Gas flow control assemblies configured to deliver a gas to a process chamber. The gas flow control assemblies include a single-piece manifold including a manifold body having a length, a first side, and a second side opposite the first side, and passageways extending through the manifold body, the passageways being open to both of the first side and the second side, and no other passageways are formed on any remaining sides, an inlet conduit, an inlet valve, a filter, and an outlet conduit, coupled to one of the first side and the second side, wherein at least some of the inlet conduit, the inlet valve, the filter, the outlet valve, and the outlet conduit are coupled to the first side, and the others are coupled to the second side. Methods and gas panel assemblies for controlling gas flow to a process chamber are described, as are other aspects.
