Underwriters Laboratory classification

Health and Safety Factors. Sulfur hexafluoride is a nonflammable, relatively unreactive gas that has been described as physiologically inert (54). The current OSHA standard maximum allowable concentration for human exposure in air is 6000 mg/m (1000 ppm) TWA (55). The Underwriters Laboratories classification is Toxicity Group VI. It should be noted, however, that breakdown products of SF, produced by electrical decomposition of the gas, are toxic. If SF is exposed to electrical arcing, provision should be made to absorb the toxic components by passing the gas over activated alumina, soda-lime, or molecular sieves (qv) (56). 

Underwriters Laboratories Classification of Comparative Hazard to Life of Gases and Vapors... 

UNDERWRITERS LABORATORIES CLASSIFICATION OF COMPARATIVE LIFEHAZARD OF GASES AND VAPORS... 

The limiting oxygen index of Tefzel as measured by the candle test (ASTM D2863) is 30%. Tefzel is rated 94 V-0 by Underwriters Laboratories, Inc., in their burning test classification for polymeric materials. As a fuel, it has a comparatively low rating. Its heat of combustion is 13.7 MJ/kg (32,500 kcal/kg) compared to 14.9 MJ /kg (35,000 kcal/kg) for poly(vinyHdene fluoride) and 46.5 MJ /kg (110,000 kcal/kg) for polyethylene. 

Underwriter s Laboratories Classification (uic). This is a standard classification for grading the relative fire hazard of flammable liquids against the following standards ... 

Flammability of Liquids, No. 340, Underwriters Laboratories Northbrook, 111., 1972 Flame Arresters, No. 525, 1973 Flammable Liquid Dispensing, No. 1238,1975 Group Classification of Flammable Liquids and Gases, Test Report MH8593, 67C2889,1967. 

Underwriters Laboratories, Inc., Subject 723, Standard Test Method for Fire Hazard Classification of Building Materials, August 1950. 

The American Society for Testing Materials (1) has described this test. The Underwriters Laboratories, Chicago, has test equipment as described above. The Forest Products Laboratory, Madison, Wise., has built a smaller tunnel, approximately 1 foot wide and 8 feet long. As far as the writers know, this type of tester has not been installed in any private industrial or commercial testing laboratories. This severely restricts the rate of accumulation of test data by this method. In spite of this, classifications by this method are being incorporated in various building codes. 

Wood—fire hazard classification, card data service." Serial No. UL527. Underwriters Laboratories, Inc., Northbrook, 111. 1971. 

Every laboratory facility should be equipped with at least a manually activated alarm system, although an automatic system is preferable since it wiU continue to function when the facility is unoccupied. Automatic alarms are especially useful in academic institutions since there are break periods when the population of the campus is very low. In many cases, depending upon local code requirements and the occupancy classification, an automatic fire alarm system may be required rather than optional. Every component of a system should be approved by Underwriters Laboratories, the Factory Mutual System, or other nationally recognized accrediting and testing organizations. 

Underwriters Laboratory Incorporated is a nonprofit organization that conducts scientific investigations, studies, experiments, and tests related to hazards of life and property. As part of its role, it publishes standards, classifications, and specifications aimed at reducing hazards. It evaluates and tests products. It authorizes UL recognitions of tested products that comply with its standards. UL is best known for testing and certification of electrical equipment. Its services extend to fire-related and other products. 

Shields convert the nighttime retail establishment into a veritable fortress in short order. They can stop the penetration of clubs, knives, and small-caliber firearms. Under the Florida Law, the enclosure must meet Underwriters Laboratory Standard UL 752 for Medium-Power Small Arms, Bullet-Resisting Equipment or the American Society for Testing and Materials Standard D3935 (Classification PCI 10 B 3 0800700) (Florida Department of Legal Affairs, Division of Victim Services, 1993, p. 1567). 

Materials with highly cross-linked epoxy resin reinforced with woven fiber glass are the most common in use. Bromine is reacted with the epoxy matrix and is used to provide fire retar-dancy. Most epoxy-based materials satisfy the Underwriters Laboratories (UL) classification of V-0 for fire retardancy. The generic term for this family of epoxy resin materials is FR-4, with FR standing for flame retardant and 4 an assigned number indicating epoxy. Epoxyfiberglass materials are sold by many snpphers and have become a commodity material. 

NEMA has published separate standards publications in a number of classifications. A considerable amount of NEMA standardization activity is in cooperation with other organizations engaged in standardization, such as ASTM, Edison Electrical Institute, NFPA, Underwriters Laboratories, IEEE, and other associations, laboratories, or Government bodies. 

---