BSA Flow Software Installation and User's Guide - CSI

This is the principle of the spherical check illustrated for the conventional
PDA in Figure 7-24: the phase differences Φ 12 and Φ 13 should point at the
same diameter, D. For the DualPDA the corresponding phase differences
would be Φ U12 and Φ V12 (see 7.2.2 The concept of the DualPDA)
If the two local curvatures differ, Φ 12 and Φ 13 will point at diameter values
differing by ∆D (Figure 7-24).
Figure 7-24. Difference, ∆D, in the diameter value corresponding to the two phase
differences Φ12 and Φ13.
One validation criterion in BSA flow software is the maximum allowable
deviation from sphericity. Thus, if ∆D exceeds a certain limit set by the
user, the particle is not accepted.
Phase measurements will always have some associated uncertainty (Figure
7-25). The detectors will be specified within certain tolerances, partly there
will be noise present influencing the accuracy.
Figure 7-25: Effect of uncertainty in the estimation of the phase difference.
Concentration Apart from size and velocity, the PDA can also be used for measuring
measurements particle concentration. A description of how this is achieved is given in
chapter 7.11 (Mean diameters and algorithms for concentration and flux
measurements).
BSA Flow Software:Reference guide 7-29