I have all k machines with a central feed acid system,recenty the doc here changed alot of patients to a different bath,from that comes my problem,about five of my machines will not pick up from the jugs,I did try removeing the check valves ,but is seems that once the first little air hits the pump it stops picking up.

Fresenius machines have always been notorious for their pumps air-locking. It's just the nature of the beast for the kind of pumps they use.

Chuck

When you do your pm's use the jugs this could check whether or not the pump can pull up but so can a bleach cycle but that doesn't check bicarb. Central feed has some pressure behind it to feed the machine but with jugs the pump is doing all the work. I agree with Chuck to that air locks seem to happen alot.

Yeah, best make sure you use jugs for the concentrate and Bicarb intake during all your PM's from now on. If you don't your first sign of a weak acid pump will likely be a REALLY aggravated nursing staff. Been there.

I used jugs for my PMs until I found out all the conductivitys were running high due to my central acid/bicarb feed pressure. Now I calibrate hooked up to the wall. But I stick a jug on the machine before each PM to see how weak the pump is. I know that's extra work but it's better doing that than listening to the staff complain because the machine won't pull out of a jug. BTW most problems that I have found have been due to air locks caused by the staff lettin a jug run dry or waiting too long when switching from the wall to a jug.

Strong springs and Inline check valve combined may add to the problem your having.