[Development of a two stage virtual impactor for stationary source PM10 and PM2.5 sampling]

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Industrial Hygiene

Background:

• Absence of a national standard for stationary source PM10 and PM2.5 sampling in China.
• Limitations of existing commercial samplers in Chinese industrial settings.
• Need for a robust and adaptable sampling method for fine and coarse particulate matter.

Purpose of the Study:

• To develop and evaluate a novel two-stage virtual impactor for stationary source PM10 and PM2.5 sampling.
• To assess the performance of the developed impactor against international standards.
• To ensure suitability for diverse Chinese industrial emission conditions.

Main Methods:

• Design and fabrication of a two-stage cylindrical virtual impactor (74 mm diameter).
• Performance evaluation using laboratory-generated aerosols.
• Analysis of collection efficiency curves against ISO 7708:1995 standards.
• Investigation of flow rate ratios and nozzle-to-nozzle distances for optimal performance.

Main Results:

• The developed virtual impactor demonstrated a collection efficiency curve meeting ISO 7708:1995 requirements for PM10 and PM2.5.
• The impactor's compact size (74 mm diameter) is compatible with typical Chinese stationary source sampling ports.
• Versatility in using filter papers or thimbles allows for effective sampling across a range of dust concentrations.
• Cutoff size (D50) is tunable by adjusting the minor-to-total flow rate ratio; optimal nozzle spacing identified.

Conclusions:

• The developed two-stage virtual impactor is a viable and effective tool for stationary source PM10 and PM2.5 sampling in China.
• Its design addresses limitations of current samplers, offering improved adaptability and performance.
• The impactor provides a pathway towards establishing a national standard for particulate matter monitoring.