Ball valve

How to read it

Inside a ball valve is a ball with a passage through it. In the DOE’s Mechanical Science handbook, turning the handle lines the hole up with the inlet and outlet to open the valve, and turning it across the flow shuts it. Kuphaldt’s Lessons In Industrial Instrumentation says simple ball valves with full-sized bores suit on/off service better than throttling, and that the characterized or segmented ball valve is the better design for throttling.

The DOE’s chart draws the ball valve as a small circle between two short uprights across the line. Kuphaldt’s chart gives that form and a second one: two triangles meeting point to point with a hollow circle where they meet. It draws the characterized ball valve with a shape of its own inside the circle.

Also searched as: ball valve p&id symbol, ball valve symbol.

Look-alikes

A solid dot where the triangles meet is a globe valve. Between two short uprights, a slanted stroke in place of the circle is a butterfly valve. Kuphaldt’s chart also has a ball check valve, drawn as a small circle against a point on the line with no uprights; it is a kind of check valve.