Hilchos Maasei Hakarbanos 4:8

If one received from an offering less blood than is necessary for sprinkling on the altar, the blood is not sanctified. Optimally, one should intend to receive all the animal’s blood, as follows: he holds the windpipe and esophagus in his hand and places them with the jugular vein in a bowl. He slits both of them, or the greater part of them, so that all the blood will collect in the bowl. After slaughtering the animal, the knife is raised so that the blood not flow down it, but rather down the animal’s neck. He wipes the blood off of the knife on the outside rim of the bowl.

Hilchos Maasei Hakarbanos 4:9

The space above the bowl is considered the same as inside the bowl. If one was collecting the blood of an animal and the bottom of the bowl opened before the blood reached the bowl's airspace, the blood is not sanctified. This is because when the blood enters a space where it won’t come to rest, it is not considered as if it had come to rest.