XCell™ Lab Controller
User Guide
14 repligen.com XC-LAB-UG-V4
Figure 2. ATF pressure and exhaust strokes
6.2
ATF backflush
In most tangential flow filtration processes, liquid typically only moves across the filter from the
retentate side to the filtrate side. During ATF, liquid moves both from the retentate side to the
filtrate side as well as from the filtrate side to the retentate side. Liquid transfer from the filtrate
side to the retentate side is referred to as
backflush
and the action plays an essential role in the
differentiated ATF performance (
). Alternating flow generates negative pressure across the
hollow fiber filter during each pump stroke. The section of the hollow fiber experiencing the
negative pressure (and the consequential backflush) depends on the direction of the pump stroke.
Backflush effectively reduces or eliminates filter fouling by displacing material from the lumen wall
Incorrect ATF operation with insufficient pump displacement and/or low ATF flow rates create
reduced levels of backflush, which can compromise results. Smart mechanisms, built into the
algorithm and alarms (both default and user defined), automatically compensate and help minimize
, provides additional approaches and solutions to fouling and
other frequently observed challenges.
6.3
ATF flow rates and displacement volumes
Figure 3. Backflush example
Backflush in pressure stroke (left); backflush in exhaust stroke (right)
