I've got a 1yr old K machine that has an measured output at the drain port of 525ml, but set flow rate is 500ml. I'm doing the annual PM and book specifies that 515ml is the upper limit. This leads me to several questions. (go easy I'm still fairly new with the K's)
I went back and double checked Dear, Loading, Flow pressures and all good. Also caled Balance Chambers, just to see if they were off from factory cal. Factory = 61.3, Caled = 62.0 Rechecked flow output, still 525ml.
Should I worry about this?
Any ideas? Don't rule out Rookie tech mistakes!
Thanks.

Make sure you do not have any valve errors present (utilize th troubleshooting guide). Also, when checking BC calibration utilize a 100ml cylinder, better yet, a gram scale is even better. However, if using a graduated cylinder, keep in mind of the meniscus, If not familiar, type in "meniscus" under "find". Also, double-up on BC calibration, making sure results are the same.

Graduated cylinders can be inaccurate by one or two percent. We used to use a 50 ml graduate to cal the UF pump on H machines and we found out that most of the time we would get 36 ml in the graduate, but using a buret which is the Fresenius reccomendation would give an accurate 35ml. At least one manufacturer,(Nalgene)of graduates told us that they cannot guarantee accuracy. So a ten ml overage on a 500ml volume might be just a normally inaccurate graduate. Why is the balancing chamber on a 1 year old machine set at 62ml? That's higher than anything that I have seen in a properly functioning balance chamber. Is the conductivity within normal range using an independent meter at that BC volume? I am guessing that someone changed that to make up for a low conductivity, which should have been corrected by an acid, bicarb pump and conductivity cal. And if you really want to check the BC volume, just check the flow at the drain line during regular dialysis mode at three different flows. Count 20 pulses, each pulse should be around 30ml, so if your BC volume is 61.3 the level in the 1000ml graduate should be 613ml. Since that is a bigger sample than the two pulses that you get during the cal it tends to be more accurate. Watch for a different BC volume at different flows, which indicates a problem with the membranes. That is the way that you used to have to cal D & E machine balancing chambers.

Thank You Atlanta Tech and Ktech,
I recaled the Bal Chamber again, still = 62, Haven't seen any valve errors or flow errors, thankfully.
Tried the large scale chamber verification.
At 400, 600, & 800 flows - 20 pulses = 615ml. So my graduates (Nalgene, which I bought less than a year ago) must not be 100% accurate or something!? I went back and reset bal cal to 61.5ml. Rechecked flow at drain twice = 523ml(in the graduate).? Conductivity is about 0.1 to 0.2 above the TCD, and the meter matches the screen.
I'm not sure where to go from here?
Thanks again guys.

Seems as if the machine is trying to tell you that the BC value should be about 65, which seems quite high. You might try set it there and see what you get wrt flow and cond. Also, there should have been a difference between the flow rates at 61.3 versus 62. Weird that there wasn't. Have you checked to see if there is a difference between flow at the drain and flow to the dialyzer? I don't think a leaking V-29 would give you these symptoms, but anything's possible I guess. Also, I never got the BC cal to work with a graduated cylinder. A scale seems to be required, though I haven't tried it yet, as K's are still kinda new to me too. Interesting problem, let us know what you find, wii ya?

There's only about 1.5% difference in volume between 61.3 and 62. On a 500 mL/min flow rate, the difference you'd see over a one minute test is only about 7 mL. Unless you're using a burette (which would be a HUGE burette), you probably wouldn't notice that.

A "rookie" might just stick the hose down into the graduated cylinder which could give a variance due to water that's already in the hose dribbling out into the cylinder. What I would recommend is doing the test again. But make sure you remove the hose from the drain port on the back of the machine and collect the fluid from right there.

If that is the way you're already doing it, you may have a leaking BC membrane. Usually, you can see a slight pulse after the BC dead heads during it's cycle. You'll see the normal pulse of water and then a smaller pulse as it dead heads. It's easiest to see this with the drain hose off and watching it coming out of the nipple on the back of the machine.

Let us know what you find out. Good luck!