Is there anything we have to do after we replace the bc membranes?? I have an H machine that started having conductivity problems and TMP problems after I replaced the bc membranes because of Low Flow errors. Any ideas??

If you don't have Low Flow Error before you changed the membrane, but happen after you changed it. Most likely you did something wrong. Reverse what your doing, may found the problem.

Did you mix up some valve wires?

I'm not sure about this, but i think that new BC chambers need to be recalibrated for their fluid volume. I think the number is 60.0 +/- a few tenths. Is this number the default value the machine needs to produce the correct conductivity and TMP?

You have to do the balance chamber calibration. Use a gram scale if you have one. It is more accurate. I also agree with Ktech and Tommy. You might have goofed something up. Check all your wiring. Check it against a known good machine's wiring.

Run through heat disinfect with shunt door open for couple hr's.. Helped me out once with the volume. Dont know why but did.

What did you do that would change the volume of the bc? Just wandering- the chamber is the concave part and unless you sanded some off or left something inside the volume did not change even if the membranes were a different thickness. I was just in a level II class last month and Russ Bell told us not to recalibrate after changing membranes.

maybe i'm reading this wrong but did you change the bc membranes because of flow errors? then have cond. and tmp problems?

I originally changed the bc membranes because of low flow errors, and then after that the machine is having TMP and conductivity problems. It looks like all the wiring is correct.

Over a long period of time the balancing chamber volume will go down because the membranes develop wrinkles and dimples where the valves inject. Those dimples don't squash out tight against the opposite wall like a new flat membrane does. I have seen balancing chambers that have lost as much as 2.5 ml in volume because of this. With the concentrate that we use an actual 1.0 ml BC volume decrease that is not calibrated for will cause a .5ms increase in cond. I am speaking about 4, 5 or 6 years of useage and around 25,000 hours. If you don't check and change the BC cal then you will have high conductivity because the machine will continue to inject the portion of acid and bicarb based on the larger volume BC. When you change the membranes then you will probably also need to calibrate the BC back to the original factory volume. Talking about 20+ years of machine history, Fresenius BC volumes have gone up over the years. Machines from the early 80's had a volume around 60.0ml. Machines from the early 90's to around 2003 had a BC volume around 60.8. After 2003 every machine that I have seen has a factory set BC volume around 61.3. The material that balancing chambers are made of has changed during that time period also. Many of the BC's from the late 80's developed cracks in the segments of the BC itself, and resulted in conductivity problems. I have not seen a bad BC segment for a very long time now. In class they don't tell yuo about that BC volume going down over the years. And, if you have doubts about the accuracy of your method of checking BC volume, then check a brand new machine and see if you come up with the factory set volume. I prefer using the prime feature in the BC cal and collecting 20 pulses, instead of the two. Also, write the factory volume on all new machine BC's, since Fresenius no longer does that. That way if you lose the cal, say for a bad RAM chip on a function board, you will still have a record of the volume. Older machines came with a blue spec sheet from the factory that had all the module serial numbers and the BC volume on it, but Fresenius stopped doing about six years ago.

What are the conductivity and TMP problems? High, low, or unstable conductivity? Can't maintain TMP, failing self test? Positive or negative TMP problem?

The machine will run fine for a while but then intermittently conductivity will go down to about 11 for about 5-10 minutes, then it will come back up to normal.
With the TMP, again it will run ok for a while but then it will go to +60 and it gets stuck there for a long time, when I look at the actual TMP is is about 330 or 340.
Tried recalibrating TMP but this did not work.
thanks for your comments

I have a known good balancing chamber with all the valves and wiring. Then, I piggy back to the trouble machine. If the problem solved, then I will check the balancing chamber valves one by one, by using one new/good valve. Yes, it is time consuming. For my experience, ohming or valve leak test do not help much, unless that valve is very bad.

That sounds like you still have an intermittent flow alarm. Have you checked the deair pressure when this happens? If you have the old style hydroblock maybe the deair orifice O ring is bad. Does the temperature also drop? That would really be an indication of a flow alarm also.

This message has been edited. Last edited by: Ktech,

Yes, you are right. There is still an intermittent low flow error. The hard thing is that it doesnt happen when I am testing, only when it is in treatment and it will only happen for a couple of seconds, before the techs can get to it, the alarm clears itself. How can I troubleshoot if alarm doesnt come on during my testing??