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Flushing and Cleaning
NOTE
The following flushing and cleaning recommendations are
based on three cassettes in series. These recommendations
are guidelines. Actual flushing and cleaning volumes and
operating conditions depend on the membrane type, cutoff,
and screen used, as well as the applied flow rate and retentate
pressure. Evaluate flushing and effective cleaning procedures
for each process to reach optimized conditions for each specific
application.
Flushing
An initial flush is required to remove storage solution from the
membrane in new cassettes. Flushing should also be performed
after each cleaning, depyrogenation, and sanitization step to
remove residual solutions. Flushing is primarily done with purified
water but may be performed with cleaning or buffer solutions.
1. Fill the tank with flushing solution.
2. Fully open the retentate valve and direct the retentate and
permeate lines to drain.
3. Turn on the feed pump and pump flushing solution into the feed
port of the Pellicon
®
holder at a feed flow rate of 1–4 L/min/m
2
.
4. When flow is established, partially close the retentate valve, if
necessary, to achieve a conversion of 30–90%.
(Conversion = permeate flow rate/feed flow rate).
NOTE
A high conversion will result in faster overall flushing, but
will require high trans-membrane pressure. Membranes
with low permeability (low cutoff) will generally not achieve
conversion at the high end of the range.
5. Flush until a total of approximately 150-300 liters of flushing
solution per m² of installed filter area have been pumped
through the system to drain. Achieving a minimum of
approximately 100 L/m
2
through the permeate and 30 L/m
2
through the retentate is recommended. Depending on individual
removal criteria, the total flush volume can be optimized.
6. At the end of the flush, continue pumping until the flow path
lines are drained.
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