Which device controls system pressure?

• A. Solenoid Valve
• B. PPE
• C. Regulator
• D. Caliper

Answer: (C)

Controlling system pressure is about keeping the downstream pressure at a set value despite changes upstream or varying load. The device that does this is a regulator. It senses the downstream pressure and uses a spring, diaphragm, or piston to adjust the flow path automatically, so as pressure tends to rise, the regulator reduces flow, and as pressure tends to fall, it allows more flow. The result is a stable, predictable pressure level for actuators, gauges, and other components.

A solenoid valve, by contrast, mainly controls whether fluid can pass and which path it takes; it can change pressure indirectly but does not maintain a target pressure. PPE is safety gear, not a pressure-control device. A caliper is a measuring tool used for dimensions, not for regulating pressure.