Wikipedia defines VR as immersive multimedia or computer-simulated reality that simulates a physical presence in places in the real world or an imagined world, allowing the user to interact in that world. When it comes to chemical feed systems, that translates into seeing the full system layout before a single component is assembled, and being able to asses the design visually, rather than relying on general arrangement drawings or P&IDs. You can view / interact with a chemical feed system utilizing a head- mounted display (HTC VIVE shown), which enables you to understand the spatial requirements, envision how it looks, and do this from anywhere in the world.
The next phase in “but wait there’s more” is AR, in which you not only see a virtual representation of your chemical feed system, but you see it in your facility where will actually be placed. AR lets you overlay your design atop real world images, videos or GPS data. The fine distinction is that the real world content and the computer generated content are not able to react with one another. You can see that the skid fits, and assess if there’s adequate room for maintenance and access to the panels, calibration columns, etc.