A pneumatic control system includes a manifold that defines: a channel for conveying a fluid, a discharge port, a drain port, and an expansion chamber defining a chamber axis. The discharge port defines a flow axis extending between a first end and second end and a receiving region at the second end. The pneumatic control system also includes a filter assembly with a filter member disposed in the expansion chamber, and an actuator configured to selectively control fluid communication between the channel and the discharge port. The chamber axis is substantially coplanar with the flow axis. A filter cap assembly includes a filter cap body enclosing an end of the expansion chamber and selectively removable from the manifold to provide access to the filter assembly. A purge valve body is configured to selectively control fluid flow between the expansion chamber and the drain port.