In AutoCAD P&ID I want to create a connection between a pipe and a medium like water or acid. For example, if I choose water as the medium, I want the line colour to be green, if I choose acid, I want it to be orange. How can I do this?
When you define a pipe line segment in P&ID you define the CAD properties of that line, including its layer, colour and line type etc. The only way to change these properties is through the Properties window.
However, you do have the option to define multiple pipe line segments which correspond to the medium flowing through them, so you could have specific lines on your tool palette for each medium."