Low Sensitivity Or Poor Repeatability - Agilent Technologies 7890 Series Troubleshooting Manual

Low Sensitivity or Poor Repeatability

Agilent 7890 Series Troubleshooting
• Flow block fittings on the flow manifold
Alternately, use an electronic leak detector to check these
fittings/connections.
If these checks do not resolve the problem, contact Agilent
for service.
A small leak in the Multimode EPC inlet can cause low
sensitivity or poor repeatability. Check for and isolate a small
leak as described below.
If you have recently performed maintenance, first check for
leaks on any fittings/parts you handled.
1
Perform the inlet pressure decay test. If the test passes,
consider the inlet leak-free and check other possible causes
for the low sensitivity or poor repeatability.
2
If the pressure decay test fails, set the inlet to split mode. Set
a column flow of 3 mL/min, a septum purge flow of 3
mL/min, and a purge flow of 50 mL/min. Press [Prep Run].
Monitor the inlet total flow. If the total flow is much greater
than 6 mL/min, check/tighten the following fittings:
• Septum nut
• Column
• Split vent trap
• Liner/O-ring
• Split vent line connection to the inlet body
• Flow block fittings on the flow manifold
If the problem continues, the leak may be small.
3
Use an electronic leak detector to check the
fittings/connections.
If these checks do not resolve the problem, contact Agilent
for service.
7
Checking for Leaks
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