Valves for annular conduits and associated systems and methods are disclosed. A fluid transmission system in accordance with one embodiment of the invention includes a first conduit having a first wall aligned with a flow direction in the first conduit and a second conduit disposed annularly around the first conduit with a second wall aligned with the flow direction. An access channel can be positioned to have an aperture in fluid communication with the first conduit and can be isolated from fluid communication with the second conduit. A valve element can be positioned in fluid communication with the access channel and can be movable between a first position and a second position, with the valve element being positioned to allow a first amount of flow through the access channel when in the first position and being positioned to allow no flow or a second amount of flow less than the first amount of flow through the access channel when in the second position. The valve can be installed in aircraft fuel lines or other systems.