Inlet cooling

Question

Hi, 
 
 I noticed something strange with the cooling of my Inlet, when my oven starts cooling my Inlet heats up. 
 The cooling of my Inlet is working fine when I test it separately, but when my gc oven starts to cool the Inlet is not able cool further down or stay at a set temperature. 
 
 Is normal for agilent systems? I don't have a lot of experience with agilent gc/ms systems, but I have never seen this on any kind of other gc/ms. 
 Its a gc 8890 with mmi, and compressed air as coolend.

Den · Accepted Answer

The problem has been solved in the meantime. With the installation of the system the service engineer installed the noise reduction filter for the inlet. This filter was blocking the airflow almost completely. After removing the filter the cooling is working perfectly. 
 Thanks for the help and effort searching for the cause of the problem.

paulsalverda · Answer

Page 82 & 83 in the 8890 Operating Manual - G3540-90014 
 "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 LN2 hardware cools the inlet faster than the LCO2 hardware. Never use LCO2 or LN2 as your coolant while the instrument is configured in Compressed air mode."

Inlet cooling

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