Definition check: “Free air” means air stated at the atmospheric pressure and temperature of the specific location (reference ambient). Is this statement correct?

Introduction / Context:
Flow ratings for compressors often use “free air delivery” (FAD). The meaning of “free air” must be clear to compare capacity across sites and conditions.

Given Data / Assumptions:

• Local site atmospheric pressure and temperature define the reference state.
• Standard air is a different concept (fixed reference such as 1.013 bar and 15°C or 20°C).
• Humidity may be specified separately but is not implied to be zero.

Concept / Approach:

“Free air” refers to the actual ambient state where the compressor ingests air. Converting measured volumetric flow to this reference allows consistent volumetric comparisons. It differs from “standard air,” which uses a universal standard condition regardless of site altitude/temperature.

Step-by-Step Solution:

Verification / Alternative check:

Industry datasheets routinely state “FAD at site conditions,” while “SCFM” or “Nm³/h” indicate standard conditions. The definitions co-exist for different purposes.

Why Other Options Are Wrong:

Sea-level or fixed-temperature caveats are unnecessary; humidity need not be zero for the definition, though moisture content can be specified.

Common Pitfalls:

Confusing free air with standard air, leading to erroneous capacity comparisons across elevations and climates.

Final Answer:

True