Fritz Brad G
Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352, USA.
Health Phys. 2009 May;96(5 Suppl 2):S69-75. doi: 10.1097/01.HP.0000343154.15026.17.
Ambient air monitoring for non-research applications (i.e., compliance) occurs throughout the world. Often, air sampling systems employed for these purposes employ simple yet robust equipment capable of handling the rigors of demanding sampling schedules and harsh environments. At the Hanford Site (near Richland, Washington) concentrations of radionuclides in ambient air are monitored continuously at 44 locations. In 2004, mechanical dry-gas meters were incorporated into the Hanford Site ambient air sample collection system to allow the direct measurement of sample volumes. These meters replaced an airflow measurement system that required two manual flow measurements and a sample duration measurement to determine sample volume. A six-month evaluation of the dry-gas meters compared sample volumes calculated using the original flow-rate method to the sample volume measured directly by the dry-gas meter. The two methods provided sample volumes that were within 15% of each other 87% of the time. The results indicated that for instances where the sample volume measured by the two methods differed by more than 15%, the dry-gas meter method provided a more accurate sample volume measurement. The results of the evaluation further indicated that the dry-gas meters provided more accurate sample volumes for all samples, resulting in greater confidence in the calculated concentration results.
用于非研究用途（即合规性）的环境空气监测在全球范围内都有开展。通常，用于这些目的的空气采样系统采用的是简单但坚固的设备，能够应对严苛的采样计划和恶劣环境的考验。在汉福德场地（华盛顿州里奇兰附近），在44个地点对环境空气中的放射性核素浓度进行持续监测。2004年，机械式干式气体流量计被纳入汉福德场地环境空气样本采集系统，以实现对样本体积的直接测量。这些流量计取代了一种气流测量系统，该系统需要进行两次手动流量测量和一次采样持续时间测量来确定样本体积。对干式气体流量计进行了为期六个月的评估，将使用原流量法计算的样本体积与干式气体流量计直接测量的样本体积进行了比较。这两种方法在87%的时间内提供的样本体积相差在15%以内。结果表明，在两种方法测量的样本体积相差超过15%的情况下，干式气体流量计法提供了更准确的样本体积测量值。评估结果还表明，干式气体流量计为所有样本提供了更准确的样本体积，从而使人们对计算得出的浓度结果更有信心。
