BALANCES
This chapter states the requirements for balances used for materials that must be accurately weighed (see General Notices,
8.20 About). Unless otherwise specified, when substances must be “accurately weighed”, the weighing shall be performed
using a balance that is calibrated over the operating range and meets the requirements defined for repeatability and accuracy.
For balances used for other applications, the balance repeatability and accuracy should be commensurate with the requirements
for its use.
本章规定了用于必须精确称量的物料的天平的要求(参见 凡例 8.20“关于”)。除非另有规定，当物质必须“准确称量”时，称量
应使用在操作范围内进行校准的天平，并满足对重复性和准确性的要求。对于用于其他场景的天平，天平的重复性和准确度应
与其使用要求相称。关
For a discussion of the theoretical basis of these requirements, see Weighing on an Analytical Balance <1251>, which may be a
helpful—but not mandatory—resource.
于这些要求的理论基础的讨论，请参阅在分析天平上称重<1251>，这可能是一个有用的但不是强制性的资源。
Change to read:变更导读
REPEATABILITY 重复性
Repeatability is assessed by weighing one test weight NLT 10 times. [NOTE—The test weight must be within the balance’s
operating range, but the weight need not be calibrated. Because the standard deviation is virtually independent of sample mass
within the balance’s capacity, use of a small test weight, which may be difficult to handle, is not required.]
可重复性通过对一个测试重量称重NLT 10次来评估。[注-测试重量必须在天平的工作范围内，但重量不需要校准。由于在天
平的容量内，标准偏差实际上与样品质量无关，因此不需要使用可能难以处理的小测试重量。]
Repeatability is satisfactory if twice the standard deviation of the weighed value, s
, divided by the desired smallest net weight (i.e., smallest net weight that the users plan to use on that balance),
does not exceed 0.10%. The repeatability measurement establishes the smallest net amount of material that may be
weighed on the balance in conformance with the 0.10% limit. The minimum weight, Mmin, is described by the inequality Mmin
≥ 2000 s . For example, if s is found to be 0.00015, then Mmin must be ≥ 0.30000 g or
300.00 mg. If the standard deviation, s, obtained is less than 0.41d, where d is the scale interval
of the balance, then the inequality becomes Mmin ≥ 2000 (0.41d). For example, for a 4-place analytical balance, d is 0.0001 so
that Mmin must be ≥ 0.0820 g or 82 mg.
如果称重值的标准差s除以期望的最小净重(即用户计划在该天平上使用的最小净重)的两倍不超过0.10%，则可重复性是令人
满意的。重复性测量确定了可在天平上称量的材料的最小净量，符合0.10%的限度。最小称量值（Mmin）用Mmin≥2000s的
不等式来描述。例如，如果s测得值是0.00015，那么Mmin必须≥0.30000 g或300.00毫克。如果得到的标准差s小于0.41d，其
中d为天平的示值精度，则不等式为Mmin≥2000 (0.41d)。例如，对于4位分析天平，d为0.0001，因此Mmin必须≥0.0820 g
或82 mg。
ACCURACY 准确度
The accuracy of a balance is satisfactory if its weighing value, when tested with a suitable weight(s), is within 0.10% of the
test weight value.
A test weight is suitable if it has a mass between 5% and 100% of the balance’s capacity. The test weight’s maximum
permissible error (mpe), or alternatively its calibration uncertainty, shall be NMT one-third of the applied test limit of the
accuracy test.
[NOTE—Applicable standards are the following: American Society for Testing and Materials (ASTM) E617 (available from
http://www.astm.org) and International Organization of Legal Metrology (OIML) R 111 (available from http://www.oiml.org).]
如果用合适的砝码测试天平的称重值与测试重量值的误差在0.10%以内，则天平的准确度是令人满意的。
如果测试重量在天平容量的5%到100%之间，测试重量是合适的。试验重量的最大允许误差(mpe)，或其校准不确定度，应为不
超过准确度测试的应用测试极限的三分之一。
[注-适用标准如下:美国测试和材料协会(ASTM) E617(可从http://www.astm.org获得)和国际法定计量组织(OIML) R 111(可从http://
www.oiml.org获得)。
