LUBING has defined an operating point only for the comparability of the different nipples. For this purpose, we have set the water column to 20 cm and the lifting height of the underpin to 3 mm. With the values measured at this point of the curve, we can compare the nipples nominally. The curves of individual nipples are then different again, so that they are adapted to the needs of the species. The flow rates are adapted to the age of the birds. Day-old chicks use the underpin only laterally or slightly in the vertical direction, with only small amounts of water flowing through the nipple. If the birds are older and therefore stronger, they lift the underpin up to the maximum lifting height. Then the maximum flow rate is reached.