Chromatography Forum

Hello Guys,

Anybody has experience with working with proportioning valve on a Dionex Ultimate 3000 instrument. We are getting no flow coming out of the valve, even though all the 3 lines leading into it have a good flow. I guess we will have to get the proportioning valve out and sonicate it to get the clog out. The problem is we do not have any experience with it. Does anyone have had similar problem and have replaced/sonicated the proportioning valve to fix the proble. If yes- is there a method to do it?

Thank you!

Hi niltan,

I am a Dionex field service rep. May I ask what prompted you to check the flow coming out of the proportioning valve? Perhaps low system pressure or no flow coming out of the pump at all? Also, what model pump do you have and when was the last time it was properly serviced?

With the pump flow turned off, I don't believe you should see anything coming out of the proportioning valve.

I would suggest first priming the pump thoroughly for ~5 minutes. To do this, you will need to open the purge knob (located at the top right of the pressure transducer) about a half turn to the left before clicking the prime button in Chromeleon. When finished purging, remember to close the purge knob. Now verify that the flow rate setting in Chromeleon is correct and turn on your pump flow. Hopefully things will be much better at this point. If not, I would suspect the check valves next, followed by a decoupled piston.

If you still think the proportioning valve is clogged, you can confirm this by using a union to connect one of the mobile phase lines directly to the pump inlet line. I think that sonicating the proportioning valve is a bad idea. Please contact your local Dionex service rep if you think the valve needs to be replaced.