The process of determining PM₁₀ and PM_2.5 emissions is technically demanding requiring the use of over 40 calculations. To measure PM₁₀ and PM_2.5, a sample of gas is extracted from the stack at a predetermined constant flowrate through in-stack cyclone(s). The sizing device separates particles with nominal aerodynamic diameters of PM₁₀ and PM_2.5. The flow rate used to extract the gas sample is critical in ensuring that correct particle sizing occurs.

Once a sample is obtained, it is analysed gravimetrically to determine the particulate mass for each size fraction.

For PM₁₀/_2.5 emissions six inch sampling ports are always required and in some cases where the gas velocity is high six inch ports are required for PM₁₀ sampling.(See pictures below)

As observed by the picture on the right the standard method 5 probe used for particulate sampling can fit through a 4" port fitting.

The image verifies that the Method 201A PM₁₀ cyclone does not fit through a 4" port fitting.

Image demonstrating that the Method 201A PM₁₀ cyclone can pass through a 6" port fitting.