Hello everyone,

I'm trying to rehabilitate an old, abused pro-star 230. I took a look at the back plate of the pumphead and the place where the back of the pump head itself and noted a fair bit of dark red/orange rust as well as some pitting. This led me to believe that someone put something they shouldn't have through the system and it needed to be passivated again. Also, I found it wasn't pumping properly, and after trouble shooting with the manual, I found that both the inlet and outlet check valves weren't sealing properly, and the UHMW-PE piston seal had also been corroded so that half of the interior spring was missing.

I replaced the inlet-check valve and the outlet check valve, and the system could pump. For the backplate and the pumphead, I wiped down with 6 M nitric acid (roughly 23%) until all the visible rust was gone, and then wiped down some more before rinsing with copious amounts of sodium carbonate solution and DI water.

I replaced the inlet valve and outlet valve with replacements from Opti-Max, and the system was pumping fine for my quick 5 minute tests. I decided to then passivate the entire system by first flushing for 30 min, 2 ml/min with DI, then 30 min @ 2 ml/min with propanol, then 60 min @ 2 ml/min with water to remove the propanol, and then 30 min @ 0.5 ml/min 6 M nitric acid, and then pumping overnight with DI at 2 ml/min to flush out all the acid. I switched out the water twice.

Coming back, I found tons of iron particulate on the mixer filter, and the system wasn't pumping properly. I sonicated the filter, inlet check valve and outlet check valve and saw a lot of metal particulate that came out, and now neither valve seems to be sealing properly.

I'm wondering if anyone else experienced this, and if there's some way to recover the valves? Right now i'm thinking of sonicating them in nitric acid to try and remove any more iron that might be in them that sonication didn't get out, otherwise I'll have to spend hundreds more on replacing the valves.

Thanks