UL-471-BULLETIN-2008=12P.pdf
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1、FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION Subject 471 January 25, 2008 SUMMARY OF TOPICS The following is being proposed for preliminary review and comment only: 1. For Preliminary Review Only: Addition of supplement for requirements for refrigerators and freezers that employ fl
2、ammable refrigerants in the refrigerating system COMMENTS DUE: February 25, 2008 This proposal is for review and comment only (no ballot at this time). Please note that comments on a preliminary review document will not receive a response from the proposal author through CSDS. Instead, the proposal
3、author will be asked to review the comments and adjust the proposals and/or supporting rationale as the author determines to be appropriate. The preliminary review process is an informal mechanism that provides authors with the opportunity to refi ne their proposals before they advance to the next s
4、tage in ULs standards development process. In some cases, the author of the proposals may choose to discontinue them. In this case, the author need not do anything after preliminary review has ended. Normally, the next step in the process is the more formal STP ballot and stakeholder review process.
5、 Only comments posted during the STP ballot and stakeholder review process will be provided with a response in CSDS. For your convenience in review, proposed additions to existing requirements are shown underlined. 1. For Preliminary Review Only: Addition of supplement for requirements for refrigera
6、tors and freezers that employ fl ammable refrigerants in the refrigerating system RATIONALE Proposal submitted by: Randy Haseman Underwriters Laboratories Through ULs historical studies, it has been noted that in the 1930s and 1940s, refrigerators typically used refrigerants (for example, SO2), whic
7、h were both toxic and fl ammable. When the non-toxic, non-fl ammable refrigerants were developed, there was a signifi cant shift in the industry to begin using these new refrigerants, and use of the old refrigerants was almost entirely abandoned. Presently, with environmental concerns playing a larg
8、er role in consumer trends, UL is aware of technical considerations, market forces and international activities that are causing the refrigeration industry to evaluate the use of fl ammable refrigerants or blended refrigerants with a fl ammable component. The United States Environmental Protection A
9、gency (EPA), has expressed an interest in the development of requirements for the use of fl ammable refrigerants. The use of these alternative refrigerants is considered more environmentally acceptable since they have a zero ozone depletion potential and a low global warning potential. Due to the ab
10、ove, UL has developed requirements for the use of fl ammable refrigerants in refrigerators and freezers. A Supplement to UL 250 “Requirements for (Household) Refrigerators and Freezers Employing A Flammable Refrigerant In The Refrigerating System” was published on August 25, 2000. Copyright Underwri
11、ters Laboratories Inc. Provided by IHS under license with ULLicensee=University of Texas Revised Sub Account/5620001114 Not for Resale, 02/17/2008 23:23:03 MSTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION The UL 2
12、50 Supplement was developed as a result of ULs participation with the International Electrotechnical Commission SC61C working group, the comments received to previous Subject 250 bulletins, and ULs continuous work with fl ammable refrigerants. The following proposal for commercial refrigerators usin
13、g a fl ammable refrigerant is based on the UL 250 Supplement and is similar to the fl ammable refrigerant requirements contained in IEC 60335-2-89, the international standard for commercial refrigerating appliances. If adopted, the requirements would form Supplement SB of the standard. PROPOSAL (NEW
14、) JANUARY 25, 2008SUBJECT 471-2- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=University of Texas Revised Sub Account/5620001114 Not for Resale, 02/17/2008 23:23:03 MSTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR
15、CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION SUPPLEMENT SB - REQUIREMENTS FOR REFRIGERATORS AND FREEZERS EMPLOYING A FLAMMABLE REFRIGERANT IN THE REFRIGERATING SYSTEM SB1 Scope SB1.1These requirements cover commercial refrigerators and freezers that employ a refrigerant that has been identifi ed as ha
16、ving fl ammable characteristics. SB1.2 These requirements do not apply to commercial refrigerators and freezers that employ ammonia as the refrigerant. SB1.3 The requirements in this supplement are in addition to the applicable requirements in the Standard for Commercial Refrigerators and Freezers,
17、UL 471. SB2 Defi nitions SB2.1Protected Cooling System A system in which: a) All refrigerant tubing and refrigerant containing components are located external to the refrigerated compartment, or b) Any part of a rollbond type cooling system, that is located inside a refrigerated compartment, is cons
18、tructed so that the refrigerant is contained within an enclosure with at least two layers of metallic materials separating the refrigerant from the refrigerated compartment. The enclosure has no joints other than the bonded seams of the evaporator where the bonded seam has a width of at least 6 mm (
19、0.24 in.), or c) Any part of the cooling system that is located inside a refrigerated compartment has the refrigerant contained in an enclosure which itself is contained within a separate protective enclosure. If leakage from the containing enclosure occurs, the leaked refrigerant is contained withi
20、n the protective enclosure and the appliance will not function as in normal use. The protective enclosure contains no joints within the refrigerated compartment, or d) All parts of the cooling system are located within a refrigerated air handling compartment. This compartment separates all refrigera
21、nt containing components from the food storage compartment. SB2.2Unprotected Cooling System A refrigeration system where refrigerant tubing or refrigerant containing components are located inside the food storage compartment, and these parts do not have additional protection as defi ned in SB2.1 (b)
22、, (c) or (d). SB2.3Refrigerated Compartment The internal portion of the refrigerator which contains the refrigerated air. A food storage compartment and an air handling compartment can be separate parts of the refrigerated compartment. SB2.4Ignition Source An electrical switching component. Heaters,
23、 motors, etc. that comply with the temperature test requirements in SB5.3 are not considered ignition sources. SB2.5Critical Points Interconnecting joints between parts of the refrigeration circuit. SB2.6 Dead Space A space with a bottom and sides with no intentional air fl ow that could contain a l
24、eaked quantity of refrigerant as determined by testing in Section SB5. JANUARY 25, 2008SUBJECT 471-3- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=University of Texas Revised Sub Account/5620001114 Not for Resale, 02/17/2008 23:23:03 MSTNo reproduction or ne
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