Clean your split vent line people!

[cleh]

Yes, it can be removed and you can then try flushing the split line or sonicating the injection port. If you can't clean it you can have the split line replaced at a reasonable price. Scientific Instrument Services does a great job replacing this type of tubing and even glass lined tubing. I'm sure other members of the forum may know of other vendors that do this type of repair. Good luck.

[Peter Apps]

The inlet gas lines on a 3800 run through a square connector on the bulkhead between the top of the GC and the pneumatics cabinet (just follow them form the inlet, you'll find it). Unscrew the manifold, pull out the lines, remove the inlet from the GC and connect a syringe with some solvents to the end of the lines with a bit of plastic pipe. Cautiously apply pressure to push the solvent into the lines. Repeat with different solvents. Flush through very thoroughly with clean gas before you reassemble.

You might find a set of pencil filters on the cabinet side of the manifold, they will probable need replacing.

Peter

[fendersim]

You can clean the 1079, but it's not easy and in my experience usually doesn't solve the problem.

All tubing is welded in place which makes access difficult.

You can try squirting solvent back down the lines into the chamber (remove column and place beaker under outlet to catch the solvent).

If you're brave you can remove the whole thing and drop it in a HUGE beaker full of solvent and sonicate it.

But usually, it's best just to buy a new injector body.

[MichaelVW]

Thanks for the advice everyone. I did manage to take the injector apart and solvent rinse / sonicate it. This hasn't solved my problem but it didn't make anything worse so I'm calling it progress. The pressure reported on the instrument panel still isn't up to where it should be (6.7 psi when set to 21.1 psi). My regulator is set at 70... if I increase it I do see the instrument pressure rise but I don't want to just crank it and not fix the problem.

[chromatographer1]

You mentioned that you had replaced the display numerous times.

The transponder may be maladjusted. At least the reading changes as the pressure increases.

A pressure gauge inserted into the inlet might be a useful diagnostic tool.

But if you get good work out of the instrument, count your blessings.

best wishes,

Rod

[Peter Apps]

Thanks for the advice everyone. I did manage to take the injector apart and solvent rinse / sonicate it. This hasn't solved my problem but it didn't make anything worse so I'm calling it progress. The pressure reported on the instrument panel still isn't up to where it should be (6.7 psi when set to 21.1 psi). My regulator is set at 70... if I increase it I do see the instrument pressure rise but I don't want to just crank it and not fix the problem.

Check to make sure that the pressure going into the GC is not reading in KPa - if it is you want it at about 400.

Peter

[cody84]

Been almost half a year, but with the 1079 I think you could squirt some solvent into the vent line, crank up the purge flow, or blow air through after the solvent. Exhaust for the split vent is on the left side (those rubber tubes coming out). We used to bake the hell out of our injectors once in a while with a baking septum and nut replacing the injector switch/nut. (Also keep the flow rates nice and high during bakeout to flush stuff out).

[MichaelVW]

A new EFC works wonders. Pity I didn't get to see exactly what was wrong, but everything seems kosher now.

It was suggested that maybe the reason the instrument panels keep going out is that we're not getting clean enough power... we have a basic UPS... though I'm not sure how long it has been here and whether it might just need to get replaced or if we need something else.