The heart of the Fire Resistance test is the 'Cone Calorimeter' developed by
Vytenis Babrauskas, Ph.D. (the Ph.D. is in Fire Science). The cone Calorimeter is located within a 'hood' above the test sample. UL, ASTM, Bellcore, Western Fire Center, and additional labs, utilize this device. The smoke is sampled as it passes the cone calorimeter while being exhausted out of the test chamber. I don't know the details, but I do know that the duct is a given diameter at that point. For more information on the calorimeter see the following link (then click on 'facilities'. There is a link for detailed technical info). http://www.westernfire.com/ Additionally, Bob Backstrom of UL's Northbrook, Ill. office, is a fire safety expert and was involved with the development of the standards utilized by UL and Bellcore. He could also be of help. John A. Juhasz Product Qualification & Compliance Engr. Fiber Options, Inc. 80 Orville Dr. Suite 102 Bohemia, NY 11716 USA Tel: 516-567-8320 ext. 324 Fax: 516-567-8322 -----Original Message----- From: JENKINS, JEFF [mailto:jeff.jenk...@aei.com] Sent: Thursday, April 22, 1999 9:37 AM To: 'John Juhasz'; 'Rich Nute'; JENKINS, JEFF Cc: 'emc-p...@ieee.org' Subject: RE: Excessive smoke John, is the smoke measured in a room of a specified volume? That is to say, how is compliance with the 28% Oxygen Rating Index determined? Jeff -----Original Message----- From: John Juhasz [mailto:jjuh...@fiberoptions.com] Sent: Thursday, April 22, 1999 6:38 AM To: 'Rich Nute'; 'jeff.jenk...@aei.com' Cc: 'emc-p...@ieee.org' Subject: RE: Excessive smoke Good Answer (with respect to the standards noted below). However, I would like to expand on this discussion, if I may, with regards to telecom equipment in a CO (Central Office) environment and meeting Bellcore specifications (realize that typically equipment that will go into a CO environment will also need to meet UL 19503rd ed.). In the case of Bellcore NEBS GR-63, the content of smoke is measured with regard to 'Oxygen rating index' (should be 28% or greater) during the Fire Resistance testing. The previous version of the specification (TR-NWT-000063) specifically measured all the content of the smoke to determine smoke corrosivity. Although the current standard (GR-63) is relaxed, the RBOCs (Regional Bell Operating Companies - becoming less numerous of late) reserve the right to view the video tape of the fire test when considering a product, and if they feel that the product is producing too much smoke (regardless of the oxygen index) they become concerned. They're concerned about bringing down a central office to 'clean' the surrounding equipment from the corrosive elements of the smoke. So those of you who will also need to meet the Bellcore NEBS requirements (telecom equip to be located in a CO) in addition to UL1950 3rd Ed., this will be a concern. John A. Juhasz Product Qualification & Compliance Engr. Fiber Options, Inc. 80 Orville Dr. Suite 102 Bohemia, NY 11716 USA Tel: 516-567-8320 ext. 324 Fax: 516-567-8322 -----Original Message----- From: Rich Nute [mailto:ri...@sdd.hp.com] Sent: Wednesday, April 21, 1999 2:30 PM To: jeff.jenk...@aei.com Cc: emc-p...@ieee.org Subject: Re: Excessive smoke Hi Jeff: > If a component abnormal test generates excessive and sustained smoke > (several minutes), but does'nt breach reinforced or double insulation, nor > emit flame from the enclosure, is it considered a failure? Intuitively, it > seems like it would be, because of toxicity, but I have been unable to find > anything in the safety standards to support this. I have checked EN 60950, > EN 50178, UL 1012, and CSA C22.2 No. 107.1. For the purposes of product safety and compliance with safety standards, smoke is a "permitted" emission during fault testing. The safety issue is whether a safeguard is damaged or breached due to the heat which produced the smoke. If insulation is not damaged (as per the hi-pot test), and excessive heat or flame does not breach the enclosure (as per the cheesecloth test), then the product is considered acceptable for the purposes of product safety. Typically, product safety standards do not address the toxicity of smoke. This is because all smoke contains toxic materials. The only solution to smoke toxicity is to eliminate smoke, which means eliminating all overheating situations. Which is nearly impossible. However, any smoke from a product is likely create fear and anxiety in the mind of the user and nearby persons. Any smoke in a clean room will likely be cause for scrapping all stock in the clean room. While smoke always contains toxic materials (e.g., carbon monoxide), the concentration of the smoke (toxic material) in the volume of the room together with the room ventilation determines whether or not inhalation of the smoke is likely to cause an injury. If the volume of smoke is small compared to the volume of the room, then it is likely the concentration of toxic material will be below the TLV (threshold limit value) for that material. So, it is a good idea (for the satisfaction of your customers) to eliminate or reduce any significant smoke emissions that might occur during fault testing. Best regards, Rich ------------------------------------------------------------- Richard Nute Product Safety Engineer Hewlett-Packard Company Product Regulations Group AiO Division Tel : +1 619 655 3329 Effective 6/12/99: +1 858 655 3329 16399 West Bernardo Drive FAX : +1 619 655 4979 Effective 6/12/99: +1 858 655 4979 San Diego, California 92127 e-mail: ri...@sdd.hp.com ------------------------------------------------------------- --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). 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