Chromatography Forum

I am working a Thermo Surveyor LC system.

The pistons are moving, but no liquid is pumped. Even when I purged, nothing coming out. I disconnected the degasser outlet tubing and proportioning valve respectively, unrestricted flow was alright, which means liquid gets in pump head. I guess the problem is in the pump head. I suspect there is a big volume of air accidentally sucked in (someone else was using it and reported this problem to me). I do not know how to remove air. I tried drawing out by a syringe, but not quite sure from where to start. Do I need to open the pump head up? I am sort of reluctant to do that.

my first guess would be air trapped in the check valves. Remove inlet and outlet check valve and sonicate them for 10-15 minutes in a beaker filled with 75% water/25% isopropyl alcohol. Repeat if necessary.
That should take care of the air and of anything else that might prevent the sapphire or ceramic balls inside the check valves from moving freely.

I would agree that the problem is most likly in the check valves.. Either clean or replace them.

I assume you have a Surveyor MS pump or MS plus pump? Or do you have the Surveyor LC pump?

There are also a couple of other things that can cause errors like this.. One is the proportioning valves.. Along if the pump you got a small tool that looks like a large pin with no point.. Use this to gently exercise the proportioning valves.. But this is usually only a problem if you can't get proper flow on one channel..

It can also be due to incorrectly mountet solvent filters.. If you are using the original filters supplied with the pump make sure that the tube screwed into the filter isn't inserted to far into the filter.. It shouldn't be more then 2-3 mm into the filter. If you are using any other sort of solvent filter, this shouldn't be an issue.

Hope this helps you.. Otherwise repost and i bet we can find a solution!