Definitions check: “Mean effective pressure” (MEP) for a compressor is the hypothetical constant pressure that, acting on the swept volume, would produce the same work per cycle; it is not a volumetric quantity.

Introduction / Context:
Terminology matters: volumetric performance and work indicators are different concepts in compressor engineering. Mean effective pressure (MEP) is a work proxy, not a flow definition.

Given Data / Assumptions:

• Compressor cycle on a p–v diagram.
• Swept (displacement) volume V_s and indicated work per cycle W_ind.

Concept / Approach:
MEP is defined so that W_ind = MEP * V_s. It allows comparison of different machines independent of size. Volumetric quantities like “actual volume delivered at standard conditions” are instead Free Air Delivery (FAD) or relate to volumetric efficiency—not MEP.

Step-by-Step Solution:

Verification / Alternative check:
Handbooks present MEP as a notional constant pressure creating the same area (work) under the indicator diagram over the stroke volume.

Why Other Options Are Wrong:

• Actual volume delivered at STP: This is FAD.
• Volume delivered or sucked: Raw volumetric measures; neither is a pressure nor work term.

Common Pitfalls:
Equating volumetric efficiency or FAD with MEP; they measure different aspects—flow vs. work.

Final Answer:
none of the above