INC. PAGE iii Contents Page 1 Introduction.1 2 Scope .1 3 Argon1 3.1 Properties1 3.2 Production .1 3.3 Commer
11、cial uses.1 4 Nitrogen2 4.1 Properties2 4.2 Production .3 4.3 Commercial uses.4 5 Helium 4 5.1 Properties4 5.2 Production .4 5.3 Commercial uses.4 6 Oxygen-deficient atmospheres.5 7 Inert gas containers6 7.1 Regulations6 7.2 Cylinders7 7.3 Tank cars.8 7.4 Highway vehicles.8 8 High pressure inert gas
12、 cylinders.9 8.1 Storage and handling 9 8.2 Use10 8.3 Disposition of empty cylinders.11 9 Estimating container contents 11 9.1 Gas cylinders.11 9.2 Liquid cylinders11 10 Liquefied inert gases11 10.1 Storage and handling 11 10.2 Handling liquefied inert gases in transfer systems or in open containers
13、13 11 Storing, handling, and using liquefied inert gas cylinders 13 11.1 General rules.13 11.2 Filling.14 11.3 Moving cylinders14 11.4 Storage and use of cylinders.14 11.5 Disposition of empty cylinders.15 12 Inert gas piping and manifold systems.15 13 Bulk inert gas systems .16 14 References.16 15
14、Additional reference .17 Tables Table 1Physical constants of argon.2 Table 2Physical constants of nitrogen.3 Table 3Physical constants of helium .5 -,-,- This page is intentionally blank. -,-,- CGA P-92008 COMPRESSED GAS ASSOCIATION, INC. PAGE 1 1 Introduction This publication is one of a series com
15、piled by CGA to provide information on the transportation, handling, and storage of compressed gases, cryogenic liquids, and related products. 2 Scope The purpose of this publication is to present information regarding the characteristics and handling of the three major inert gasesargon, nitrogen, a
16、nd helium. Requests for specialized technical information should be di- rected to any one of the manufacturers of these gases. The publication is intended primarily for users of the inert gases. Some of the requirements do not apply to the manufacturers or distributors of these gases. 3 Argon 3.1 Pr
17、operties Argon is a colorless, odorless, and tasteless, monatomic gas that is a product of the radioactive decay of po- tassium 40 in the earths crust. About 1% of the atmosphere is argon (0.934% by volume). Argon is nontoxic, chemically inert, and only slightly soluble in water. It is nonflammable
18、and inhibits combus- tion. It can act as an asphyxiant by displacing the amount of oxygen necessary to support life. Argon gas is about 38% more dense than air. It can be liquefied to a colorless liquid that boils at 302.6 F (185.9 C) at atmospheric pressure. Liquid argon at its normal boiling point
19、 is 39% heavier than water. Above its critical temperature of 188.1 F (122.3 C), argon can exist only as a gas regardless of pressure. Argon is classed according to type and grade (quality verification level QVL). Gaseous argon is denoted as Type I and liquefied argon as Type II. The grade (QVL) ind
20、icates the maximum amount of impurities that can be present. Further details are given in CGA G-11.1, Commodity Specification for Argon 1.1 Some of the physical constants of argon are listed in Table 1. 3.2 Production The most common method of producing argon is by fractional distillation of liquid
21、air in an air separation plant. The crude liquid argon stream is purified to remove impurities consisting primarily of oxygen. The resulting ar- gon product is 99.99%+ pure. Argon is also recovered and purified from purge gas streams of ammonia plants. 3.3 Commercial uses The largest use of argon is
22、 in welding where it provides an inert gas shield to the arc, which prevents oxidation of the metals being welded. It has a number of important uses in metallurgical processes. In the argon-oxygen decarburizing process, oxygen is used to remove carbon, and the argon is used for “stirring” and remova
23、l of nitrogen. Basic oxygen furnaces (BOF) are bottom blown with argon as a stirring medium and to lower the ni- trogen content of the steel. Argon is used in continuous casting processes as an inert shield, in processes for degassing molten aluminum, and in the production of titanium sponge and all
24、oys. In the lighting industry, it is used to fill incandescent light bulbs and with other rare gases to fill special bulbs and display tubes for special color effects. Argon is used with other gases in Geiger counter tubes. In the electronic industry, argon is used in chemical vapor deposition, and
25、it is used in other industries for sputtering and annealing. 1 References are shown by bracketed numbers and are listed in order of appearance in the reference section. PAGE 2 COMPRESSED GAS ASSOCIATION, INC. CGA P-92008 Table 1Physical constants of argon 2, 3, 4 2 U.S. Units SI Units International
26、symbol Ar Ar Molecular weight 39.95 39.95 Density of the gas at 70 F (21.1 C) and 1 atm 0.103 lb/ft3 1.650 kg/m3 Specific gravity of the gas at 70 F (21.1 C) and 1 atm 1.38 1.38 Specific volume of the gas at 70 F (21.1 C) and 1 atm 9.71 ft3/lb 0.606 m3/kg Boiling point at 1 atm 302.6 F 185.9 C Densi
27、ty of the liquid at boiling point and 1 atm 87.02 lb/ft3 1394 kg/m3 Weight of the liquid at boiling point 11.63 lb/gal 1.39 kg/L Gas/liquid ration gas at 70 F (21.1 C) and 1 atm, liquid at boiling point vol/vol 841.2 841.2 Melting point at 1 atm 308.6 F 189.2 C Critical temperature 188.1 F 122.3 C C
28、ritical pressure 711.5 psia 4906 kPa, abs Critical density 33.44 lb/ft3 535.6 kg/m3 Triple point 308.8 F at 9.99 psia 189.3 C at 68.9 kPa, abs Latent heat of vaporization at boiling point and 1 atm 69.8 Btu/lb 162.3 kJ/(kg) Latent heat of fusion at triple point 12.8 Btu/lb 29.6 kJ/(kg) Specific heat
29、 of the gas at 70 F (21.1 C) and 1 atm Cp 0.125 Btu/(lb)(F) 0.523 kJ/(kg)(C) Cv 0.075 Btu/(lb)(F) 0.314 kJ/(kg)(C) Ratio of specific heats (Cp/Cv) 1.67 1.67 Solubility in water, vol/vol at 32 F (0 C) 0.056 0.056 4 Nitrogen 4.1 Properties Nitrogen is an element that at atmospheric temperatures and pr
30、essures exists as a colorless, odorless, taste- less diatomic gas. About four-fifths of the atmosphere is nitrogen (78.03% by volume). Nitrogen is nontoxic and chemically inert at ordinary pressure and temperature conditions. It is nonflammable and inhibits combustion. It can act as an asphyxiant by
31、 displacing the amount of oxygen necessary to support life. As a gas at ambient temperature, nitrogen is about 3% less dense than air. It may be cooled and compressed to a colorless liquid that under atmospheric pressure boils at 320.4 F (195.8 C). As a liquid (at normal boil- ing point), nitrogen i
32、s about 81% as heavy as water. When heated above its critical temperature of 232.4 F (146.9 C) nitrogen can exist only as a gas regardless of the pressure that may be exerted upon it. 2 kPa shall indicate gauge pressure unless otherwise noted as (kPa, abs) for absolute pressure or (kPa, differential
33、) for dif- ferential pressure. All kPa values are rounded off per CGA P-11, Metric Practice Guide for the Compressed Gas Industry 5. -,-,- CGA P-92008 COMPRESSED GAS ASSOCIATION, INC. PAGE 3 Nitrogen is classed according to type and grade (QVL). Gaseous nitrogen is denoted as Type I and liquid nitro
34、- gen as Type II. The grade (QVL) indicates the maximum amount of impurities that can be present. Further de- tails are given in CGA G-10.1, Commodity Specification for Nitrogen 6. Some of the physical constants of nitrogen are listed in Table 2. Table 2Physical constants of nitrogen 2, 3, 4 U.S. Un
35、its SI Units International symbol N2 N2 Molecular weight 28.01 28.01 Density of the gas at 70 F (21.1 C) and 1 atm 0.072 lb/ft3 1.153 kg/m3 Specific gravity of the gas at 70 F (21.1 C) and 1 atm (air = 1) 0.967 0.967 Specific volume of the gas at 70 F (21.1 C) and 1 atm 13.89 ft3/lb 0.867 m3/kg Boil
36、ing point at 1 atm 320.4 F 195.8 C Density of the liquid at boiling point and 1 atm 50.47 lb/ft3 808.5 kg/m3 Weight of liquid at boiling point 6.747 lb/gal 0.809 kg/L Gas/liquid ratio Gas at 70 F (21.1 C) and 1 atm, liquid at boiling point, vol/vol 696.5 696.5 Melting point at 1 atm 345.8 F 209.9 C
37、Critical temperature 232.4 F 146.9 C Critical pressure 493 psia 3399 kPa, abs Critical density 19.60 lb/ft3 314.0 kg/m3 Triple point at 1.81 psia (12.5 kPa, abs) 346.0 F 210.0 C Latent heat of vaporization at boiling point 85.6 Btu/lb 199.1 kJ/kg Latent heat of fusion at melting point 11.1 Btu/lb 25
38、.8 kJ/kg Specific heat of the gas at 70 F (21.1 C) and 1 atm Cp 0.249 Btu/(lb)(F) 1.04 kJ/(kg)(C) Cv 0.177 Btu/(lb)(F) 0.741 kJ/(kg)(C) Ratio of specific heats (Cp/Cv) 1.41 1.41 Solubility in water, vol/vol at 32 F (0 C) 0.023 0.023 4.2 Production Liquid nitrogen is produced by fractional distillati
39、on of liquefied air in air separation plants. The nitrogen product obtained is 99.99%+ pure. Gaseous nitrogen is generally obtained by vaporizing liquid nitrogen. Pressure swing absorption (PSA) and selective screen membrane technology are alternative methods of pro- ducing gaseous nitrogen on site
40、at consumer locations. These prepackaged units process air and are designed to meet a wide range of flow and purity requirements. Inert gas generators meet requirements for relatively low purity nitrogen in medium quantities. These units are operated primarily to generate blanketing atmospheres by r
41、eacting a hydrocarbon fuel with air to produce a mixture of nitrogen, water, carbon dioxide, hydrogen, and oxides of carbon. The product stream can be purified by various methods according to process requirements. PAGE 4 COMPRESSED GAS ASSOCIATION, INC. CGA P-92008 4.3 Commercial uses Nitrogen is wi
42、dely used in the food industry to prevent oxidative deterioration, mold growth, and insect infesta- tion. Coffee, margarine, leafy vegetables, and meat are several foods in the long list of food products using nitrogen in processing or packaging. One of the largest uses of nitrogen is in the manufac
43、ture of ammonia where a mixture of three parts hydrogen and one part nitrogen constitutes the synthesis gas. In the chemical industry, nitrogen is used in many proc- esses to exclude oxygen or moisture, or as a diluent. It is also widely used in polymerizations. In petroleum refining, nitrogen is us
44、ed in the regeneration of spent reforming catalyst. Its uses in the semiconductor industry include purging, blanketing, pressurizing systems, and as a coolant fluid. It is also used as a carrier gas in chemical deposition. 5 Helium 5.1 Properties Helium is an element that at atmospheric temperatures
45、 and pressures exists as a colorless, odorless, tasteless, monatomic gas. Helium is nontoxic and chemically inert. It is nonflammable, does not present a fire hazard, and inhibits com- bustion. It can act as an asphyxiant by displacing the amount of oxygen necessary to support life. As a gas at ambi
46、ent temperature, helium is about 86% less dense than air. Helium is the only known substance that will not freeze under its vapor pressure. It has no triple point, existing only as a liquid under its vapor pres- sure to the absolute zero temperature. Helium gas can be liquefied after sufficient cool
47、ing and expansion. Its normal boiling point at atmospheric pressure is 452.1 F (268.9 C). As a liquid (at normal boiling point), he- lium is about 12% as heavy as water. When heated above its critical temperature of 450.3 F (267.9 C), helium can exist only as a gas, regardless of the pressure. Heliu
48、m is classed according to type and grade (QVL). Gaseous helium is denoted as Type I and liquefied he- lium as Type II. The grade (QVL) indicates the maximum amount of impurities that can be present. Further details are given in CGA G-9.1, Commodity Specification for Helium 7. Some of the physical constants of helium are listed in Table 3. 5.2 Production Helium is a nonrenewable natural resource extracted commercially from helium-bearing natural gas generally containing 0.3 vol % helium. According to the U.S. Geological Survey, Mineral Commodity Summaries, Helium- 1998, the