The use of the type of tip (carbon or transparent) is depending on the type of pipetting technology (see “what is the difference between system liquid and air displacement”). The technology determines the technique used for liquid level detection in the system.
Black carbon tips are used when the liquid level detection is based upon conductivity. The ions in the liquid will cause a signal through the tip when the tip touches the liquid. This signal tells the system the liquid level has been found. Systems operating on system liquid will always use the black carbon tips.
Liquid level detection can also be done using transparent tips. The basic principle is different. There will be a pressure or flow sensor in the channel. When the tip touches the liquid, the pressure in the channel changes slightly.
The advantage of the use of transparent tips is often in the price. If the application does require the use of a lot of tips, or if tips cannot be washed, this advantage increases tremendously over the lifetime of the system.