What seals the gauge line fitting to the gauge manifold?

The gauge line fitting is typically sealed to the gauge manifold using a combination of threads and a sealing material, such as Teflon tape or thread sealant. These materials help prevent leaks by filling in any gaps between the fitting and the manifold threads. Additionally, some fittings may use O-rings or gaskets to provide a more secure seal. Proper torque during installation is also crucial to ensure a tight connection.