Self-actuated pressure regulator (PCV)

ISA 5.1-2009 (self-actuated regulators) / PIP PIC001

Drawn as

A bow-tie body with a diaphragm dome on its stem, a spring above the dome, and a thin sensing line from the dome to the pipe downstream of the valve.

Meaning

Pressure-reducing regulator with no instrument loop: downstream pressure acts on the diaphragm directly. Fuel gas, instrument air, nitrogen and blanket gas. Tag PCV. No dedicated component; control-valve is the closest stand-in.

Variants

Internal sensing: no external line is drawn
Some legends draw the sensing line as a dashed or plain thin line
Blanketing regulators sit on a tank roof