If we’re still talking about the piston washing part of the configuration, there should be 2 separate lines for that (inlet and outlet) that often are led in the same container (the liquid in that container should be replenish or better yet changed to a fresh one - once in awhile)
If you see some liquid coming out of the outlet in question, while the inlet is dty/empty, then there is some sort of mistaken setup. Follow the lines (there are many in the Explorer system – I know) and make sure there are some rationales for their dispositions.
I don’t recommend any lines that aren’t in use to e led in any sort of salt containing liquids. Here I’m thinking of the B1 line (inlet) – it shouldn’t be in the phosphate buffer if not used. Place it in 23 – 30 % ethanol/water. Better yet: Use it as a elution/gradient line (ie. 2 M NaCl). I assume (judging from the mobile phase nature) you’re working with tagged protein. The best way of using this system and most of the systems with genuine multiple pumps configuration (here 2) is to use them both and thus mix the gradient in high pressure mode.
Another thing: When starting the system (not only this particular one but generally) all the lines should be primed so that air is to be seen in any of them. Because there is a risk of introducing air in the flow from lines that aren’t in use – simply because the valve is rotating during gradient runs and the ports are passing by inlets that not necessary are in use and maybe filled with air.
As mentioned above the Explorer has a huge number of valves, ports and lines, so if I should be of more help, I’d have to be on site. Which isn’t the scope here
Do you have some support/service office nearby. Maybe they could get things in system. I wouldn’t be so sure (their service is pretty far from perfect . I know that for a fact) but that’s a path to follow. (?)
You are welcome to write back and ask questions again if something new comes up to surface.
Best Regards
