Best way to maintain check valves?

[EmpowersBane]

I know this is a popular topic but I'm looking for opinions on the best way to maintain check valves using a UPLC system. We experience a lot of problems with check valves sticking, causing erratic pressure etc but one of our engineers recommend to me to flush the A1/B1 lines in 90:10 Aqueous:Acetonitrile for about 30 mins following a long gradient run using buffered mobile phase?

I did this and for 10 months now not a single issue with the check valve, do you think its just luck or is there something to priming out the A1/B1 lines to wet the seals and flush away and residual buffer? There seems to be dozens of tips on how to stop check valve failure!

[dap]

Warm water it the best flushing solvent however you should renew it at lest once a day to prevent algae growth. 5-40 % i-propanol/methanol/acetonitrile should be fine too.

[DR]

Flushing post run is always a good idea.

Also, if one of your MP is straight ACN, see if ceramic check valves are available. ACN can cause problems w/ the more traditional ruby ball/sapphire seat.

[leadazide]

If more of my customers would listen and follow advice about a post-run flush method I could die a happy man..

[Khanom]

I agree with DR, after acetonitrile and/or buffer mobile phase/s have been used for a project, it is useful to flush the system with 85% water / 15%methanol. When buffers with a very high salt content are used, it is also useful to back-flush the pump pistons, please see the pump’s user manual.

[James_Ball]

I agree with DR, after acetonitrile and/or buffer mobile phase/s have been used for a project, it is useful to flush the system with 85% water / 15%methanol. When buffers with a very high salt content are used, it is also useful to back-flush the pump pistons, please see the pump’s user manual.

Definitely a flush with buffer free mobile phase after. Another thing I have done, especially if the instrument will be used within a day or two after is to keep a very slow flow through the instrument of 50/50 water/methanol, about 0.2ml/min for non uplc systems. This seems to keep the check valves clean and also keeps the piston seals from sticking to the piston, which will cause wear on both once flow resumes. The pressure is normally low enough that it doesn't cause excessive wear on the pump seals and you don't worry about any microbial growth in the system.