Abstract: An assembly of a display panel and a mounting base for a plurality of light-emitting elements. The mounting base is adjacent to one side of the display panel, and the display panel has a plurality of light-transmitting apertures, holes or openings representing at least two different fluid flow paths and specific fluid devices, such as valves and fluid containing cylinders. A microprocessor is used to control the operation of voltage sources coupled to the light-emitting elements so that, by selectively actuating a first set of light-emitting elements, a visual representation of a first fluid flow path can be provided to indicate the flow of a first gas from one location to another. Alternately, the assembly can be operated such that a second fluid flow path can be visually represented while the light elements of the first path are deactuated.