Preliminary Evaluation of a Modified NBS PM(10) Sampler for Indoor Particulate Measurements

摘要

Modifications have been made in the prototype NBS portable sampler to overcome several design flaws. The modifications included replacement of the case, redesign of the filter holder, and addition of a motor control circuit. Results obtained in a brief performance evaluation indicate that the modified sampler yields PM10 data comparable to that obtained with a conventional ambient-type dichotomous sampler. The battery pack (six 1.25V Ni-Cd D cells) used with the modified NBS sampler provides at least 24 hours of operation at a flow rate of 6 1pm. The constant current motor control circuit added to the sampler provides a very uniform flow rate (within + or - 5%) over a 24-hour sampling period. The circuit also automatically decouples the motor when the battery output drops below a voltage that delivers a flow rate of 6 1pm. The performance of an indoor air sampler developed by Harvard University was also evaluated in this study.