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1、FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION Subject 2158 October 13, 2006 SUMMARY OF TOPICS The following changes in requirements are being proposed: 1. Addition of Fire Containment Requirements STP BALLOTS DUE: November 27, 2006 COMMENTS DUE: November 27, 2006 For your convenience
2、 in review, proposed additions to existing requirements are shown underlined and proposed deletions are shown lined-out. 1. Addition of Fire Containment Requirements BACKGROUND The following Rationale and Proposal were developed and submitted by a task group consisting of Chuck Williams (UL) Task Gr
3、oup Chair, Catalina Catanu (Camco Inc.), John Gorman (CSA), Charles Jackson (Whirlpool Corporation), Laura Stinnett (General Electric) and Steve Vogt (Whirlpool Corporation). The proposals were editorially modifi ed to comply with ULs Standards development procedures and policies. RATIONALE Proposal
4、 submitted by: Dryer Fire Containment Task Group In 2002, the National Fire Protection Association estimated that approximately 16 deaths, 309 injuries and 15,000 clothes dryer fi res occur annually in the United States causing $76 million in property damage. Representatives from UL, the Consumer Pr
5、oduct Safety Commission (CPSC), and the Association of Home Appliance Manufacturers (AHAM) met several times to discuss issues related to dryer fi re safety. Although there was a great deal of discussion on the purported causes of clothes dryer fi re incidents, there was only consensus on the need f
6、or better data on actual causes of these fi res. Some of the chief defi ciencies noted were (1) lack of defi nition of dryer fi res, (2) lack of dryer fi re frequency distribution by severity, and (3) lack of determination on alleged dryer failures versus root cause. As a result, industry representa
7、tives agreed to collect fi eld incident data on clothes dryer fi res in an attempt to better understand the potential causes of fi res involving clothes dryers. In November 2000, a meeting was held at CPSC at which time the elements of the incident survey program were agreed upon. Manufacturers cond
8、ucted a data collection program on clothes dryer fi re incidents from February 2001 through August 2001. The goal of the survey was to collect data from incidents. Data was collected on a total of 191 clothes dryer incidents. The number of clothes dryer incidents that each manufacturer compiled was
9、based on an approximation of that companys market share as published by industry trade magazines. Commencing February 1, 2001, each manufacturer obtained data on each of their known incidents by examining and testing their products until their designated number of incidents was obtained. Copyright U
10、nderwriters Laboratories Inc. Provided by IHS under license with ULLicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 09/03/2007 01:32:20 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION UL, CPSC
11、, and Canadian Standards Association (CSA) attended a meeting at AHAM on August 14, 2002. At that meeting AHAM staff provided a detailed summary of the survey conducted by manufacturers on clothes dryer fi re incidents. Based upon the AHAM study, in the cases where some evidence of a fi re was obser
12、ved, no one cause stood out as a leading contributor to dryer fi res. Many different potential contributing factors were identifi ed, including the load, electrical system, mechanical system, and gas system. In 66 out of the 191 incidents investigated, the drum was identifi ed as the area of involve
13、ment. The precise factor contributing to the fi re was unknown in many of the cases. Based upon the lack of conclusive data and the interest of the group to deal with the most severe type of clothes dryer fi res, UL and CSA suggested a joint task group be formed to develop a test protocol for fi re
14、containment of electric clothes dryers. It was anticipated that a separate proposal would need to be considered for the ANSI standard covering gas-fi red clothes dryers. UL formed a task group that consisted of representatives from clothes dryer manufacturers and CSA. UL and task group members have
15、conducted testing in their facilities to determine the viability of such a test proposal and as an aid in developing the test parameters. Test procedures were developed to reproduce conditions that occur in clothes load and lint fi res in clothes dryers. These test procedures were based upon many ye
16、ars of experience of members of the task group in conducting similar fi re containment testing. It was recognized by the task group that manufacturers would need to evaluate the robustness of the design of their clothes dryers to ensure that consistent results are achieved in certifi cation testing.
17、 The following test items represent the main parameters that the task group discussed: 1) Test Load The type of load to be used for the test. Most reported fi res in drums have been cotton towel loads. Task group members conducted fi re testing with cotton towels and the cotton cloths used for testi
18、ng in the Standard for Electric Clothes Dryers, UL 2158. It was agreed that the load specifi ed for the test should lead to repeatable test conditions. It was felt that cotton towels varied considerably and would be difficult to specify as the test load. Testing showed that the two loads when ignite
19、d in a dryer burn similarly. In some cases the UL 2158 cotton cloths burned hotter and longer. The cotton test cloths have been used for years to represent clothes for other testing covered by UL 2158. We concluded that UL 2158 cotton test cloths would be a representative load for cotton towels. 2)
20、Test Load Size The size of the test load was discussed. Task group member testing was done with two sizes of loads. The sizes were the maximum rated load of the dryer and one-half the rated load using the Department of Energy value for energy testing (1.0 lb per ft3). The rated load determination is
21、 described in Clause 4.2.2 of UL 2158. Testing showed that the smaller load provided a longer burning fi re, and that there was more complete burning of the load. Rated loads almost completely fi ll available space in the drum, and restrict the amount of oxygen available to support a fi re. It was c
22、oncluded that the test should be done with a 1.0 lb per ft3load. 3) Fire Indicator The test machine will be covered on all external surfaces (front, back, sides, top and bottom) with cheesecloth. Cheesecloth is an open weave material that allows maximum oxygen available to support burning. Cheeseclo
23、th has been used in many standards as a fi re indicator. The specifi cations for the cheesecloth are contained in Clause 4.6.1 of UL 2158. Ignition of the externally placed cheesecloth during the test is the failure criteria. 4) Test Confi guration It was concluded that testing in an alcove or close
24、t would restrict the amount of oxygen to support burning. The testing will be done freestanding in the test room to allow maximum air (oxygen) to the test machine. OCTOBER 13, 2006SUBJECT 2158-2- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=IHS Employees/111
25、1111001, User=Wing, Bernie Not for Resale, 09/03/2007 01:32:20 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION 5) Test Room The testing will be done in a closed, draft-free room. Mechanical ventilation will be al
26、lowed in the test room, as long as an air-stream is not directed across the test machine. The test room is to have a provision for discharge of the combustion products and a provision for fresh air intake so that no oxygen-defi cient air is introduced into the test confi guration during the test. 6)
27、 Ignition Source Methods of igniting the test load were discussed. Task group members conducted tests with alcohol, propane torches, and fi replace log fi re starter products. UL conducted testing with the propane torch. The propane torch method was shown to provide more consistent ignition and burn
28、ing of the test loads for the clothes load fi re containment test. 7) Test Condition Two tests involving separate machines are proposed under static (no drum movement) and dynamic (drum rotating) conditions. A study of clothes dryer fi re incidents by the manufacturers showed that fi res have been r
29、eported under both conditions. 8) Draft Simulation Field measurements of air fl ow through clothes dryer installations were conducted by a manufacturer. It was found that typical air fl ow through a clothes dryer that was not operating was 7 CFM. In order to simulate this condition it was concluded
30、that testing would be conducted with an external blower connected to the exhaust duct to produce 7 + 1 CFM through the exhaust duct prior to starting the testing. The blower is to simulate a typical draft that normally fl ows through an exhaust duct due to atmospheric differences between the inside
31、of a dwelling and the outdoors. It was recognized that air fl ow may occur into the dryer from outside or vice versa. It was concluded the conducting the test with the simulated draft fl ow from the dryer to the outside represented the worst case condition. 9) Baffles Baffles are typically plastic r
32、ated HB, and are a fuel source for a fi re. If the dryer has plastic drum baffles, the maximum number are to be positioned above the center-line of drum above the test load at the start of the test. The positioning of combustibles above the fi re was considered a worst case condition for a fi re tha
33、t might occur in a clothes dryer drum. 10) Cheesecloth To simulate the burning of lint inside a clothes dryer, the task group members concluded that cheesecloth (cotton) could be used. A clothes dryer manufacturer was able to duplicate actual results of a fi re incident due to burning lint using 8 l
34、ayers of cheesecloth. Cheesecloth is made of cotton fi bers. Cotton fi bers burn easily and do not melt or draw away from fl ames. Manufactured cellulosic fi bers (rayon and acetate) and synthetic fi bers shrink from a fl ame and melt away without igniting. Wool and silk fi bers burn slowly and may
35、self extinguish. Cotton was chosen to simulate the most extensive burning of lint (cloth fi bers) in a clothes dryer fi re. Cheesecloth is an open weave material that allows maximum oxygen available to support burning. The specifi cations for the cheesecloth are contained in Clause 4.6.1 of UL 2158.
36、 11) Smoke Explosions There is a small likelihood of a small smoke explosion occurring while conducting this test. The smoke explosion in dryer fi res is likely caused by smoldering, creating a combustible medium without direct fi re (ignition) contact for a while and sudden fi re due to an ignition
37、 source abruptly uncovered consequent to some movement of the clothes load or dryer parts. These explosions may result in the door being forced open. We do not have any data suggesting that explosions are reported in incidents of clothes dryer fi res. It is assumed that manufacturers will determine
38、the robustness of the design through a thorough investigation that includes conducting tests on the clothes dryer in order to confi rm that a smoke explosion is not inherent in the clothes dryer design. As a means of verifi cation that a smoke explosion that occurred during testing is a random event
39、, testing three additional samples is required. All three samples will need to comply with the test criteria. A defi nition of a smoke explosion is being added to the standard. OCTOBER 13, 2006SUBJECT 2158-3- Copyright Underwriters Laboratories Inc. Provided by IHS under license with ULLicensee=IHS
40、Employees/1111111001, User=Wing, Bernie Not for Resale, 09/03/2007 01:32:20 MDTNo reproduction or networking permitted without license from IHS -,-,- FOR INTERNAL UL OR CSDS USE ONLY NOT FOR OUTSIDE DISTRIBUTION PROPOSALS 2.7A Baffle a paddle inside the drum that lifts and tumbles clothes. 2.21A Smo
41、ke explosion a sudden expansion of gases, which causes an overpressure inside the appliance, caused by ignition of a mixture of combustible smoke from a smoldering clothes load with air. 4.6 Cheesecloth for heating and abnormal tests 4.6.1 Whenever cheesecloth is required for a test in this Standard
42、, the cloth shall be bleached cotton cheesecloth running approximately 34 g/m2with a thread count in the range of 10-13 9-12 threads/cm. 19.6 Load fi re containment 19.6.1 Appliances having a rotating drum or basket shall be tested as described in Clauses 19.6.2 19.6.19, and there shall be no igniti
43、on of the cheesecloth located on the outside of the appliance. 19.6.2 Tests shall be conducted in a closed, draft-free room. When mechanical ventilation is employed during the test, an air stream shall not be directed across the appliance. With the concurrence of those concerned, an air stream may b
44、e directed across the appliance. The test room shall have vents for the discharge of the combustion products and have provisions for fresh air intake so that no oxygen-defi cient air is introduced into the test confi guration during the test. 19.6.3 The supporting surface for the appliance shall be
45、calcium silicate board, fi ber cement board, or other material that is noncombustible. Metal shall not be used. With the concurrence of those concerned, metal drains or a similar device may be located in the supporting surface. The supporting surface shall be cleaned between tests. 19.6.4 All labels
46、 that are applied by the manufacturer shall be applied to the intended surfaces of the test appliance. Printing on the labels is not required for this test. The manufacturer shall provide the wiring diagram on the test appliance as intended. 19.6.5 The appliance shall be connected to a source of pow
47、er for all test conditions. The supply circuit for the appliance is to be provided with time-delay fuses of the maximum rating for the branch circuit to which the appliance can properly be connected. 19.6.6 The appliance shall be operated in time dry cycle. For any appliance that does not employ a t
48、imed dry cycle, any moisture sensing devices shall be defeated. When the software associated with a moisture sensing device does not allow operation of the appliance by defeating the moisture sensor, the software may need to be modifi ed to allow heated operation of the appliance. 19.6.7 The applian
49、ce shall be leveled starting with any adjustable feet at the maximum distance from the bottom of the appliance to the supporting surface. 19.6.8 The top, two sides, front, and back external surfaces of the appliance shall be completely covered by single layer, cheesecloth panels. The cheesecloth panels shall be held in close contact with the external surfaces of the appliance. A mechanical means, such as, small pieces of metal fo