Chromatography Forum

I am running a Varian 325 detector and two prostar 218 solvent delivery pumps with Chem Station.
One pump keeps leaking at pump head (25 mL SS) even after changing check valves and pump seal. Piston looks fine.
QUESTION 1: ideas?

QUESTION 2: can you use a single pump and get reproducible isocratic results? So far, this has not worked for me.

RELATED QUESTION 3: for 218 pumps, do you need to always use two pumps

With piston seal you need to change anti-extrusion gasket, not always but that is solution for your first question.
You will achieve reproducible isocratic results when you fix the leak)
Question 3 - No.