36
4.7.2
Remove Trapped Air from the Retentate Line
Direct the retentate and permeate lines to feed tank.
Figure 25
Setup for Buffer Conditioning — Recirculation
Procedure
1. Set up the system for recirculation.
2. Open the retentate and permeate valves.
3. Adjust the pump speed to give the recommended cross flow flux. Refer to Table 3.
4. Close the retentate valve until the feed pressure increases by 0.7 to 1 barg
(10 to 15 psig) or valve is completely closed, then open immediately.
Caution: Do not exceed a feed pressure of 3 barg (45 psig).
5. Repeat this step at least three times to remove air.
6.If necessary, adjust the pump flow rate to maintain a feed pressure of 1 to 2 barg
(15 to 30 psig) for UF membranes.
7. Recirculate fluid for 10 to 15 minutes if conditioning for pH and ionic stability at
ambient temperature. For equilibrating temperature between the hardware and
fluid stream, continue until the temperature has stabilized.
8. Check the torque on the cassette holder (not required for auto-torque (AT)
systems).
9. Remove the excess buffer from the feed vessel. Keep all piping, tubing, and
cassette assembly to and from the feed vessel flooded with buffer to prevent air
from entering the system.
It is necessary to determine the system hold-up volume in the feed/retentate flow
path. This volume will dilute the process fluid and must be considered when
calculating concentration factor. Refer to Section 3.3.
Retentate
Permeate
Feed
Tank
Feed
Pump
Rp
Pp
Fp
