Shimadzu LC-20AB Pump pressure fluctuation

Discussions about HPLC, CE, TLC, SFC, and other "liquid phase" separation techniques.

6 posts Page 1 of 1
Recently I got access to binary Shimadzu HPLC LC-20AB Pump from another lab. One of the pump on the HPLC system was never used and now it seems there is air bubble trapped in the pump. We tried purging the system and also loosening the joints to let air bubble escape but to no avail. Does anyone know how to rectify this problem. Thanks in advanced. Cheers
Shimadzu pumps don't dry-prime well. Open the purge valve, attach a syringe to the end of the purge waste tubing, and suck while purging. Shimadzu probably supplied, in the spares kit, a syringe with a blunt needle and a ferule swaged half way up that's just the right size for the purge waste tubing, for exactly this purpose.
I have this exact problem right now!
We've had our shimadzu over two years and this is the main problem I always get. I have learned you can basically never change solvents in your bottles or else it does this.

We get this issue where the pressure wildly fluctuates as if there's air in the pump and the pressure indicates one side of the pump or a check valve is stuck.

However, this time, I have tried everything and we are still down. I've manually primed, taken off and sonicated all pump parts, replaced seals, taken off check valves and made sure there's flow through them at least 6 times, I've checked the plungers for scratching, leaks etc. After everything, I wonder if one of the pump pistons is not moving.

Any luck getting yours back up?
A few more suggestions:
(1) Be sure and use fully degassed mobile phase.
(2) Wet prime with a syringe to get the fluid 100% fully through the pump heads before starting.
(3) Try to prime (to waste, not to the column) with a small restrictor or backpressure regulator attached to help the pump. Maybe 20-30 bars at first and perhaps use a solution such as pure IPA. Once primed, then re-introduce your mobile phase into the system.
(4) Have the pump heads and/or check valves been fully cleaned and serviced recently? There should be no signs of buffer crystals, leaks or sticking parts.
(5) Dirty or partially obstructed solvent pickup frits can also cause priming problems too. Replace or clean the frits regularly. If you use aqueous buffers, the frits and solutions they sit in are likely to be contaminated in algae and bacteria. These can contaminate the entire flow path and cause all kinds of sticking and cavitation.
cody841 wrote:
I have this exact problem right now!
We've had our shimadzu over two years and this is the main problem I always get. I have learned you can basically never change solvents in your bottles or else it does this.

We get this issue where the pressure wildly fluctuates as if there's air in the pump and the pressure indicates one side of the pump or a check valve is stuck.

However, this time, I have tried everything and we are still down. I've manually primed, taken off and sonicated all pump parts, replaced seals, taken off check valves and made sure there's flow through them at least 6 times, I've checked the plungers for scratching, leaks etc. After everything, I wonder if one of the pump pistons is not moving.

Any luck getting yours back up?


I was able to fix the problem by sonicating the seals and parts in IPA and it has solved the problem. I did notice some particles in IPA after sonication.
Hi, Good times, i know its not what you discussing here and maybe it's not to be discussed at all, but I am trying to copy shimadzu LCSolution from my work to my laptop to make some comparisons at home and it didn't work, i had copied GCSolution, but it seems like LCSolution cd is missing somewhere, can you upload an iso file for me, please, thanks in advance..
6 posts Page 1 of 1

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