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Safety factor guidelines

Designers unfamiliar with plastic products can use the suggested preliminary safety factor guidelines in Table 2-11. They provide for extreme safety. Any product designed with these guidelines in mind should conduct tests on the products themselves to relate the guidelines to actual performance (Chapter 4, RP PIPES, Stress-Strain Curves). With more experience, more-appropriate values will be developed targeting to use 1.5 to 2.5. After field service of... [Pg.129]

The SF usually used based on experience is 1.5 to 2.5, as is commonly used witli metals. Improper use of a SF usually results in a needless waste of material or even product failure. Designers unfamiliar with plastic products can use tlie suggested preliminary safety factor guidelines in Table 7.3 tliat provide for extreme safety intended for preliminary design analysis only. Low range values represent applications where failure is not critical. The higher values apply where failure is... [Pg.459]

Let s take the example of benzene, which at 12,000 ppm, is 100% LEL. The National Fire Protection Association (NFPA) states that equipment can operate, without LEL monitors or controls, if the LEL is less than 25% LEL. For benzene then, 25% LEL is equal to 3,000 ppm. This upper boundary becomes a dictating factor in the selection and design of the oxidation equipment. If the concentration is higher than 25% LEL, the NFPA requirements state that an LEL monitor is required. Using an LEL monitor, NFPA guidelines allow operation up to 50% LEL (a 2 1 safety factor). Thus, 100% LEL is explosive if the stream is at 25%, a factor safety of four exists. [Pg.478]

In most cases, limited information is available regarding the toxic effects of chemicals. Empirical guidelines are then used in an attempt to protect most of the aquatic ecosystem s biota. The regulation of chemicals, for instance, generally uses safety factors from 10 to 1000 depending on the number of species tested. Mesocosm studies or comparisons with real field situations are accepted with lower safety factors on a case by case basis, since these studies reduce the uncertainty linked to the relevance of laboratory models in terms of site-specific data. [Pg.92]

Kister (1] surveyed tbe multitude of published criteria for maximum downcomer velocity. He pointed at tbe poor accuracy and inconsistency of these criteria, then incorporated them together with his own experience into the single set of guidelines shown in Table 6.5. The values in Table 6.5 are not conservative, and some may even be slightly optimistic. For a conservative design, a value from Table 6.5 can be multiplied by a safety factor of 0.75. [Pg.289]

The selection and justification of uncertainty factors are critical in using this approach. The National Academy of Science has provided guidelines for using uncertainty factors (13). "Safety factor" or "uncertainty factor" is defined as a number that reflects the degree or amount of uncertainty that must be considered when ADIs are estimated from variable toxicity data bases. It includes extrapolation based on intraspecies (human population) as well as interspecies (from animal to human) variability. When the quality and quantity of experimental data are satisfactory, a low uncertainty factor is used when data are judged to be inadequate or equivocal, a larger uncertainty factor is needed. In those cases where the data do not completely fulfill the conditions for one category, or... [Pg.453]

Define the temperature failure criteria for the material. The experimental formulas were blended and extruded. The extruded products were measured for heat deflection temperature using ASTM D 648 as a guideline. Multiple measurements at various heating rates were conducted. An appropriate engineering safety factor was applied to the data. A critical temperature failure criteria was defined as 70°C for these particular experimental formulas. 70°C was considered the maximum sustained temperature the extrusions could withstand and still provide acceptable engineering performance. [Pg.66]

The laminate fulfilled heat deformation resistance class A 90 with a temperature limit of 130°C classified under the fiammability classification of DIN 4102-1 B2 - DIN EN 13501 / B s2 dO. The reduction factors in calculating load capacity were in accordance with DIN 18820. The safety factor SO is in accordance with the guidelines for wind-farm composite materials (Germanischer Lloyd - RichtUnie fUr die Zertifizierung von Windkraftanlagen). [Pg.446]


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