Difficulty: Easy
Correct Answer: compresses 3 m³/min of free air (at local atmospheric conditions)
Explanation:
Introduction / Context:
Compressor capacities are quoted in different “bases” such as free air, standard air, or compressed (actual) conditions. Knowing what a “3 m³/min compressor” means prevents sizing mistakes and ensures apples-to-apples comparison between vendors.
Given Data / Assumptions:
Concept / Approach:
Three common bases exist. Free Air Delivery (FAD) expresses the delivered mass flow as an equivalent volume at local ambient conditions. Standard air uses a fixed reference (e.g., 1.013 bar and 15–20°C). Compressed (actual) volume is the discharge volume at delivery pressure/temperature. Unqualified ratings in general practice imply FAD, not standard or compressed volume.
Step-by-Step Solution:
Verification / Alternative check:
Vendor datasheets typically label exceptions explicitly (SCFM/Nm³/h or “at discharge state”). Absence of such labels supports interpreting the figure as FAD.
Why Other Options Are Wrong:
Standard air requires a declared standard; compressed-state volume depends on discharge conditions; stating “at delivery pressure and temperature” would need exact values, which are not given.
Common Pitfalls:
Confusing FAD with SCFM/Nm³/h; comparing different bases without conversion; overlooking ambient altitude/temperature impacts on FAD.
Final Answer:
compresses 3 m³/min of free air (at local atmospheric conditions)
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