Pump calibration accuracy

Using the Pioreactor
1

hi everyone. so i wanted to calibrate my media pump today, i have a beaker with water and a scale d=0.01g. I think my issure is easyily fixable: So i ssh into my Pio and follow the instructions, i let the pump pump for 0.40s and write down what my weighing scale says, do i then hit TARE and continue or do i not TARE and continue with the pumping? in my head, TARING makes sense so i did that and continued. So another 2 times 0.4s is pumped, i give the pio my grams of water and continue. I did it 4 times already, afterwards when i want the pio to pump lets say 1 mL it is totall not accurate. The best i got was 0.88g instead of 1g for 1ml. But i also realise while doing the calibration for the pumps that the pumping seconds are not so accurate either because lets say the first 40s are different to the second 40seconds if there is still a drop of water on the end of the tube. How did you guys take care of that?

greetings
leo

2

Hi @LeoKleym,

Yes, it’s correct to tare between each dose.

There are some improvements you can make to the calibration like adding a luer lock on the end (as it pinches the diameter, making it less likely to bead on the end). You can find some details here: Two changes you can make to your Pioreactor to achieve more accurate doses

In general, calibrations should ideally be done as closely to the production set up as possible. Example: same height of vial / tubing, distance from pumps, pressure, etc. This isn’t always possible, so there’s also some inaccuracy.

Another option is to reduce the DC% (>= 60% is okay I think), which slows the pump down, and will allow for more accuracy (in theory).

3

awesome, thanks for the reply! how do i change the DC?

4

When you start the pump calibration, it’s one of the initial questions asked (we call it duty cycle there).