INDEX temperature accuracy test

Two methods (ASTM D-1218, ASTM D-1747) are available for measuring the refractive index of viscous liquids. Both methods are limited to lighter-colored samples for best accuracy. The latter test method (ASTM D-1747) covers the measurement of refractive indexes of light-colored residual fuel oil at temperatures from 80 to 100°C (176-212°F). Temperatures lower than 80°C (176°F) may be used provided that the melting point of the sample is at least 10°C (18°F) below the test temperature. This test method is not applicable, within reasonable standards of accuracy, to liquids having darker residual fuel oil (having a color darker than ASTM Color No. 4 ASTM D-1500). 

Check the accuracy of this setting by loading a fresh sample of truns-decahydronaphthalene and measure its refractive index at the test temperature following the procedure described in Section 12. If the value for the refractive index differs from the certified value by 0.0001 or more units, then repeat the procedure given in 11.1 until a satisfactory check is obtained. 

The HcReynolds abroach, which was based on earlier theoretical considerations proposed by Rohrschneider, is formulated on the assumption that intermolecular forces are additive and their Individual contributions to retention can be evaluated from differences between the retention index values for a series of test solutes measured on the liquid phase to be characterized and squalane at a fixed temperature of 120 C. The test solutes. Table 2.12, were selected to express dominant Intermolecular interactions. HcReynolds suggested that ten solutes were needed for this purpose. This included the original five test solutes proposed by Rohrschneider or higher molecular weight homologs of those test solutes to improve the accuracy of the retention index measurements. The number of test solutes required to adequately characterize the solvent properties of a stationary phase has remained controversial but in conventional practice the first five solutes in Table 2.12, identified by symbols x through s have been the most widely used [6). It was further assumed that for each type of intermolecular interaction, the interaction energy is proportional to a value a, b, c, d, or e, etc., characteristic of each test solute and proportional to its susceptibility for a particular interaction, and to a value x, X, Z, U, s, etc., characteristic of the capacity of the liquid phase... 

Design practices stem from standard fire test procedures in which the temperature history of the test furnace is regarded as an index of the destructive potential of a fire. Thus, the practice of describing the expected effects and damage mechanism is based on temperature histories. This standard design practice is convenient but lacks accuracy in terms of structural performance. The severity of a fire should address the expected intensity of the heat flux that will impact the structure and the duration of heat penetration. A simple analysis of the expect nature of an unwanted fire can be based on the heats of combustion and pyrolysis of the principal contents in the facility. The heat of combustion will identify the destructive nature of the fire, while the heat of pyrolysis will identify the severity of the fire within the compartment itself and will also identify the destructive potential of the fire in adjacent spaces. 

The refractive index of a transparent substance is the ratio of the velocity of light in air to its velocity in that material under like conditions. It is equal to the ratio of the sine of the angle of incidence made by a ray in air to the sine of the angle of refraction made by the ray in the material being tested. The refractive index values specified in this Codex are for the D line of sodium (589 nm) unless otherwise specified. The determination should be made at the temperature specified in the individual monograph, or at 25° if no temperature is specified. This physical constant is used as a means for identification of, and detection of impurities in, volatile oils and other liquid substances. The Abbe refractometer, or other refractometers of equal or greater accuracy, may be employed at the discretion of the operator. 

For the refractometric method, the apparatus consists of an Abbe refractometer, a suitable source of white light and a small quantity of suitable contacting liquid. The test specimen for refractometer method should be 12.7x6.3 mm, with one flat face and one perpendicular surface. The two surfaces (preferably polished) shall intersect along a sharp line (without a rounded edge). The test specimen is attached to the prism of the refractometer with a drop of liquid of refractive index higher than the test specimen by at least 0.01 and it should not soften or dissolve the specimen. ASTM D542 suggests a list of liquids for a variety of plastics. Measurements are to be carried out at specified conditions, 296 2 K, and 50 5 per cent RH. Temperature is to be accurately controlled. For maximum accuracy. Sodium D lines are recommended. 

Change of Viscosity with Temperature and Pressure. The engineei frequently must estimate the viscosity of an oil at other than the customary testing temperatures. This may be done by Fig. 443, but greater accuracy is possible by use of ASTM viscosity-temperature charts (see Fig. 4-45). However, in order to use these charts it is necessary to know the viscosity at two temperatures, or to know one viscosity and the Viscosity Index. Kinematic viscosity (or centipoises) can be obtained,by the use of Eqs. (3-2), (3-3), and (3-4) on page 25. 

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