Investigation of flow rate calibration procedures associated with the high volume method for determination of suspended particulates. Final report 1976-77

Determination of total suspended particulate (TSP) in the ambient air by the high-volume method requires three independent measurements, mass of particulate collected, sampling flow rate, and sampling time. Several potential sources of error in each of the three above measurements have been identified. Implementation of technically sound, standardized flow rate calibration has long been recognized as one of the most effective means of improving the accuracy and precision of TSP data. Procedures for accomplishing this have not been standardized. The purpose of this project was to investigate potential sources of error in the flow rate calibration used in making TSP measurements using the EPA reference method. The first task was a theoretical study of the flow rate calibration and measurement techniques applicable to the high-volume sampler, and secondly to design and carry out an experimental program to assess the validity of the theoretical study concerning temperature and pressure corrections for calibration and use of the high-volume sampler. The indications from this study are that to comply with EPA's requirement that all ambient air quality data be referenced to standard conditions of 298K (25C) and 760 mm Hg and to increase the comparability of TSP data, the flow rate should bemore » based on the flow rate of a standard volume and reported as mass/std volume, e.g., g/SCM. This procedure would require that ambient temperature and barometric pressure at the time of sample collection be known in order to calculate the flow rate based on standard volume.« less