Replacing Gradient Proportioning Valve vs rebuild?

[jelwell]

Hi All,

I have an old system that I've brought back from the dead, but am now starting to have issues. I was getting air bubbles in the line after the Gradient Proportioning valve and before the pump. I checked my helium sparge and everything seems to be working fine there. My GPV has never worked quite right with the "A" reservoir never pumping, but "B", "C", and "D" worked fine.

I opened up the pump housing to see if there were any leaks around the GPV and saw none. Checked all the connections, and, now, when I go to prime the pump, only the "B" reservoir will prime! I can't even get liquid to the the pump on the "C" and "D" reservoirs.

I switched the GPV out for a spare one that came with this system from another division in our company and the "B" won't prime on that one, but "C' and "D" are working fine. I went online to look at replacement GPVs only to find them listed at $3000.

My questions are: Can I send the GPVs I have out somewhere for rebuilding (I can't find it anywhere on Waters' website)? Once they are rebuilt, will that help with the air in line issue?

[jelwell]

Oh, before the GPV completely stopped working, I did check to see if the frits on the inlets were blocked causing cavitation. They were not...

Any input would be GREATLY appreciated!

[Bull76]

Hi,

Waters GPV's aren't designed to be serviced. But if your handy you could remove the faulty channel from the GPV and remove one of the working channels and install it onto your working GPV. That would give you a fully working GPV. You have to be careful not to damage the diaphragm when removing and installing the solenoid. Good luck it should work.

Regards,
Bull76

[jelwell]

Thank you for your reply! Is it possible to buy new solenoids to attempt this repair. I believe I have 3 faulty ones on one system and 2 on the other. So I am one shy of a set. Also, if I I would damage the diaphragm, is that available for purchase and replacement?

Thanks

[Bull76]

Hi,

No parts are available from Waters to rebuild the GPV. Better off buying a new GPV. Sorry but no easier option due to lack of parts.

Regards,
Bull76.

[LCbob]

First off I would check the fittings between the GPV and the pump, if it's a 2695 we are dealing with here the middle fitting can be tricky to tighten up.

[sketcher]

A GPV valve should be somewhere around $1500. Unless Waters has doubled their prices in the last month?