There are two types of 3-way ball valves: L-Port and T-Port. An L-Port can send flow one way or the other or can shut it off completely. A T-Port will perform all the same flow tasks as an L-Port but cannot be shut off. In addition, the T-Port can mix flows by sending or receiving flow to/from both ways of the Tee.

L flow patterns, sometimes called 90-degree balls, are most often used to allow flow from one common inlet port out into one of two different outlet ports. This is why L-pattern flow three-way ball valves are often called diverter valves.