Our 1260 II runs dry.

Hello  fding ,

If the pressure is high, it is not necessarily because of air. It could be because of a clog in your system. In the event it is air though, I suggest you flush the system with IPA, which is a much better solvent to get air out than ACN is.

Other things to try is to try to switch the valve to bypass (right click on the sampler in your software > Switch valve to Bypass) and see how much pressure it drops. If it is a big drop, it is definitely something in the sampler. The most likely culprits are the sample loop, needle and needle seat.

I do not know what sampler you have, but this is a good article to backflush the needle seat.

 https://community.agilent.com/knowledge/lc-portal/w/lc-knowledgebase/7693/backflushing-the-needle-seat-of-the-agilent-vialsampler?utm_medium=web&utm_source=acom-search-results&utm_campaign=community&_gl=1*uim0lx*_ga*MTQwMzc0MTIxMy4xNjY1NTA2MjAx*_ga_721QN8V7L1*MTY2NTUyNDc1OS41LjEuMTY2NTUyNjA0NC4wLjAuMA..

Some good info for troubleshooting where the clog is coming from

 RE: Auto Sampler 1260 is Clog very high pressure 

If your issue is not resolved by the backflush of the seat, you might want to look into flushing the needle, You can take the example of where they use the needle seat in the above example of how to backflush the needle seat, but instead of connecting the seat, you can connect the capillary that goes toward the metering device and the loop and the needle (which is normally connected on port 2 initially)

If after all that it is still high, try to find exactly where the clog is and change the capillary or the part that is creating a high backpressure.

Hope this helps

Gabriel

 Hi Gabriel,

Thanks for your advice, I switched MP to IPA, will flush the system overnight, if the pressure is still high, will do  backflush the needle seat tomorrow.

After overnight flushing, the pressure is still in high level, I did backflush needle seat, the pressure is back to normal now. thanks