ABSTRACT Several low-volume inlets (flow rates ≤ 16.7 liters per minute (Lpm)) are commercially available as components of low-cost, portable ambient particulate matter samplers. Because the inlets themselves do not contain internal fractionators, they are often assumed to representatively sample “total” mass concentrations from the ambient air, independent of aerodynamic particle size and wind speed. To date, none of these so-called “TSP” inlets have been rigorously tested under controlled conditions. To determine their actual size-selective performance under conditions of expected use, wind tunnel tests of six commonly used omnidirectional, low-volume inlets were conducted using solid, polydisperse aerosols at wind speeds of 2, 8, and 24 km/h. With the exception of axially-oriented, isokinetic sharp-edge nozzles operating at 5 and 10 Lpm, all low-volume inlets showed some degree of nonideal sampling performance as a function of aerodynamic particle size and wind speed. Depending upon wind speed and assumed ambient particle size distribution, total mass concentration measurements were estimated to be negatively biased by as much as 66%. As expected from particle inertial considerations, inlet efficiency tended to degrade with increasing wind speed and particle size, although some exceptions were noted. The implications of each inlet's non-ideal behavior are discussed with regards to expected total mass concentration measurement during ambient sampling and the ability to obtain representative sampling for size ranges of interest, such as PM2.5 and PM10. Overall test results will aid in low-volume inlet selection and with proper interpretation of results obtained with their ambient field use. Copyright © 2018 American Association for Aerosol Research

中文翻译：

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六个低容量“总”悬浮颗粒 (TSP) 入口的尺寸选择采样性能

摘要 几个小体积入口（流速≤ 16.7 升/分钟 (Lpm)）可作为低成本、便携式环境颗粒物采样器的组件在市场上买到。由于入口本身不包含内部分馏器，因此它们通常被假定为具有代表性地从环境空气中采样“总”质量浓度，与空气动力学颗粒大小和风速无关。迄今为止，这些所谓的“TSP”进气口均未在受控条件下进行过严格测试。为了确定它们在预期使用条件下的实际尺寸选择性能，使用固体多分散气溶胶在 2、8 和 24 公里/小时的风速下对六个常用的全向、低容量入口进行风洞测试。除了以 5 Lpm 和 10 Lpm 运行的轴向定向等速锐边喷嘴，所有低容量入口都显示出一定程度的非理想采样性能，作为空气动力学颗粒大小和风速的函数。根据风速和假设的环境颗粒尺寸分布，估计总质量浓度测量值的负偏差高达 66%。正如从粒子惯性考虑所预期的那样，入口效率往往会随着风速和粒子尺寸的增加而降低，但也注意到了一些例外情况。每个入口的非理想行为的影响就环境采样期间的预期总质量浓度测量以及获得感兴趣的尺寸范围（例如 PM2.5 和 PM10）的代表性采样的能力进行了讨论。总体测试结果将有助于选择低容量入口并正确解释在环境现场使用中获得的结果。版权所有 © 2018 美国气溶胶研究协会