Pressure measurement — categories of relative measurement: Select the correct trio that names the common categories: absolute pressure, gauge pressure, and differential pressure.

Introduction / Context:Pressure instruments are specified by how they reference pressure. Understanding the categories helps in selecting suitable sensors and interpreting datasheets. The standard categories are absolute, gauge, and differential—each referencing a different baseline pressure.

Given Data / Assumptions:

• Absolute pressure: referenced to an absolute vacuum.
• Gauge pressure: referenced to ambient atmospheric pressure (often labeled psig or barg).
• Differential pressure: the difference between two arbitrary points.

Concept / Approach:Absolute sensors include an internal vacuum reference; gauge sensors vent one side to atmosphere; differential sensors have two ports and output the difference. Variants like barometric sensors are special cases of absolute or gauge measurement, but the primary taxonomy remains the absolute/gauge/differential triad.

Step-by-Step Solution:

Verification / Alternative check:Transducer catalogs list part numbers with suffixes -A (absolute), -G (gauge), -D (differential). Calibration procedures and labeling on process transmitters use the same categories.

Why Other Options Are Wrong:

• “Exact/reflective/referenced”: Nonstandard terms for pressure categories.
• “Absolute, exact, and differential”: “Exact” is not a pressure reference type.
• “Absolute, gauge, and reflective”: “Reflective” relates to optics, not pressure referencing.
• Barometric/vacuum/osmotic: Mixed concepts; not the standard taxonomy for sensor types.

Common Pitfalls:Confusing measurement category with range (e.g., vacuum vs. positive pressure) or with sensing technology (piezoresistive, capacitive, etc.).

Final Answer:absolute, gauge, and differential.