Chromatographic Troubleshooting
Electronic pressure control
219
Safety shutdown
Systems equipped with electronic pressure programming have a safety
shutdown feature to prevent gas leaks from creating a safety hazard. If
the system cannot reach a pressure setpoint it beeps. After about 45
seconds the beep will stop and the message:
EPPB: SAFETY SHUTDOWN
ACTUAL SETPOINT
will appear on the display, and the system will shut down by turning off
all electronic pressure and heated zones, and locking the keyboard.
A safety shutdown can occur when:
1. There is a leak in the system (see Pressure control problems). This
includes missing septa or columns!
2. The column is not restrictive enough to reach desired pressure (i.e.,
530
columns will not go to 100 psi with available flow). Note: When
using pressure programming, this may occur during a pressure ramp
to too high a pressure.
3. There is insufficient supply pressure.
4. Configuration is set wrong. Check the mode switch on the inlet
controller board (see Proper configuration).
To recover from a safety shutdown, turn the GC power off, then on. Then
reset temperature and pressure zones to desired values. (After safety
shutdown, pressure setpoint is automatically reset to zero.)
