A valve assembly for a dental suction system. The valve assembly includes a valve body having an inlet, an outlet and a fluid flow path extending between the inlet and the outlet. The valve assembly also includes a valve plug positioned at least partially within the valve body and including a through-passage. The valve plug is rotatable relative to the valve body to selectively alter a flow of fluid along the fluid flow path. The fluid flow path exhibits a varied cross-sectional area along a length of the fluid flow path.