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Start up of cassettes
5.8 Cassette Cleaning
Filter cassettes should be cleaned after every filtration run to prevent a sediment
layer build-up on the membrane and in the retentate channels. Over time, this
layer becomes compacted, making it difficult to remove completely. As a result,
this will decrease the flux rate of your filter cassettes and reduce their lifespan.
We recommend the following cleaning agents and conditions for the various
membrane materials. This table gives suggested procedures only; requirements may
vary in individual cases:
Cleaning agent
Concentration
pH
Time [min]
Temperature [°C]
Polyethersulfone
and Hydrosart
®
Sodium hydroxide
1 N
14
60
50
Phosphoric acid
2% by weight
1.3
30
50
Adjust the following pressures:
p
inlet
= 29 psi|2.0 bar|200 kPa
p
ret
= 0 psi|0 bar|0 kPa
Microfilter cassettes:
Recirculate cleaning solution with permeate valves closed for 60 minutes.
Repeat with fresh cleaning solution and permeate valve open. Repeat as required.
Ultrafilter cassettes:
Recirculate cleaning solution with permeate valves open for 60 minutes. Repeat as
required.
Flush the filter cassettes with purified water as described in [
Æ
Cassettes”, page 13]. Determine the flux rate of the cleaned cassette as described in
[
Æ
Chapter”5.5 Determining Clean Water Flux for Filter Cassettes (CWF)”, page 15].
Compare results with the previously determined clean water flux (CWF). It is normal
to have a greater drop in clean water flux rate after the first processing and complete
cleaning. Good cleaning practice will result in less water flux deviation.
If the flux rate remains below this level after further cleaning attempts, please
contact your local Sartorius Stedim application specialist.
Generally, the Sartorius Stedim Biotech product and material limitations, especially
regarding pH and temperature stability of the membranes and cassettes, must be
adhered to.
Detection Method of NaOH cleaning agent clearance:
− Neutral pH effluent in both retentate and permeate.
− Conductivity.
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