FlexStand Benchtop Cartridge Support Assembly, standard flow path with 50 mm (1.5") TC connections and single 0 to 60 psig (1 to 4 barg) SS pressure gauge

Air trapped in the pore structure of the membrane

Air-locked membrane, in which case, water layers trap a pocket of air between inner and outer surfaces of the membrane; effectively reducing the available surface area. This may be observed following autoclaving. Remedy: recirculate cold water (5-15C) on the retentate side with the permeate side closed, very gradually increase retentate backpressure until a stable 20 psig is reached and hold this condition for 10 minutes or until expected permeate flux is reached Note that this does not affect feed pressure or TMP; due to the permeate side being closed, but only raises the absolute pressure on both sides of the membrane; causing the trapped air to diffuse rapidly into the water.

Pump head is not turning

Check for error messages on pump display, check voltage setting is correct on power supply and power is delivered to the motor

Pump is turning but flow is inadequate

Check occlusion setting on pump (if applicable)

Tubing has become drawn inside the pump head and has flattened within pump head. Open pump head and stretch tubing while at the same time closing the pump head. Check to see that the settings are correct on the tubing gates on either side of the pump head for the tubing installed. Refer to Pump Manufacturer's instructions for details if applicable.

Blockage or partial blockage of flow path

Flush through to clean blockage. If necessary replace tubing and connectors. Please refer to order information for tubing and connectors.

Feed inlet at cartridge is blocked

Switch feed and retentate lines to reverse flow and flush with deionized water (DI) or water for injection (WFI).

Fouled cartridge

For feed flow rate versus pressure drop and cleaning of cartridge refer to Operating Handbook - Hollow fiber cartridges for membrane separations.

Retentate valve closed or restricted

Open valve

Speed of pump (RPM) is too high

Reduce pump speed

Inside dimension of tubing is too large

Ensure tubing i.d. is sized properly for the connection. See the table of permeate connections.

Split tubing at barb

Check tubing for wear or splitting. Replace tubing if necessary.

Tubing clamp incorrectly installed

Ensure the clamp is installed and tight.

Clamp is loose

Check and tighten clamp

Gasket worn, damaged, improperly mounted or wrong size

Inspect gasket for wear, damage and proper sizing. Replace if necessary.

Membrane pore size is too small for target molecule

Select the smallest pore size that still allows efficient passage of the target molecule (in general 10 x larger opening than the target protein) For most mammalian cell culture clarification 0.2 to 0.65 micron pore sizes are used.

Air trapped in the pore structure of the membrane, or glycerol humectant not properly removed

Cartridge not wetted properly. Please read the chapter New cartridge rinsing procedure in the Operating Handbook - Hollow fiber cartridges for membrane separations. For pre-treatment with alcohol please read the document Hollow fiber cartridge preparation instructions.

Auxiliary equipment such as manometers and pumps not working properly

Check the function of all auxiliary equipment. Repair/replace if necessary.

Bent tubing

Check that the flow path is not restricted

Liquid viscosity too high

Check the viscosity of the liquid. Viscosity is a function of temperature. (Lower temperature gives higher viscosity.) Let low-temperature liquid reach operating temperature before starting the run.

Microbial growth in buffers. The buffer normally becomes opalescent due to microbial growth.

Check buffers, especially those with phosphate, for microbial growth. Replace with fresh buffer if necessary.

Membrane pore size is too large for target molecule

Select the largest pore size that retains the target molecule (in general choose a
membrane 3-5× smaller than the target protein). For example, either 30,000 or
50,000 NMWC ultrafiltration membranes are recommended for mAb concentration and
diafiltration.

Cartridge not wetted properly

Cartridge not been wetted properly. Please read the chapter New cartridge rinsing procedure in the Operating Handbook - Hollow fiber cartridges for membrane separations. For pre-treatment with alcohol please read the document Hollow fiber cartridge preparation instructions.

Membrane is not integral

Please contact your local GE Healthcare technical support representative.

Faulty diaphragm valve

Get valve serviced by GE Healthcare service engineer or replaced.

Gasket worn, damaged, improperly mounted or wrong size

Inspect gasket for wear, damage and proper sizing. Replace if necessary.

Leakage from process connectors

Check and tighten connectors.

Dimension of tubing is incorrect

Ensure tubing i.d. is sized properly for the connection. See the table of permeate connections.

Fouled cartridge

Clean the cartridge according to instructions.

Split tubing at barb

Check tubing for wear or splitting. Replace tubing if necessary.

Tubing clamp incorrectly installed

Ensure the clamp is installed and tight.