Heat exchange prior to sample injection

Chromatography Forum: GC Archives: Heat exchange prior to sample injection
Top of pagePrevious messageNext messageBottom of pageLink to this message  By Les on Monday, May 12, 2003 - 03:55 pm:

I have been posed a question regarding an on-line oxygenate analyzer for gasoline. The unit, which I have not personally seen, has a sample heat exchange unit composed of stainless tubing. The stream travels into the GC oven through a small diameter SS tubing and out to the injection port. The manufacturer claims this necessary and we're waiting on the explanation. The sample is then directed to a 0.2 uL VICI LS valve. The analyzer tech had a previous unit that while running with the heat exchanger, caused low results as compared to laboratory GC. The tech removed the heat exchanger and the on-line unit matched up with the lab. Now the new unit has the same exchanger. Would someone know the purpose of this heat exchange system? I don't personally see the need for this type of system. Injecting 0.2uL seems small enough to not cause problems with temperature. Please let me hear some of your comments....before the tech removes the heat exchanger!
Thanks Les


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Tuesday, May 13, 2003 - 06:32 am:

Additional Info please !

What temperature is the oven? If higher when compared to the sample will the sample cool the sample valve? Do you have a leak in the heat exchange system? What oxygenate levels are lower with the heat exchanger?


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Les on Thursday, May 15, 2003 - 04:40 pm:

manufacturer has replied. The exchanger is used for sample streams that setup in sample lines when ambient temp is low. They have no problems in our tech removing the exchanger. The stream actually runs from the sample point through the oven at 70C and back out to the stream in a large bore tube. The sample for analysis arrives in a small bore down the middle of the large bore to the LSV. All academic now. Thanks.


Add a Message


This is a private posting area. A valid username and password combination is required to post messages to this discussion.
Username:  
Password: