Final answer:
The center port of a gauge manifold set is typically used for connecting the pressure source.
Step-by-step explanation:
The center port of a gauge manifold set is typically used for connecting the pressure source. The gauge manifold set consists of multiple ports, with each port having a specific purpose. The center port is usually used for attaching the pressure source, such as a gas cylinder, tire, or vacuum system. This allows the pressure to be measured and monitored using the gauge attached to the center port.