11 Replies Latest reply on Feb 28, 2018 2:55 AM by gchaplain

    Helium burning fast


      I am a new faculty and there was a GC system (7890A G3440A) in a storage room which had not been used for years. I purchased a headspace autosampler (7697A) a few month ago, and had it installed.


      The problem is the helium gas only last for 10 days even with 3 ml/min total gas flow at the standby condition, 1 ml/min for the front column and 2 ml/min for the back column.


      I guess it's leaking somewhere. Is there any protocol you can recommend to resolve the issue?



        • Re: Helium burning fast

          Hi jeongdaei,

          I added a couple of tags for visibility. There are several different models of GC's and headspace models that can be connected together. Compounding the variety of models is that there are several different methods of connecting a headspace to a GC. If you would like to respond with some model numbers and connection type, the community may be able to make some suggestions. This is something that would best be handled through a support ticket .  Please contact our support to get a case created for further assistance: http://www.agilent.com/en-us/contact-us/page

          • Re: Helium burning fast

            Good Morning,


            If you have a helium leak detector it would really help with what I'm going to ask next.


            On the copper lines from the helium cylinder, use the leak detector to check every joint to the GC. Every swagelok connection and every point where there is a joint including the helium cylinder connection, connection ot the manifold, pressure gauges, connections within the manifold and adaptors from teh manifold to the copper line.


            If you haven't got a leak detector I recommend using something like some acetone in water in a squirt bottle. spray these on teh joints ( only a little) and see if it bubbles. That should show if there is a significant helium leak.

            • Re: Helium burning fast

              The Leak Detector solution (acetone in water) is a good start, but be aware that leaks can be hidden (especially under or inside benchwork).  If you try and can't find obvious leaks, try getting a tank clamp and moving the He tank as close to the GC as possible.  Also, the tank valve itself is frequently a source of leaks.  If you're not used to working with tanks, please be aware that the main valves have backseats on them and you should always fully open or fully close a tank... don't just crack it open.


              Good luck!

                • Re: Helium burning fast

                  Well, I replaced the regulator with a new one, and found out that it's not the source. I also applied acetone/water (70%v/v) on all the connectors outside of the GC, but could not locate a leak. Now I need to have a technician in to investigate? Thank you for your advice!

                    • Re: Helium burning fast

                      I would do a pressure test of the rest of your system.


                      1 - Disconnect from the GC and HS units and cap them off.  (Ideally if you have a spare pressure gauge, make sure one is installed somewhere in the line.)

                      2 - Pressurize all the lines, etc. to the working pressure.

                      3 - Turn OFF the valve onthe tank (leave any delivery line valve open), record the pressure at the primary and secondary regulator (and the extra .

                      4 - Check the pressure after 15 min.  and again after an hour.


                      If the pressure holds on the manifold (no visible pressure drop over an hour), then your manifold is leak free and I'd call Agilent for service.  If the pressure drops, your leak is in the manifold and that should be checked (you don't necessarily need an Agilent service person for that).


                      I hope this helps!