7
Troubleshooting
Insufficient Solvent Flow from the Pump Outlet
Thermo Scientific
Accela Pump Hardware Manual
89
Insufficient Solvent Flow from the Pump Outlet
If there is insufficient flow when the pump is running, the problem is usually a result of one of
the following:
•
Pump Cavitation
•
Blocked Proportioning Valve
•
Blocked Check Valve
Pump Cavitation
A restriction in flow from the solvent reservoir to the pump can cause the pump to cavitate,
which results in erratic mobile phase delivery. In extreme cases, there might be no flow at all.
The reason is usually either a blocked solvent reservoir filter or a restricted solvent inlet line. A
possible but much less probable cause is a restriction inside of the vacuum degasser.
If replacing the solvent reservoir filter does not solve the problem, do the following:
1. Disconnect the solvent reservoir A line from the inlet port of the degasser and verify
unrestricted flow of solvent through the tubing.
2. If the solvent flow is normal, reconnect the line to the inlet port of the degasser and
disconnect the corresponding degasser outlet line.
3. Check for unrestricted flow of solvent through the degassing chamber. The flow out of
the degasser is normally slower than that going to the degasser.
4. Repeat the procedure for solvents B, C, and D.
Suspect a problem with the degasser only if there is virtually no flow coming out of the
degasser.
Blocked Proportioning Valve
If flow from the degasser is normal, then the next area to check is the proportioning valve.
Y
To check for blockage in a proportioning valve
1. Set the pump to deliver 100% of solvent A at a flow rate of 1000
μ
L/min.
2. Measure the actual flow rate.
3. Repeat steps 1 and 2 for each channel.
If one or more of the values are low, clean the LDA by flushing it the appropriate solvents, as
described in
“Cleaning the LDA Components without Disassembling the LDA”
on
page 56
.
