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Size-Selective Sampling Performance of Six Low-Volume "Total" Suspended Particulate (TSP) Inlets
Robert W Vanderpool1, Jonathan D Krug1, Surender Kaushik1
1US EPA, 109 TW Alexander Drive, MD D205-03, RTP, NC 27711.
Aerosol Science and Technology : the Journal of the American Association for Aerosol Research
|April 24, 2018
Summary
Low-volume particulate matter inlets often fail to accurately measure total mass concentrations. Wind tunnel tests revealed significant underestimation due to particle size and wind speed, impacting air quality monitoring accuracy.
Area of Science:
- Environmental Science
- Atmospheric Science
- Air Quality Monitoring
Background:
- Low-volume inlets are used in portable particulate matter samplers.
- These inlets are often assumed to measure total mass concentrations regardless of particle size or wind speed.
- Rigorous testing of these "total" particulate matter (TSP) inlets under controlled conditions has been lacking.
Purpose of the Study:
- To evaluate the size-selective performance of commonly used low-volume inlets.
- To determine how aerodynamic particle size and wind speed affect sampling accuracy.
- To assess the representativeness of "total" mass concentration measurements.
Main Methods:
- Wind tunnel tests were conducted on six omnidirectional, low-volume inlets.
- Solid, polydisperse aerosols were used.
- Tests were performed at wind speeds of 2, 8, and 24 km/hr.
Main Results:
- Most low-volume inlets exhibited non-ideal sampling performance influenced by particle size and wind speed.
- Measurements were negatively biased by up to 66% depending on conditions.
- Inlet efficiency decreased with increasing wind speed and particle size.
Conclusions:
- Low-volume inlets do not always provide representative "total" mass concentration measurements.
- Inlet performance varies, impacting the accuracy of PM2.5 and PM10 data.
- Results aid in selecting appropriate inlets and interpreting ambient sampling data.