The purpose of this standard is to provide minimum requirements for stainless steel and ductile-iron body knife gate valves with resilient and metal seats, including tapping knife gate valves, for use in water, wastewater, and reclaimed water systems, including materials, design, testing, rejection, marking, and shipping.<\/p>\n
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| 7<\/td>\n | Foreword I.\tIntroduction. I.A.\tBackground.\u2003Knife gate valves are generally used for isolation of pipes in water and wastewater treatment plants. Knife gate valves can be metal or resilient seated, bidirectional or unidirectional. I.B.\tHistory.\u2003The need for standardization of knife gate valves was recognized by the American Water Works Association (AWWA) in 2007, resulting in the formation of a standards committee. Subsequent revisions of C520 were approved by the AWWA Board of Dir 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 | ||||||
| 10<\/td>\n | II.B.\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 II.C.\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 <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | II.D.\tAdvisory Information on Scheduling Requirements.\u2003Valves made in accordance with this standard in large sizes are not \u201cproduction run\u201d products. They are custom designed and manufactured for the specific application. As a consequence of this, the val 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 | ||||||
| 13<\/td>\n | III.B.\tData to Be Provided by the Manufacturer or Supplier.\u2003Sec. 4.1 describes the minimum data to be provided by the supplier. Because these valves may be custom designed and manufactured, purchasers may require more detailed or comprehensive data. Such <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | III.C.\tModification to Standard.\u2003Any modification of the provisions, definitions, or terminology in this standard must be provided by the purchaser. IV.\tMajor Revisions.\u2003Major revisions made to the standard in this edition include the following: 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 | ||||||
| 15<\/td>\n | AWWA Standard SECTION 1:\u2002GENERAL Sec.\u20021.1\tScope Sec.\u20021.2\tPurpose Sec.\u20021.3\tApplication <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | SECTION 2:\u2002REFERENCES <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | SECTION 3:\u2002DEFINITIONS <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | SECTION 4:\u2002REQUIREMENTS Sec.\u20024.1\tData Provided by Manufacturer or Supplier <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | Sec.\u20024.2\tMaterials <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | Sec.\u20024.3\tGeneral Design <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | Table 2\tStem material Table 3\tStainless-steel valve shaft and stem alloys <\/td>\n<\/tr>\n | ||||||
| 26<\/td>\n | Sec.\u20024.5\tPower Actuators Sec.\u20024.6\tWorkmanship and Coatings <\/td>\n<\/tr>\n | ||||||
| 27<\/td>\n | SECTION 5:\u2002VERIFICATION Sec.\u20025.1\tProduction Test Requirements <\/td>\n<\/tr>\n | ||||||
| 28<\/td>\n | Sec.\u20025.2\tProof-of-Design Test Requirements <\/td>\n<\/tr>\n | ||||||
| 29<\/td>\n | Table 4\tCycle leakage test requirements <\/td>\n<\/tr>\n | ||||||
| 31<\/td>\n | APPENDIX A <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" AWWA C520-19 Knife Gate Valves, Sizes 2 In. (50 mm Through 96 In. (2,400 mm)<\/b><\/p>\n |