🔍 Key Concepts

• Bellows operation in a pressure regulator (how force changes with pressure) • Lever and pivot geometry shown in the illustration (which way does the lever move if bellows force increases or decreases?) • Relationship between gland seal pressure, bellows force, and pivot rod motion (up vs. down)

💭 Think About

• Trace the force path starting at the gland seal pressure acting on the bellows: if the pressure drops, what happens to the bellows force and its compression? • Look carefully at the lever and pivot arrangement: when the bellows shortens or lengthens, does the end of the lever connected to the pivot rod go up or down? • Think about the regulator’s purpose: if seal pressure falls, should the mechanism move toward opening or closing the supply, and which pivot-rod motion would cause that?

✅ Before You Answer

• Be sure you can explain whether bellows force increases or decreases when gland seal pressure drops • Confirm from the drawing which direction the pivot rod moves when the bellows is pushed up versus pulled down • Eliminate any choices where bellows pressure change and pivot-rod motion contradict the lever geometry shown in the figure