Problem with GC-FID back inlet

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abs
abs's picture
Problem with GC-FID back inlet

I am having problem with back inlet of GC-FID (6890 agilent series) instrument. The pressure of the back inlet is not upto its set point but only half of pressure is observed.

I change merlin mciroseal, gold plated seal on back inlet but still no increase in pressure. The liner is split(4mm id, part no. 5183-4647 agilent).

Everything is working fine apart from pressure of back inlet and try without column by blocking the back inlet with block spetum but still no pressure increase.

Would anyone can suggest me the reason behind this and to affix problem. Any help really appreciate and if you want more details please do reply.

Many thanks in advance

Abs

Dr. Analytical
Dr. Analytical's picture
Abs:

Abs:
Have you also changed the septum?  You did not mention it, but that is the most common source of a leak.  Also, have you been using this inlet on a regular basis, or not?

If you have a leak detector, first check all the components for a leak, which is the most common problem with GC inlets.  If you do not have a leak detector, then try some IPA on the various (cooled) components to see if there is a leak.

If no leaks, then check the inlet pressure of your carrier.  There are also some frits somewhere in the inlet gas lines that I know of, but do not know any details.  If these become plugged, you will have similar problems.

abs
abs's picture
First of all thanks for your

First of all thanks for your reply, change the septum and check all the inlets with leak detector but still no result. All the gas inlets are working fine, usage is every week once or twince depending upon samples.

Would you able to put some more light on this as your help is really appreciated.

Many Thanks

Abs