repligen.com XC-LAB-UG-V4
2. Insufficient utilities. Repligen provides vacuum pumps suitable for multiplexing, however
there is a limit that depends on the number and size of devices. Please check the utility lines
and connections for leaks.
3. A2C line leaks. The A2C line may not be connected correctly to the air filter at each end or it
may be leaking. Check connections and tighten parts.
4. Device leakage. An air leak on the air side of the device can happen at points where steel to
steel or steel to plastic connections are not properly threaded together.
5. The dip-tube is higher than the liquid level, or the incorrect dip-tube is being used leading to
insufficient liquid being drawn into the XCell ATF® Device.
6. The bioreactor does not have a sufficiently large exhaust gas line or filter-or the filter is wet
and blocked. Bioreactors built for standard fed-batch operation have filters and exhaust lines
that are too small for the combined needs of higher oxygen demand and ATF flow. In addition,
evaporation increases during ATF. We recommend oversizing the exhaust line and, in some
cases, having two lines with one in place as a backup. If water regularly causes blockages,
heating the filter can help.
If the value reported by the controller is within the far end of the 10% range, without moving closer
to the desired setpoint, then the system is operating within specification. Stopping and starting the
XCell ATF® Device or changing the setpoint to a different value for a few minutes (and then returning
to the original value) might help bring the flow within the middle of the 10% range.
Too many air bubbles inside the A2B tubing
To remove large air bubbles mid-run, the XCell ATF® Device can be lowered slightly, and the ATF
Flow can be increased for several minutes - before returning values to their baseline levels. To avoid
large air bubbles, place the dip tube or entry point for the A2B line as far away from the sparger as
possible.
Small bubbles, even if numerous, should not impact sensor or controller performance.
Permeate flow too low or negligible
Upon first starting the permeate pump, time should be allowed for priming to complete (i.e. draw
liquid through the dead volume in the filter module and out to the permeate side). If the cell
concentration is low, you may increase the permeate pump 10x in order to accelerate the priming
process. If mid run, check the P3 pressure profile and inspect the filter for clogging.
A2B flow sensors not communicating
Confirm cables are connected properly.
Displacement Volume alarm does not make sense
This can happen when the system starts up and there is a mismatch between the filter size
configured and the expected value of displacement volume. To resolve this issue, navigate to the
Settings page where default values are displayed and modify one of the expected displacement
volumes. A good example is to set the displacement volume value for ATF4 to 410 instead of 411.
Alternately, pressing the reset to default button also solves the issue.
Displacement volume too low
The displacement volume varies slightly (up to 10%) from the expected value before the controller
takes action. If the value is lower and outside the range but the ATF Flow is working correctly, then
there is an error and you should contact Repligen.
Flow control used to be stable but is not stable or accurate anymore
This could be because PCV command value (PCVcmd) is not closely tracking P2, meaning the valve is
not responding correctly to the control output. Dust may be trapped inside the valve, causing it to
stick or react in a jolting fashion; a service is required on the equipment.
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