Engineering CAD Training

A: Principle: Level measurement depends on correct hydrostatic reference, not just signal tuning. Here the CAD discrepancy put the LT above the intended datum, so density and pressure changes look like level changes, driving valve slam during transients. Option B traps engineers who know tuning theory but miss that no amount of tuning fixes a biased measurement.

A: Principle: In a closed loop, the controller adjusts valve position to meet the process variable. With fixed upstream pressure and same setpoint, the valve simply moves to a different opening to hold downstream pressure, provided it's not saturated. Option A catches people who think in open-loop terms and forget the controller action.

A: Principle: Relief devices limit pressure, not phase separation or inventory control. The PSV will lift on pressure rise, but it can't stop liquid from leaving with the gas when level control fails. Option A tempts engineers who associate any upset with relief, ignoring the pressure-only function.

A: Principle: Different drawing types encode different information layers. Control intent comes from the P&ID, physical reality from the GA, and mismatches drive field errors if not reconciled. Option D attracts people burned by revision control who overgeneralize it.