What symbols are commonly used to represent components in pneumatic diagrams?

The use of circles to represent tanks in pneumatic diagrams is a common practice rooted in the standardized symbols used in fluid power systems. These symbols help convey the function of various components in a streamlined manner, allowing those familiar with the diagrams to easily interpret the systems being represented.

In pneumatic schematics, tanks hold and store compressed air, and it is visually intuitive to depict them as circles, helping to communicate the idea of storage capacity in a simple form. This standard also aids in making the diagrams clear and consistent, which is particularly important when troubleshooting or designing systems.

The other choices refer to shapes that do not typically represent the components mentioned in standard pneumatic diagrams. While triangles, hexagons, and rectangles may be used in various engineering contexts, they do not have the same standardized usage in pneumatic applications. Thus, circles for tanks stands out as the appropriate representation in this context.