Agilent G1316A Clog...

[akthmps]

It appears I have a clog on one side of my G1316 column oven (it is the 6uL side plate). The system was experiencing high back pressure and I've determined the clog to be in the temperature-controlled mobile phase line on the right side.

I have back flushed the line, connecting the line from the injection valve to the exit port of the 6uL side. It works fine (<50 barr) at 5mL/min across a variety of solvents when back flushed. However, the minute I reverse the direction and flow through the heated line (with no column connected at the exit port, just a kim wipe pushed underneath to collect the liquid) it very quickly goes over pressure. I'm trying to back flush now with THF and acetonitrile to see if I just haven't found the "right" solvent yet for flushing this line out.

I've looked online but I'm really confused about the part number I'm needing to order should I not be able to remove the clog. Can anyone tell me what specific part number I'll need from Agilent to replace the 6uL heated side plate in the G1316A column compartment? Do I need to replace the entire plate or can I simply replace the line inside? I'm guessing I'll need the entire plate.

Thanks,
Aaron

[Consumer Products Guy]

I'm probably going to catch hell for this suggestion, but since you have backflushed successfully with a full range of solvents, and it stil overpressures when pumping in the "correct" direction, why not just run it through "backwards"? It's just a heated tube.

Or, if you're only using one column (no switching valve), just use the 3 ul side?

Yes, I believe the whole side heater assembly would need replacing.

[bisnettrj2]

That's really odd. If you can't get it unclogged, then I believe it's the entire plate, call Agilent to see if they sell it, then go online to see if you can find a column heater for less that you can use for parts. If you had a newer column compartment, you could use the low-volume heaters that mount directly to the left or right plates, but I think that's probably not an option for you. The part number is G1316-60006, and a short search online revealed prices is the $15-1700 range from non-Agilent suppliers, and $1437.36 from Agilent.

A couple questions:
1. What type of tubing are you running from the autosampler to the column compartment - PEEK or stainless steel? If you're using PEEK, I'm wondering if there isn't a small piece lodged in the entrance to the heater, that only affects the system when you reconnect tubing to the entrance because it then blocks the entrance?
2. How did this problem present itself? All of a sudden, right after an injection, in the middle of a run? What mobile phase were you running when it happened? What were you injecting (sample type, sample diluent)? Some details might help, might not.

I would attach a line directly from the pump (no point in subjecting the valve to unnecessarily high pressures) to the unclogged heater and then to the entrance port of the clogged heater, and put both heaters at about 60 C. Then I would increase the flow rate in 50 to 100 microliter per minute increments, using isopropanol. Make sure to attach some wide-bore PTFE tubing from the exit port of the clogged heater and direct the flow to a waste container. I would do this just to see if there is a flow rate that may (in combination with a little heat and time and associated pressure) alleviate your issue. Might help, might not, but it may save you time and a thousand dollars. Just make sure to record the backpressure through the system to just before the clogged compartment prior to trying this flush procedure, so you can determine the backpressure developed by the clogged heater.

If you can't get any flow through the heater, you can always use the 3uL heater - I never saw much of a difference between using the left or the right, and I doubt you will either unless you're running at high temps (50 C and up) or high flow rates (more than a mL/min or so). You can also remove the 6uL heater and try to visually inspect the entrance to see if there is a blockage, if you can't see inside it well enough with it installed.

[akthmps]

Thanks for the suggestions. I like the idea of running it through "backwards".

Thank you for the part number. The tubing from the injection valve is stainless. I like the idea of trying to increase the temp to 60C.

As you've mentioned, the obvious solution is to switch to the 3uL side. However, quite some time ago, somebody broke a nut off inside the exit port of the 3uL side and I'd probably need a dremel to get it out at this point. I haven't messed with it myself, I was just hoping to get the 6uL side restored.

I'll try the suggestions tomorrow and see what happens.

[lmh]

I'd have another go, and spray water fairly ferociously from a Hamilton syringe in the entire inlet-side fitting too (wash the entire port and threads). Sometimes you can have one bit of dirt that is dislodged by the back-flow, but hangs around in the fitting and finds its way back into the place where it was causing trouble when you return the flow to forwards (i.e. you've got a bit of dirt acting like a ball-valve/check-valve).
Good luck!

[Consumer Products Guy]

I like the idea of running it through "backwards".

Good thing to try.

quite some time ago, somebody broke a nut off inside the exit port of the 3uL side and I'd probably need a dremel to get it out at this point. I haven't messed with it myself, I was just hoping to get the 6uL side restored.

I'd try a screw extractor tool; go to Sears, Ace Hardware, or auto parts store. Tap it in, unscrew.