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- Posts: 6
- Joined: Wed May 30, 2018 7:31 am
I'm having a strange issue with the gradient proportioning valve (GPV) in a Waters 2695. Basically, when the valve is set to open it doesn't allow solvent to flow (e.g. to perform a dry prime). The problem occurs for all four solvent channeld.
I have checked the flow path both before and after the GPV without discovering any problems. In fact, if the solvent stream is connected directly from the degasser to the pump (bypassing the GPV) the system runs completely fine, so there can be no issue with e.g. the check valves or any blockages.
So I thought I'd narrowed the problem down to the valve, and sourced a replacement one. However, now that I've replaced the valve the problem remains exactly the same. I guess there is some problem with the circuit board that controls the GPV maybe?
Does anyone have any suggestions as to what the problem might be, or how I can further diagnose it?
Thanks very much,
Pete