Cunningham slip correction factor

Figure 9.15 shows the Cunningham slip correction factors for air at 1 atm pressure and 20°C for the smallest particles, there is a significant correction to the speeds calculated using Eq. (O). 

Figure 18. Cunningham slip correction factors (Q) for spherical particles in air as calculated from Equation (19) at 298 K and 1 atm.

Here cc is the Cunningham slip correction factor given in Table 2.2. It should be included when rp is comparable with the mean free path of the gas molecules. 

Data from inertial impactors are normally presented as 50% effective cutoff diameters. For the Andersen cascade impactors containing round jets and flat collection surfaces, the 50% effective cutoff diameter would yield a value of 0.14 for the inertial impaction parameter K. The Cunningham slip correction factor is equal to... 

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