The difference between a standard ball valve and a full-port ball valve is in the size of the ball and bore in relation to the nominal pipe size of the valve. For example, the bore size in a 3/4-inch full-port ball valve is 3/4-inch in diameter, while the bore diameter in a standard ball valve is 1/2-inch in diameter. Full-port bore size equals pipe size; standard-port bore size is the next smaller pipe size.
Full port valve bodies require high torque to open and close the ball. An example of a full port valve from Belimo would be the B240VS. The valve body has a 1 ½” threaded connection, and a 1 ½” ball opening. The Belimo Characterized Control Valve offerings, CCV and HTCCV, are standard port valves.
The full-port ball valve provides minimal resistance to flow and thus creates only a very small pressure drop when it is full open; it is typically used for isolating flow. The standard-port ball valve causes a larger pressure drop when it is full open; it is typically used for regulating flow to a coil.