The purpose of this standard is to provide the minimum requirements for double-disc swing-check valves, suitable for waterworks service, 2-in. through 48-in. (50-mm through 1,200-mm) NPS, including materials and testing.<\/p>\n
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| 7<\/td>\n | Foreword I.\tIntroduction. I.A.\tBackground.\u2003Double-disc swing-check valves have been commonly used on pump discharge applications in the waterworks industry for more than half a century. These check valves are designed to prevent backflow by automatically closing rapidly on flow-re I.B.\tHistory.\u2003The need for standardization of double-disc swing-check valves was recognized by the American Water Works Association (AWWA) in 1992. The AWWA Gate and Check Valve Committee worked to publish the first edition of ANSI\/AWWA C518 beginning in I.C.\tAcceptance.\u2003In May 1985, the US Environmental Protection Agency (USEPA) entered into a cooperative agreement with a consortium led by NSF International (NSF) to develop voluntary third-party consensus standards and a certification program for direct <\/td>\n<\/tr>\n | ||||||
| 8<\/td>\n | II.\tSpecial Issues. II.A.\tGeneral.\u2003Conditions under which a valve is to be operated must be evaluated carefully by the purchaser. The evaluations must include the determination of the hydraulic characteristics of the system in which the valve will be installed and the operat <\/td>\n<\/tr>\n | ||||||
| 9<\/td>\n | II.B.\tAdvisory Information on Product Application.\u2003This standard does not describe all possible applications or manufacturing technologies. The purchaser should identify special requirements and required deviations from this standard and include appropria II.C.\tChlorine and Chloramine Degradation of Elastomers.\u2003The selection of materials is critical for water service and distribution piping in locations where there is a possibility that elastomers will be in contact with chlorine or chloramines. Documented <\/td>\n<\/tr>\n | ||||||
| 10<\/td>\n | II.D.\tPermeation.\u2003The selection of materials is critical for potable water, reclaimed water service, and distribution piping in locations where there is likelihood the pipe will be exposed to significant concentrations of pollutants consisting of low-mole III.\tUse of This Standard.\u2003It is the responsibility of the user of an AWWA standard to determine that the products described in that standard are suitable for use in the particular application being considered. III.A.\tPurchaser Options and Alternatives.\u2003The following information should be provided by the purchaser: <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | III.B.\tModification to Standard.\u2003Any modification to the provisions, definitions, or terminology in this standard must be provided by the purchaser. IV.\tMajor Revisions.\u2003Major changes made to the standard in this revision include the following: <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | V.\tComments.\u2003If you have any comments or questions about this standard, please call AWWA Engineering and Technical Services at 303.794.7711, FAX at 303.795.7603, write to the department at 6666 West Quincy Avenue, Denver, CO 80235-3098, or email at standa <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | AWWA Standard SECTION 1:\u2002GENERAL Sec.\u20021.1\tScope <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | Sec.\u20021.2\tPurpose Sec.\u20021.3\tApplication SECTION 2:\u2002REFERENCES <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | SECTION 3:\u2002DEFINITIONS <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | SECTION 4:\u2002REQUIREMENTS Sec.\u20024.1\tData to Be Provided by the Manufacturer Sec.\u20024.2\tMaterials <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | Sec.\u20024.3\tGeneral Design Table 1\tEnd-to-end dimensions for wafer and threaded-lug valves <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | Sec.\u20024.4\tWorkmanship and Coating SECTION 5:\u2002VERIFICATION <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | SECTION 6:\u2002DELIVERY Sec.\u20026.1\tMarking Sec.\u20026.2\tShipping <\/td>\n<\/tr>\n | ||||||
| 27<\/td>\n | APPENDIX A <\/td>\n<\/tr>\n | ||||||
| 31<\/td>\n | Specification and Data Sheet for Check Valves <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" AWWA C518-18 Dual-Disc Swing-Check Valves for Waterworks Service<\/b><\/p>\n |