Definition check: “Free air delivery is simply the volume of air that a compressor can deliver freely.” Is this statement correct?

Difficulty: Easy

Correct Answer: False

Explanation:


Introduction / Context:
“Free air delivery” (FAD) is a standardized term essential for comparing compressors. It is often misstated as just the raw delivered volume, which causes confusion in selection and performance assessment.



Given Data / Assumptions:

  • Industrial air compressor context.
  • Standard reference state (e.g., 1.013 bar and 15°C or as specified).
  • Delivered flow measured and then corrected to the standard state.


Concept / Approach:
FAD is the volume flow rate of air delivered by the compressor, converted back to “free air” conditions (a defined standard temperature and pressure). It is not the raw volume at discharge conditions, nor simply “as is” volume. The correction uses the ideal gas relation to reference different operating sites and discharge pressures to a common basis.



Step-by-Step Solution:
Measure mass flow m_dot leaving the compressor.Convert to standardized volume: V_FAD_dot = m_dot * R * T_std / p_std.Report this standardized volumetric flow as FAD.



Verification / Alternative check:
Datasheets list SCFM or m^3/h (free air) at named reference conditions; on-site measurements require correction for local temperature and pressure.



Why Other Options Are Wrong:

  • “True”: ignores the essential correction to standard conditions.
  • Conditional “true” answers (sea level, oil-free, filter status) do not change the definition.


Common Pitfalls:
Using discharge volumetric flow directly for comparison; always convert to the agreed standard state to compare machines.



Final Answer:
False

More Questions from Compressors, Gas Dynamics and Gas Turbines

Discussion & Comments

No comments yet. Be the first to comment!
Join Discussion