Chromatography Forum

I'm trying to get an HP 5890 II up and running. I'm relatively new to hands-on maintenance of GC's so I'd appreciate advice from the experts out there. I'm having problems with two gas flows - the Aux Gas on both FIDs and the both Inlet Purge Vents - I get no flow through either of these.

With the Aux Gas, I do get He flow up to the flow block. I've taken out one of the flow blocks and they seem to be in good shape but even just connecting the He to the Aux Gas connection without the other valves (Hyd and Air) in the block I couldn't get any flow by opening the Aux gas valve and varying the inside needle valve through its range. Then I took out the Aux gas valve and still don't get any gas flow through the flow restrictor alone - the gauge supplying the Aux gas doesn't lose pressure in a several minutes when the gas supply is shut off. It looks like the flow restirctor is plugged. Does this seem possible or reasonable? The only source I could find was priced at $125 for the restrictor - any ideas on a way to fix this without spending the money on a new restrictor?

The other problem I'm having is no flow through the Purge Vent. I've tried with the purge solenoid on and off on the control panel and don't see any flow (although I can hear a "click" when the status is changed). The purge vent flow goes through the chemical traps and I'm wondering if they might be plugged - I bought the GC a couple years ago and the tags on the traps have 1999 and 2002 written on them but I don't know how much the GC was used from early 2000's until I purchased it. Any ideas on troubleshooting this further?

Thanks

About the click of purge valve - did you tried both A and B?
Otherwise - try to detect valve control voltage - valve terminals are placed near the back side of main board.

About the gas flows. As far I remember - every knob in gas module has on top a slit for small flat screwdriver. This is actual flow controller. Rotating the knob - is just on/off for gas line.

About datasystem - you can try our UniChrom (http://www.unichrom.com/dle.php)

Look at this thread (hope the photos show, they show for me) which shows the 5890 stuff I have, and would like to find a new home for. Included are some flow blocks and controls. http://chromforum.org/viewtopic.php?f=7 ... 6&start=15

These would be very reasonable, and if you're in USA and pay shipping, you could try out such parts and just pay the upfront agreed-upon price if they work for you - yes, the honor system. Post your E-mail address if interested and I'll contact you.

If the Aux valve has the adjustable screw inside the center of the knob, then I don't think you need the restrictor in the back of the block. The restrictor was there to control the flow using pressure where the knob did not have the adjustable screw for the needle valve. Try it without the restrictor and see if you can adjust the flow.

For the purge vent flow, make sure you have the Total flow knob opened up. You set the head pressure with the pressure knob, then set total flow with the other. If the total flow isn't high enough you won't get any flow from the vent, it will all go through the column.