Three way ball valves look alike from the outside, but the port pattern decides what the valve can actually do. The difference is easy to picture. An L port ball has a passage that turns a corner. It takes one incoming line and sends it to one of two outlets, so it works as a diverter. A T port ball has a straight-through passage plus a side connection. It blends two streams into one outlet, which makes it a mixer.
For diverting, an L port is the right call. One supply line feeds either line A or line B, and the closed outlet stays sealed while the other runs. For blending, a T port lets two flows meet inside the valve body and leave as a single mixed stream.
We make both patterns on the same body at our Cangzhou plant. The valve is rated 1000 psi, comes in sizes from 1/4" to 2", and the ball is held by four PTFE seats so the sealing line stays stable in every position. An ISO5211 pad is cast onto the top, so you can bolt on a pneumatic actuator without an adapter plate in most sizes.
If the duty is mixing, pick T. If it is diverting, pick L. Getting this detail right saves rework later in the line.