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preface to fifteenth edition

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PRACTICAL LABORATORY INFORMATION 11.137<br />

11.8 SIEVES AND SCREENS<br />

TABLE 11.53<br />

U.S. Standard Sieve Series<br />

Sieve opening<br />

Sieve opening<br />

Sieve no.<br />

mm inch Sieve no.<br />

mm<br />

inch<br />

125 5.00 10 2.00 0.0787<br />

106 4.24 12 1.70 0.0661<br />

90 3.50 14 1.40 0.0555<br />

75 3.00 16 1.18 0.0469<br />

63 2.50 18 1.00 0.0394<br />

53 2.12 20 0.850 0.0331<br />

45 1.75 25 0.710 0.0278<br />

37.5 1.50 30 0.600 0.0234<br />

31.5 1.25 35 0.500 0.0197<br />

26.5 1.06 40 0.425 0.0165<br />

22.4 0.875 45 0.355 0.0139<br />

19.0 0.75 50 0.300 0.0117<br />

16.0 0.625 60 0.250 0.0098<br />

13.2 0.530 70 0.212 0.0083<br />

11.2 0.438 80 0.180 0.0070<br />

9.5 0.375 100 0.150 0.0059<br />

8.0 0.312 120 0.125 0.0049<br />

6.7 0.265 140 0.106 0.0041<br />

3.5 5.60 0.223 170 0.090 0.0035<br />

4 4.75 0.187 200 0.075 0.0029<br />

5 4.00 0.157 230 0.063 0.0025<br />

6 3.35 0.132 270 0.053 0.0021<br />

7 2.80 0.111 325 0.045 0.0017<br />

8 2.36 0.0937 400 0.038 0.0015<br />

Specifications are from ASTM E.11-81/ISO 565. The sieve numbers are the approximate number of openings per linear<br />

inch.<br />

11.9 THERMOMETRY<br />

11.9.1 Temperature and Its Measurement<br />

The new international temperature scale, known as ITS-90, was adopted in September 1989. However,<br />

neither the definition of thermodynamic temperature nor the definition of the kelvin or the<br />

Celsius temperature scales has changed; it is the way in which we are <strong>to</strong> realize these definitions<br />

that has changed. The changes concern the recommended thermometers <strong>to</strong> be used in different<br />

regions of the temperature scale and the list of secondary standard fixed points. The changes in<br />

temperature determined using ITS-90 from the previous IPTS-68 are always less than 0.4 K, and<br />

almost always less than 0.2 K, over the range 0–1300 K.<br />

The ultimate definition of thermodynamic temperature is in terms of pV (pressure volume) in<br />

a gas thermometer extrapolated <strong>to</strong> low pressure. The kelvin (K), the unit of thermodynamic temperature,<br />

is defined by specifying the temperature of one fixed point on the scale—the triple point

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