Millistak+HC AppGd_textC.qxd - Millipore

The moderately higher capacities
achieved with the pilot-scale Opticap
prefilter and process-scale (16-inch)
Although the prefilter accounts for the
majority of the pressure build-up in the
system, the comparatively small sterile
filter area used in the lab-scale tests
exaggerates its pressure contribution.
As a result, the lab tests underestimate
the capacities achieved with the relatively
larger sterile filters used in the
pilot- and process-scale tests.
stacked-disk filter are due to differences
in the relative areas of the sterile filters
used, as shown in the following table:
Prefilter Area Sterile Filter Area Area Ratio
Lab-scale 23 cm 2 4 cm 2 5.7
Pilot-scale 650 cm 2 200 cm 2 3.3
Process-scale 1.8 m 2 0.69 m 2 2.5
These and other tests have produced
the following results in process-scale
trials for secondary clarification of a
CHO cell culture prior to sterile filtration
(0.22 µm). The ratio of prefilter
area to sterile filter area is approximately
2.5 :1. Performance is measured
at a constant feed rate (flux) to
the prefilter of 100–150 LMH:
Capacity Pressure
(L/m 2 ) Differential (psid)
Run 1: 60% Cell Viability
Millistak+ HC B1HC Prefilter 476 30
0.22 µm Durapore Filter 1100 5
Run 2: 80% Cell Viability
Millistak+ HC B1HC Prefilter 443 30
0.22 µm Durapore Filter 1088 5.5
Millistak+ HC Filters Application Guide 9