TSI Instruments 3082, Operation And Service Manual, Page: 202 / 225

B-20 Electrostatic Classifier Model 3082 and SMPS Spectrometer Model 3938
Determination of P
3
Penetration through the connecting tubing was calculated using equations
for penetration through a circular tube from Gormley and Kennedy (1949).
Note: When using the flow equalizer accessory, the penetration for this
path may be determined too high. A small percentage of the
overall diffusion loss will not be corrected for in this case.
Determination of P
4
Penetration through each of the Differential Mobility Analyzers (Model 3085
and Model 3081) was determined using published data on the transfer
functions for these DMAs by Chen et al. (1998), Birmili et al. (1997) and
Reineking and Portstendörfer (1986). The penetration was also validated
experimentally.
Determination of P
5
P
5
is already included in the counting efficiency of the CPC and includes
penetration inside the CPC, activation efficiency and optical detection
efficiency.
Equivalent Length Concept
Finally, for Penetration calculations, each individual flow path is
characterized by its equivalent length. This equivalent length is then
substituted into Gormley and Kennedy’s equations to calculate the
penetration. The following equivalent length values are used for each
flow path:
Inlet impactor 0.071 cm (P
1
) 2.1 m
Inlet impactor 0.0508 cm (P
1
) 1.5 m
Inlet impactor 0.0457 cm (P
1
) 0.57 m
Classifier Platform and Neutralizer (P
2
) 1.51 m
Aerosol inlet hose to long DMA (P
3
) 0.33 m
Aerosol inlet hose to nano DMA (P
3
) 0.20 m
DMA outlet hose to CPC (P
3
) 0.25 m
Long DMA 3081A (P
4
) 9.1 m
Nano DMA 3085A (P
4
) 4.1 m
1nm-DMA 3086 (P
4
) 4.1 m