Agilent Technologies 8890 - Page 83

5Methods
Operation Manual 83
Fault Detection This parameter is available with N2 cryo and CO2 cryo Cryo types. Shuts
down the inlet temperature if it does not reach setpoint in 16 minutes of continuous cryo
operation. Note that this is the time to reach the setpoint, not the time to stabilize and become
ready at the setpoint.
Cryo Use Temperature If N2 cryo or CO2 cryo is the Cryo type, this setpoint determines the
temperature below which cryogenic cooling is used continuously to hold the inlet at setpoint.
Set the Cryo Use Temperature equal to or higher than the inlet setpoint to cool the inlet and
hold the setpoint until the inlet temperature program exceeds the Cryo Use Temperature. If the
Cryo Use Temperature is less than the inlet setpoint, cryogen will cool the inlet to the initial
setpoint and turn off.
Timeout Detection This parameter is available with N2 cryo and CO2 cryo Cryo types. Use
this setting to conserve cryogenic fluid. If selected, the instrument shuts down the inlet and
cryogenic cooling when no run starts in the number of minutes specified. The setpoint range is
2 to 120 minutes (default 30 minutes). Turning cryo timeout off disables this feature. We
recommend cryo timeout enabling to conserve coolant at the end of a sequence or if
automation fails. A Post Sequence method could also be used.
Use cryo temperature behaves differently in Compressed air mode than it does in N2 cryo or
CO2 cryo mode. In Compressed air mode, the air coolant is used to cool the inlet regardless of
the Use cryo temperature setpoint during the cooling cycle. If the inlet reaches setpoint, the air
coolant is turned off and stays off. If the oven temperature is high enough, or the inlet was very
hot previously, it is possible that the inlet temperature will rise and the GC will go not ready. For
this reason, it is better to set the instrument cooling configuration as N2 cryo, or CO2 cryo,
using compressed air as the coolant. Using compressed air, the LN
2
hardware cools the inlet
faster than the LCO
2
hardware.
Never use LCO
2
or LN
2
as your coolant while the instrument is configured in Compressed air
mode.