1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULUNDERWRITERS LABORATORIES INC. CERTIFICATION REQUIREMENT DECISIONThis Certification Requirement Decision is prepared by UL LLC. It is normative for the applicable ULProduct Certification Program(
2、s); however, it is currently not part of the UL Standard(s) referencedbelow.Product Category (CCN): ZDUZStandard Number: UL 979Standard Title: Standard for Water Treatment AppliancesEdition Date: September 29, 2016Edition Number: 2Section / Paragraph Reference: 25.3Subject: Alternate requirements fo
3、r parts subjected only to pump generated waterpressure.DECISION:25.3.1 A part of an appliance that is subjected to pumped water pressure during normal or anticipatedabnormal operation shall withstand a pressure corresponding to 1.5 times the maximum working pressure,or 1.5 times the maximum setting
4、of a pressure relief device, whichever is greater.RATIONALE FOR DECISION:UL 979 requirements did not address system parts that were operating at a boosted water pressure dueto internal pumps. This created some confusion when applying the requirements of Section 25. The testpressure of 1.5 times the
5、maximum pump pressure reflects the value used for testing of pressurized waterfiltration systems evaluated to NSF 50 (Equipment for Swimming Pools, Spas, Hot Tubs and OtherRecreational Water Facilities) or NSF 58 (Reverse Osmosis Drinking Water Treatment Systems).Hazards due to rupture of a part und
6、er water pressure is considered less severe than a part undercompressed gas or vapor pressure, thus the lower test pressures. These pressures conform to other ULand industry standards for similar products.Copyright 2016 UL LLCUL LLC, in performing its functions in accordance with its objectives, doe
7、s not guarantee or warrant thecorrectness of Certification Requirement Decisions it may issue or that they will be recognized or adoptedby anyone. Certification Requirement Decisions are the opinion of UL LLC. in practically applying therequirements of the standard. They do not represent formal inte
8、rpretations of the standard underAmerican National Standards Institute (ANSI) processes. UL LLC shall not be responsible to anyone forthe use of or reliance upon Certification Requirement Decisions by anyone. UL LLC shall not incur anyobligation or liability for damages, including consequential dama
9、ges, arising out of or in connection withthe use or reliance upon Certification Requirement Decisions. The electronic version of the CertificationRequirement Decision is the current version and previously printed copies may be outdated.This document is published as a service to ULs certification customersUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULSTANDARD NUMBER: UL 979 -2-No Text on This Page
