Stack Particle Size Analysis

This poster on stack particle size analysis by microscopy was presented at the Source Evaluation Society (SES) Conference in 2015 in Tuscon Arizona. The poster was a collaboration between Tim Vander Wood of MVA Scientific Consultants and Jim Serne of TRC, an engineering, consulting and construction management firm.

Abstract: Cyclones and impactors are used to determine particle size distributions based on aerodynamic separation of particles and weighing of the collected fractions. Uncertainties in these methods come from the collection efficiency curves of each stage or cyclone and the ability to accurately measure the weight of the collected fraction. The collection efficiency curves particularly impact the PM2.5 fraction. Direct particle sizing by microscopic measurement of collected particles (e.g. on Method 5 filters) determines physical particle sizes with significantly lower uncertainty than that related to collection efficiency curves. Furthermore, “catch, count and measure” can be used in situations where cyclones and impactors cannot: in wet environments, in situations where the mass loading is too low to accurately weigh, in stack where impactor or cyclone do not fit and in extreme temperatures. If required, the physical dimensions of the particles can be converted to aerodynamic diameter.

Utilizing scanning electron microscopy (SEM) for stack particle size measurement is useful where stack geometry, cyclonic flow or moisture preclude the use of Method 201A, and when the stacks are simply too clean to use gravimetric methods. One of the most common questions that we get from prospects is “Do regulatory agencies accept results from microscopy particle size measurement?” Our clients have submitted microscopy particle sizing data to state agencies, and many states have accepted them.

In addition, we will help our clients address any questions from regulatory agencies regarding microscopy particle size analysis methods, data accuracy and robustness of the measurements.

If your facility or clients encounter situations where 201A is not appropriate, we will be happy to assist.

Please contact us at info@mvainc.com or 770-662-8509.