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1、 CGA E-162008 COMPRESSED GAS CHECK VALVES UP TO 3000 PSIG FIRST EDITION COMPRESSED GAS ASSOCIATION, INC. 4221 Walney Road, 5th Floor Chantilly, VA 20151 Phone: 703-788-2700 E-mail: PAGE ii COMPRESSED GAS ASSOCIATION, INC. CGA E-162008 PLEASE NOTE: The information contained in this document was obta
2、ined 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 assume no liability
3、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 circumstances may not w
4、arrant 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 or suggestions wi
5、ll 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 specifications or regulations
6、; 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 bulletins, and saf
7、ety 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 00-88 Industrial Gases Apparatus Committee FIRST EDITION: 2008 2008 The Compressed Gas Association, Inc. All rights reserved. All materials contained i
8、n 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 any means, electronic or mechanical including photocopying, recording, or any informa- tion storage and retrieval system without permission in writing
9、from The Compressed Gas Association, Inc. All requests for permission to reproduce material from this work should be directed to The Compressed Gas Association, Inc., 4221 Walney Road, Suite 500, Chantilly VA 20151. You may not alter or remove any trademark, copyright or other notice from this work.
10、 -,-,- CGA E-162008 COMPRESSED GAS ASSOCIATION, INC. PAGE III Contents Page 1 Introduction.1 2 Scope .1 3 Definitions.1 4 Design requirements2 4.1 Durability2 4.2 Operating temperature 2 4.3 Connections.3 4.4 Application and usage.3 5 Materials.3 5.1 Material compatibility.3 5.2 Materials in oxidizi
11、ng service.3 5.3 Cleanliness3 6 Marking.3 6.1 General3 6.2 Direction of flow.3 6.3 Additional markings.4 7 Performance data.4 8 Qualification testing4 8.1 General4 8.2 Proof test.4 8.3 Burst test (hydrostatic).4 8.4 Cycle test.4 8.5 Vibration test5 9 Production testing.5 9.1 Cleanliness5 9.2 Leak te
12、sting.5 9.3 Other considerations .5 10 Maintenance.5 10.1 General recommendations5 10.2 Frequency of testing5 10.3 User responsibility.5 11 References.5 Figure Figure 1Typical check valves 2 -,-,- This page is intentionally blank. CGA E-162008 COMPRESSED GAS ASSOCIATION, INC. PAGE 1 1 Introduction M
13、any years of field use and experience have shown that various types of equipment using Compressed Gas Association (CGA) standard cylinder valve, pipeline, and manifold connections are reliably safe when operated in accordance with manufacturers instructions. Under certain circumstances, the users fa
14、ilure to follow these instructions can cause the backflow of unwanted gas into a pipeline, cylinder, or other equipment. The purpose of a check valve is to reduce the possibility of a reverse flow of gas or simply to keep the atmos- phere, moisture, dirt, etc. from backing up into a system when chan
15、ging connections. Check valves are not intended to act as fire stops (flame arrestors) or as replacements for shutoff valves. Check valves that meet the requirements of this standard must not be misconstrued as a substitution or re- placement for the backflow check provisions in NFPA 51, Standard fo
16、r the Design and Installation of Oxygen- Fuel Gas Systems for Welding, Cutting and Allied Processes; CGA E-2, Hose Line Check Valve Standards for Welding and Cutting; or NFPA 99, Standard for Health Care Facilities, unless properly specified for that particu- lar use 1, 2, 3.1 Safe use of gas piping
17、 equipment including check valves can only be assured by the observance of proper op- erating procedures and safe practices recommended by the equipment manufacturers, industry associations, and regulatory bodies. 2 Scope This standard applies to check valves used in general industrial and medical c
18、ompressed gas service designed for service pressures up to 3000 psig (20 680 kPa) and used in conjunction with cylinder valve or manifold con- nections specified by various standards of CGA.2 These connections may be incorporated as part of equipment such as regulator inlet connections, manifold con
19、nections, or other high pressure hose line (pigtail) inlet and outlet connections. See CGA E-3, Pipeline Regulator Inlet Connection Standards; CGA E-9, Standard for Flexible PTFE-Lined Pigtails for Compressed Gas Service; CGA E-11, Standard for Stationary Compressed Gas Cylinder Discharging Manifold
20、s for Working Pressure up to 3000 psig; CGA V-1, Standard for Compressed Gas Cylinder Outlet and Inlet Connections; and CGA V-10, High Pressure Gas Trailer Connections 5, 6, 7, 8, 9. This standard does not apply to check valves used as an integral part of a regulator, residual pressure cylinder valv
21、e, gas pump, or otherwise internal component of other equipment. This standard does not apply to cryo- genic or liquefied gas check valves. Flammable, toxic, high purity, or specialty gas applications can require additional specialized design require- ments. 3 Definitions For the purpose of this pub
22、lication, the following definitions apply. 3.1 Check valve Device designed to allow gas to flow in one direction only. NOTEA check valve typically consists of a housing (or housed within an inlet/outlet nipple or hose line (pigtail) end fitting) and valve/seat mechanism that is biased by pressure an
23、d/or a spring in the closed direction (see Figure 1). 1 References are shown by bracketed numbers and are listed in order of appearance in the reference section. 2 kPa shall indicate gauge pressure unless otherwise noted as (kPa, abs) for absolute pressure or (kPa, differential) for differen- tial p
24、ressure. All kPa values are rounded off per CGA P-11, Metric Practice Guide for the Compressed Gas Industry 4. -,-,- PAGE 2 COMPRESSED GAS ASSOCIATION, INC. CGA E-162008 Figure 1Typical check valves 3.2 Flow coefficient (Cv) Numeric constant used to characterize flow capacity and comparable to an eq
25、uivalent orifice size. 3.3 Cracking pressure Pressure at which the valve mechanism begins to open, allowing gas to begin flowing greater than the maxi- mum allowable leakage rate. 3.4 Direction of flow Path a gas travels at a decreasing pressure gradient. 3.5 Leakage Unintentional escape of gas from
26、 a pressurized device. 3.6 Pigtail High pressure 3000 psig (20 680 KPa) rigid tubing or flexible hose used to transfer gas media between cylin- ders, manifolds, and equipment such as regulators. NOTEThe term pigtail originally comes from rigid leads that have one or two loops and look like a pigs ta
27、il. 3.7 Proof pressure Leak test pressure used for qualification testing at 125% of the maximum working pressure. 3.8 Maximum working pressure Maximum rated pressure at which the valve is designed to operate, sometimes referred to as service pressure. 4 Design requirements 4.1 Durability These check
28、 valves shall be of substantial construction with adequate durability for use in industry on applica- ble compressed gas equipment up to 3000 psig (20 680 kPa). All parts shall be firmly retained in the check valve so they cannot be readily loosened, lost, or susceptible to damage and early failure.
29、 Field repairs are not recommended unless proper instructions are available from the manufacturer. 4.2 Operating temperature The operating temperature range shall be between 20 F and 120 F (29 C and 49 C) at the maximum op- erating pressure. -,-,- CGA E-162008 COMPRESSED GAS ASSOCIATION, INC. PAGE 3
30、 4.3 Connections The mounting and assembly of gas connection joints shall be designed to form gas-tight seals at maximum operating and test conditions when attached to mating components. 4.4 Application and usage It is recognized that check valves in gas supply systems are used for a multitude of ap
31、plications with different requirements such as high pressures and low flow or low pressures and high flow. Also, substantial differences in flow capacities and opening pressures may need to be noted and compared against system requirements using competent engineering judgment and interpretation of r
32、equired specifications. 5 Materials 5.1 Material compatibility Materials shall be resistant to the mechanical, chemical, and thermal effects of the gases to which they will be exposed under operating conditions in their intended service. Nonmetallic materials also shall be evaluated for resistance t
33、o rapid compression and decompression as would be seen in actual service. Gas service shall not be considered interchangeable unless approved by the supplier or manufacturer. Check valves specified for fuel gas service should be evaluated for material compatibility due to the various mixed gas compo
34、nents used. Some fuel gases commonly contain certain amounts of dirt, paraffins, or soot, which should be expected in service, and this needs to be considered during design. 5.2 Materials in oxidizing service Materials in contact with oxidizing gases (for example, oxygen, nitrous oxide, compressed a
35、ir) shall be carefully selected to ensure that they are adequately resistant to ignition. Material selection should be made based on criteria for hazard evaluation contained in ASTM G63, Standard Guide for Evaluating Nonmetallic Materials for Oxygen Service and ASTM G94, Standard Guide for Evaluatin
36、g Metals for Oxygen Service 10, 11. Generally, the total mass of nonmetallic material used should be minimized to limit the available fuel. The system designs should be considered where check valves can create “dead-end” passages creating areas for adiabatic heat of compression to occur. 5.3 Cleanli
37、ness Components in contact with the gas stream shall be free from contaminants with the minimum cleanliness level “clean for oxygen service” in accordance with CGA G-4.1, Cleaning Equipment for Oxygen Service 12. Only the correct type lubricant as recommended by the manufacturer shall be used. 6 Mar
38、king 6.1 General The marking shall be legible and some permanence such as a metal stamping or an environmentally resistant, attachable label. 6.2 Direction of flow An arrow permanently marked on the check valve body shall identify the gas flow direction. Manufacturers identification Check valves tha
39、t do not use or are not part of a CGA-specific connection such as an American Standard 1/4-18 NPT thread shall have the manufacturers name or trademark marked for proper identification. -,-,- PAGE 4 COMPRESSED GAS ASSOCIATION, INC. CGA E-162008 6.3 Additional markings Along with flow direction arrow
40、s and the manufacturers name or trademark, it is strongly recommended that check valves also identify: maximum service pressure, gas service, model or part number designation, and open date code (example: JUL 05). 7 Performance data Due to the various design criteria used to develop check valves of
41、different models and different manufacturers, some common performance data should be made available, such as gas service, maximum working and crack- ing pressures, and flow charts and/or flow coefficient (Cv), These performance data allow the user to accurately determine if a check valve meets the r
42、equirements of the application. Performance data can be in the form of packaging, data sheets, literature, technical “hot line”, etc. as determined by the manufacturer. 8 Qualification testing 8.1 General If check valves are an integral part of a CGA cylinder valve connection, all criteria of the CG
43、A V-1 testing re- quirements shall be met 8. 8.2 Proof test In a reverse flow condition, the valve mechanism shall be capable of withstanding a proof pressure test at 125% of maximum operating pressure for 5 minutes without bubble leakage. This test shall be performed with oil-free, dry air or dry n
44、itrogen. Check valves for helium or hydrogen service shall be tested with helium. 8.3 Burst test (hydrostatic) A burst test is conducted to test the safe containment of parts in case of overpressurization. This does not ap- ply to internal valve mechanism parts since the device does not need to oper
45、ate after being subjected to the test. Leakage of the check valve during the burst test does not disqualify the valve from passing. A leaking valve passes the burst test if the valve reaches the required test pressure without rupture or separation of parts. 8.3.1 Burst test in normal direction of fl
46、ow The valve body (housing) shall be capable of withstanding in the normal direction of flow a pressure of not less than four times the maximum rated service pressure for one minute without rupture or separation of parts. 8.3.2 Burst test in reverse direction of flow The valve assembly shall be capa
47、ble of withstanding a pressure in the reverse direction of flow of not less than four times the maximum rated service pressure for one minute without rupture or separation of parts. 8.4 Cycle test The valve mechanism shall be subjected to a minimum of 10 000 cycles at normal room temperature. Cyclin
48、g shall be timed in 5-30-second cycles from 0 psig (0 kPa) to a minimum of 75% of the maximum working pres- sure. A cycle test is not intended to be a destructive test, but to provide some assurance that wear, over- stressed springs, etc. will not cause problems in service. A proof test (8.1), verification of proper operation, and a visual examination of valve components shall be conducted to confirm acceptance. -,-,- CGA E-162008 COMPRESSED GAS ASSOCIATION, INC. PAGE 5 8.5 Vibration test A vibration