- Hewlett-Packard Reference Manual

Chromatographic Troubleshooting
Electronic pressure control
218
Electronic pressure control
The electronic pressure control option provides very accurate and precise
control of column head pressure, resulting in retention time
reproducibilityof better than 0.02% RSD when there are no column
effects. The inlet pressure can be set constant, programmed, or set to
maintain a desired column flow rate. This mass flow control can be
maintained even at vacuum column outlet pressures. A safety shutdown
feature stops the run and can trigger an alarm if the column breaks or
pressure otherwise falls. In addition, a bypass flow maintains a small
positive column pressure in the event of power failure, protecting the
analytical column.
Symptom Possible Cause
Not enough pressure 1. Septum leaks or is missing
(Safety shutdown activated) 2. Column is broken
3. Column ferrule seal leaks
4. Gas supply is off
5. Supply pressure is inadequate
6. Desired pressure may not be achieveable with
the column in use.
Pressure goes to O or max. 1. Configuration is wrong. See the section
Proper
configuration.
Not Ready light flickers 1. Septum and/or column connection leaks.
(oscillating pressure) 2. Pressure set higher than the operating limit
Pressure not controllable 1. Configuration is wrong. See the section
Proper
configuration.
Electronic Pressure Control Problems
If you have checked these possible causes and still have a problem, call
HP Service.