1.1 本试验方法 2 涵盖排放气体中浓度低于20mg/m的颗粒物（粉尘）浓度的测量方法 3 在标准条件下，特别强调浓度在5 mg/m左右 3 . 1.2 为满足本试验方法的要求，将微粒样品称重至规定的准确度水平。在低粉尘浓度下，这是通过以下方式实现的: 1.2.1 精确且可重复的称重程序， 1.2.2 使用低皮重称重盘， 1.2.3 以常规采样速率延长采样时间，或 1.2.4 在常规采样时间以更高的速率采样（大容量采样）。 1.3 本试验方法不同于试验方法 D3685/D3685M 要求对过滤器坯料进行质量测量，规定称重程序，并要求在测试期间监测烟气流量的变化。它要求在样品过滤器上收集的颗粒物质的质量至少是过滤器坯料上正质量差的五倍。可以采用高容量采样技术或延长采样时间来满足该要求。该试验方法对取样温度波动和等速取样偏差有严格的要求。该测试方法消除了堆内过滤技术。 1.4 该测试方法可用于自动监测系统（AMS）的校准。如果排放气体含有不稳定、反应性或半挥发性物质，测量将取决于过滤温度。 1.5 以SI单位表示的值将被视为标准值。本标准不包括其他计量单位。 1.6 本标准并不旨在解决与其使用相关的所有安全性问题（如果有）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践并确定法规限制的适用性。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ======意义和用途====== 5.1 颗粒物和收集残留物排放率的测定是大气污染治理实践中广泛应用的重要测试手段。控制装置后的颗粒物测量对于确定进入大气的总排放率是必要的。 5.1.1 当国家、州、省或其他地区机构批准时，通常需要这些测量来确定是否符合法规和法令。 5.1.2 控制装置前后进行的测量通常是证明符合法规或合同性能规范所必需的。 5.2 通过该测试方法获得的收集残留物对于表征烟囱排放也很重要。然而，除非对收集的残留物进行化学分析，否则这些数据的效用是有限的。 5.3 通过将监测仪器的输出与使用该测试方法获得的数据相关联，这些测量结果也可用于校准连续微粒排放监测系统。

1.1 This test method 2 covers a method for the measurement of particulate matter (dust) concentration in emission gases in concentrations below 20 mg/m 3 under standard conditions, with special emphasis of concentrations around 5 mg/m 3 . 1.2 To meet the requirements of this test method, the particulate sample is weighed to a specified level of accuracy. At low dust concentrations, this is achieved by: 1.2.1 Precise and repeatable weighing procedures, 1.2.2 Using low tare weight weighing dishes, 1.2.3 Extending the sampling time at conventional sampling rates, or 1.2.4 Sampling at higher rates at conventional sampling times (high-volume sampling). 1.3 This test method differs from Test Method D3685/D3685M by requiring the mass measurement of filter blanks, specifying weighing procedures, and requiring monitoring of the flue gas flow variability over the testing period. It requires that the particulate matter collected on the sample filter have a mass at least five times a positive mass difference on the filter blank. High volume sampling techniques or an extension of the sampling time may be employed to satisfy this requirement. This test method has tightened requirements on sampling temperature fluctuations and isokinetic sampling deviation. This test method has eliminated the in-stack filtration technique. 1.4 This test method may be used for calibration of automated monitoring systems (AMS). If the emission gas contains unstable, reactive, or semi-volatile substances, the measurement will depend on the filtration temperature. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 The measurement of particulate matter and collected residue emission rates is an important test method widely used in the practice of air pollution control. Particulate matter measurements after control devices are necessary to determine total emission rates into the atmosphere. 5.1.1 These measurements, when approved by national, state, provincial, or other regional agencies, are often required for the purpose of determining compliance with regulations and statutes. 5.1.2 The measurements made before and after control devices are often necessary to demonstrate conformance with regulatory or contractual performance specifications. 5.2 The collected residue obtained with this test method is also important in characterizing stack emissions. However, the utility of these data is limited unless a chemical analysis of the collected residue is performed. 5.3 These measurements also can be used to calibrate continuous particulate emission monitoring systems by correlating the output of the monitoring instruments with the data obtained by using this test method.