What are the symptoms of worn balance chamber membranes?
On a machine with high hours, do you replace just the membranes or membranes, housings and valves at one time?
Appreciate any info!
<Atlanta Tech>
Posted
Steve,
There was an earlier forum regarding temp and conductivity fluctuations on a Fresenius machine. Turned out it was a balancing chamber membrane. As for braun troubleshooting, this is beyond me. However, if it turns out that you need to replace the membranes, economicaly and technicaly, replace the set and forgo valve replacement. That is, If the valves appear to be in good order.
I hope this assists you.
<Steve>
Posted
I'll keep that in mind. Thanks for responding.
<Dennis>
Posted
We currently use B/Braun Advanced and Plus'. We have replaced one membrane in that 4+ years of experience. To answer your question, the one problem we had was a tear in a membrane. The machine continuously failed DFS Pressure Test. When everything else was eliminated, we took the balance chambers apart and discovered the tear. Hope that is helpful.
On the wrench screen (1st page) lower rh corner there is a box with LLC and LLS numbers. They increment up during preparation selftest indicating what specific test is in progress. LLC 12500 is the membrane test on the Dialog advanced. Info on this is in Chapter 3 of the service manual. I have the PDF format manual on my laptop, rev 5/2003, and the selftest description starts on page 3-35. your results may vary, but it's in there.
We have Fresenius H's, but maybe the following will prove useful even with other types. Most of our machines have a low conductivity when there is a tear; if it is usually 13.9 it will be on the order of 13.4 with a tear. Some machines have flow alarms which fluctuate very rhhymically as the balancing chamber switches sides. Still others will begin to fail TEST on the pressure holding part. If the diaphragms get too worn, but not torn, they can make the conductivity go up ( believe it or not ) to the point that the machine becomes unusable. The chamber switches based on pressures in H's, though, so if there is another type of mechanism ( magnetic reed switch, etc.) to make the chamber switch in the Brauns this may not apply. One good troubleshooting tip for H's is this: Fill the pitcher on the side with straight concentrate and run the machine in the "Conductivity Calibration" mode. If there is a big leak from new to spent in the BC the conductivity will go up very noticeably ( to around 30 last time I saw this ), then level off gradually as the machine runs more. If you don't see this this doesn't always means there's no leak, but if you do see this there almost certainly is. The best thing is to keep track of how many hours are on the first few machines that get tears. That way you can replace the other diaphragms when they are about shot but before they actually go bad based on their accumulated hours. If you don't, and they all start to fail at nearly the same time because they all have about the same hours you will be devoting most of your time to them for months especially if you have many machines and few techs.
The reason conductivity drops on the Fresenius machines is that the conductivity monitor sensor is downstream of the B/C's, such that pre-dialyzer and post dialyzer fluid can mix(causing a dilution) before conductivity is measured. The Dialog's conductivity cells are upstream of the B/C's so any dilution happens after conductivity is measured. Thanks for the tip though. I hadn't thought the difference in condo cell placement would be relevant.We have just purchased some 2008K's for our hospital services department, and I am as yet unfamilliar with them.
Steve If you contact B-Braun they can fax you a sheet to tell you which part of the dfs pressure test is not passing it will break it down to certain valves or down to the membranes being bad this sheet will be a big help just my advice dont just start changing valves or menbranes with out knowing what is wrong with the machine can be alot of different things wrong do to the dfs pressure test fail
