Looking for idea.. low backpressure on single piston IC pump

[IC_Gal]

We have a Dionex DX120 and the pump will not prime. We've confirmed the eluent bottle has ~ 5- 7 psi Helium. The pump lost prime and was leaking a day ago. We put in a new piston seal and the pump was running well for about a day. It is not leaking anywhere we can see. No leaks are observable inside the instrument where the column and suppressor are but we can't get the backpressure to greater than about 250 psi. Normally it is about 2200 psi.

Please let me know if you have any ideas as to what may be happening..
We appreciate any help..

[Consumer Products Guy]

1. did you re-prime, like even using a syringe, after the repair?


2. is it actually pumping the correct volume of liquid, like direct eluent flow into a graduated cylinder, and measure the actual flow?

[tom jupille]

Sorry if I'm flogging the obvious, but do you have a column connected?

[IC_Gal]

Thanks for the suggestions...

Yes, we've got a column connected...

I wish we could prime with a syringe..
There is no easy way to prime with a syringe on this model of pump. An old model and certainly one of its drawbacks...

Update..
After some back and forth with service folks it turns out the o-ring from the previous piston seal had lodged in the pump head and we installed the other one on top of it. We've taken that out and put the new piston seal in there and it seems to be running fine now. This is the first time I've seen anything like this happen.

I've got my fingers crossed we'll be ok. Standards look good..