Shimadzu LC20 check valve startup problems

[martijnvf]

Hello,

I was wondering what you use after you have installed new check valves (inlet and outlet) to get rid of the air and get the check valves going.
We have just installed new check valves on our LC20 pump and without a column, pressure is build up, but as soon as a column is in place (higher backpressure), no pressure builds up (as if the check valves are closed?).

We already tried flushing them with isopropanol, 10% acetone, still no result.

Anyone any experience with this phenomenon?

With best regards,

Martijn

[hedge8727]

Hi,

I would suggest trying to tighten the check valves onto the pump head a little more firmly. I had a similar experience and this corrected the issue. Pulling IPA with a syringe out of the outlet check valve works well for removing air.

Hedge

[martijnvf]

Hello Hedge,

thank you for the help. I tried it and got them working, but not at low flow-rates (low % during gradient). When I run at 100% B, with 0.3mL/min (the pump with new check valves), the pressure is stable, at 50/50 (A/B), pressure is also stable but at 20% B troubles begin. They do not seem to function when they have to deliver low flow-rates. I contacted the supplier and they are sending me new ones.

Hope this helps.