precise water level detector

Hi all

Im trying to fill a 20 mL glass curvete with water.

In order to do it I'm using a peristaltic pump but I need a precise way do stop it when the water level reach 20 mL.

Any ideas ?

regards
Miza

when the water level reach 20 mL.

Is that 20 mL, 20.0 mL, 20.00 mL, or 20.000000000 mL?

In other words, what is your tolerance?

Clear glass? Clear liquid? Known density being pumped in?

Probably the easiest is a scale.

High accuracy may be hard depending on the peristaltic pump - my pumps don’t put out a very constant stream, more a quick succession of pulses, the speed of the scale, and how much liquid drips from the hose after your pump stops.

Use a drip nozzle to fill the container and an optointerrupter to count drops.

Calibrate the first time around. This is a surprisingly accurate and very repeatable method, typically to about 0.05 ml, depending on drop size.