| Riniraish | Date: Пятница, 2013-09-06, 10:53:35 | Message # 1 |
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Group: Гости
| Doors are also rated in hourly increments over three hours, but these ratings are not often used because of their cost. See NFPA 252 Chapter 8 and Section 8.1.3.1 for detailed information on the test and ratings.
Photo 1 shows a sample of the construction of a wooden panel door commonly used in residential and business occupancies. This type of door cannot meet the test for fire rating under NFPA 252 because of the thin cross-sections of its panels where they join the rails and stiles. A modern door such as this one will be made up of many pieces of wood laminated together with the grain running in different directions so that it is less likely to warp. Older doors will be made up of solid wood rails and stiles with thin wood panels in between.
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