中英文对照资料—天平与砝码

The intent of this section is to bring the requirements for weights into conformity with American National Standard ANSI/ASTM E617, “Laboratory Weights and Precision Mass Standards." This standard is incorporated by reference and should be consulted for full descriptions and information on the tolerances and construction of weights.1  本节的目的是使对砝码的要求符合美家标准ANSI/ASTM E617“实验室砝码和精密质量标准物"。此标准以索引的方式整合在起，砝码的容许公差和构造应参考完整的说明和资料。

Pharmacopeial tests and assays require balances that vary in capacity, sensitivity, and reproducibility. Unless otherwise specified, when substances are to be “accuray weighed" for Assay, the weighing to be performed with a weighing device whose measurement uncertainty (random plus systematic error) does not exceed 0.1% of the reading. Measurement uncertainty is satisfactory if three times the standard deviation of not less than ten replicate weighings divided by the amount weighed, does not exceed 0.001. Unless otherwise specified, for titrimetric limits tests, the weighing shall be performed to provide the number of significant figures in the weight of the analyte that corresponds to the number of significant figures in the concentration of the titrant.  药典测试和检测所需的天平要求多种负荷、灵敏度和可重现性。除另有规定，否则当物质被要求在含量测定中“称定"时，用来称重的设备在测量中的不确定性（随机加系统误差）不过读数的0.1%。如果不少于十次重复称重的标准差乘以三除以称得的重量，结果不过0.001，则测量的不确定性令人满意。除另有规定，对于滴定法限定检测，需行称重以提供与滴定液浓度有效数字位数相对应的待分析物重量的有效数字位数。

The class designations below are in order of increasing tolerances. 以下的类别标号是按照容许公差的升序排列。   Class 1.1 weights are used for calibration of low-capacity, high-sensitivity balances. They are available in various denominations from 1 to 500 mg. The tolerance for any denomination in this class is 5 μg. They are recommended for calibration of balances using optical or electrical methods for accuray weighing quantities below 20 mg.  1.1级砝码是用于校准低负荷、高灵敏度的天平。它们有多种类型，从1 mg到500mg不等。对此级内任何种类砝码的容许公差都是5μg。他们被建议用于校准以视觉或电子方法精密称定低于20mg重量的天平   Class 1 weights are designated as high-precision standards for calibration. They may be used for weighing accuray quantities below 20 mg. (Forweights of 10 g or less, the requirements of class 1 are met by USP XXI class M.)  1级砝码被称为用于校准的标准物。它们可用于称定低于20mg的重量。（对于10g或更轻的砝码，1级的要求可被美药典XXI M级满足。）   Class 2 weights are used as working standards for calibration, built-in weights for analytical balances, and laboratory weights for routine analytical work. (The requirements of class 2 are met by USP XXI class S.)2 2类砝码被用于作为校准的工作标准，分析天平的内置砝码，以及常规分析工作的实验室砝码。（2类要求可被美药典21 S级满足。）2   Class 3 and class 4 weights are used with moderate-precision laboratory balances. (Class 3 requirements are met by USP XXI class S-1; class 4 requirements are met by USP XXI class P.) 2  3类和4类砝码与中等的实验室天平起使用。（3类要求可被美药典21 S-1级满足；4类要求可被美药典21 P级满足。）2 

A weight class is chosen so that the tolerance of the weights used does not exceed 0.1% of the amount weighed. Generally, class 2 may be used for quantities greater than 20 mg, class 3 for quantities of greater than 50 mg, and class 4 for quantities of greater than 100 mg. Weights should be calibrated periodically, preferably against an absolute standard weight.  对砝码的类别行选择，以便所用砝码的容许公差不过称重物重量的0.1%。通常，2类砝码可用在于20mg的重量，3类砝码可用在于50mg的重量，4类砝码可用在于100mg的重量。砝码必须定期行校准，基于个标准砝码。  1  Copies of ASTM Standard E 617-81 (Reapproved 1985) may be obtained from the American Society for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103. 1 美ASTM标准E 617-81副本（1985年再次审定）可从美测试和材料组织中获得，地址：1916 Race Street, Philadelphia, PA 19103。

  Note that the designations S and P no longer designate weight classes but rather weight grades, that is, design limitation such as range of density of materials, surface area, surface finish, corrosion resistance, and hardness. 2 请注意，所用的名称S和P不再指砝码类别，而是指砝码等级，即设计的限度，如材料的密度范围，表面积，表面抛光，耐蚀性，和坚硬度。

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