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<1251> WEIGHING ON AN ANALYTICAL BALANCE分析天平称重
Weighing is a frequent step in analytical procedures, and the balance is an esntial piece of laboratory equipment. The general information described here applies directly to electronic balances ud in analytical procedures. Although many portions of the chapter are applicable to all balances, some are applicable only to analytical balances. This chapter should not be considered all-inclusive, and other sources of information (e.g., the US National Institute of Science and Technology and balance manufacturers) may be uful and applicable when analysts perform a weighing operation or implement a weighing procedure. The information given in this chapter is applicable not only to balances ud for materials that must be accurately weighed
(e Balances〈41〉) but also to balances ud in all analytical procedures.
称重是分析过程中的一个常见步骤，天平是实验室必不可少的设备之一。这里描述的一般信息直接适用于分析方法中使用的电子天平。虽然本章的许多部分适用于所有的天平，但有些只适用于分析天平。本章不应该被认为是包罗万象的，当分析人员进行称重操作或实施称重程序时，其他信息来源(例如，美国国家科学技术研究所和天平制造商)可能是有用和适用的。本章所提供的信息不仅适用于必须精确称量的物料的天平(参见天平<41>)，也适用于所有分析方法中使用的天平。
QUALIFICATION确认
Urs should consult Analytical Instrument Qualification〈1058〉, standard operating procedures, and recommendations from manufacturers when they devi qualification plans.
用户在制定确认计划时，应参考分析仪器确认《1058》、标准操作规程和制造商的建议。
Installation安装
The balance's performance depends on the conditions of the facility where it is installed. Analysts should consult information provided by the manufacturer before they install a balance.
天平的性能取决于安装它的设备的条件。分析师在安装天平之前应参考制造商提供的信息。
texturesupport surface支持表面
The balance should be installed on a solid, level, nonmagnetic surface that minimizes the transmission of vibration (e.g., a floor-mounted, granite weigh bench). If a metallic support surface is ud, the surface should be grounded in order to prevent the buildup of static electricity.
the police天平应该安装在一个坚固的、水平的、无磁性的表面上，以最大限度地减少振动的传递(例如，一个安装在地板上的花岗岩称重工作台)。如采用金属支撑面，应将支撑面接地，以防止静电积聚。
L ocation位置
If possible, the balance should be located in a room that is temperature and humidity controlled. The location should have a clean, consistent electrical power supply. The location should be free of drafts and should not be near ovens, furnaces, air conditioner ducts, or cooling fans from equipment or computers. The balance should be positioned away from outside windows so that direct sunlight does not strike the balance. The balance should not be installed near sources of electromagnetic radiation such as radio-frequency generators, electric motors, or hand-held communication devices (including cordless telephones, cellular
telephones, and walkie-talkies). The balance should not be located near magnetic fields induced by laboratory instrumentation or other equipment.
如果可能的话，天平应放置在温度和湿度可控的房间内。该场所应具有清洁、稳定的电源供应。该场所应没有通风，不应靠近烤箱、火炉、空调管道或设备或电脑的冷却风扇。平衡的位置应该远离窗外，这样直射的阳光就不会破坏平衡。不应安装在电磁辐射源附近，如射频发电机、电动机或手持通
讯设备(包括无绳电话、移动电话和对讲机)。天平不应放置在实验室仪器或其他设备产生的磁场附近。
The performance of the balance should be assd following installation and before u in order to demonstrate adequate performance. In some situations, it may not be possible to position the balance in an optimum environment. Examples of potential facility issues include the following:
应在安装后和使用前评估天平的性能，以证明其具有足够的性能。在某些情况下，可能不可能在一个最佳的环境中找到平衡。潜在设施问题的例子包括:
1.Air currents sometimes are prent in the laboratory.
在实验室里有时会有气流存在
2.Temperatures in the laboratory vary excessively (check the manufacturer's literature about
temperature nsitivity).
实验室温度变化过大(检查制造商关于温度敏感性的资料)。
3.Humidity is either very low or very high. Either condition may increa the rate at which thelocus
sample weight varies becau of pickup or loss of water. Low humidity increas the buildup of
static electricity.
湿度不是很低就是很高。这两种情况都可能增加样品重量因吸水或失水而变化
的速率。低湿度会增加静电的积聚
4.Adjacent operations are causing vibration.
相邻的操作引起振动
5.Corrosive materials are ud nearby or are routinely weighed.
在附近使用或常规称量腐蚀性物质
6.The balance is located within a fume hood becau it is ud to weigh corrosive or hazardous
materials.
该天平位于通风柜内，因为它用于称量腐蚀性或有害物质
7.The balance is adjacent to equipment that produces a magnetic field (e.g., a magnetic stirrer).
天平靠近产生磁场的设备(如磁力搅拌器)。
8.Direct sunlight strikes the balance.
你是谁用英语怎么说阳光直射在天平上aeis
In situations when the balance is located near equipment or systems that induce vibration, drafts, electromagnetic radiation, magnetic fields, or changes in temperature or humidity, the asssment should be conducted with tho systems operating in order to duplicate a worst-ca scenario.
当天平位于设备或系统附近时，这些设备或系统会引起振动、气流、电磁辐射、磁场或温度或湿度的变化，为了重现最坏的情况，应在这些系统运行时进行评估。
Operational Qualification操作确认
An operational qualification should be performed either by the ur or by a qualified third-party vendor after the equipment has been installed.
设备安装完成后，应由用户或合格的第三方供应商进行操作确认。
As a minimum, the power should be turned on and the balance should be allowed to equilibrate according to the manufacturer's instructions (1–24 h, depending on the type of balance) before u. Depending on the balance, analysts should include the following procedures in the operational qualification:
在使用前，至少应打开电源，并按照制造商的说明让天平平衡（1-24小时，视天平类型而定）。根据差额情况，分析人员应在操作确认中包括以下程序:
1.Mechanical mobility of all moveable parts
所有可活动部件的机械机动性
2.Control of stable indication
稳定指示的控制
3.Manually triggered or automatic adjustment by means of built-in weights
手动触发或通过内置砝码自动调整
4.Operation of ancillary equipment
辅助设备操作
5.Tare function
皮重功能
6.Initial calibration
初始校准
Several types of electronic analytical balances u built-in weights for manually triggered or automatic adjustment. This adjustment usually is applied to reduce the drift of the balance over time and to compensate for drifts caud by variations in the ambient temperature.
几种类型的电子分析天平使用内置的重量手动触发或自动调整。这种调整通常用于减少平衡随时间的漂移，并补偿环境温度变化引起的漂移。
Calibration normally is performed as part of the operational qualification, but it also can be performed periodically thereafter. Calibration should be performed at the location where the balance is ud in normal operation.
校准通常作为操作确认的一部分进行，但之后也可以定期进行。校准应在天平正常工作时使用的地方进行。
Performance Qualification性能确认
Table 1 provides a list of the most important balance properties that should be assd during performance qualification. Depending on the risk of the application and the required weighing process tolerance, some of the tests may be omitted. Tests also can be omitted if there is evidence that the property in question has only minimal effect on the weighing performance. Any procedures ud should be consistent with in-hou standard operating procedures, applicable for the specific balance, and adequately justified. Performance qualification should be performed periodically as described in standard operating procedures, and the frequency of each of the individual tests can vary depending on the criticality of the property.
表1列出了在性能确认过程中应该评估的最重要的天平性能。根据应用的风险和所需的称重过程公差，这些测试中的一些可以省略。如果有证据表明所涉及的特性对称重性能的影响很小，也可以省略测试。使用的任何程序都应该与内部的标准操作程序一致，适用于特定的天平，并充分证明。应按照标准操作规程的规定定期进行性能确认，每个单项测试的频率根据性能的紧急程度而有所不同。
The weights that are ud to perform the tests should be stored and handled in a manner that minimizes contamination. Before executing the tests, the technician should place the weights in the vicinity of the balance for an appropriate time to reach sufficient thermal equilibrium. If possible, tests should be carried out with a single test weight in order to minimize handling errors, but multiple test weights are permitted.
用于执行测试的砝码应以尽可能减少污染的方式存储和处理。在执行测试之前，技术人员应在适当的时间内将重量放置在天平附近，以达到足够的热平衡。如果可能的话，应该使用单个测试权重进行测试，以尽量减少处理错误，但允许使用多个测试权重。
The tests should be recorded in such a manner that the data can be ud to easily track balance performance and to assist in laboratory investigations as needed. Meaningful acceptance criteria can be t depending on the required weighing tolerance, i.e., the maximum allowed deviation permitted by specifications, regulations, etc., of a quantity to be weighed from its target value. Procedures should be in place to address test results that are outside acceptable ranges and to provide assurance that balance cleanliness and environment have not affected the result. Also, a procedure should be in place for removing a balance from operation when obrved results fall outside acceptable ranges.
测试应以这样一种方式进行记录，数据可以方便地用于跟踪平衡性能，并在需要时协助实验室调查。有意义的验收标准可以根据所要求的称重公差来设定，即标准、规定等允许的一个数量与其目标值的最大偏差。应制定程序来处理超出可接受范围的测试结果，并保证平衡的清洁度和环境没有影响结果。此外，当观察到的结果超出可接受范围时，应制定一个程序来消除操作中的平衡。
Table 1. Suggested Performance Tests and Acceptance Criteria
表1：建议的性能测试和接受标准
Property 性能Definition
定义
Examples
举例
Acceptance Criteria
皮肤保养秘诀接受标准
Sensitivity 灵敏度Change in the displayed value divided by the
load on the balance, which caus this change.
称量值变动值除以载重变动值，一般在零点和
天平最大载荷间测量
The test load at or sufficiently clo to the
capacity of the balance.
测试载重接近天平最大载荷
NMT 0.05% deviation from 1 (the nsitivity
of a correctly adjusted balance), where 〈41〉 is
applicable. For other us, respective
脱产成考tolerance requirement divided by 2.
如果适用<41>，则偏差≤0.05%（正确调整
平衡的灵敏度）
其它情况，以相应的要求允差除以2
Linearity 线性Ability of a balance to follow the linear
relationship between a load and the indicated
weighing value. Nonlinearity usually is
expresd as the largest magnitude of any
linearity deviation within the test interval.
天平在载重和指示的重量之间保持线性关系
的能力。非线性一般表达为在测试间隔内的任
何线性偏差的最大级别
From 3 to 6 points over the range of the
balance.
天平范围内3到6ge点
NMT 0.05% deviation where 〈41〉 is
applicable. For other us, respective
tolerance requirement divided by 2.
如果适用<41>，则偏差≤0.05%fruit
其它情况，以相应的要求允差除以2
Eccentricity 偏心率Deviation in the measurement value caud by
eccentric loading—in other words, the
asymmetrical placement of the center of gravity
of the load relative to the load receiver.
Eccentricity usually is expresd as the largest
magnitude of any of the deviations between an
off-center reading and the center reading for a
given test load.
由于偏心载重引起的测量值的偏差，换句话
Performed in the center of gravity and the
four quadrants (for rectangular platter shapes)
or at analogous locations for other platter
shapes. Test load usually should be 30% of
the capacity of the balance or higher (refer to
the manufacturer's manual for any possible
upper limit).
测量四角称量值（四边形称量盘）或其它形
状称量盘类似的位置。测试用载重一般为天
一季度是几个月NMT 0.05% deviation where 〈41〉 is
applicable. For other us, respective
tolerance requirement divided by 2.
如果适用<41>，则偏差≤0.05%
其它情况，以相应的要求允差除以2
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