The Inlet Pressure Or Flow Fluctuates - Agilent Technologies 7890 Series Troubleshooting Manual

4
GC Not Ready Symptoms

The Inlet Pressure or Flow Fluctuates

98
A fluctuation in inlet pressure causes variations in the flow rate
and retention times during a run. Do the following:
• Check if the gas purifier or gas generator is operating at or
near capacity.
• Check the supply gas for
• Verify that the supply pressure regulator is functioning
properly. Systems with long supply tubing lengths may
require a step-down regulator near the GC. Also, use an
additional regulator to smooth out fluctuations caused by gas
generators.
• Check for leaks. (See
be present somewhere in the system. Use an electronic leak
detector to find leaks, then correct them. Do not forget to
check the column—a broken column is a very large leak.
• Check for large restrictions in the inlet liner or split vent
trap.
• Verify that the correct liner is installed. Some liners have
large pressure drops caused by design or tight packaging.
• Check for extreme changes in room temperature during runs.
Correct laboratory temperature problem or move the
instrument to a more suitable location.
• Check for a restriction in headspace, purge and trap, and any
other external sampling devices.
• Verify Auto Flow Zero feature is On. See AutoFlowZero.
sufficient delivery
"Checking for Leaks".) A large leak may
Agilent 7890 Series Troubleshooting
pressure.